Faállományok kiszáríthatják a homoki gyepek altalaját - valóban a klímaváltozás ellen küzdünk a fásítások erőltetésével?

Tölgyesi Csaba elsőszerzőségével megjelent legújabb cikkünk az Ecography szaklap hasábjain. A cikkben rámutatunk, hogy a jelenleg előtérbe helyezett klímavédelmi céllal végzett fásítás nem megfelelő élőhelyek illetve fafajválasztás mellett negatívan befolyásolhatja az élőhelyek vízviszonyait tovább szárítva az egyébként is vízdeficittel jellemezhető élőhelyeket. A cikk összefoglalója az alábbiakban olvasható, a teljes szöveg szabadon hozzáférhető az újság honlapján.

Underground deserts below fertility islands? Woody species desiccate lower soil layers in sandy drylands

Tölgyesi Cs., Török P., Hábenczyus A.A., Bátori Z., Valkó O., Deák B., Tóthmérész B., Erdős L., Kelemen A.

Woody plants in water-limited ecosystems affect their environment on multiple scales: locally, natural stands can create islands of fertility for herb layer communities compared to open habitats, but afforestation has been shown to negatively affect regional water balance and productivity. Despite these contrasting observations, no coherent multiscale framework has been developed for the environmental effects of woody plants in water-limited ecosystems. To link local and regional effects of woody species in a spatially explicit model, we simultaneously measured site conditions (microclimate, nutrient availability and topsoil moisture) and conditions of regional relevance (deeper soil moisture), in forests with different canopy types (long, intermediate and short annual lifetime) and adjacent grasslands in sandy drylands. All types of forests ameliorated site conditions compared to adjacent grasslands, although natural stands did so more effectively than managed ones. At the same time, all forests desiccated deeper soil layers during the vegetation period, and the longer the canopy lifetime, the more severe the desiccation in summer and more delayed the recharge after the active period of the canopy. We conclude that the site-scale environmental amelioration brought about by woody species is bound to co-occur with the desiccation of deeper soil layers, leading to deficient ground water recharge. This means that the cost of creating islands of fertility for sensitive herb layer organisms is an inevitable negative impact on regional water balance. The canopy type or management intensity of the forests affects the magnitude but not the direction of these effects. The outlined framework of the effects of woody species should be considered for the conservation, restoration or profit-oriented use of forests as well as in forest-based carbon sequestration and soil erosion control projects in water-limited ecosystems.

Szintézis a Palaearktikus gyepek biodiverzitásáról és a veszélyeztető tényezőkről

Megjelent az 2020 nyarán publikálásra kerülő az Elsevier kiadó által gondozott 'Encyclopedia of World's Biomes' művésznévre hallgató cikkgyűjtemény Palearktikus gyepekkel és cserjésekkel foglalkozó részének tizenkét cikkét bevezető szintézisfejejezet Jürgen Dengler elsőszerzőségével. A cikk frissíti a 'Grasslands of the World' (Taylor and Francis, CRC Press, 2018, Török & Dengler: Palaearctic Grasslands in Transition: Overarching Patterns and Future Prospects) tanulmánykötetben szereplő cikk adatait, illetve a cikkgyűjtemény kiegészült őshonos cserjések ismertetésével is. A kötet vonatkozó fejezete (és a kelet-európai régióra vonatkozó rész) elérhető lesz a honlapomon is, de letölthető lesz a cikkgyűjtemény oldalán is. Az összefoglalója az alábbiakban olvasható.

Grasslands of the Palaearctic Biogeographic Realm: Introduction and Synthesis

Dengler J.,  Biurrun I., Boch S., Dembicz I., Török P.

Grasslands are spontaneously occurring herbaceous vegetation types that are mostly dominated by grasses or other graminoids and have usually > 10% herb-layer cover, while woody species area absent or have a significantly lower abundance than the herbs. In the Palaearctic biogeographic realm, natural and secondary grasslands (76% and 24% of all grasslands, respectively) cover about 10.0 million km2, i.e., 18% of its territory, which constitute 41% of global grasslands—more than any other biogeographic realm. In “The encyclopedia of the world's biomes,” the Palaearctic grasslands are placed in the section “Grasslands and shrublands,” where we defined 10 regions, which are treated in individual chapters: Western Europe, Northern Europe and Baltic States, Eastern Europe, Mediterranean Region, Middle East and Caucasus, Russia, Kazakhstan and Middle Asia, Mongolia, China, and Japan. These regions cover the huge majority of the realm and about 98% of its grasslands. Each chapter describes the extent, physiogeography, origin, biodiversity and typology of the grasslands in the region, the threats for grassland diversity and extent, as well as grassland management and conservation. Grasslands are important habitats for many groups of taxa. Dry calcareous grasslands and steppes constitute habitat of most of Europe's butterfly and Orthoptera species, and they host significant number of European endemic plants. In small spatial scales (i.e., below 100 m2) Palaearctic grasslands, especially meso-xeric ones, can hold even higher species diversity of plants than tropical rainforests. However, Palaearctic grasslands are also among the most intensively and negatively human-impacted habitats. Changes in grassland management, like overgrazing or other types of intensification as well as abandonment were assessed as the most important recent and future threats. Other important reasons of decline in grassland diversity are habitat loss and altered site conditions. The negative impact of climate change and invasive species is predicted to be stronger in the future. In the last years, various conservation efforts to monitor, maintain and promote grassland extent and diversity were made. However, to counteract the negative trends, these efforts urgently need to be intensified and their efficiency needs to be improved.