Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 88. (Budapest 1996)

Csontos, P., Horánszky, A. , Kalapos, T. ; Lőkös, L.: Seed bank of Pinus nigra plantations in dolomite rock grassland habitats, and its implications for restoring grassland vegetation

CONCLUSIONS Under the studied black pine plantations the over-all paucity of seeds in the soil especially when members of the dolomite grassland vegetation are taken into account makes the landscape restoration difficult, since we can not expect considerable regeneration from buried seeds (cf. GRAHAM & HUTCHINGS 1988, DONELAN & THOMPSON 1980 and WARRera/. 1993). An additional risk factor is that the majority of the dolomite grassland species lack effective dispersal methods, but wind dispersed seeds of other vegetation types are already present in the seed bank. Following massive disturbances like clear felling or forest fires wind dispersed species will obviously colonize the habitat immediately (POSCHLOD & JORDAN 1992). In our case Calamagrostis epigeios and Conyza canadensis, are the most likely to form dense populations following disturbance. Considering the results, our suggestions for landscape restoration are the following: In the first place a network of glades should be cut in the forest, with width about double the tree height of the surrounding stands. Following establishment of grassland vegetation on these glades their width should repeatedly be enlarged until neighbouring glades join each other. The execution of the enlarging operation cannot be more frequent than at every fourth year, since JÁRÓ et al. (1988) found a three year recovery time of soil variables (e. g. decomposition of needle carpet, humus content and -quality) by monitoring a Pinus nigra clearcut area, and the recolonization of grassland species which are lack of seed bank can be expected in the third year after clearing (POSCHLOD & JORDAN 1992). * * * Acknowledgements - Special thanks are due to K. THOMPSON (Sheffield) who critically revised the first version of the manuscript. Discussion with A. SENDTKO (Freiburg) is also acknowledged. We arc grateful to I. IsÉPY and I. PINTÉR for allowing us to work in the greenhouse of the University Botanical Garden. This research was supported by the Hungarian Scientific Research Fund (OTKA No. 3167). REFERENCES BORBÁS, V. (1900): A Balaton tavának és pailmellékének növényföldrajza. (The vegetation of Lake Balaton and its surroundings.) - AM. Földrajzi Társaság Balaton-Bizottságának kiadása, Budapest, 431 pp. BORHIDI, A. (1956): Feketefenyveseink társulási viszonyai. (Zönologische Verhältnisse unserer Schwarzföhrenwälder). - Bot. Köziem. 46: 275-285. BÖDis, J. (1993): A feketefenyő hatása nyilt dolomit sziklagyepre. I. Texturális változások. (Degradation of dolomite grassland communities due to Pinus nigra plantation. I. Textural changes.) - Bot. Köziem. 80 (2): 129-139. CsAPODY, V. (1968): Keimlingsbestimmungsbuch der Dicotyledonen. Akadémiai Kiadó, Budapest, 286 pp.