Role of small habitat islands in human transformed landscapes nature conservation, cultural and ecosystem services Dr. Balázs Deák Department of Ecology
Landscape transformation Area of natural habitats considerably decreased during the past centuries Human activities: urbanisation, agricultural intensification Increased level of habitat loss since the industrial revolution East-west gradient in Eurasia Level of landscape transformation decreases from lowlands to highlands
Human induced landscape changes Loss of habitats Fragmentation: a large expanse of habitat is transformed into a number of smaller patches of smaller total area, isolated from each other by a matrix of habitats unlike the original (Wilcove et al. 1986) Isolation: measure of the lack of habitat in the landscape surrounding the patch. The more isolated a patch is, the less habitat there is in the landscape that surrounds (Fahrig et al. 2003) Fahrig et al. (2003) Annu. Rev. Ecol. Evol. Syst.
Landscape fragmentation Fahrig et al. (2003) Annu. Rev. Ecol. Evol. Syst.
Fahrig et al. (2003) Annu. Rev. Ecol. Evol. Syst.
Fragmented but not isolated
Fragmented and Isolated
Negative consequences of fragmentation Small habitat size can be detrimental for several species Small population size (inbreeding, decreased resistance against stochastic events) Increased edge effect -> increases the chance for interaction with hostile habitats (e.g. with arable lands) Increased pollution Altered abiotic conditions (humidity, temperature, water movements etc.) Invasion of weeds and adventive species Species with a high mobility can leave the patch by chance
Negative consequences of isolation Decreased movement between habitat patches Limited re-colonization of species after disturbances Reduced gene flow, genetic isolation Effects are species specific Challenges in management
Effects of isolation on plant species Specialist species are especially sensitive for isolation (low tolerance against disturbance, low dispersal rate) Darwin s wind hypotheses (Darwin 1859): there is a higher chance of mortality related to good dispersal in isolated habitats -> good disperser strategy can be a bad choice in transformed landscapes Long lived species with a good competitive ability have a higher chance for survival Ruderal species are favoured by isolation (Grime 1979) Galapagos island Phalacrocorax harrisi
Extinction debt The number of (specialist) species can coexist in a certain habitat patch is in a strong correlation with the area of the habitat patch Extinction debt refers to the number of species in an isolated area that likely will become extinct in the next future (Helm et al. 2006) Extinction debt is paid when the species number in a certain area is in equilibrium with the habitat parameters of the patch Can be delayed by long lived and clonal species
3rd Military survey (1869-1887) Ortofoto (2013) Military map (1999)
Mondró-halom 74 species, loess grassland Inula germanica, Ranunculus illyricus, Rosa gallica, Kochia prostrata, Agropyron cristatum, Saxifraga bulbifera, Trifolium alpestre, Rosa gallica, Lychnis viscaria, Thalictrum minus Deák et. al (2015) Kitaibelia
Role of kurgans in preserving steppe vegetation Steppe is one of the most endangered biom 80-95% of its original stands has been destroyed In many cases steppe vegetation could persist only in small fragments inadequate for arable lands Field margins, road verges, balks, rocky outcrops AND kurgans térkép
Burial barrows Kurgans Made of the topsoil of the neighbouring areas Built mostly in the Eneolitics (2800-2200 BC) Present in all regions of the steppe biom Height (0,5-15m), surface (0.01-1 ha) Preserve historical artefacts, sacral places, folkloristic and cultural importance, part of the steppic landscapes
Deák et al. 2016 Biodiversity & Conservation
Map of kurgans in Hungary Tóth 2006 Geology, Geomorphology, Physical Geography Series
Landcover types on kurgans Originally covered by grasslands Present days: arable lands, forest plantations, urban areas AND grasslands Gradient from lowlands to highlands Gradient from west to east Hungary 7% (Tóth 2006) Ukraine 23% (Sudnik-Wójcikowska et al. 2011) Kazahstan???
Biodiversity conservation potential Despite their small area, kurgans harbour a high biodiversity Ukraine; 721 species, 72 red listed species on 106 kurgans (Astragalus borysthenicus, A. dasyanthus, A. pallescens, Cerastium ucrainicum, Crocus reticulatus) Diverse topography provides high environmental heterogeneity
Threatening factors Threaten the physical structure of the kurgans and/or the habitats Main categories: urbanization, agriculture, other human or biotic Increasing negative trend with agricultural intensification
Country Urbanisation HUN ROM BUL UKR RUS KAZ Settlements x x x x x* Infrastructure (roads, channels) x x x x x* x* Single buildings x x x* x* Water reservoires x x Mineral extraction x* x Agriculture Ploughing x x x x x x* Orchards, gardens x x x Chemicals x Afforestation x x* x* Overgrazing x x x Animal farms x Fishponds x Other anthropogenous Archeological excavations x x* x x x Turism x x Fire x x x* Plant collection x Military objects x War x Garbage deposition x Biotic Woody encroachment x x Weeds x x Invasive species x x Encroachment of reed x
Landscape scale changes Threatening factors Agricultural intensification Urbanisation Woody encroachment Mineral extraction
Landscape scale changes - Isolation Many of the kurgans are surrounded by a hostile matrix Nature conservation problems: Isolated populations Management of small isolated areas is challenging Exposed to several disturbance factors
Selection of kurgans 44 kurgans in East Hungary Covered by loess grassland Field survey Situated in hostile matrix (radius 200m) Height > 3m Field data List and percentage cover of vascular plants Environmental predictors: area, slope, past destruction, recent disturbance, encroachment of native and alien woody species Deák et al. 2016 Biological Conservation
Ebéd halom (Bihar)
Két-halom (Hortobágy)
Mondró halom (Bihar)
Results 337 species, 54 grassland specialist species (10.6 ha) Agropyron cristatum Phlomis tuberosa Ranunculus illyricus Aster sedifolius Some kind of recent disturbance was present in every kurgans Woody encroachment (>10%) was typical in 59% of the kurgans Past destruction on 82% of the kurgans
Dependent variable Explanatory variables Estimate Std. Error z value p Specialist (species number) Area <-0.001 <0.001 0.862 0.389 Slope 0.044 0.016 2.655 0.008 Recent disturbance -0.423 0.090 4.546 <0.001 Past destruction -0.121 0.072 1.626 0.104 Alien woody cover -0.007 0.003 2.126 0.034 Specialist (cover) Recent disturbance -0.317 0.083 3.712 <0.001 Past destruction 0.196 0.075 2.745 0.012 Native woody cover -0.012 0.009 1.224 0.221 Problem species (species number) Recent disturbance 0.064 0.062 1.362 0.173 Problem species (cover) Past destruction -0.085 0.061 1.363 0.173 Slope -0.031 0.015 2.001 0.046 Recent disturbance 0.149 0.073 1.970 0.049 Past destruction -0.221 0.065 3.278 0.001 Native woody cover 0.004 0.003 1.705 0.088 Alien woody cover 0.011 0.008 1.350 0.177
Conclusions No significant effect of habitat area -> all sizes of kurgans should be protected Steep slopes (specialists, problem species ) Prevented ploughing Provided a dry environmental conditions Increased leaching of humus and nutrients from the top and slopes Recent disturbance (specialists, problem species ) Decrease in grassland area and proper micro-sites Limited re-establishment for specialists High ratio of disturbed surfaces
Conclusions Past destruction (specialists, problem species ) local increase in slope -> environmental changes favourable for specialists (Agropyron cristatum, Artemisia santonica, Carex praecox) No effect of moderate native woody cover Presence of alien woody species suppressed specialist species (specialists ) Shading Increased soil N-availability (Robinia pseudoacacia)
Take home message In spite of their small area kurgans act as biodiversity hotspots in intensively used landscapes Both from nature conservation and cultural point it is essential to preserve these habitats Most of the kurgans are effected by some kind of human disturbance or detrimental natural process We need more efficient legal restrictions, agrienvironmental schemes and management plans for kurgan protection
Role of small habitat islands in sustaining biodiversity in agricultural landscapes Local biodiversity hotspots Increases landscape permeability, decreases the effects of isolation Green corridors (river balks, dams, road verges, field margins) Stepping stones (abandoned quarries, rocky outcrops, kurgans) Application in nature conservation planning
Kurgans in steppe reconstruction Sudnik-Wójcikowska & Moysiyenko (2014)
Ecosystem services Increasing aesthetic values of the landscape Sustainment of pollinator populations Biological control by predator insects Yield maximalization Application in Agri-Environmental Schemes Small scale grassland restoration Grassy margins for insects Interrow grasslands
References Deák et al. (2016): Cultural monuments and nature conservation: The role of kurgans in maintaining steppe vegetation. Biodiversity & Conservation 25:2473 2490. Fahrig (2003) Effects of habitat fragmentation on biodiversity. Ann. Rev. Ecol. Evol. Syst. 34, 487 515. Deák et al. (2015a) Mondró-halom kurgan (Hencida, East Hungary), a refugium of loess grassland vegetation. Kitaibelia 20:143 149. Deák et al. (2016) Factors threatening grassland specialist plants - A multi-proxy study on the vegetation of isolated grasslands. Biological Conservation 204: 255-262. Sudnik-Wójcikowska & Moysiyenko (2014) Indicative role of the flora of kurgans in the Wild Field (southern Ukraine). Monit Srod Przyr 15:75 83. Tóth (2006) Results of the national mound cadastering from the aspect of geological conservation. Acta Debrecina Geol Geomorphol Phys Geogr Ser Debr 1:129 135.