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The Importance of Forest Patches in Supporting Steppe-Species: A Case Study from the Carpathian Basin

Erdős L., Tölgyesi C., Körmöczi L., Bátori Z.

Polish Journal of Ecology

2015

Vol. 63, nr 2

213--222

Moderating effects of trees on the environment in their immediate proximity are considered an important force in structuring plant communities, especially in harsh environments. In the semi-arid regions of the middle Carpathian Basin, such facilitative influences are expected to become crucial for the survival of several plant species, given the current warming and drying tendencies. We used 20 × 20 m plots to analyze whether grassland species adapted to mesic conditions penetrate forest patches, where they are able to survive. Using transects and the moving split window analysis, we also investigated how far the positive effects of the forest patches extend into grasslands, and whether this enables the existence of a steppe community that cannot tolerate extreme dry conditions and unfavorable soils. We found that beside forest-related species, forest patches hosted large numbers of grassland-related species. Among them, plants of closed steppe grasslands were the most numerous, which usually cannot tolerate the harsh conditions of open sandy grasslands, and are often confined to areas with better water and soil conditions. Our results showed that there is a 5–8 m wide closed steppe zone around the forest patches. Some species that are not able to survive in open xeric sandy grasslands are restricted to this zone. Unfortunately, while considerable attention is paid to the research, protection and restoration of sandy grasslands, forest patches are usually neglected. Our results emphasize that the establishment of individual trees and groups of trees should be actively promoted, because they have considerable nature conservation benefits by supporing closed steppe species.

Dynamics of sandy desertification and detection of sandy land/steppe boundary : vegetation and soil properties

Xu D., Xu X., Xie Y., Wang K.

Polish Journal of Ecology

2012

Vol. 60, nr 2

251-263

Desertification is one of the most serious environmental problems on a global scale. China suffers from desertification over large areas. Landscape boundaries profoundly influence the structure and function of landscapes, and influence ecological processes both locally and over large scales. Data on soil properties and vegetation collected on three 110 km parallel transects across sandy land-steppe transition zone in Yanchi county, Ningxia region, northwestern China, were used to analyze changes along the sandy land/steppe boundary by using the Moving Split Window (MSW), to determine desertification dynamics, and to explore changes of vegetation and soil properties among different desertification degree. Combining the dissimilarity profiles of soil particle size with importance value (IV) of vegetation, four boundaries were detected along transects. According to the four boundaries, we divided the whole sandy land/steppe ecotone area into five desertification categories: potential desertification (PD), light desertification (LD), medium desertification (MD), severe desertification (SD) and extreme desertification (ED). Sand fractions increased, while silt and clay fractions, soil organic C, total N and available N decreased and exhibited clear gradient changes from the potential desertification land to the extreme desertification land. All areas we studied have been desertificated at different degree based upon soil particle compositions at different depths. With the aggravation of sandy desertification, the steppe species dominating in the potential desertification land gradually gave place to arid and sand tolerant perennials and therophytes and eventually to psammophyte annuals and shrubs in the extreme desertification land.