Azores Central Islands Vegetation and Flora Field guide

Transcription

1 Quercetea 7: , 2005 ALFA, Lisboa. Portugal Azores Central Islands Vegetation and Flora Field guide Eduardo Dias, Cândida Mendes*, Cecilia Melo*, Dinis Pereira*, Rui Elias* INTRODUCTION LOCATION: Azores belongs to the biogeografic region of Macaronesia, in North Atlantic Ocean, at half distance from Europe and America. Their nine islands extend in a width of 615Km, between 36º 39 longitude N and 25º to 31 latitude W. Belonging to Portugal, they constitute, politically, an autonomous region. AREA: The total area is close to 2304 Km2, irregularly distributed by the nine islands: the three larger islands, S. Miguel, Pico and Terceira, include 69% of the total area of the archipelago. ELEVATION: from 0 to the 2351 meters of altitude. VEGETATION: A total of six major vegetation types have been recognized, in agreement with the altitude, each one with several types of communities. The total inventory of the vegetation is still incomplete and just about twenty communities were described. Among the most significant types, are the coastal communities, the humid areas (lagoons and salt grasslands, bogs, wet grasslands, streams and lagoons), forests (temperate Atlantic, subtropical, of clouds), Atlantic heathlands, grasslands and formations of recent lavas. The native vegetable communities' dominant species are, in majority, endemics. FLORA: The natural flora are constituted for about 300 vascular plants with 27% of endemics and about 1000 knowned tallophytes (mosses, lichens, etc.), with an endemicity percentage close of the 5%. However, for this last group, the total value is still ignored because the lack of studies. GEOGRAPHY Azores are an archipelago of nine volcanic origin islands and several islanders, located in Atlantic North Ocean. Biogeograficaly, belong to Macaronésia, designation of the medium-atlantic archipelagos of Azores, Madeira, Canaries and Cab Verde. Of this region, Azores are the northwest, the more distant more the mainland and, geological, the most recent. Important factor is its dispersion for a vast area of the ocean, 6 I 5 km of distance from Santa Maria to the Corvo. The first and the closest of the European continent, at 1400 Km from Lisbon is equality the oldest island, Sta. Maria. Corvo, on the other hand, is Departamento de Ciências Agrárias e Ambiente. Universidade dos Açores. Apartado Angra do Heroísmo. Portugal. eduardomfdias@clix.pt; 123

2 Dias, Eduardo et al. just 1600 Km from Newfoundland, in the American continent. The area and altitude of each one of the nine islands are very distinct. Corvo, being the smallest, with only 17 Km2, reaches 780 m of altitude, while São Miguel, the largest, with 746 Km2, has an altitude about 1103 m. The largest elevation is the Mountain of Pico Island, with 2351 m, an isolated volcanic cone of extraordinary dimensions. Although they re volcanic origin, Azores has a diversified orography caused by many volcanic forms and materials that modelled and still model the surface. The oldest areas, usually with a mantle of piroclastic materials, spreads from a large caldera volcano, present round forms with deep valleys and deep water lines in the high lands and alluvial deposits and coluvial in the low lands. The most recent areas, usually modelled by eruptions of basaltic lavas, show a topography drawn by the volcanic forms, from small cones to the extensive lavas flows. No doubts, that the dominant forms of the Azorean landscape are the large calderas, imposing volcanic structures that are in each island origin, in alignment along the main tectonic lines E-W. Most of the soils are of the type andossol, but the litossols occupy a significant surface. Some evolved soils -vertissols- has also been identified in the oldest deposits. The complete classification of the azorean soils and cartography are incompleted. The natural vegetation is, actually, restricted to the less fertile soils of organic type on lavas (histossols), fields of volcanic ashes (inceptissols) or of recent lavas streams. The azorean climate is strongly oceanic, with small temperature change, high precipitation and humidity values. The average annual temperature is about 17.5 C, being February the coldest month, with medium values of 13.8C of temperature, in the areas close to the coast. Frosts are rare below 600 m of altitude, but night frosts can happen above 1000 m. In opposite, precipitation has an important difference from E island to the W, from 710 mm/year to 1592 mm/year in Santa Cruz of the Flores Island. This effect controls the vegetation formations at low altitudes as it correspond the presence or absence of a summery time. At the altitude areas has little importance, since the values here are always high for the typology of these communities. More important is the air humidity with annual values close to 75-80% HR at the coast. The saturation values are reached in many days of the year, in the high lands. The climatic factor of major importance for the azorean natural communities is the wind. The dominant winds frequently reach high intensity; appear from the quadrant S-W, with high values of humidity. The wind, determine the structure and the forest communities'distribution. The natural landscape of Azores only met the man's transformation five centuries ago, when they were discover by the Portuguese caravels. According to the historic descriptions, these islands were, essentially, covered with dense forests. The first man changes, even before the land occupation, were the cattle introduction. In the first years, the colonization was centred in selected areas, always close to coast. The extensive forests were essentially explored in the begin for collects-wood, firewood, fruits. The several periods of economic richness of Azores, first pastry and urzela, after the wheat, then the orange and, finally, of milk, they show a crescent transformation of the natural landscape in agricultural areas, from the coast to inland. The historic events, the environment of each island (geology, relief, area, resources, etc.), the historical course and the value of the soils determine the transformation of the landscape and the human geography, acquiring specific patterns in each one. For instance, while in the largest island with better resources in soils-são Miguel-the initial distribution of properties, for noble people, took the 124

3 Azores Central Islands Vegetation and Flora concentration of richness and lead to a transform of almost all landscape; in the second largest island Pico - with poor soils, fields of recent lavas and the frequent volcanic activities, it has smaller agricultural occupation and a low population density, without important urban centres, being, still today, an island with vast natural spaces. In the magnificent Mountain of Pico is located the highest point of Azores. In its slopes, appears a group of volcanic and still active apparels, from which flowed vast fields of basaltic lava, some of historical eruptions. They constitute privileged places of vegetation and endemic species, as the Mistério da Prainha, in first plan. As general pattern, the distribution of the Azorean village can be seen as a ring around the island, fleeing from the sea rigidities and rude conditions of the altitude. Like this, the altitudinal zonation is explained in the actual landscape: after the coast, usually unoccupied, appear the agricultural lands of annual cultures (in past, the wheat) or mediterranean (as the vineyard), the one that is followed the villages, in a parallel coast line; depending on the relief, they are followed agricultural fields again or, more frequently, permanent pastures. In the hillsides North, always colder, is also possible find the temperate fruit trees here or, in alternative, in the poor soils, the production forests; the high areas of the mountain are left with their bushes and indigenous forests, as source of natural resources, in matter noble wood (as the cedar) and firewoods. The integration in U.E, leading to high production policies and the avaibilility of machineries and others production facilities, creates deep alterations in this model, appearing dissonant occupation forms with the local ecological resources. In the most typical pattern of the Azorean landscape, the populations extend in a ring around the island at some distances of the coast, as the most effective form of use of the soil, leaving the low lands, of better soils and hotter climate, for the annual cultures (in past, the wheat) and the ones of measured altitude, of wettest and windiest climate, for the permanent cultures (in rule, the pastures). The high lands and the mountains were left with the natural place settings, as source of resources (firewoods, wood, water, etc.). VEGETATION The total knowledge of the Azorean vegetation is still incomplete. The classic understandings of altitudinal zonation have been changed by recent studies that proved the exposed to the winds and the soil s humidity as the main factors for the communities'distribution. So, while the presence of the placic in altitude soils (horizon of deposition of oxides of iron and magnesium, that turn them impermeable) originates the existence of vast wet areas in the endorreic plateaus, the characteristic formation of seas of clouds, above 700 m of altitude, for the wet winds, allows the existence of subtropical forests (cloud forests). On the other hand, there s information that, before the human presence, the best soils would have imposing forests, with more than 20 meters height (attested by the bars of indigenous wood found). With the agricultural occupation of these soils, are only possible find today forests with little more than 10 meters height. The vegetation coastal presents three main types of communities: the vegetation of dunes, dominated by Spartina versicolor. The other two, more frequent, 125

4 Dias, Eduardo et al. are the vegetation of drained lavas and the one of cliffs. The first and extremely rich in endemic species, with a microzonation from the strip of small halophytes, as Spergularia azorica, close to the line of water, going by the halophytes of large size, as Azorina vidalii or Euphorbia azorica, to the dense bushes of Erica azorica. In the second type, the dominant specie depends of the cliff s geomorphology, but the Festuca petraeae and the Erica azorica are, for norm, important elements. The azorean forests belong to the macaronesian element, in its more Atlantic species and constitute relic elements of the Tertiary period in the European continent, of subtropical conditions, denominated by species alive fossils per-glaciers. While Lauraceae family possesses great importance in the formations of the other archipelagos, is, in Azores, substituted by more elements wet-temperate, as the Ilex, Vaccinium, Taxus and Juniperus species. However, the type of leaf laurifolia is still the dominant and most of these forests belong to the type Laurisilva. Recent studies could individualize four types of azorean forests. In the low lands, the mesic forest formations of Myrica faya-picconia azorica, are structurally, poor. The areas of productive soils and sheltered had a rich Laurisilva mesic which don't remain alive examples. The wet Laurisilva is the richest forest of Azores. It grows to stocking altitude and it can reach more than 10 meters height in the examples that remain. It possesses a large structural complexity; until seven different straits and great diversity of species, including rare endemics. The dominants are Laurus azorica, Vaccinium cyiidraceum, Frangula azorica and Erica azorica. These formations are already extremely rare, for the great search of their resources, meeting small stains in São Miguel, Terceira and Pico. The forest of clouds is a hyperhumid Laurisilva, dominated by Laurus azorica, llex perado ssp. azorica and Juniperus brevifolia, more than the five meters and, structurally, complex and dense, being taken almost impenetrable. Is difficult to define strata, because most of the individuals are epiphytes or they are born in trunks died above the soil, which is permanently soaked of water collected by the cup of the trees. Therefore, the mosses, that collect all of the available surfaces, take an important paper in the cycle of the nutrients, above the soil, and in the control of the water s cycle. Of this formation, important unaffected areas exist. The cedar forest is a mountain formation, tolerant to the stress of the water s permanent saturation in the soil. In its typical structure, is formed by a forest of Juniperus brevifolia and a moss carpet (Sphagnum sp.) in the soil. Is an endemic formation of Azores, with high mosses diversity The sub-alpine formations can only be found in the Mountain of Pico, in the Pico Island, above the l900 m. They are of bush scattered, dominated by Calluna vulgaris, Daboecia azorica and Erica azorica. Some species, in great extinction risk, are restricted of this community. The colonizer communities of lavas are, basically, formations of Erica azorica. The ecological effects of the insularity are very intense in the colonization process. Therefore, a group different from formations doesn't exist, but an aggregation of the local species with larger tolerance to the water s stress, with predominance of Erica azorica and Myrsine africana. The presence of a carpet of mosses is dependent of the local water balance. In good conditions, the succession process can be, surprisingly, fast and, in 400 years, to form a mature forest. Pico Island is particularly rich in these formations, for the youth of many of their lavas, but these can also be found in Faial and in Terceira. Three types of natural grasslands were recognized, in Azores: the coastal grasslands, of Festuca, Polypogon and Juncus; the mountain grasslands, very rich in endemic species, from their dominant ones-holcus rigidus, Festuca petraea, Deschampsia foliosa and Luzula purpureo-splendens-rare but spectacular and gigantic herbaceous, like Lactuca, Angelica, 126

5 Azores Central Islands Vegetation and Flora Rumex or Ranunculus; and the wet grasslands of margins of ponds or bogs, with some beautiful species as orchids, Myosotis and Alisma. These communities are, today, difficult to find for the pressures of marginal pasturing and the progress of forage species, initially sowed in the pastures. The wet areas (frequent in Azores) are a complex group of communities. However, its study and classification are not already made. Among the communities already recognized are evidenced, for its ecological importance: I-The bogs, with important areas in Terceira and Flores islands, are classified habitats, of great importance in the conservation of the water resources. Is interesting to verify the singularity of these formations in these latitudes, they are geographically isolated, for with typical elements just of the boreal areas; II-The helophytes bushes, with important endemic species, as the Plathantera micrantha or Daboecia azorica. Just as the wet grasslands, also these suffer strong pressures of the pasturing, being in extinction risk; III-The lagoons, a lot of times azorean symbols, are oligotrophics endemics communities of Isoetes azorica habitat. Its total natural patrimony, in matter the microscopic communities, is almost unknown and, in many cases, they could be extinct for the recent eutrophization of some of them or for other pressures that it has been taking, besides, to its total disappearance. The azorean hyper humid Laurisilva grows only in altitude, in conditions of saturation of atmospheric humidity and of the soil, because it lives in a permanent sea of clouds. Although the trees dominant are almost the same of the other laurisilvas, they constitute the strict habitat of many other species, as the rare heyiphils (epiphytes on leaves). Its role in the collects is important in the water resources of these islands. However, its demand for sheltered places has been taking to the disappearance of extensive areas in the azorean mountains. FLORA Since the first botanical explorations of Azores, beginning sec. XIX centaury, it has been recognized, for indigenous flora of Azores, about 300 vascular plants. Its actual flora contains 1007 plants being, for that, the increment of 707 done by plants introduced by man, most in the last fifty years. The largest biological diversities are reached in the endemic forests of Laurisilva mesic. Its structural diversity, with more than seven strata, high covering of epiphytes, climbing plants and ferns give an appearance of sub-tropical forest. Associate to this elevated structural diversity there are numerous habitats of rare or in extinction danger animal and vegetable species. The areas that remain of these formations are extremely small and they are, usually, in private properties. The species classified as endemics has been suffering important revisions, by two reasons: taxonomy and better knowledge of other areas. Curiously, its total numbers have been maintaining stable around the 70 plants (tax of endemicity of 23%). A numbers of the indigenous plants of Azores are common with the archipelago of the Madeira, being able to consider as a natural nursery of Azores. Typically, Azores has few species for family, which is an indicator of a drop species tax: 8l families exist for the 300 vascular plants. Of the 41, that possess endemic plants, 17 are just represented by one species and 80% don't have more than two species. 127

6 Dias, Eduardo et al. The high insularity degree and the suave ecological conditions can be the main causes of this spectrum. There exists just one endemic genus-azorina-with a single species. Most of the endemic species is alive fossils, philogeneticaly primitive, related with the dominant families in the Tertiary European flora, partially extinguished during the glaciations. The delicate flowers of the endemic plants suffer peculiar adaptations to the insular land, as it is the loss of strong colours, the decrease of the size or the attraction of polinizer and more generalistic insects, as in the flower of Tolpis azorica. Here also the own fruits lost the dispersion capacity the long distances, typical of this type of plants, as form of assuring that the wind doesn't take them outside of the island. The ferns are an interesting group of the Azorean flora, witch deserves reference. It exist about 80 different ferns, but only 53 can be considered indigenous. Some, relics of the Tertiary, are very rare species in the European continent, but they can be easily found in Azores, like Trichomanes and Hymenophylum. Strong elements in this group are the paleotropical tendencies with, for instance, the family Lycopodisceae. Acording with the last revision, 156 of the 300 plants natives can be considered rare and, of these, an important numbers has not been found in the last years. Therefore, the number of species in extinction danger is very high and superior to 60, including important endemics as Myosotis, Ammi, Chaerophyllum, Lactuca, Pericallis, Lotus or Euphrasia. The bryoflora (mosses and liverworts) is rich, comparatively with the vascular flora. There are classified about 450 species, with a tax of endemicity of 5%, but new species are added all the years. In this group is present a large fitogeographic spectrum: strictly boreal species, as the group of Sphagnum, they appear with other typically tropical; they are some curious species of bipolar distribution equally (just in small points of Northern and South Hemisphere). In the most hidden parts of the azorean mountains is still possible to find areas no disturbed by the man. There, some communities live in its purer form. Only in those conditions, some communities seem to survive, as the wet grasslands (in first plan that has just been found in the gapes between the natural forests and the oligotrophic lagoons. THREATS The largest threats to the azorean vegetal patrimony can be synthesized as: 1 - Historic aggressions. In the past, some exploration forms took some species, to a reduced number of individuals. This number can be below the natural capacity of the species in surviving. In these cases, direct conservation actions, for manipulation of seeds, become necessary. 2 - The recent development of these islands, accentuated by the arrival of pressures and economic supports of the European Community, motivated the occupation of poor soils areas, with natural vegetation until then. In the last twenty years, the areas of natural vegetation were reduced in 50%, mainly for pastures. 128

7 Azores Central Islands Vegetation and Flora 3 - The adaptation to actual production has been causing strong damages in the natural remain s communities. With the construction of roads and the needs of water, highways have torn many natural stains and most of the ponds and lakes meet in danger by the direct extraction of water, even some are already missing. For the same process, it has been verifying the bogs drying. 4. The coastal vegetation is threatened by the construction of summer vacation houses or tourist and for the associated social structures. The interest for the traditions, a lot of times with commercial ends, it came to accentuate the value and the search of many species accelerating its extinction danger. Recently, that search relapsed on the (Juniperus brevifolia), what has been taking to the illegal discount of hundreds of trees of this species, putting in risk not only some of their populations and varieties, as well as natural communities where is the dominant species. 5. One of the important causes of the disappearance of species, in the last years, is related with the invasion of exotic species, introduced in Azores and turned aggressive. Pittosporum undulatum in the low lands, Carpobrotus edulis in the coastal vegetation and Hedychium gardnerianum in the wet areas, it has been conquering wide areas. A group of more than 10 exotic species can be considered as aggressive invaders for the natural vegetation. 6. Equally, some introduced animals put in serious danger some species or cause significant alterations in communities. For instance, the rabbit is pressing in serious danger some endemic herbaceous and cause disturbances in the effective forest trees. 7. The direct exploration of species or resources, from the natural areas, as the cut of trees-as the, Juniperus brevifolia-or collecting the peat in São Miguel (called, leiva) for the pineapples production cause irreversible alterations. 8. Genetic contamination, for introduction of species or similar varieties, inter-islands, from or out of the archipelago. 9. Diseases and curses introduced by the ungovernable importation of great amounts of alive materials (e.g. decorative plants, fruit bowls, seeds, green forages, etc.). The most dramatic destruction of the forests is its mechanical discount for substitution for other, usually pasture, This conduct has been transforming important areas in the last years, doesn't allow any proctetion of the natural biodiversity. However, and because the natural areas, that still subsist, are always in poor lands, the obtained incomes of these transformations are very reduced. 129

8 Dias, Eduardo et al. MAIN VEGETATION TYPES AND ECOLOGY INTRODUCTION There are still in Azores significant areas with total degree of purity as the Mountain of Pico (Pico island), Sta. Bárbara (Terceira island), Morro Alto (Flores islands) among other places, housing almost the totality of Azorean ecosystems in it s original state. Azorean vascular includes 1007 species, including 300 indigenous species and 70 endemic from Azores and Macaronesia. About 50% of natural species are in extinction danger. It also exists in Azores 275 species of mosses and 175 liverworts. The vegetation of the Azores is for a significant part determined by the Atlantic climate. Because the Azores are part of the Atlantic climate system (mild winters and relatively cool summers with heavy rains scattered throughout the year), the vegetation has a constant supply of water. The Azorean flora is not only characterised by the usual Atlantic plant species, but also by Mediterranean, tropical and a wide range of cosmopolitan species. Many plant species occurring on the islands are exotic and were introduced by the early colonisers as food resources. They thrive well in the warm and humid climate and were able to spread quickly in the absence of their natural enemies. The ginger plant (Hedychium gardenerarum) that originates from the Himalayas out-competes many endemic species plants in their natural habitat and has become a significant threat to the survival of many of them. The Hydrangea macrophylla was introduced 150 years ago and since cattle do not graze it, it was used as a natural border in pastures. The natural vegetation above 700 m is a dense humid laurel-juniper shrub-forest. The islands of Pico, Faial and Terceira have the largest remnants of these unique native forests. COASTAL VEGETATION The coastal area constitutes the strip from the area of the tides up to where, for different means, it became preponderant, the permanent deposition of sea salts in terrestrial communities. Coastal vegetation includes sharp hillsides, lava flow fields and sand dunes. The landscape space occupied with this vegetation is very narrow. These biotopes, due to their geographical position and ecological fragility have been suffering an extensive alteration of their original communities in result of the human action. The occupation of these soils is due to the richness of these formations, but mainly for the climatic conditions: these are the only places with Mediterranean tendencies. 130

9 Azores Central Islands Vegetation and Flora VEGETATION OF ROCKY COAST This community extends on whole Azorean coast, with the exception of small places, for geomorphologic reasons (sands and tuffs - geological formations usually of origin in underwater eruptions, the case of the islanders) or human disturbance (garbage/trash deposits, constructions etc.). Actually, the most common form of Azorean coast is lava exposed to sea abrasion. As global characteristics, we can consider these settlements always of low covering (up to 50%, but usually below the 30%), formed for Spergularia azorica, Euphorbia azorica, Corema album ssp. azorica, Juncus acutus, Festuca petraea, Asplenium marinum and Crithmum maritimum. The width of these communities'floristic diversity is big, appearing from very poor formations and always of low density in areas of strong hydrodynamic and compact lavas, to rich formations and of considerable structural diversity (bushes, big and small herbaceous and micro chamaephyte). HALOPHYTIC GRASSLAND These are endemic formations of Azores but nowadays very rare, due to the fact that the habitat develops at favourable places to traditional agriculture. An intense agricultural occupation delegated us small stains of these formations in inaccessible or marginal situations, for that, its distribution, structures and floristic composition, as well as its extension earth-inside and interaction forms with other communities, will always be unknown. Under this classification are rocky coastal formations, occupied by dense herbaceous in a relatively rich soil substrata, with frequent disturbances, that impede the development of arborescent communities. More frequent species are Polypogon maritimus, Gaudinia spp., Sonchus tenerrimus, Chrithmum maritimum, Briza maxima, Festuca petreae, Daucus carota ssp. azoricus and Lotus creticus. COASTAL SHRUBLANDS The coastal shrubs appear as the last covered areas in the coast zonation and, sometimes include the transition for interior formations. 3 different communities of coastal shrublands were described: Erica shrublands, Faya tree shrublands and mixed shrublands. Erica shrublands: communities constituted almost totally (or totally) by Erica azorica with medium to high density. These bushes forms floristic poor communities, with 1,5 m of maximum height, mono stratified, with all of the individuals of the same size in places exposed to the sea winds. Faya tree shrublands: dominated by Myrica faya and is characterized by floristic and structural poor communities, also mono stratified, in atmospheres with a certain shelter degree, in poor substrata (recent lava) and with summer hydrologic stress. In suave environmental conditions this Faya tree shrubs can grow to larger complexity and floristic richness. 131

10 Dias, Eduardo et al. Mixed shrublands: In peculiar conditions, of accentuated topography (recent lavas of aa type), probably with watery line at low depth, it may occur complex communities in a mosaic distribution. In the highest parts of the lava, dense shrubs of Erica azorica, Myrica faya, Juniperus brevifolia and eventually Myrsine africana, appears (as well as Pittosporum undulatum); in the lowest parts of lava is dominated by bushes of Corema album, Silene vulgaris spp. marine and Chritmum maritinum, with herbaceous elements of Festuca petraea, Carex hochstetteriana, Daucus carota ssp. azorica, among others. These very particular formations are of great interest, but very rare and in extinction danger. DUNES VEGETATION The Azorean coasts have a weak capacity for the development of natural sand beaches and still less for the formation of dunes. Most of the places with sand beaches are restricted to small re-entrance of the coast. The "wide" extensions of sand dunes as in the bay at Praia da Vitória (in Terceira island) are extremely rare in Azores. The Dune vegetation includes: (1) The beach, understood by the strip of sand immediately above the tides line to the beginning the dune front. The area that suffers the direct effect of the tides doesn t possess terrestrial vegetable settlements. The superior part of the beach possesses very scattered settlements of Salsola kali; (2) dune, where the recent uses of this area (beach used areas, port construction, etc.) provoked the disappearance of the characteristic continuity of the dune system. Other pressures, by chance older (pasture and exotic plant introduction, for example Cynodon dactylon), destroyed great part of these dune communities. These formations are dominated by Arundo donax, Salsola kali, Lotus creticus and Tamarix gallica. WETLAND COAST VEGETATION These are very restricted systems in Azores. They are under intensive human pressure because of its location in places with great potential for urban structures constructions. Most of these biotopes are associated to dune systems, as it is the case of the bay of the Praia da Vitória. They are dominated by Juncus spp. and other species as Solidago sempervirens and Scirpus maritimus. Several Wetland Coast Vegetation identified in Azores: Halophytic formations of Juncus in oozy soils: Although not belonging properly to the dune systems, these communities appear frequently associated to them. In Azores, these formations occur in dune depressions where fine alluvium deposits were accumulated above the sand. The only found place, up to now, of this biotope was in a humid dune area of Riviera (Terceira island). It s possible to distinguish the sequence of hygrophytes settlements, halophytes, xeric halophytes, and interstitial (out of the profile, beach). In terms of floristic, in these formation develops species like Danthonia decumbens, Cyperus longus, Scirpus maritimus, Spartina versicolor and Atriplex spp., among others. 132

11 Azores Central Islands Vegetation and Flora Halophytic formations of Juncus in loamy soils: Whenever these rare communities were identified, similar ecological conditions were found: irregular deposits of sands above a superficial mantle of basaltic lavas, at the tide level, but protected by higher lava shrubs formations that allows the passage of salt water at punctual conditions: high tides or storms; this system has also a fresh water supply, usually due torrential regime riversides or fresh water nascent. With halophytic characteristics, much more marked than previous Juncus communitie, and, for that, is a low-density biotope. In more expressive forms (Lages do Pico) has a high vegetal formation dominated by Juncus maritimus, Solidago sempervirens, Apium nodiflorum and Carex spp., among others. Humid grassland (in coastal lagoons): The vegetation here considered constitutes the remaining communities'of the original structure of the Paúl of Praia da Vitória. Humid grassland occurs in the lowest areas of Paúl, in lands permanently soaked and submits to immersion during a part of the year. The communication with the sea is, still maintained through tubes, allowing a periodic flow of salt water, unloaded, in the high tide, directly to the nucleus of the Paúl. On the other hand, fresh water coming from water hillsides draining and from the raise of the hydrologic level in the winter also enters the system. The Soaked Grasslands, here considered, are locating in permanently soaked area. The dominant species are herbaceous, in a grassland structure. The most frequent species are Paspalum distichum, Alisma lanceolata, Apium nodiflorum and Lythrum hyssopifolium. Coastal lagoons of Salty Waters: Of the old lagoon salty waters of Paúl da Praia (and where it was fished eels and sardines), it just remains a small permanent puddle and the ditches through where is done waters flows and re-flows. These correspond to areas with high quantity of deposits and with draining waters. The superior stratum of vegetation is always emerged (Scirpus maritimus, Juncus acutus ssp. multibracteatus) and the inferior, frequently immersed (Paspalum distichum, Polypogon monspeliensis, Ruppia sp.). Other example of these coastal lagoons can be seen in S. Jorge Island. NATURAL GRASSLANDS Grasslands are natural communities, not implanted nor maintained artificially, they are not used for domestic cattle pasturing and are dominated, by spontaneous or even endemic species of Azores. Coast grassland (described at coast vegetation) Wet hillside grassland (described at wetland vegetation) Holcus grassland, this grassland community constitutes Azorean endemic formations. The dominant species is Holcus rigidus, with a clear adaptation to slope deposits conditions. Typically, these communities grow in the base of big mountains, being limited to the strip of slope deposits. These formations are rare, and only recognized in a reduced number of places. Its typical form was found in the base of slopes, as in Rocha of Juncal (Terceira), Caldeira of Faial (Faial) or Caldeira of Stª Bárbara (Terceira). In this last one, forms vast grassland in the base of the valley that surrounds the mountain almost completely. This grassland type contains rich mosaics especially in wet organic matter sediments, where Mentha aquatica, Tolpis azorica, Sphagnum palustre, Eleocharis multicaulis, Juncus 133

12 Dias, Eduardo et al. effuses dominate, and stony mosaics of certain drainage, where grows Agrostis gracililaxa, Pteridium aquilinum, Poa trivialis, Erica azorica, Blechnum spicant and Holcus lanatus. We enhance the presence of some rare endemic species like Rumex azoricus, Lactuca watsoniana, Pericallis malvifolia and Leontodon rigens. Festuca grassland is, probably, the most European element of Azorean grassland. These grasslands are well known throw whole Europe, from the sub Mediterranean alpine to the Siberian areas. In Azores, only two species represents these rich genera in Europe - with, at least, 170 species. The two species of Festuca genera in Azores are endemic, and although, ecologically, very different in their habitat (Festuca petraea, coastal; Festuca jubata, from mountain), and rarely in contacted (with the exception Flores and Corvo islands, in the ravines with more than 700 m, that connects coast and mountain), they can be considered physiographic similar. The halophytic grassland, with windy/marine erosion/deposition of the soil, where Festuca petraea develops forming regular cushions and promotes soil fixation. By other hand mountain grasslands, with windy/hydrologic erosion/deposition of soil, where Festuca jubata also forms similar regular cushions, with obvious soil fixation functions. Associated to Festuca jubata (mountain grassland) tuffs of are, low herbaceous species as Poa trivialis, Lysimachia azorica, Centaurium scilloides, Potentilla sp., Selaginella kraussiana and Holcus lanatus; in the spaces among tuffs, corresponding to water flowing lines are implanted Juncus effusus, Eleocharis spp. Sphagnum spp. Deschampsia grassland is, certainly, a vegetable formation of great ecological interest in Azores. Its distribution, although very restricted, it is coherent with specific ecological conditions. This habitat on the highest mountain above ecological limit of the trees. It is easy to notice that, in these extreme climate conditions (especially strong winds and cold temperatures), few other species can accompany Deschampsia foliosa. The one that do, use the cushions of Deschampsia foliosa as shelter, as several bryophytes, and other like Selaginella kraussiana, Centaurium scilloides, Holcus rigidus and Potentilla spp. WETLANDS These areas possess in Azores a great ecological importance and dimension. These habitats correspond to areas whose soils, at least periodically, are soaked or emerged by water, for enough time to cause effects in the local communities'composition. Standing Water Wetland: We include in this group big lakes, with are mostly caldera lakes of oligotrophic nature, as well as the small ponds, permanent puddles of different trophy status and the complex group of water lines. Large Oligotrophic Lake: these lakes, although being predominant elements of the Azorean landscape (S. Miguel and Flores island), the most explored natural resource by tourism and an extremely important agglomerate of natural patrimony, they are, very superficially known in their ecology and their vegetation was never described in full detail, except in some punctual examples. These lakes have big volumes of water, usually deep (for example Lagoa da Caldeira Negra, in Flores island has 108 m of depth) and, 134

13 Azores Central Islands Vegetation and Flora then, with probable stratum in their waters. Small Oligotrophic Lagoon: These small lagoons are in great number in Azores. It s frequent to see these standing water formations suffering human provoked unbalances (infilling, eutrophyzation and disappearance for rupture of the impermeable layer), another show infilling signs or even disappearance for natural reasons. The young lagoons possess, in the general, a low covering degree and a low floristic diversity. Communities of Littorella uniflora and / or Isoetes azorica dominate the deeper zones, while less deeper parts has compact formations of Littorella uniflora, Eleocharis palustris and Callitriche stagnalis, at the margin Juncus spp. and Eleocharis spp. dominant. Developed lagoons and puddles possess a larger floristic diversity, frequently associated to peat formation (unlike the youths). Littorella uniflora loses it s importance giving up place to the Eleocharis palustris and Callitriche stagnalis or Isoetes azorica. The submerged margin area possesses a community dominated by Cyperus alternifolius, Cyperus longus, Juncus articulatus and Eleocharis multicaulis. In certain lagoons, carpets of Sphagnum spp. not possessing the described settlements dominate the adjacent sub-coast area, but it is already a peatbog that prolongs the hydrological basin of the lagoon. This complex group is today strongly altered by the human intervention, due to exploration of water, alteration of hillsides basin of the standing water formation, pollution and vegetation cover alteration. Stream (ribeiras): The streams, in Azores generally flow the sea. This happens due to the geomorphology of the islands, formed by mountains of hillsides. For obvious reasons, these water lines suffered, since very early, strong interventions of the Man: they were the first source of energy (together with the winds) and of drinking water. But they were, also, the easiest garbage conducts, the easiest roads for trunks transport and the easiest source of water for the domestic animals. Therefore, since the beginning of the colonization, these habitats were, progressively, altered, in their communities'constitution, and in their hydrology. There are 3 types of streams: (1) Permanent creeks corresponding to mountain streams, associated to natural communities this are hydrologic regulators and, for that, with permanent flows, although with some seasonal variation. In this mountain habitat, usually on a solid rocky bed, it settles a peculiar community of bryophytes, in a continuous carpet, formed by species of helophytic and hydrophytes nature (Heterocladium heteropterum, Jubula hutchinsiae, Fissidens rivularis, Rhynchostegium riparioides and Schistidium rivulare) strongly fixed to the substratum. (2) Permanent streams with the development of natural communities witch are extremely rare, nowadays, in the global of Azores. These were identified to Sta Maria, S. Jorge and S. Miguel islands. Some species have always been found associated to these streams and, for that, can be used as indicative: Equisetum telmateia, Nasturtium officinalis and Apium nodiflorum. (3) Temporary streams are without natural vegetation in their great majority. Peatlands: The vegetation of peatlands areas develops at permanent or periodically flooded places; 135

14 Dias, Eduardo et al. these types of communities are dependent of this water, and origins peat formation. Peatlands are frequent in high altitude mountain areas, without or with little human disturbance, where, several types of wetland communities may occur in an inter-dependent way. The development of this natural vegetation is related with the high precipitation indexes and the formation of placic, an impermeable iron soil horizon, or the existence of compact rocks on the surface. Minerotrophic peatlands: The status of nutritious existent in the water that feeds the peatland is significantly higher than the existent in the water of the rain; this is due essentially to the external supply of nutrients, coming for lateral transfers of water or emergencies of water from depth. In here we include dystrophic pools and temporary pools. Dystrophic pools occur in peatlands with rich and acid water, and are florist poor. The temporary pools are extemporary and their vegetation is dominated by Littorella uniflora, Callitriche stagnalis and Isoetes azorica. Wet High Grasslands, dominated by Juncus effusus, Rumex conglomeratus, Eleocharis multicaulis and Dryopteris azorica or Osmunda regalis, in permanently soaked environmental. Wet hillside Grassland are located in a smooth hillside above an impermeable subtract with Hydrocotyle vulgaris, Lysimachia azorica, Galium palustre and Sphagnum spp. Grassland in water nascent witch is extremely rich in floristic terms. Basin Sphagnum peatbog are small current peatland that has result from the infilling of a puddle or pond in an endorreic basin. This peatbog is homogeny, with the water level maintained above or at the surface, what has as consequence a very constant and poor floristic cover, totally dominating by Sphagnum spp., with presence of few other species as Eleocharis multicaulis. In the margins, due to nutrients that are dragged throw the hillsides; dominate hummock communities of Polytrivhum commune, Calluna vulgaris, among others. Transition Sphagnum peatbog, are similar to basin formation but this develops in large basin areas. This is the most common type of Azorean Sphagnum communities. In these transition peatbogs the micro relief is more evident and dispersed throw the entire peatbog surface. The accentuated structure of hummock and hollow allows actives mineralization in hummocks and promote the progress of numerous other species. The hummocks show several vascular species: Polytrichum commune, Calluna vulgaris Potentilla sp., Lysimachia azorica, Blechnum spicant, Lotus uliginosus, Agrostis gracililaxa, Deschampsia foliosa, Luzula purpureo-splendens, Holcus lanatus and several bryophyte species. In the hollows, appear Eleocharis multicaulis and Hydrocotyle vulgaris, besides several Sphagnum species. Hillside forested peatland are, probably, the most atypical situation and the more characteristic of Azorean peatland. It s an endemic formation of this archipelago. The habitat is formed by two different communities: (1) a continuous carpet of Sphagnum spp.; (2) tree cover, where, depending on the 136

15 Azores Central Islands Vegetation and Flora exposition, it dominates the Laurus azorica, Vaccinium cylindraceum, Ilex perado ssp. azorica or Erica azorica. Ombrotrophic peatlands: Here the status of nutritious available in the water that feeds the peatland depends, primarily of the rainwater, the ph is low. Although could exist other species, the best adapted to these conditions are the genera Sphagnum spp. In this group we include all peatland types, whose involving area topography makes them dependent of rainwater. Blanked Sphagnum peatland characterized for covering vast areas in mountain picks and in high plateaus, extending, per times, for the adjacent hillsides, in areas with high levels of rain and a impermeable subtract. This blanket peat formation is geomorphologically different from other sphagnum peatbogs but is not possible to find any floristic differences. Juniperus forested peatland is one of the most interesting habitat in Azores. The great singularity of this formation is due; to have as dominant arborescent species the endemic Juniperus brevifolia, and this genus is little known as representative of these formations. Juniperus forested peatland occurs is very wind exposed a place, that s why few other species occur in this extreme clime situation, where rarely, individuals of Ilex perado ssp. azorica and Vaccinium cylindraceum emerge. In the high herbaceous level, Culcita macrocarpa and Dryopteris spp. can be present, although as little developed individuals, as well as Juncus effusus. Raised bogs are theoretically the most evolved peatbog formations, to witch, in Azores, all bogs formations will tend. Nowadays these are rare type of Sphagnum dominate community given the extreme conditions their evolution needs to reach this state. Raised bogs are very sensitive to external disturbances. These bogs have a higher ombrotrophic plateau, floristic poor, and lateral margins, in a lower level, which might have some subsidiary sources of nutrients from external waters (beside rain), and so richer in species. NATURAL FOREST VEGETATION The Azores Natural Forest find theme self s in a diffuse ecological position with a strict relation with the other types of Azorean vegetation. Recent studies contradict the opinion of some scientist that visited the Azores islands in the last century, which defended the non-existence of forest formations in this archipelago. The historical descriptions show that different forest types covered most part of the island s territory. Nowadays most of this formations, especially in low altitudes, were destroyed, but we still can distinguish several types of forests with different ecological tendencies; paleomediterranean, macaronesian, subtropical mountain and north-atlantic forests, that correspond to unique sintaxas with there own structure and dynamic process. 137

16 Dias, Eduardo et al. Fayal Forest s These formations are very rare nowadays and we can consider theme almost extinct. Their natural areas are now occupied by vine culture or introduce vegetation, predominantly Pittosporum woods. They develop in incipient recent coastal lava soils, rich in potassium, with moderate climate conditions (low wind exposure, meso-mediterranean precipitation values, medium temperatures). The structure and floristic composition is very simple, dominated by Myrica faya and Picconia azorica. Some endemics are associated with the herbaceous layer like Carex hochstetteriana and Polypodium azoricum. Laurifolia Forest s These formations are dominated by laureal species and they develop in moderate climate conditions especially due to wind exposure. They can be divided in three subformations: Laurifolia Mesic Forest s are constitute by a high floristic diversity, being the natural forest stand with higher number of codominant tree species (Laurus azorica, Frangula azorica, Picconia azorica e Myrica faya). The herbaceous layer is dominat by the pteridophytes Diplasium caudatum, Dryopteris azorica, Dryopteris crispifolia. It s also present some rare herbaceous species like Bellis azorica and Platanthera micrantha or P. azorica. The environmental conditions are characterized by low wind exposition, high precipitation, low atmospheric humidity with no water soil saturation. Nowadays this type of forest is very rare, being the invasion of introduce species and pasture occupation the principal factors of disappearance. Laurifolia Humid Forest s - with a high floristic and structural richness, this forests is dominated by Laurus azorica, Ilex perado spp. azorica, Erica azorica and Frangula azorica. The herbaceous layer is formed especially by pteridophytes showing an unusual diversity of fern species (Culcita macrocarpa, Dryopteris azorica, Dryopteris affinis, Pteris incompleta and Diplazium caudatum). The environmental conditions are characterized by low wind exposition, high precipitation, high atmospheric humidity with water soil saturation in some periods of the year. Nowadays this type of forest is also very rare. Laurifolia Hiper-Humid Forest s - in present times this is the most common laurel forest, because it s the type that develops in higher altitude, where human impacts are less significant. It differs from the other laurel forests in the composition of the dominant species. Erica azorica disappears and gives place to Vaccinium cylindraceum, but the other dominant species maintain the same. The herbaceous layer is formed by Dryopteris azorica, Culcita macrocarpa and it appears frequently Trichomanes speciosum. It shows a less vertical structure complexity, but in stead it has a larger horizontal structure complexity, with the formation of hummocks/hollows. The hollows are formed by running water, creating a zone with 138

17 Azores Central Islands Vegetation and Flora permanent water soil saturation, resulting in poor habitat for plants germination. Most of the seedlings establish in the hummocks zones where they find more suitable conditions for growing. The environmental conditions are characterized by humid wind exposition and high precipitation. Ilex Forest s also called cloud forests are adapted to extreme conditions of atmospheric humidity and permanent cloud cover. They develop in acid lavas, between altitudes of 700 and 900 m, normally north exposed. The environmental conditions are characterized by an extreme wetness, high precipitation and occult precipitation, low wind exposure and high hill shade. The ground cover is formed by forest peat, resulting from low leafed mineralization in result of the permanent water soil saturation. In face of these specific conditions this forest s only exist in some islands, where they are very rare. This forest formation was a complex interior structure, dominated by horizontal mosaic of hummocks/hollows and the dynamics process area very related with the hollows wetness and the concentration of biological activity in the hummock. Ilex forests show a high floristic diversity. The emergent canopy is dominated by Ilex perado spp. azorica and the canopy shows highs cover percentage of Juniperus brevifolia and Vaccinium cylindraceum. The herbaceous layer is dominated by the pteridophytes Culcita macrocarpa and Dryopteris aemula It s also common the presence of Trichomanes speciosum carpets. The epiphytic layer is well developed and most of the trees are covered by epiphytic species like Hymenophyllum tunbrigense and Elaphoglossum semicylindraceum. Juniperus Forest s develops in extreme conditions of wetness and wind exposition. They are typical formations of expose mountaintops. This type of formations can be dividing in two types: Juniperus woodland is formed by a continuous and homogeneous layer of Juniperus brevifolia, that creates shadowed underwood habitat and stops the development of Sphagnum spp. peatland., allowing only the grow of understory shadow adapted species. The epiphytic bryocommunity it s very characteristic from this forest formation, and it forms a bryophitic sleeve over the J. brevifolia branches. Juniperus Wodland with Peat bog it s a transition community between Juniperus Woodland and Juniperus Forested Peat Bog. It distinguishes from the anterior formation from having a sparse canopy of J. brevifolia permitting the development of Sphagnum spp. peat bog carpet. Erica Forest s are adapted to severe conditions of wind exposition and low soil hydrological availability. This community is very poor in species. It has a woodland structure, formed by a homogeneous canopy of Erica azorica. The understory scrub vegetation is sparse mainly composed by Laurus azorica and Myrsine africana. In the herbaceous layer its relevant the presence of Pteridium aquilinum and Dryopteris azorica. The herbaceous-bryophyte layer is well developed and dominated by Thuidium tamariscinum. 139

18 Dias, Eduardo et al. SHRUBLANDS Vegetable formations, dominated by chamaephyte or microphanerophyte, mono stratify, dense or scattered, with possible presence of trees emerging, in a casual or scattered way. The shrubs can be low, when dominant species are true chamaephyte (as Calluna vulgaris, Daboecia azorica and Thymus caespititius); or arborescent, when the dominant species are microphanerophyte (Hypericum foliosum) or mesophanerophyte of restricted size (Juniperus brevifolia, Erica azorica, Laurus azorica and Myrica faya). In Azores there are several of shrubland habitats types, following described. Local stress shrubland habitats Observed circumstances show that the evolutionary potentiality of shrubs formations is annulled by a permanent or periodic external factor that transforms the bush dominated habitat in the local potential formation or opens possibility for an extremely slow temporary evolution. In this case, are, for instance, the coasts formations on high to medium slope hillsides, typically covered by a almost pure bush formation of Erica azorica witch density and height depends of salty winds intensity. These formations should be considered as mature, for the semi-permanent winds action, and for the age and demography that some possess along the Azorean coasts. Coastal shrublands: Erica shrublands (described in coast vegetation) Faya tree shrublands (described in coast vegetation) Mixed shrublands (described in coast vegetation) Alluvium shrublands: Appear in the base of hills or scarps, on fine slope deposits, corresponding to places with some disturbance. This habitat possesses some ecological similarity with described Holcus Grassland, with which, per times, it forms mosaics, but in this case it constitutes a less disturbed situation. Alluviums shrublands are open communities with reduce structuring. Two cases were inventoried: Erica mixed shrublands occurs on acid gravel slope deposits, and is dominated by Erica azorica and Juniperus brevifolia, it s a open vegetal community, with scattered grassland mosaics. In this grassland species like Holcus rigidus, Festuca petraea, Tolpis azorica, Huperzia selago ssp. selago and Lycopodium cernuum develops. Euphorbia shrublands Euphorbia stygiana ecology of, an Azorean endemic, is still very badly known. Their settlements are very small and dispersed for several habitats. However, this formation occurs with some regularity in slopes or deposits of mountain slopes, giving the indication that prefers habitats with some disturbance. Mountain shrublands 140

19 Azores Central Islands Vegetation and Flora This formation develops on mountain picks, very exposed to the wet winds, on pomitic impermeable substratum. This habitat distribution area is restricted, because nor all mountainous have such high wetnwss. These bushes make the transition space between soaked shrublands, Juniperus Forests and Deschampsia Grassland. Pedologic Mature shrubland These shrublands were found in circumstances where, for predominantly soil limitations, the vegetable community limited in its structural complexity, forming low shrublands in response to these limitations. Their presence is due to local conditions, wetness in inhospitable geological substratum that will need several thousands of years to allow a more complex colonization. Mountain arborescent shrubland appears in sheltered mountainous hillsides, but with great entrance of water, of hillside drainage or fog water interception. In it s structure possesses an irregular Sphagnum carpet spp. under a community of Laurus azorica, Ilex perado ssp. azorica, Vaccinium cylindraceum; in the most exposed places, the vegetation is more open, prevailing the Juniperus brevifolia and Calluna vulgaris, in more rocky subtract Erica azorica may dominate. Calluna wet shrubland: this community constitutes the mature form of Calluna vulgaris shrubland (Callunetum, heathlands) in Azores. Lajido shrubland The term lajido is used at Pico Island to designate flat basaltic compact lava surface where the penetration of the roots is impossible, as well as water and deposit surface retention. Their surface is almost nude of vegetation, especially is more exposed parts. The only species installed are growing in lava fissures being, for that, a scattered and little developed community. Species like Erica azorica, Myrsine africana, Laurus azorica, Calluna vulgaris, Daboecia azorica, Thymus caespititius may occur. Volcanic sand shrubland The presence of bushes in this substratum is quite rare, in Azores. This substratum is of easy colonization, reason why is almost all occupied with cultures or with degraded by intense exotic cover. There are 3 volcanic sand shrubland found, in Azores: Graciosa, (Pico Timão); Pico (sand mountain formation); and Faial (Cabeço do Fogo). Predominant species are Thymus caespititius, Daboecia azorica, Racomitrium lanuginosum, Platanthera micrantha and Centaurium scilloides; in costal volcanic sands Corema album is identified. Successional Scrubs These groups of formations correspond to primary and secondary succession scrubs. The pioneer scrubs developed in recent lava flows. The colonization velocity and the typology of these communities show a great variability. The colonization processes varies not only with the age, but also with the type of subtract material, structure and morphology, the local bioclimatic conditions and from island to island. There are no specific colonization communities, the floristic composition is very similar with the climaxes communities, and however they have important structural differences. This effect is possibly related with 141

20 Dias, Eduardo et al. the insular effects, in particular floristic poverty of the islands. The zoom effects seem to act as one import succession process. 142

21 Azores Central Islands Vegetation and Flora FIELD TRIP INTREPERTATION SHEET 1 PICO ISLAND 143

22 Dias, Eduardo et al. 1 - COAST VEGETATION OF CACHORRO The coast vegetation of Pico Island at Cachorro Lajido área has a zonal distribution, as expected. The first determinant factor is the hydrodynamics of the ocean, inducing the salt spray and wave s invasion of the terrestrial coast areas. These coastal areas of Cachorro are facing North, where the ocean storm are intense all the year, with strong winds and high waves. It is common the waves achieve 7 meters high and the salt-water can washes areas above 20 meters slopes. The erosion is very intense and only because of its basaltic composition it can be so swallow. Most of the North face coasts are deep slopes (achieving meters), cause by erosion pressure. Even here we can only find swallow areas in deep seltzer bays. The waves erosion can also be understand from the extended zonation in this coast, with the shrub vegetation only present very far from the coast line, and a large desert zone in the front line. The second factor is the balance between the salt in the substrata and the fresh water. Salt spray deposits produce the halophytic conditions, but also change the ph conditions, acid in most of the island soils. The fresh water can be abundant in the coast areas as a laminar flux, developing small ponds in the wintertime, and it has one effect of washout the salt and minimized the water stress. In some Soulth swallow coast areas, the forest vegetation can achieve almost the sea line by this effect. In here, it has one important effect, as the lavas structure, drained from the mountain, in its layers, important amount of fresh water. It gives the possibility of the shrub vegetation arriving so far in the coast line, with the presence of typical mountain species, like Myrsine africana, Juniperus brevifolia or Lysimachia azorica. It also explains a front line of wet vegetation after the shrubs, with Juncus spp. The third factor is the geologic structure of the rocks bed. Here, most of the coast is of pahoehoe basaltic lavas flow. They gave a platform almost flat when they flow, and the sea erosion broken the front as a strait rocky cliff. They are very difficult to be colonized until they have fresh water near the surface, and most of the front areas have low-density vegetation, only in the fissures. Some areas have aa lavas, like Cachorro, and the vegetation communities are quite different. Very easy to colonize, these lava rich nutrients, allow lichen communities in the exposed surface and dense vascular communities in the fissures. They retain also, as the erosion of waves stopped, large amounts of clay and a halophitic grass can become stablished, dominated by Festuca petraea. In very small shelted areas, the coast can be build up with rock deposits of different sizes. Here xerohalophitic communities can be dominant in the front line. But the shrub vegetation arrived very fast, usually with Myrica faya or, in some islands, with Dracaena draco. In the Cachorro Lajido area we can find, on the aa lava beds, a first community of Spergularia azorica sparce in the fissures (1), with Asplenium marinum and Atriplex spp. On second line (2) a community of Festuca petraea starts in the fissures and covers all the areas as the distance to sea line increase. The transition between these communities and the shrub zone starts with the presence of Erica azorica shrubs, sparse in the grass carpet. The front of dense shrub zone is usually with Erica azorica. Myrica faya, in the dry areas can dominate from large areas inland, increase in size until arriving to a 144

23 Azores Central Islands Vegetation and Flora forest. In less dry areas more complex community will develop with Picconia azorica and Laurus azorica. On the pahoehoe lava fields, the deep cliffs are usually absent of vegetation (3), on the top flat, the terrestrial vegetation star with the community of Spergularia azorica and Crithmum maritimum very sparce in the fissure (4). The second zone is a communitie of Festuca jubata with annual grasses (5). Very often these lava can have already permanent humidity in the fissures. Then a tall herbs community can develop with Foeniculum vulgare and Daucus carota ssp. azorica, Before the bushes zone (6), it is frequent the formation of wet condition, were a community of Juncus and Solidago sempervirens developed. In the upper faces of lava, Erica azorica and Myrica faya start to grow. The next stage is a dense shrub formation (7), with Erica azorica, Myrica faya, Juniperus brevifolia, Corema album (some places), and Myrsine africana. Under layer, Carex hochsteteriana is common. 145

24 Dias, Eduardo et al. 146

25 Azores Central Islands Vegetation and Flora 2 - THE LAURUS FOREST OF AZORES At the middle altitude on Azores, the climate conditions are excellent for most plants grow and similar to a temperate greenhouse. The average temperature is about 18ºC, with low variation along the year, the rain is about 1500 mm, distributed by all season, and no stress is usually present. It should also be notice that there are no natural large vertebrates on Azores, so the animal pressure over the natural vegetation was very small. Even the radiation is smooth with very few days on the year with clean sky. Most of the days, in fact, there are a cloud cover. In these condition, under developed soils and if no local disturbance arrived (like lava flow or flooding) the potential vegetation is a tall Laurus forest. It is a very complex formation, achieving, nowadays 20 meters, with more than 7 stract and 300% of cover. We have been called of mesic Laurifolia forest and it belongs to the classical Laurisilva formations. The number of areas nowadays with this community is very small and can only be found in inaccessible sites. The good soils have been a major attraction for farming. They have one emergent canopy (1) of one species dependent of the regional conditions: in less altitude places it is usually Myrica faya, and a continuous under canopy of Laurus azorica, Fragula azorica and Picconia azorica (2). In the higher altitudes the emergent canopy can be of Ilex perado ssp. azorica and Juniperus brevifolia been present in the continuous canopy. A second, less dense canopy, of young trees of Laurus and Picconia (3) can be present, usually supporting climbers like Rubus and Ruppia agostinhoi. A third stract of shrubs (4), includes Myrsine africana, Hedera azorica, Vaccinium cylindraceum and most of small plants of the dominant trees. Lower it started the stract of ferns, with large ferns making a dense cover (5) with Culcita macrocarpa, Dryopteris azorica and Athyrium filix-femina and a second strat of small ferns (6), like Dryopteris aemula, Blechnhum spicant, Phyllitis scolopendrium and, some times, even Trichomanes speciosum, associated with tall herbs, like Carex vulcani, C. peregrine. At this level, the forest is more or less impenetrable, as the dense ferns and climbs are associated to a dense cover of dead trunks and branches. The absence of large vertebrates results in a dense cover near the soil. As the old description said, it is possible to walk in the forest of Azores without to walk on the soils. The low stract of vascular is formed with slender plants like Bellis azorica, Plantanhtera micrantha or Prunella vulgaris. Below them, a carpet of bryophytes usually covers almost all the soil. The epiphytic communities have also dense mousses carpet (7) with ferns like Polypodium azoricum, Elaphoglossum semicylindricum and Hymenophyllum spp. (8). In very shelter conditions, spectacular curtains of Neckera can be present. All of these formations are endangered, most of all by the exotic plants like Pittosporum undulatum. This Australian tree has arrived to all of them and a large number have been completely transformed as this tree become dominant or replace all the natural vegetation. 147

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27 3 - PICO ISLAND CENTRAL PLATEAU LAVA VEGETATION AND ECOLOGY Azores Central Islands Vegetation and Flora Azorean volcanic islands are testimony of successive eruptions that were in their origin. Over time, lava fields undergo progressive changes. Wind and water wear down the volcanic rock, starting with the softer materials. Streams with a steep gradient can sometimes cut through a lava pile. Heating and cooling by sun and seasonal changes further expand and contract the lava masses, aiding in their break-up. These processes move very slowly. Eventually men activities can interfere in these natural succession mechanisms altering lava structure and plants re-established in the nutrient-rich volcanic soil. In Pico island central plateau landscape the vegetation develops above rich nutrient and impermeable basaltic lava. Its surface has a wrinkled or ropy-looking surface appearance. This lava is the substrate of very different vegetation mosaics, what can be due to the fact that it is a extremely irregular lava subtract, with quite different environmental conditions associated to each part of the relief. Besides the impermeable nature of this lava there are some ruptures from where the water flows. But main water fluxes on this formation occur through the space existent between different layers that result from different eruptions. The vegetation zonation of these lava fields varies with environmental factors like height of the substratum, exposition to the wind, and wetness degree but it also depends and changes with human activities and soil uses intensity. Generally speaking is possible to distinguish at least 4 types of vegetation communities occupying different heights of the lava substrate. (1) In raised parts of the lava, corresponding to less wet conditions, there are dense mosaics of forested formations. In wind exposed places this forest is dominated with Juniperus brevifolia and Vaccinium cylyndraceum with scattered herbaceous species like Tolpis azorica, Rubia agostinhoi and Holcus rigidus. On other hand, wind protected places on high zones of the field lava has different forest dominant species, like Laurus azorica, Frangula azorica and Ilex perado ssp. azorica with a lower fern stratum dominated by Drypotris azorica. In the middle slope of the lava species like Calluna vulgaris and Erica azorica dominate with herbaceous stratum of Lysimachia azorica, Holcus rigidus and Hypericum foliosum, in lighter expose places. Nowadays in Pico middle high pastures or natural grassland pastured areas, these forest formations were pushed to the higher parts of untransformed lava, and represent the remain of original forest formation that survived landscape human transformation. Pico pastures are extremely rich on vegetal species, due to these dense lacy of hedges in human landscapes. (2) In the intermediate zone of lava, the line of water is visible but the mosaics grow in small hummocks above the water level. In here herbaceous dominate the vegetal community. Hypericum foliosum and Anthoxanthum odoratum are present but scattered. The dominant genus is Carex. In more wet formation Carex nigra is the commonest. (3) In the lower area of the undulated lava, water is accumulated and conditions are favourable to peatbogs occurrence, in witch Sphagnum species form a dense carpet, enhancing Sphagnum auriculatum and Sphagnum subnitens. Other species seam adapted to these extreme wet conditions, like Lycopodiella inundata, Scirpus fluitans, Eleocharis multicaulis, among others. The transformed lava 149

28 Dias, Eduardo et al. fields or the pastured natural areas tend to loose the peatbogs and replace them with fens, more herbaceous communities due to the nutrient enrichment of water and direct animal trampling on Sphagnum sensitive carpet. This changing can be seen in places like margins of Capitão lagoon, and Pico da Urze. On the other hand, places with more recent (and less transformed) natural lava is Paul s lagoon and Caveiro. (4) In some large and deep basin zone on the lava fields, water can be accumulated in such quantities that might form small pools where hydrophytes like Litorella uniflora, Potamogeton polygonifolius, among others, can grow. This lava fields are, biologically, extremely important, once it supports several protected and rare Azorean Habitats. It is also habitat to several protected species: Arceuthobium azoricum, Erica azorica, Frangula azorica, among others, and also endemic species, for example Ilex perado ssp. azorica, Tolpis azorica and Rubia agostinhoi. In these lava studies we found peatbogs with more than 2 m deep, representing an extremely import water retention structure, especially in islands with a limited water resources. 150

29 4 - VEGETATION OF HISTORIC LAVA FLOWS MISTÉRIOS DA PRAINHA Azores Central Islands Vegetation and Flora Mistérios da Prainha is a large carpet of lava from one historic eruption (1572) of Bocas do Fogo volcanos. It spread from the higher part of the island in a large carpet until the northern coastline. Mistérios means in Portuguese mysteries, and was used to name the historic eruption, as the people didn t understand what was happening. In these lava fields, different lava colonization process can be found as they have different ecologic conditions from the wet high mountains until the drier lowlands. On the high part, the lava flow formed a plateau and two different lava types can be found: the aa and the pahoehoe lava. The first had flowed as waves concentric to the chimney, with a very rough surface, generally clinkery and full of fissures where the roots can grow. The seconds, pahoehoe, flows tend to be relatively thin, from a few inches to a few feet thick and with a smooth, billowy, or ropy surface. In this very difficult surface for plants colonization and more stress tolerant ones are dominant here. The aa lava waves are colonized by two different communities, side by side, one in the top of lava wave, and the other in the valley. The first one is a stress tolerant, associate to dries subtract but windy and humid air conditions (1). Erica azorica, Calluna vulgaris are the dominant shrubs. The Deschampsia foliosa and Holcus rigidus communities can cover the most exposed areas. Some rare species are associated to this habitat, like Planthantera micrantha and Palhinhea cernua or Euphrasia azorica. The depressions (2) are a different habitat, very wet, sometimes flooded, and rich in nutrients from chemical erosion of lava surface, shelter and wormed. It has a high-density community of Juniperus brevifolia Ilex perado ssp. azorica, with almost all the species of the mature forest and some others of the colonization stage, like Huperzia spp. The rare species of Ruppia agostinhoi and Euphorbia stygiana can be quite abundant here, and it has some of the rare population of Daphne laureola. The bryophytes cover all the subtract and most of the endemic species can be found. The dense cover of ferns, including the Culcita macrocarpa have the same size as the vascular shrubs, as all are limited by the high of the near summit of lava wave: all of this dense and complex community, similar to one elfin forest, are unable to grow on very exposed condition. The pahoehoe lava has a much low vegetation stage. The dense surface of lava can only be cover by bryophytes and lichen. Most of the higher vegetation is rooted in the fissures. The dominant species are similar to the one of upper part of Mountain, with Calluna vulgaris, Daboecia azorica, and Thymus caespititius. The black rock can became very warm in the summer time, and an annual community can be found in the small depressions of the flat surface with Agrostis gracililaxa. The volcano chimney, Bocas, has still the main composition of piroclast deposits at surface. A dense heath of Erica azorica is the dominant colonizer community (4) with Descampsia foliosa and Festuca jubata. 151

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31 Azores Central Islands Vegetation and Flora 5 - WET SYSTEM OF CAVEIRO Caveiro volcano systems are located in the highest point of the East side of Pico Island, achieve 1065 meters of altitude. It is a complex of lavas flows and dome volcano s over an older pomitic deposit. This one is impermeable to water by placic formation. On these conditions, the volcano slopes works as a giant water collector from the clouds and rain and conduct it to the valleys, were it arrives rich in nutrients and form mires. By the orography of the island, with the high Pico Mountain, at West, these are become the meeting point of the clouds transport by the trade winds. These mountains are almost all the year emerging in clouds and the precipitation arrives to values of 3500 ml/year. But the effect of intercept the clouds water and fog increase these values 3 or 4 times. Meteorology station at the summit of Terceira Island, at the same conditions, have collecting data of ml/year as the total of water collected by the system. Under these conditions the environment is all-time saturate and the mineralization is not possible, lead to accumulation of peat. The forest communities can only grow on the lava slopes, developing a special case of forested bogs. The flat areas with water deposits have Sphagnum bogs to fen, depending of nutrients status in high dystrophic water. The transition zone between the forested bogs and the open bogs has a mixed formation of Juniperus brevifolia, an endemic tree that can support permanent immersion, with tall nitrophylous herbs, using the disturbance gaps. All the system is interconnected and support periodic disturbance with the storms. Dieback processes were describe for the Juniperus bogs communities and are under quantitative description. The patches areas are important refugees for rare nitrophylous endemic plants and seems to be an import source of nutrients for the open bogs, as a related change in sphagnum density have been observed. These forests systems only depend of water and nutrients from clouds can very much be considered as elfin cloud-forest. The high summits and the directly exposed slopes to trade winds have a Juniperus brevifolia peat bog. Depending of the dieback stage, these communities can have different density of sphagnum species, almost absent under the mature stage of the forest. This forest has a dense endemic epiphytic community associated that covers all the trunks and branches where most soils processes take place. On the shelter slopes of the lava flow and dome, a wet forest (1) dominated by Ilex perado ssp. azorica as emergent canopy and a under layer of Laurus azorica, Vaccinium cylindraceum and Juniperus brevifolia, are established. These formations have a mosaic structure, as the depression of the lava is filled with forest peat, and the trees and shrubs can not rooted. Only the ferns and mosses can occupied the margin of these areas. In some cases, trees to root use the tree like Culcita macrocarpa trunk, given one kind of forested hummock. A dens epiphytic community cover all the upper surfaces, including grasses carpets of Luzula purpureo-splendens, Carex vulcani and Carex peregrine and Holcus rigidus. The ferns are also abundant with large ferns like Dryopteris azorica, or the sensitive ferns of Hymenophillum spp. and Elaphoglossum semicylindricum. In the climbers, Hedera azorica and Smilax divaricata are present. In the base of slopes, a transition community is present, dominated by Juniperus brevifolia (2). It changes in catenal effect from high density with forest peat to open shrubs rooted in hummocks of 153

32 Dias, Eduardo et al. Polytrichum spp. on a Sphagnum carpet. The water erosion open large gaps, where rare endemic herbs are associated, like Angelica lignescens, Lactuca watsoniana and Ammi trifoliatum. The flat areas, flooded, have complex communities of Sphagnum bogs and fens (3) with a distribution seem to be related with the nutrients status. Carex spp., Eleocharis multicaulis and endemic Agrostis (graxililaxa and azorica) are the dominant species in the fens. Dystrophic ponds and streams are also present (4). Juncus effusus, Sphagnum spp., Eleocharis palustris and Potamogeton polygonifolius are the dominant species on this community. 154

33 Azores Central Islands Vegetation and Flora FIELD TRIP INTREPERTATION SHEET 2 SÃO JORGE ISLAND 155

34 Dias, Eduardo et al. 6 - VEGETATION ZONATION OF FAJÃ DOS CUBRES LAGOON- COASTAL WETLANDS Coastal wetlands results from particular conditions and they have a very restricted distribution in the Azorean archipelago. Nowadays the rarity of this systems it s even more pronounced in result of there intense human destruction. The lagoons of Fajã dos Cubres and Fajã de Santo Cristo in the island of São Jorge are two rare examples. In the North coast of the island of São Jorge, one can see two fajãs, or coastal platforms. The coastline that encompasses this fajãs is a geological continuum that also includes cliffs and cobble shores as hydrological basins of a few streams (ribeiras) and unccounted groundwater outflows that reach the sea in this region. This two platforms where formed by massive landslides resulting from the earthquake of The landform was shaped by a combination of marine and freshwater erosion. The lagoons in both fajãs have several similarities; they are separated from the sea by boulder ramparts and they received constant freshwater input from groundwater reservoirs. However the hydrology and ecology of the two lagoons are fundamentally different. The Santo Cristo lagoon is essentially marine with the prevailing influence from the sea, and in opposite the Fajã dos Cubres lagoon is most estuarine, largely freshwater-dominate, and with interesting zonation of halophyte and hygrophyte vegetation communities. The Fajã dos Cubres lagoon can be divided in two zones with different hydrology s; the western section (Zone I), bordered on one side by seaward boulder rampart. This part is more influenced by the tidal cycle and reaches higher values of salinity (surface salinity 6% - 15%). The eastern section (Zone II) is separate from the western part by a central islet, so consequentially this part is little affected by tidal cycle, showing lower salinity values (6%-0%). This section it s very affected by groundwater entrance. The environmental gradient of salinity and water depth creates the principal factors that affect the zonation of plants in the margins of this lagoon. The vegetation zonation profile (W E) can be described as follow (Figure 2): A) Halophytic vegetation: A.I Halophytic community develops in the boulder rampart exposed to high hydro dynamism. It s a sparse community of halophytic species dominated by the micro-camephytic Crithmum maritimum AII Halophytic community in the inner part of the boulder rampart, exposed to low hydro dynamism. It s a sparse community of halophytic species like; Juncus acutus, Euphorbia azorica, Daucus carota, Atriplex hastata, Lotus corniculatus. In the eastern zone this community also occurs but with more Foeniculum vulgare and Lythrum hyssopifolia. The ferns Cyrtomium falcatum and Asplenium marinum exploit the crevices between the rocks. B) Hydrophytes vegetation: BI Emergent hydrophytes community develops in the margin of the lagoon forming a dense belt of Juncus acutus with a low percentage of Solidago sempervirens. 156

35 Azores Central Islands Vegetation and Flora BII Submerge hydrophytes community develops below the lower limit of tidal excursion and it s composed by a broad band of Ruppia maritima. On the eastern part of the lagoon, the surface water it cover with a mass of floating green weed, mainly Enteromorpha intestinalis and species of Chaetomorpha. Upon it s decay, the resulting detritus sinks to create the lagoon floor of thick, black mud that is a import feeding ground for aquatic birds, especially visitors species. The lagoon it s a important habitat for birds including marine birds (e.g. Calonectris diomedea, Sterna dougallii, Sterna hirundo and Larus cachinnans atlantis), aquatic visitor birds (e.g. Ardea cinerea, Fulica atra, Tringa sp.), aquatic resident birds (e.g. Gallinago gallinago). 157

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37 7 - THE NATURAL GRASSLANDS OF PICO DA ESPERANÇA ST. JORGE Azores Central Islands Vegetation and Flora The natural grasslands of Pico da Esperança Reserve is an unique case at Azores. Grass formation is not rare at natural areas, but only in small extension and specific habitats. But in this Reserve, all the natural areas are cover with endemic grass communities. As far as our results can take, the explanation is in the volcanic history. All of this area was build up in historic times by volcanic deposit of basaltic ashes. They are nutrients rich and give a neutral ph to the soils solution. But at this altitude of about 1.000m and on the absolute summit of the island, the wind is very strong. Any shrub or tree that attempted grow on this area is vanished any by the winds as the root are only in sand. The trade winds gave large amount of rain to these mountains, and there is a permanent water flow. All the communities are organized by these two factors: Deschampsia or Festuca wind resistant communities on the more exposed slopes, Agrostis or Holcus on the shelter ones; Grassy formation on the slopes and bogs formation on platforms, associate with ponds in the crater bottom or valley. These unique communities export nutrients in the run-off waters and at the discontinuities of the slopes (like the road) and exuberant communities of large endemic herbs can appear, on the shelter side of the mountain. Species very rare can have here large populations or even the largest population. This is the case of Trifolium trifoliatum, Chaerophillum azoricum, Pericallis malvifolia, Euphrasia azorica or Scabiosa nitens. The Deschampsia foliosa communities are typical of the mountains summit of Azores. Here have his largest patch, in the very exposed slopes. It is very interesting as the D. foliosa cushions can move during the years, pushed by the wind. The more exposed side of the cushion dies every year and new grows started at opposite side. Between two cushions of Deschampsia, a less tolerant species take place, like Scabiosa nitens, Leontodon filii, Tolpis azorica or Plantago lanceolata. This structure gave a mosaic aspect to the communities, with the Deschampsia leaves given a look like ocean waves when under windy conditions. The Festuca or Holcus spp. communities only developed at the shelter slopes, It has also a mosaic structure, associated with water run-off with a net of channels. Each cushion of grasses can also have endemic herbs associated, like Rannunculus cortusifolius, Scabiosa nitens, Ammi trifoliatum or Rumex azoricus. 159

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39 Azores Central Islands Vegetation and Flora FIELD TRIP INTREPERTATION SHEET 3 TERCEIRA ISLAND 161

40 Dias, Eduardo et al. 8 - PEATLAND COMPLEX OF CRIAÇÕES The ecological conditions in Criações (Terceira island), are favourable to the development of wet vegetation complexes, especially mire vegetation or other communities directly dependent of these. The soils of these place are andosols with placic (defined by an accumulation of iron, responsible for limiting water drainage), with high amount of organic matter, developed from volcanic pyroclastic material, under a wet temperate Atlantic climate. Criações landscape, correspond to a mire complex, where all peatland units are connected by a hydrological net. Several types of peatland can be identified in the area, the bogs are surrounded by a narrow strip of mesotrophic fens and the bogs itself by mixed deciduous forest. Tamujo peatbog (protected by Habitat Directive with the designation of transition peatbog) is the largest pure sphagnum formation and is the result of an infilling sequence from open water to an acid peat ecosystem. Blanket bogs are also common in the area. The most important peatland type in terms of area and biodiversity is forested formations. In fact, generally speaking, local mires are significant rich in floristic diversity and have a complex vegetation structure. The Pico X mire complex contains plant communities that are typical for Azorean peatland. The mountain basin, due to the high entrances of water (precipitation and fog) and its surface retention, is dominated by Sphagnum communities forming extent areas of blanket bogs. In the hills due to more extreme ecological conditions (wind and water surface movement) the predominant formation is forested peatland dominated by Juniperus brevifolia, in the middle hill water quantity is smaller, allowing some organic matter decay and nutrients became available to vascular plants, forming richer and denser humid forests with Laurus azorica, Ilex perado spp. azorica and Juniperus brevifolia. In the basin of Pico X complex predominate Flat bogs and few small island of fens. Flat bogs are generally characterized by a zonation vegetation gradient, which varies from the margin to the interior of the bog. Edges are hummock communities dominated, where nutrients dragged from the fill allow the development of communities of Polytrichum commune, Calluna vulgaris, or, less frequent Erica azorica and Juniperus brevifolia. Herbaceous communities like Juncus effusus occupy the intermediate zone. The centre of the bog is flat and few scattered species occur like Eleocharis multicaulis and Prunella vulgaris. Tamujo peatbog, is a flotation moss carpet above a lake, where, due to the stage of succession, dimension and an infilling origin has an atypical flat structure prevailing. These Sphagnum communities are extremely dependent of water collector s species existence in the highest parts (inside cloud forest) in Azores the most efficient are Erica azorica e Juniperus brevifolia. Fens are richer in nutrients and less acid than bogs, so shrubs and grasses are plentiful (in density and diversity), and mainly consist of Calluna vulgaris, Erica azorica, Juncus effusus, Juncus bulbosus, Eleocharis multicaulis. The bog moss layer consists mainly of Sphagnum palustre, S. centrale, S. subnitens, S. capillifolium, Leucobryum glaucum and Campylopus cetaceus. This complex, mostly state property owned, plays an important role in the Terceira island landscape including water quality buffering, water discharge and recharge, nutrient and sediment retention and is habitat for a wide variety of rare and protected plant like Bellis azorica and Trichomanes speciosum among others. 162

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42 Dias, Eduardo et al. 9 - MICRO STRUCTURE AND ZONATION OF A HUMMOCK/ HOLLOW / LAWN/ / POOL GRADIENT IN A SPHAGNUM PEATBOG Sphagnum peatbog surface isn t completely flat, it possesses a typical microstructure characterized by a wavy relief of variable compass, from some centimetres to some meters. The surface presents a mosaic of pools, hollows (or lawns) and hummocks in various stages of infill, degeneration or building up. Each of these microstructure types are associated to distinct ecological conditions, witch are reflected in an evident vegetation zonation. In fact, each microform behaves as natural vegetation entities with specific mosaics of vegetation patches and their own micro successions. In the complex micro topography of bogs, associations are represented only as fragments dispersed on microforms of the same type. The raised areas of the peatland are called hummocks, and there s above water table. These structures are higher than lawns and hollows by about 40 to 80 cm and thus they have drier conditions. Sphagnum species colonizing plateaus and hummocks grow in dense colonies that allow efficient water retention and water supply. The most common species in hummocks are Sphagnum palustre, Sphagnum centrale and Sphagnum papillosum. Drier conditions found on hummocks favour the presence of shrubs and trees as well as other mosses such as Polytrichum commune, Pseudoscloropodium purum, Thuidium tamariscinum and lichens species (like Cladonia portentosa). However, large plateaus can form wide-open areas of trees and shrubs. Under low water table conditions, vascular plants can form a dense cover with a sparse moss layer. In Azores the most frequent woody species in hummocks are Calluna vulgaris, Juniperus brevifolia and Daboecia azorica, associated with herbaceous like Luzula purpureo-splendens, Blechnum spicant and Dryopteris spp.. The peatbog depressions, where the water level is close or in the surface, are called lawns or hollows depending on the area they cover. Lawns cover large surfaces, while hollows are small depressions. Plant communities of lawns and hollows are less diverse and more scattered, dominated by Sphagnum mosses and herbaceous from witch we can point out Sphagnum auriculatum, Sphagnum subnitens, Juncus effusus, Eleocharis multicaulis and Hydrocotyle vulgaris. Frequently, in the margins of these systems, it might be formed some dystrophic pools, that may become, in situations of some slope, permanent water lines. In pools, water table is above surface, is nutrient rich, but also very acid. These microstructure supports sparse and low plant biodiversity, species like Sphagnum auriculatum, Sphagnum cuspidatum, Juncus bulbosus, Scirpus fluitans, among others are the most frequent. 164

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44 Dias, Eduardo et al ECOLOGY AND VEGETATION ZONATION OF A MOUNTAIN WATER STREAM DOMINETED BY LAURIFÓLIA FOREST The hydrological net of mountain areas of most of Azorean islands, is characterized with high structural complexity, high floristic and biological diversity, forming ecological corridors of larger structural wealth, comparing with its margin. Water line vegetation, although it seems a mere floristic component, it constitutes an essential system for the fluvial ecosystems, fomenting biodiversity and biological productivity, constituting alimentary matter for the aquatic systems, keeping sediments of the hydrological erosion, storing nutritious from lixiviation (working as biological filter of nutrients and of several pollutant substances), mainly, when the adjacent terrestrial systems are responsible for high inputs, as it is verified in medium/high altitude landscape, where it is high covering with pastoral systems. The water supply for these riversides, is due practically to the precipitation, thick fog and peatlands, these last ones, play a part of extreme importance thoroughly regulation of the flows, which is described, by Mendes (1998). The geological structure, defining topographical relief s, litologic discontinuities and other accidents, influences water lines, in it s profile and in the losses or flow earnings. On the other hand, most of the drainage lines are situated, preferentially, along geologic fracture or in discontinuity areas. The combination of these factors with the plateau situation, structures a dense hydrological net, but of reduced extensions and in very small basins. These formations are associated to elevated precipitation recharges, including the occult, which it receives. Several studies that took place in GEVA (Applied Vegetal Ecology Study Group) demonstrate the existence of several ecological/floristic types of water lines in Azorean islands. Their distinction is based in several environmental elements of the hydrological net like water regime and vegetation zonation. Here follows the vegetation description of a Mountain riverside dominated by a laurifolia Forest, where 3 distinct zones may be distinguished. (1) Gallery of natural vegetation: margin of the water line, with a variable relief, this can be more or less accentuated, depending on the combination of the erosive effort of the running water, of the consistence of the materials and of the age of the structure. The gallery ends below, near the lotic zone. This gallery presents a dominance of the following species: Ilex perado ssp. azorica, Laurus azorica Vaccinium cylindraceum and Hypericum foliosum. The structure of this gallery is very complex, and is possible to distinguish an emerging arboreal stratum, that allows the interception of thick fog, creating ideal conditions for the development of a sub-forest, where other species settle down; a high incipient herbaceous stratum, where it can be found: Dryopteris azorica, Blechnum spicant, Woodwardia radicans, Culcita macrocarpa; a grassy herbaceous stratum, with: Holcus rigidus, Deschampsia foliosa; and a low herbaceous stratum of: Lysimachia azorica, Cardamine caldeirarum and Centaurium scilloides. Besides these species others like the creepers Smilax divaricata and Rubia agostinhoi occur. Rich formation on epiphyte species from witch we detach Elaphoglossum semicylindricum and Hymenophyllum tunbrigense. Slope (Taludes) There are 2 types of slopes: 1. With a little evident vertical stratum, of Woodwardia radicans, that appears in this area forming great continuous stains, with larger predominance in the top of the slope and intermediate area. This fern 166

45 Azores Central Islands Vegetation and Flora merges with compact communities of grasses as: Festuca jubata and Holcus rigidus. Selaginella kraussiana has a scattered distribution in the whole area, forming a continuous rug from the top to the base of the slope, indicating the presence of high wetness. Along the intermediate area of the slopes, small stains appear with the small herbaceous species: Leontodon filii, e Blechnum spicant. Near the slope basin there is Sibthorpia europaea, Luzula purpureo-splendens and Culcita macrocarpa, which grows in rocky blooming covered with a fine soil layer. The moss stratum is dominated by small discontinues carpets of Mnium spp, Scapania spp. and the liverwort Conocephalum conicum. This type of slope formation occurs at altitude (above 600 m) where vegetation has no (or very little) human disturbance. 2. With Rubus spp. it stands out of the previous vegetable unit, by the significant covering of Rubus spp., resulting in a floristic impoverishment, given the aggressiveness of the invasion, forming a microhabitat favourable to others plagues and becoming too inhospitable for autochthonous species. The emergence of this type of riverside slope formation is associated to disturbances in the natural vegetation at lower altitudes (especially between m). The most evident disturbances are: deposits of garbage, erosion of the slopes and passage of roads and walking trails. Water bed not all water line courses profile possess the community characteristics of the base of riverside, the perialpine Heterocladion Cardamine formation. The development of those riversides base community's, is due to the geomorphology, condition for the existence of small islands, with small, but continuous flowing, where it develops a bryophyte communities of Heterocladion hutchinsiae and herbaceous vegetation with the domain of Cardamine caldeirarum, where jointly, appears the species Sibthorpia europaea, Carex vulcani, Lysimachia azorica, Sanicula azorica and, rarely, the Bellis azorica. The bryophyte community of the basin of the water line is occupied by: Fissidens spp., Mnium spp, Scapania nemorosa, Ricardia spp. and Conocephalum conicum. In the most torrential regime, this community disappears, because emerging substratum became scattered or even without any vegetation. 167

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47 Azores Central Islands Vegetation and Flora 11 - VEGETATION ZONATION OF AN OLIGOTROPHIC LAKE (LAGOA DO NEGRO) Lagoa do Negro is located at 540 m of altitude in the central plateau of Terceira island between Sta. Bárbara Mountain and Pico Alto pick. It s a small lake (protected by Annex B-I of Habitats Directive Decreto-Lei nº 49/2005) with 6 m 2, low depth (1.8 m maximum) rich in load sediments, witch has contributed to infilling observed in the last decades, and has an accentuated seasonal variation of 1 m. It hasn t any direct flowing, being maintained by direct rain, water superficial movement from its hillsides and water from the surrounding sphagnum peatbog. The lake s water is extremely poor in nutrients and slightly acid. This environmental condition affects the density and the type of species of the lake. It s an insular small lake with a very limited and particular number of hygrophyte and hydrophytes species. In generic terms, vegetation distribution is similar to classic standards of lake vegetation zonation, being possible to distinguish three areas: margins, benthic and unoccupied area. Margins communities constitute the transition area from the margins to the lake, and these communities are at least once a year submerged. The lake margin has two morphological types to witch correspond to different vegetal settlements: (1) soft downhill margin, with Hydrocotyle vulgaris, Polytrichum commune, Juncus effusus and Sphagnum palustre; (2) slope margin dominated by mosses, specially Polytrichum commune, but with vascular species like Osmunda regalis, Selaginella kraussiana, Prunella vulgaris and Plantago coronopus. Bentonic vegetation is very poor in diversity, only Potamogeton polygonifolius (introduced specie), Litorella uniflora and Isoetes azorica occurs in this area. This is endemic and extremely rare specie that is protected by Annex B-II of Habitats Directive. It appears only in a narrow strip corresponding to the minimum level reached by water, and restricted to areas where sediments are loose. A third identified zone, in the middle deeper part of the lake, is mentioned as unoccupied of vegetal species due to the fact of sediments are loose and has a strong undulation caused by winter strong winds. These kinds of wetland formation are also extremely important for bird species for nesting, breeding, shelter, feeding as well for crucial resting periods for accidental aquatic birds, like Ardea cinerea. 169

48 Dias, Eduardo et al VEGETATION ZONATION OF SERRA DE SANTA BÁRBARA The mountain flora of Azores consists of a relatively low number of vascular plants species, but ranks among the regions with highest concentration of endemics formations of Europe. In the low altitudes due to man impacts and the dominance of introduced species, most of natural vegetation communities were destroyed. Contrarily, mountain zones still maintain important natural communities. The Serra de Santa Bárbara is one of those examples, where it can be found, nowadays, one of the most important natural area of Europe, with a complex of functional natural habitats. The Serra de Santa Bárbara (1021 m) is the youngest volcano form of Terceira Island and lies at the NW end of the island. This active volcano has a truncated profile, diversified by trachyte domes and coulés, both inside of the caldera and on the slopes of the Serra. In the past this area was used as Baldio, were people release their cattle and collect wood freely. Presently, part of the Serra was converted to intensive pastures, an in the higher zones transformed in a natural reserve. The Serra de Santa Bárbara slopes are covered with a continuum of vegetation formations that varies in structure and in floristic composition, reflecting the great variety of habitats, each one showing different combinations of environmental factors. The most important environmental factors are the wind exposure, the excessive precipitation cloud, humidity and continuous ground wetness. The geology and geomorphology are also important factors, creating high number of microhabitats. On the North lower altitude natural areas of Serra Santa Bárbara, shelter places are covered by a well developed Juniperus-Ilex forest. This forest is dominated by dense canopies of Juniperus breviflolia and higher canopies of Ilex perado ssp. azorica. The structure is well differentiated with five layers (emergent, canopy, canopy, scrub, high herbaceous, low herbaceous, bryophyte and epiphyte). The wet arborescent scrubs follow the forest in the vegetation zonation profile, and dominate most of the slope. Due to the limiting stress factors, this formations result from forest and wood dwarfness or structural and floristic evolution of blanket forest bogs. These formations aren t uniform and change depending on the exposure. In the North Slope they are richer in species showing lauroide tendencies. They are dominated by Juniperus brevifolia, but other species like Ilex perado spp. azorica, Laurus azorica and Vaccinium cylindraceum occur with important cover values. The herbaceous layer develops at the same level of the scrub layer, due to the internal micro topography, and permits the occurrence of species with different ecological tendencies (e.g. Culcita macrocarpa, Dryopteris aemula, Tolpis azorica). The Juniperus forest peatland precede the wet arborescent scrubs in the higher parts of the Serra. This vegetation type is a rare and endemic peatbog with sparse canopies of Juniperus brevifolia and important cover of Sphagnum sp. The increasing climate severity with the increasing of altitude marks the timberline limit, beyond this line the trees grow in small patches or as scattered individuals. They are dwarfed, semi-prostrate and exhibit a krummholz growth habit, forming the helophytic mountain scrub. This vegetation formation has a complex horizontal structure, constitute by three types of patches; shrub patches (dominate by Calluna vulgaris and Juniperus brevifolia); herbaceous patches (dominate by Deschampsia foliosa, Festuca jubata or Eleocharis multicaulis) and bryophyte patches (dominated by Sphagnum spp. and 170

49 Azores Central Islands Vegetation and Flora Campylopus spp.). Beyond this limit we enter in the treeline (sensu stricto) where tree growth ceases entirely. It gives place to Deschampsia grassland, dominated by Deschampsia foliosa with cushion growing habit that creates shelter microhabitats where other herbaceous species grow, like Potentilla azorica, Centaurium scilloides and Holcus rigidus. The hydrological net is very dense in the slopes. The streams valleys are covered with gallery forest that normally derive from structural evolution of the formations on the streamside. 171

50 Dias, Eduardo et al JUNIPERUS FORESTED PEATLAND IN SERRA DE STA BÁRBARA Sta Bárbara Mountain is integrally included in Terceira's Island Natura 2000 area. It's extremely rich in rare habitats and species, representing one of the most important and well preserved biologic hot spot not only of Azores but also of Europe. The ecological conditions of the highest mountain of the island (enormous quantities of water entrances and continuous placic horizon), is favourable to the development of wet vegetation complexes, especially mires vegetation. These habitats occupy almost all mountain surfaces, but in the hillsides, predominant habitats are Juniperus brevifolia forested peatland. This forested peatland is one of the most interesting communities of Azores, being, together with their associated ones - blanket bog, on one side, and Juniperus forest, for the other - formations of great ecological interest and endemics of Azores. The sintaxonomic position of this formation can be seen as deriving of Blanket Bog witch has evolved in their maturity increasing organic matter soil depth, accentuating anoxic conditions, and soil flood etc. Or, for other hand, it can be the result of an extreme ombrotrophic situation of Juniperus forests (formation this belongs to the Forests system of the archipelago). The great singularity of this formation is the fact that the dominant arborescent specie is the endemic Juniperus brevifolia, uncommon as dominant of these formations. This peatland has shrub/tree coverage higher than 50%. If extremely dense, peat will be formed entirely with forest remains, because Sphagnum species are shade intolerant. In this dense formation, inferior vegetation layers are occupied with species like Dryopteris affinis, and Luzula purpureosplendens,. In more open formation Sphagnum carpet may reach an occupation level of 80%, and other species like Juncus effusus, Calluna vulgaris and Ilex perado ssp. azorica occur, even if in a scattered distribution. In some cases is possible to watch a space competition between Sphagnum and Juniperus in witching the moss carpet covers partially the Juniperus plant. This is a very interesting phenomenon because, besides demonstrating an advanced evolutionary state of the peatland (witch may have several meters depth of peat), it shows a parallel growing of both of these species. Juniperus is buried in the Sphagnum peat but It's roots are in the mineral subtract of geological origin, some meters below, from where It removes nutrients. 172

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