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Plant diversity along an elevation gradient in hyrcanian forest of Northern Iran

Ataei Eshagh, Kazemnezhad Farid, Eshaghnimvari Majid, Sheykholeslami Ali

Polish Journal of Ecology

2022

Vol. 70, nr 2-3

69--78

Species diversity is one of the most important and fundamental issues in ecology. The present study was conducted to evaluate effects of elevation gradient on biodiversity in a temperate mountainous forest. For collection of trees' diversity data, 44 sample plots 20 × 20 m2 were set up every 50 m of the elevation interval at the altitude ranging from 100 m to 2250 m a.s.l. Also for collection of data on herbaceous vegetation, five microplots (1 × 2 m) were established (one microplot in the center and four microplots in the four corners of the plot). Species diversity values were analyzed using Simpson and modified Shannon Wiener indices. Also, species richness was calculated using Margalef and Smith-Wilson indices for each plot. The results from Simpson and modified Shannon Wiener biodiversity indices imply approximately bell-shaped diversity curves with the greatest species richness at medium elevations (800–1300 m a.s.l). However, if ecotones (gradual changes between two communities) are excluded, one can conclude that species biodiversity decreases with increasing elevation. The lowland community has the least richness that can be the result of the anthropogenic pressure. The evenness indices for the forest sites along the elevation gradient detected no trend with increasing elevation.

Small scale spatial pattern of a soil seed bank in an old-growth deciduous forest

Wódkiewicz K., Kwiatkowska-Falińska A.

Polish Journal of Ecology

2010

Vol. 58, nr 3

487-500

We studied an old growth deciduous forest seed bank to examine how its potential role in regeneration is shaped by natural forest environment. Our research questions were: is the spatial pattern of seed bank influenced by local variation in elevation, soil moisture and light intensity, and what is the impact of herb layer characteristics on seed bank pattern. We recorded species composition of the herb layer and seed bank on a 2 x 40 m study plot divided into 20 quadrates, situated in a natural oak-hornbeam forest, in the Białowieża Primeval Forest, (NE Poland). Soil cores were sampled from two soil layers (0-5 cm and 5-10 cm) yielding altogether 40 samples of a total 15.9 dm[^3] and 0.159 m[^2]. Seeds were extracted from soil samples under a microscope. Ellenberg indicator values were used to characterize light (L) and moisture (F) conditions. Relative quadrate elevation was averaged for nine points. There were 6.65 x 10[^3] seeds m[^-2] in upper soil layer and 3.00 x 10[^3] seeds m[^-2] in lower soil layer. Seed bank structure constituted of patches 6 m diameter in the upper soil layer and 4 m in the lower soil layer. Aggregated pattern of the seed bank was influenced by clumped distribution of plants in the herb layer. Seed bank species richness in the upper soil layer was correlated with moisture (r = 0.485, P =0.03) and light (r = 0.526, P = 0.0172) values. Seed densities were correlated with moisture (r = 0.848 P <0.0001 upper and r = 0.491 P = 0.0278 lower soil layer) and light (r = 0.803 P <0.0001 upper and r = 0.751 P = 0.0001 lower soil layer). Seed density in upper soil layer was negatively correlated with elevation (r =.0.485 P = 0.0422). Higher seed density and species richness of the seed bank associated with better light conditions and higher moisture is probably caused by higher seed production in favourable conditions, and factors promoting seed persistence in soil. Our results indicate, that even subtle changes in light, moisture and mean relative elevation can shape seed bank spatial pattern on a fine local scale, differentiating the response of this community to small scale disturbances present in natural forests.