B. Papp szerk.: Studia Botanica Hungarica 33. 2002 (Budapest, 2002)

Dobolyi, Konstantin: Studies of vegetation dynamics on the rock grasslands in Csíki-hegyek (Budaörs, Hungary)

Table 9. Distribution of the nitrogen preference categories on the sites (BORHIDI 1993) (ex­pressed in percentage). Nitrogen prefer­Odvas-hegy Szekrényes-hegy Farkas-hegy Kő-hegy ence categories 1996 2001 1996 2001 1996 2001 1996 2001 1 50.3 49.0 71.7 71.3 74.5 70.7 58.7 61.8 2 37.5 37.1 18.0 20.47 18.6 17.0 23.3 16.4 3 10.5 11.8 7.8 7.1 6.6 11.2 14.9 18.7 4 1.7 1.6 2.5 1.2 0.3 1.1 3.1 3.1 5 ­0.5 ­­­­­6-9 ­­­­­­­One potential kind of degradation is spreading of nitrophilous weeds in sev­eral vegetation types and distribution of the nitrogen preference categories can in­dicate nitrogen pollution of the environment. In our case low nitrogen preference is significant on the four sites. In Farkas-hegy the proportion of the higher nitrogen preference categories have been increasing in a small extent (Table 9). DISCUSSION Although we have no early data about the original vegetation of Csíki-he­gyek, the main vegetation types could be: pubescent oak scrub woodlands, rock steppes, open and closed rock grasslands (ZÓLYOMI 1958). Most of the woods were cut several hundred years ago and the dolomite hills were pastured inten­sively. Proportion of the grasslands has increased in time, and their structure has • Odvas-hegy • Szekrényes-hegy • Farkas-hegy • Kő-hegy Fig. 1. Average naturalness value of the sites.

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