Ábrahám Levente: Válogatott tanulmányok II. - Natura Somogyiensis 9. (Kaposvár, 2006)

Juhász Magdolna - Dénes Andrea: Biomonitoring of alder swamp forests - Égeres mocsárerdő monitoring vizsgálata

44 NATURA SOMOGYIENSIS proportion is between 13-40% by coverage and between 19-31% by presence-absence in the study years. Competitors have highest proportions (by coverage 52-76%», by presence-absence 30-40%). In some years natural pioneers have an important role too, 0-6% by coverage. Natural disturbance tolérants are very few (1% by coverage) but they are present floristically, and they presumably will gain space significantly if growing place becomes drier. Table 3: Change in percentage distribution of species by social behaviour types in alder swamp forest SBT by covering by presence-absence SBT 2000 2001 2002 2003 2004 2000 2001 2002 2003 2004 Specialists 27.00 20.46 39.80 13.48 18.46 25.60 26.76 31.31 20.43 18.99 Competitors 59.10 64.90 52.20 76.31 66.95 32.10 30.04 32.17 40.01 33.76 Generalists 7.70 12.25 6.42 9.59 11.49 19.10 22.54 26.09 29.13 27.85 Natural pioneers 5.70 1.81 0.00 0.01 2.23 12.10 12.21 0.00 0.43 9.70 Disturbance tolérants 0.50 0.58 1.58 0.61 0.87 11.10 8.45 10.43 10.00 9.70 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Conclusions Coenological studies of alder swamp forests along river Drava were accomplished in five consequent years. Year-to-year changes in coenological characteristics of the community were pointed out. Analysis of data and field observations unambiguously prove that experienced changes are connected closely with changes of water supply of the growing place. The natural plant communities living on the floodplain need the floods and the high ground-water levels temporarily. Degradation processes make start and the habitats become weedy if these not occur systematically. Species composition and covering of species of the studied swamp forest are determined basically by: when the soil surface is covered by water, for how long and how high water level is. Preservation of natural state of the community needs floods of the river and temporal surface flooding of growing place connected to them. Literature BORHIDI, A. 1995: Social behaviour types, their naturalness and relative ecological indicator values of the higher plants of the Hungarian Flora. - Acta Botanica Hungarica 39: 97-182. BORHIDI, A. & KEVEY, B. 1996: An annotated checklist of the Hungarian plant communities II. The forest communities. - In: Critical revision of the Hungarian plant communities (Ed.: BORHIDI A.), 95-138. Janus Pannonius University, Pécs. JUHÁSZ M. 1997: A vegetáció jelenlegi állapota a Dráva-sík és Belső-Somogy határvidékén - Dráva Konferencia, p. 21. JUHÁSZ M. 2004: A somogyi Dráva-ártér növényzete. In: SALLAI Z. (ed.): A drávai táj természeti értékei. Nimfea Tanulmánykötetek 3:20-28. JUHÁSZ M. & DÉNES A. 2001: Időszakosan vízzel borított erdőtársulások alapállapot-felmérése a Dráva-monitoring keretében. - II. Dráva Konferencia, p. 9. JUHÁSZ M. & DÉNES A. 2004: Időszakosan vízzel borított erdőtársulások monitoring vizsgálata a Dráva mentén. - Flóra- és Vegetációkutatás a Kárpát-medencében VI. p. 71.