Ábrahám Levente (szerk.): Válogatott tanulmányok IV. - Natura Somogyiensis 15. / Miscellanea 4. (Kaposvár, 2009)
Salamon-Albert Éva - Horváth Ferenc: Külső-Somogy vegetációja III. Parlagok és inváziós növények diverzitása és tájmintázata
44 Natura Somogyiensis mesic deciduous woodlands in lowlands or on hills and mountains (Kla, K2, K5); closed dry deciduous woodlands (LI, L2a, L2b, L2x, L5); open dry deciduous woodlands (Ml, М2); bush vegetation and woodland margins (Jla, P2a, P2b, M7, M8); rocky forests (LY4); other treeless habitats (OA, OB, OC); other tree-dominated habitats (RA, RB, RC, RD, P45, P7). Sporadic and insignificant habitat types were missed out from the summarized analyses (e.g. Cl). Alien species was used as a binary variable (yes/no) in the database. The sum of estimated area in all hexagons and in hexagons where invasion threatens the habitats (by the presence of any alien species), results in the total area of the threatened habitats respectively. The following alien species were considered: Ail = Ailanthus altissima, Aneg = Acer negundo, Amor = Amorpha fruticosa, Asci = Asclepias syriaca, Ast = Aster spp., Celt = Celtis occidentalis, Ech = Echinocystis lobata, Elae = Elaeagnus angustifolia, Frax = Fraxinus pennsylvanica, Phyt = Phytolacca americana, Pru = Prunus serotina, Rey = Reynoutria spp., Sol = Solidago spp., Rob = Robinia pseudo-acacia, Vit = Vitis spp. and Oth = some additional but unnamed species. Hardly distinguished related species were aggregated into a genus (e.g. Reynoutria spp.). Among the data on plant invasion collected in the META survey annual aliens of arable fields and species of cultivated (e.g. forest) plantations were not included. In the tables sum cover of habitat types threatened by plant invasion, number and ratio of invasive species in a habitat type, and the number and ratio of habitats threatened by the given species was calculated. Regional data of habitat types which are similar from the point of invasion were also especially amalgamated for the comparison with national results (see Botta-Dukát 2008). Results Threatened habitats and diversity of alien species Results of the study have shown that habitats occurring in Külső Somogy region are differently referred to plant invasion (Table 1). Relative area of habitats threatened by alien plant species varies between 0 and 100%. Extremities (0 and 100) can be seen in case of fragmented or sporadic habitat types (e.g. A3a, LY4, М2) and it is according to their extensions. 29 habitat types (60.4%) have more than 50% relative area threatened by any alien species. Hardly threatened vegetation types - where areal ratio is over 50% - are in greater proportion among woody habitat types (65.4% from Jla to RD) than among non-woody ones (59.1% from A1 to OC) as well as the average of threatened areas in woodlands (60.8%) than in grasslands (56.1%). In case of euhydrophyte habitats (Al, A23, A3a) and transition mires (Cl) there are no vegetation patches threatened by any plant invasion. There are no correlation between high proportion of threatened area and proportion of alien species in habitat patches. 15 most important and some additional but unnamed other alien species were detected in habitats (Table 1). Alien species occured with more than a half total number in a third of habitat types both in grasslands (31.8%) and woodlands (30.8%). Occurrence of Robinia pseudo-acacia, Solidago spp., Ailanthus altissima and some other species is the most significant. Among them Solidago spp. and some other species are the most frequent in patches of grassland habitats, Robinia pseudo-acacia and Ailanthus altissima are the most frequent in patches of woodland habitats. Least threatening species are Prunus serotina, Reynoutria spp., Aster spp., Celtis occidentalis and Fraxinus pennsylvanica in the habitats. It can be observable that the most threatening species in habitat groups by Molnár et al (2008) are of colline and montane hay meadows, dry and semi
