Steppe islands : where island biogeography meets the reality of a severely fragmented habitat

Aim:In southern Ukraine steppe has survived only in nature reserves, loess ravines, old cemeteries and kurgans (tumuli, burial mounds). Kurgans are small, but numerous objects resembling “islands” in “the sea” of arable land. We asked: i) how strongly does vascular plant species richness on kurgans depend on their size and does this relationship differ between steppe specialists and generalist species? ii) Which other factors influence vascular plant species richness on kurgans? Location: Southern Ukraine. Methods: We recorded species lists and environmental conditions of 112 kurgans. With non-linear regression we analyzed species-area relationships (SARs) for all species and steppe and generalists species separately. Then, we assessed importance of other factors in explaining the residuals of the SAR models using simultaneous autoregressive models and multimodel inference. Results: Kurgan area had strong influence on species richness of all groups of species, but particularly on richness of steppe specialists. The estimates of slope of the power function (z-values) in the models for total species richness were high for total species richness (0.32), but even higher for steppe species (0.49) and lower for generalist species (0.18). For total species richness and steppe species, the most important predictors in addition to area were steepness of the kurgan (positive), distance to steppe enclave (negative) and precipitation of the warm period (negative). For steppe species also habitat amount index (positive) and the disturbance (negative) were important predictors. For generalist species, the only important predictors were land use in the surrounding (lower when only arable fields) and steepness of a kurgan (positive). Main conclusions: Our results indicate that kurgans are habitat islands only for steppe habitat specialists. For this group of species, area and isolation are important predictors of species richness, what is in accordance with the theory of island biogeography, while also local factors play a role

Benchmarking plant diversity of Palaearctic grasslands

Background and Aim: Knowledge on typical levels of plant species richness of plant communities is required both for fundamental research and biodiversity conservation. Vegetation ecologists and practitioners need reference richness values to be able to assess the diversity value of specific plant communities. Palaearctic grasslands, which cover around 22% of the realm surface, are known to host high plant diversity at small spatial scales, some of them being the world record holders. However, there are also some very species-poor Palaearctic grasslands. In any case, maximum and minimum richness values are only a small part of the story. It is evident that for a robust knowledge on plant diversity mean values averaged using many replicates are needed. As plant diversity is strongly dependent on spatial scale, here we aim at providing benchmarks of plant richness values of different Palaearctic grassland types at eight grain sizes: 0.0001 m2, 0.001 m2, 0.01 m2, 0.1 m2, 1 m2, 10 m2, 100 m2 and 1000 m2. Previous studies have already proved that richness of vascular plants, bryophytes and lichens is not congruent across vegetation types, therefore, besides total plant diversity, we aim to assess separately vascular and non-vascular plant diversity, as well as the two components of the latter, bryophytes and lichens. Location: Palaearctic grasslands and low-scrubs. Taxa: Vascular plants, bryophytes and lichens. Methods: We will use data extracted from the GrassPlot database, which stores standardized vegetation-plot data sampled in precisely delimited plots. They make a total of 117,777 plots of the eight standard grain sizes, which will be analysed together with 1,051 additional plots provided specifically for this survey by Milan Chytrý and other colleagues. The 118,828 plots span a wide range of grassland and low scrub types, including rocky, sandy, xeric, meso-xeric, mesic, wet, Mediterranean, and alpine grasslands, as well as heathlands, thorn-scrubs, ruderal communities and azonal grasslands such as dune grasslands, salt marshes, wetlands, and rocks and screes. All these vegetation types are distributed across eight biomes throughout the Palaearctic realm

Cultural monuments and nature conservation: a review of the role of kurgans in the conservation and restoration of steppe vegetation

Steppe is among the most endangered biomes of the world, especially in Eastern Europe, where more than 90 % of original steppes have been destroyed due to conversion into croplands, afforestation and other human activities. Currently, steppe vegetation is often restricted to places unsuitable for ploughing, such as ancient burial mounds called kurgans. The aim of our study was to collect and synthesise existing knowledge on kurgans by a review of research papers and grey literature. The proportion of kurgans covered by steppe vegetation increases from west to east and from lowlands to uplands. Despite their small size, kurgans act as biodiversity hotspots and harbour many red-listed species. High overall species richness and a high proportion of grassland specialists are maintained by a pronounced fine-scale environmental heterogeneity. The main factors threatening the biodiversity of kurgans are intensified agriculture and construction works. We conclude that kurgans can play a crucial role in preserving steppe vegetation, especially in intensively used agricultural landscapes in the western part of the steppe zone. Despite the vital role of kurgans in sustaining steppe vegetation, we identified serious knowledge gaps on their distribution, vegetation, flora and fauna and their potential role in steppe restoration

Cultural monuments and nature conservation: a review of the role of kurgans in the conservation and restoration of steppe vegetation

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Steppe islands in a sea of fields : where island biogeography meets the reality of a severely transformed landscape

Questions: Steppes are among the most transformed and fragmented biomes in the world, but studies on the impact of habitat loss and fragmentation on these zonal grasslands are scarce. In many regions, steppe has survived only on small habitat islands, particularly on kurgans (ancient burial mounds) surrounded by intensive croplands. We asked how the size of kurgans, their isolation and other landscape and local factors influence their species richness. Location: Southern Ukraine. Methods: We recorded all species of vascular plants and assessed local (area, steepness, disturbance level), landscape (distance to the nearest habitat patch, habitat amount in the surroundings, surrounding type, distance to settlements) and climatic (precipitation) conditions of 112 kurgans. We analysed species–area relationships (SARs) for total richness, habitat specialists and generalists. Then, we assessed importance of environmental factors in explaining the residuals of the SAR models. Results: Patch area explained more than 50% of variance in total and specialist species richness. The slopes of the power function SAR (z-values) were higher for specialists than for generalists. Connectivity measures (the distance to the nearest large habitat enclave and share of habitat in the surroundings) were more important for richness of specialists than for that of generalists, which were more controlled by the kurgan's surroundings. Conclusions: We found that for specialist species the steppe “islands” follow the theory of island biogeography closely, but less so for generalist species. Combined with the revealed importance of connectivity for specialist species richness, we conclude that the conservation value of the kurgans in the long term likely can only be achieved with larger steppe areas in the surroundings

Contribution of Cultural Heritage Values to Steppe Conservation on Ancient Burial Mounds of Eurasia = Contribución de los valores culturales para la conservación esteparia en los antiguos montículos funerarios de Eurasia

Civilizations, including ancient ones, have shaped global ecosystems in many ways through coevolution of landscapes and humans. However, the cultural legacies of ancient and lost civilizations are rarely considered in the conservation of the Eurasian steppe biome. We used a data set containing more than 1000 records on localities, land cover, protection status, and cultural values related to ancient steppic burial mounds (kurgans); we evaluated how these iconic and widespread landmarks can contribute to grassland conservation in the Eurasian steppes, which is one of the most endangered biomes on Earth. Using Bayesian logistic generalized regressions and proportional odds logistic regressions, we examined the potential of mounds to preserve grasslands in landscapes with different levels of landuse transformation. We also compared the conservation potential of mounds inside and outside protected areas and assessed whether local cultural values support the maintenance of grasslands on them. Kurgans were of great importance in preserving grasslands in transformed landscapes outside protected areas, where they sometimes acted as habitat islands that contributed to habitat conservation and improved habitat connectivity. In addition to steep slopes hindering ploughing, when mounds had cultural value for local communities, the probability of grassland occurrence on kurgans almost doubled. Because the estimated number of steppic mounds is about 600,000 and similar historical features exist on all continents, our results may be applicable at a global level. Our results also suggested that an integrative socioecological approach in conservation might support the positive synergistic effects of conservation, landscape, and cultural values. Las civilizaciones modernas y antiguas han moldeado de muchas maneras los ecosistemas globales mediante la coevolución del paisaje y la humanidad. Sin embargo, pocas veces se considera el legado cultural de las civilizaciones perdidas o antiguas para la conservación del bioma de la estepa euroasiática. Usamos un conjunto de datos que contiene más de 1,000 registros de las localidades, cobertura del suelo, estado de protección y valores culturales relacionados con los antiguos montículos funerarios de esta estepa (kurgans). Después analizamos cómo estos símbolos icónicos y distribuidos extensamente pueden contribuir a la conservación de los pastizales en la estepa euroasiática, uno de los biomas en mayor peligro de extinción. Analizamos el potencial de conservación de los montículos en paisajes con diferentes niveles de transformación en el uso de suelo mediante regresiones logísticas generalizadas bayesianas y regresiones logísticas de probabilidades proporcionales. También comparamos el potencial de conservación de los montículos dentro y fuera de las áreas protegidas y evaluamos si los valores culturales locales conservan los pastizales dentro de estas mismas áreas. Los kurgans fueron de gran importancia para la conservación de los pastizales en los paisajes transformados ubicados fuera de las áreas protegidas, en donde llegaron a fungir como hábitats aislados que contribuyeron a la conservación y conectividad del hábitat. Además de que las pendientes pronunciadas impiden el arado, cuando los montículos contaban con valor cultural para las comunidades locales, la probabilidad de que el pastizal se ubicara sobre un kurgan casi se duplicó. Ya que se estima que el número de montículos esteparios ronda los 6,000 y que rasgos históricos similares existen en todos los continentes, nuestros resultados pueden aplicarse a nivel global. Nuestros resultados también sugieren que una estrategia socioecológica integradora para la conservación podría respaldar los efectos sinérgicos positivos de la conservación, el paisaje y los valores culturales