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A 13-year change in ground-layer vegetation of Carpathian beech forests

Łysik M.

Polish Journal of Ecology

2009

Vol. 57, nr 1

47-61

13 year changes in the ground vegetation of natural beech forest were studied in the Babia Góra National Park (South Poland) and compared with the results of similar study in the Ojców National Park published previously (Łysik 2008). In 1-ha permanent research plot homogeneous vegetation patches of the size at least 1m[^2], that differed from neighbouring patches in species composition and/or species share (patch types) were specified and mapped. After intersecting two (for years 1991 and 2004) numerical maps a synthetic map, used then as a basis for evaluating the ground vegetation changes, was created. Changes in each patch and dynamics of each species were derived using adequate formulas. Shannon-Wiener and evenness indices were measured for both years. Comparison of species composition and structure of the herb layer in 1991 and 2004 gives evidence of a highly dynamic nature of the ground layer. On 27% of investigated area vegetation were totally different than 13 years before, while less than 3% of the study area stayed unchanged. On the rest of the area changes of diverse intensity occurred. However, the mean over-plot intensity of changes was about 65% (calculated according to formula 1). Plant cover decreased by about 20%, but at the same time increases were noticed in species number and patch types. There was a significant increase in the area covered by grasses and ferns at the expense of Rubus idaeus L., which used to be a dominant species in 1991. Moreover, cover share of all species become more evenly distributed in comparison with situation 13 years before (evenness index increased from 0.49 to 0.68). The most dynamic species were those associated with decaying stumps and downed logs. These results suggest that, in natural beech forests, overstory dynamics or other mechanisms (like competition with natural recruitment of trees) make the dominance of any species in ground-layer not longer than a decade.