Application of cartographic approach to the study of the vegetation of Polisto-Lovat mire system

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1 Application of cartographic approach to the study of the vegetation of Polisto-Lovat mire system Olga Galanina Komarov Botanical Institute, Russian Academy of Sciences Prof. Popov str., 2, , St. Petersburg, Russia Introduction As a result of work on the project Investigation of biodiversity of protected mire systems of the north-west of Russia, grant ¹1516/1999 RSS the territory of Polistovsky reserve (Pskov region, Russia) was studied. The reserve is located 300 km to the south from St. Petersburg. It is created in 1994/95 for protection of the western part of Polisto-Lovat mire system, which is a unique natural object. Its eastern part was taken under protection earlier, when the Rdejsky reserve was created (Novgorod region). Polisto-Lovat mire system is the largest one in the North-West of the European Russia. It is situated in the southern part of the Priilmen Lowland on the watershed of the Polist and Lovat Rivers. The total area of the mire system is estimated to be hectares. The mire system consists of several mire massifs. It has been formed by the overgrowth of shallow lakes on a place of a huge post-glacial reservoir. The process of mire development accelerated during the Subatlantic period of the Holocene. The geological and geomorphologic factors as well as humid climate promoted this process. The maximum depth of the mire system is more than 8 metres. The average depth is 3,3 m. The peat deposits are mainly composed of Sphagnum peat. Sphagnum magellanicum peat prevails all over the mire. The mire system gives a start to some rivers. There are underground watercourses too. The Polisto-Lovat mire system has more than 20 lakes located in groups. They are shallow with a peat bottom. There are numerous sand islets, which are scattered on mire territory. Polisto-Lovat mire is a typical raised bog system. Its margin parts are transitional mires. Þðêîâñêàÿ (1992) considers the Polisto-Lovat mire system to belong to the Western-Russian type of bogs of taiga zone. The mire system consists of many bog structures in various stages of development, with a number of local convex centers and outlet streams. Hummock-hollow complexes are situated on mire slopes, surrounding local centers. About half of the mire system is occupied by pool bog sites. Located on the border of southern taiga subzone and coniferous-broad-leaved forest subzone, the system contains western elements of vegetation cover (Calluna vulgaris (L.) Hull, Sphagnum tenellum (Brid.) Perss. ex Brid., S. rubellum Wils. and S. cuspidatum Ehrh. ex Hoffm.) as well as eastern ones (Chamaedaphne calyculata (L.) Moench and Sphagnum majus (Russ.) C.Jens). Besides, there are northern elements like Betula nana L., Sphagnum jensenii H.Lindb. and S. lindbergii Schimp. ex Lindb (Áîãäàíîâñêàÿ- Ãèåíýô 1933). Betula nana and Sphagnum lindbergii are on the southern border of their distribution here. The Polisto-Lovat mire system is on the Ramsar Shadow List of the Russian Federation. 130

2 Methodology The territory of Polistovsky reserve was investigated during two field seasons using the method of geobotanical profiles. Each profile consisted of plots. The full geobotanical descriptions of communities were carried out for all plots. They had exact geographical coordinates (GIS, topographic maps). The creation of a legend to the vegetation map of Polistovsky reserve was preceded by classification. The dominant approach traditionally used by Russian geobotanical school was applied to the description of vegetation. The abundance and covering of species of vegetation cover were recorded. The geobotanical descriptions of mire vegetation were put into tables, then they were grouped on the basis of the similarity of floristic composition and structure dominant species. The classification of the descriptions was carried out with the use of the dominant approach. The floristic classification of the Braun-Blanquet school was tested on the same descriptions. Remote sensing methods are applied to study mire massifs and mire systems. Black and white aerial photographs of different scales and a colour satellite image were used. The aerial photographs were interpreted in laboratory, and the directions of field study routes were planned using them. Vegetation patterns were delimited using the aerial photographs as a sketch map, and checked during the field work. The method of aerial photo interpretation is usually used for vegetation mapping. It is a necessary tool for compiling of maps in different scales. The application of computer technologies considerably facilitates this process. GeoDraw 1.14 and Geograph 1.5 for Windows programs, created by the Moscow Institute of Geo information Researches, were used. The geobotanical profiles were made with the principle to visit a maximum number of diverse patterns for one route. The geobotanical descriptions were carried out repeatedly in different communities for the subsequent classification. Herbarium of Sphagnum mosses, lichens and liverworts were collected for each plot. In the course of the work, the preliminary map was covered by a network of point-keys, which were used for extrapolation of their contents in patterns. Results and discussion The western part of Polisto-Lovat mire system contains a number of microlandscapes: lagg, sedge-sphagnum zone, hummock-hollow complex; dwarf shrub-cottongrass- Sphagnum bog with rare pine and a hollow-pool complex (Fig. 1). The vegetation of the western part of Polisto-Lovat mire system has a complex character. Ombro-oligotrophic sites with hummock-hollow and hummock-pool complexes are widely distributed. Dwarf shrub-cottongrass-sphagnum communities with pine occupy the hypsometric tops of the bog. The bog is forested by Pinus sylvestris f. litwnowii and f. wilkomii. Wooded sites alternate with open sites or sites with dead trees. The marginal parts are occupied by mesotrophic communities. Lagg is well-developed in the western border of the mire system. Being rather wide along Ratcha elevation, it is gradually narrowed to the south. Lagg (margin fen) has a width up to 100 m. It is characterized by herb-sedge vegetation (Comarum palustre L., Carex nigra (L.) Reichard and Equisetum fluviatile L.) with sparse black alder (Alnus glutinosa (L.) Gaertn). This site is the richest with nutrient conditions. The following site is the mesotrophic sedge- Sphagnum zone (Carex rostrata Stokes and Sphagnum fallax (Klinggr.) Klinggr). It is changed into dwarf shrub (Calluna vulgaris, Oxyccocus palustris Pers., Rubus chamaemorus L. and Andromeda polifolia L.), cottongrass (Eriophorum vaginatum L.), Sphagnum (S. magellanicum Brid., S. angustifolium (Russ. ex Russ.) C.Jens. and S. fuscum (Schimp.) Klinggr.) communities with sparse pine stands. In the mire centre there is an oligotrophic bog. The Finnish Environment

3 Fig. 1. A fragment of the Vegetation map of Polistovsky Reserve.1. Agricultural fields; 2. Birch-aspen forests and shrubs; 3. Lagg; 4. Sedge fen; 5. Herb-sedge fen; 6. Treeless cottongrass bog; 7. Hummock-hollow complex being formed; 8. Hollow complex with sparse hummocks; Hummock-hollow complexes; 11. Ridge-hollow-pool complexes; 12. Wooded raised bog; 13. Bog pine forest; 14. Pine bog; 15. Bog with sparse pines; 16. Wet bog hollow complex; 17. Overgrown bog stream; 18. Mineral soil islands; 19. Relic lakes. Hummock-hollow complex is allocated in a narrow strip on the slope to the Ratcha. The local centre is a wooded raised bog, where Chamaedaphne calyculata and Ledum palustre L. prevail. Lichens Cladonia arbuscula (Wallr). Flot. ssp. mitis (Sandst). and Cladonia fimbriata (L). Fr. are common. I found Cladonia glauca Flörke, a new species for the Pskov region, on the bogs (determined by Olga Katenina). To the north from Ratcha the mire can be characterized as oligomesotrophic: there grow dwarf shrubs (Chamaedaphne calyculata and Betula nana), sedges (Carex lasiocarpa Erhr.), Sphagna (Sphagnum fallax) with birch (Betula pubescens Ehrh.). Lagg is occupied by Alnus glutinosa, Equisetum fluviatile and Calla palustris L. A zone of shrubs (Salix myrtilloides L., S. lapponum L. and S. rosmarinifolia L.), sedges (Carex lasiocarpa Ehrh.) and Sphagnum spp. follows further. A small orchid Hammarbya paludosa (L). O. Kuntze was met several times in this site. To the north-east from the strip of mineral islets, the bog has more oligotrophic features. There are the first pine trees, and the vegetation gets a complex character. Hummock-hollow complexes occupy a large part of the area of the Polisto-Lovat mire system. In the course of analysing the vegetation cover of hummock-hollow complexes, the following regularity was revealed. Dwarf shrub (Calluna vulgaris)-cotton grass (Eriophorum vaginatum)-sphagnum communities with pine are widely distributed on hummocks. The height of Pinus sylvestris is 0,5-3 m. It is represented by f. litwinowii and f. wilkomii. The hummocks are flat and low. They are covered with Sphagnum fuscum as a dominant species. Sphagnum angustifolium, S. rubellum and Polytrichum strictum are also common species. Cladonia stygia (Fr). Ruoss. can be found very often on these sites. This lichen grows like a Sphagnum moss. Its length can reach up to 0,3-0,5 m. Rhynchospora alba (L.) Vahl with Sphagnum balticum (Russ.) Russ. ex C.Jens. or S. majus, sometimes Scheuchzeria palustris L. grows in hollows. Sphagnum cuspidatum Ehrh. ex Hoffm. occupies the most wet hollows. 132

4 The hummocks of another type of complexes are characterized by cottongrass- Sphagnum communities. Sphagnum magellanicum is the dominant species of moss cover. S. angustifolium and Polytrichum strictum are present as well. The hollows are covered with Rhynchospora alba, Scheuchzeria palustris and Sphagnum balticum. The pool bog complexes with sparse ridges extend to the northeast to Novgorod region. The character of vegetation cover is still the same on ridges: dwarf shrub (Calluna vulgaris)-cottongrass (Eriophorum vaginatum)-sphagnum (Sphagnum fuscum) communities with Pinus sylvestris f. pumila. Sphagnum angustifolium, S. magellanicum, S. rubellum, Polytrichum strictum, Cladonia stygia and Cladonia stellaris (Opiz) Brodo. are present as well. Sphagnum fallax occupies the transitional microsites between hummocks and hollows. The plant communities with Rhynhospora alba and Sphagnum balticum are distrubuted on the margins of pools, in which they are replaced by liverworts and S. majus. The hollows have a black colour due to the presence of liverworts and algae. Rhynchospora alba groups and individual plants of Carex limosa L. are scattered on the surface. Nymphaea tetragona Georgi. grows in the open water of bog pools. Table 1. Oligotrophic bog vegetation. Number of relèves 11 7 Associations 1 2 Sphagnum magellanicum V 3-4 Sphagnum fuscum V 4-5 Eriophorum vaginatum V +4 Andromeda polifolia V +2 Andromeda polifolia V +2 Eriophorum vaginatum V 1-4 Oxyccocus palustris V +2 Drosera rotundifolia V + Pinus sylvestris III +3 Ledum palustre III +-2 Drosera rotundifolia V + Oxyccocus microcarpus I Polytrichum strictum V 1-3 Empetrum nigrum I Chamaedaphne calyculata V +3 Sphagnum angustifolium V 2-3 Sphagnum angustifolium V 2-3 Oxyccocus palustris V +2 Chamaedaphne calyculata IV +2 Sphagnum fuscum IV +2 Sphagnum magellanicum IV 1-2 Ledum palustre III +3 Polytrichum strictum III 1-2 Empetrum nigrum II Calluna vulgaris II Pinus sylvestris V +2 Scheuchzeria palustris II Calluna vulgaris III 1-2 Oxyccocus microcarpus II Sphagnum rubellum III +2 Sphagnum rubellum I Scheuchzeria palustris II Menyanthes trifoliata I Menyanthes trifoliata I Rhynchospora alba I Rhynchospora alba I Betula pubescens I Betula pubescens - Carex limosa I Carex limosa - Aulacomnium palustre I Aulacomnium palustre - Sphagnum balticum - Sphagnum balticum I 1- Ass. Chamaedaphne-Sphagnetum magellanici subass. typicum; 2- Ass. Ledo-Sphagnetum fusci The Finnish Environment

5 Oligotrophic homogeneous vegetation of bogs, which is represented by pine-cottongrass-dwarf shrub communities, is found as well (Fig. 1). Chamaedaphne calyculata and Rubus chamaemorus prevail. Sphagnum magellanicum and S. angustifolium co-dominate in moss layer. The application of the floristic approach to the analysis of geobotanical descriptions has allowed to compare the studied vegetation of Polisto-Lovat mire system with the Prodromus of syntaxons, compiled by Áî & Ñìàãèí (1993). After grouping the vegetation complexes into types, it is possible to consider the types as mapping units for the purpose of large-scale mapping. Oligotrophic bog vegetation belongs to the following associations (Tab. 1): Ass. Chamaedaphne-Sphagnetum magellanici Bogdanowskaya-Guiheneuf 28 em. Boc 90 Subass. typicum; Ass. Ledo-Sphagnetum fusci Du-Rietz 21; Àss. Caricetum limosae Osvald 23 (Tab.3): Fac. Eriophorum vaginatum Subass. sphagnetosum angustifolii Vegetation of mesotrophic herb-sedge-sphagnum communities of marginal parts of the mire system (Tab.2): Ass. Caricetum rostratae Osvald 23 Subass. sphagnetosum fallacis; Ass. Caricetum lasiocarpae Osvald 23 Fac. Menyanthes trifoliata Subass. sphagnetosum fallacis; The vegetation of hollows belongs to the association Caricetum limosae Osvald 23. Table 2. Vegetation of herb-sedge-sphagnum mesotrophic communities of the marginal parts of the mire system. Number of relèves 8 7 Associations 1 2 Carex rostrata V 2-3 Carex lasiocarpa V +2 Scheuchzeria palustris I Carex rostrata II Carex limosa III +1 Eriophorum polystachion - Rhynchospora alba - Menyanthes trifoliata V 2-3 Drosera anglica - Equisetum fluviatile II Comarum palustre I Carex lasiocarpa - Eriophorum polystachion - Scheuchzeria palustris II Menyanthes trifoliata II Carex limosa IV +1 Equisetum fluviatile - Comarum palustre I Oxyccocus palustris V +2 Oxyccocus palustris V +2 Eriophorum vaginatum I Eriophorum vaginatum I Chamaedaphne calyculata II Chamaedaphne calyculata II Andromeda polifolia I Andromeda polifolia III +1 Drosera rotundifolia - Drosera rotundifolia II Sphagnum magellanicum - Sphagnum magellanicum - Sphagnum fallax V 5 Sphagnum fallax V 5 1 Ass. Caricetum rostratae, subass. sphagnetosum fallacis; 2 - Ass. Caricetum lasiocarpae, subass. sphagnetosum fallacis. 134

6 The associations are subdivided into some subassociations (Tab. 3). Most widespread subassociation of the investigated part of Polisto-Lovat mire system is the subassociation sphagnetosum cuspidatii. It is diagnosed by Sphagnum cuspidatum. Andromeda polifolia and, particularly, Oxyccocus palustris are common for this subassociation. It occupies the swampy sites of oligotrophic bogs and is characterized mainly by Carex limosa andscheuchzeria palustris. There are also subassociations: sphagnetosum baltici (in the western part), sphagnetosum maji (everywhere), and rare ones: sphagnetosum papillosi and sphagnetum jensenii (in the southern part). Table 3. Vegetation of the subassociations of Ass. Caricetum limosae. Number of relèves Species Subassociations Carex limosa IV 1-2 III 1-2 II I Scheuchzeria palustris V +2 IV +2 III 2 II Eriophorum vaginatum II II IV +1 V +4 Oxycoccus palustris III + V + III + V +2 Andromeda polifolia V +1 IV +1 IV +1 V +2 Chamaedaphne calyculata - I II V +3 Drosera rotundifolia I I - IV + Sphagnum magellanicum V 2-3 S. majus V 5 I - - S. cuspidatum - V 5 I - S. balticum I - V 5 - S. angustifolium V 4-5 Rhynchospora alba IV 2 IV +2 III 2 - Drosera anglica III II I - Ass. Caricetum limosae: 1- subass. sphagnetosum maji; 2- subass. sphagnetosum cuspidatii; 3- subass. sphagnetosum baltici; 4- subass. sphagnetosum angustifolii. In the north-eastern part of the reserve, where hummock-pool complexes are distributed, the association Hepatico-Rhynchosporetum albae Bogdanovskaja-Guiheneuf 28 em. Botch 92 was described. Its diagnostic species are Hepaticae (Cladopodiella fluitans, (Nees) Buch, Gymnocolea inflata (Huds.) Dum. and Mylia anomala (Hook.) S.Gray). This association indicates a regress of bog vegetation and its destruction under the influence of water stagnation and allocation of CH 4 and H 2 S (Áî & Ñìàãèí 1993). Áîãäàíîâñêàÿ-Ãèåíýô (1928) believed that these sites will be developed into small pools, or a restoration of Sphagnum cover will take place. According to Áî & Ñìàãèí (1993) the processes of regeneration of Sphagnum cover occur regularly by Sphagnum lindbergii or S. tenellum. Áîãäàíîâñêàÿ-Ãèåíýô (1969) emphasized the important role of Sphagnum papillosum in the restoration of Sphagnum cover of black hollows and bare peat. This question attracts my attention in connection with the interest to the geography and ecology of Sphagnum mosses. Species like Sphagnum jensenii, S. lindbergii, S. pulchrum and S. tenellum are rare in North-West Russia. During my research I found and confirmed the presence of two rare species on the bogs of Polisto-Lovat mire system: Sphagnum jensenii (the definition is checked up by Ekaterina Kuzmina) and S. tenellum. Also S. lindbergii could grow in hummock-pool sites, but it has not been found so far. The Finnish Environment

7 Acnowledgements I am grateful to Viktor Smagin for helping me to classify the mire vegetation by the method of Braun-Blanquet. References Áîãäàíîâñêàÿ-Ãèåíýô È.Ä.. Ðàñòèòåëüíûé ïîêðîâ âåðõîâûõ áîëîò ðóññêîé Ïðèáàëòèêè // Òð. Ïåòåðãîôñêîãî åñòåñòâåííî-íàó íîãî èí-òà ¹ 5. Ñ Áîãäàíîâñêàÿ-Ãèåíýô È.Ä. Î ðàñïðîñòðàíåíèè íåêîòîðûõ âèäîâ ñôàãíîâ íà Ïîëèñòîâñêèõ áîëîòàõ // Áîò. æóðí Ò. 18, ¹ 1-2. Ñ Áîãäàíîâñêàÿ-Ãèåíýô È.Ä. Çàêîíîìåðíîñòè ôîðìèðîâàíèÿ ñôàãíîâûõ áîëîò âåðõîâîãî òèïà (íà ïðèìåðå Ïîëèñòîâî-Ëîâàòñêîé áîëîòíîé ñèñòåìû). Ë., ñ. Áî Ì.Ñ., Ñìàãèí Â.À. Ôëîðà è ðàñòèòåëüíîñòü áîëîò Ñåâåðî-Çàïàäà Ðîññèè è ïðèíöèïû èõ îõðàíû. ÑÏá., ñ. Þðêîâñêàÿ Ò.Ê. Ãåîãðàôèÿ è êàðòîãðàôèÿ ðàñòèòåëüíîñòè áîëîò Åâðîïåéñêîé Ðîññèè è ñîïðåäåëüíûõ òåððèòîðèé. ÑÏá., ñ. 136