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
42 Natura Somogyiensis Vegetation pattem with different origin and former land use could be developed in abandoned fields. Abandoned fields can be established from unused vineyards, arable lands or orchards. Some annual species strongly affect the vegetation composition of 2-5 year-old abandoned field, but perennial species dominate on the 5-10 year ones. On the 10-50 year-old abandoned fields semi-natural grasses, on the oldest ones (50- years) woody vegetation could exist. Biological invasion is one of the most important danger in habitat changes, connected to fragmentation of natural vegetation (Cronk and Fuller 2001). Status of biological invasions and actual knowledge about species concerned in Hungary was earlier summarized (Török et al 2003, Mihály and Botta-Dukát 2004, Botta-Dukát and Mihály 2006). There are numerous papers as case studies from smaller areas of Hungary about alien species responsible for biological invasion (e.g. Balogh 2001), but not in Külső- Somogy region. Data on species distribution and habitat preferences of them could be gained by combining with maps and any other databases, e.g. phytosociological ones (Botta-Dukát 2008). In our work, as the third study of a landscape series, we present and evaluate basic statistics of abandoned fields and plant invasion connected to semi-natural woodlands and non-woody habitat types and groups in Külső-Somogy region. Analyses are executed for the cover of abandoned and invaded areas at landscape scale, and for 15 selected alien species in habitat types and groups with MÉTA method and mapping (GIS database for Hungarian Habitats, Magyarországi Élőhelyek Térképi Adatbázisa, Horváth et al 2008) based on a landscape ecology oriented protocol fitted to the whole territory of Hungary (BöLöNi et al 2007, Molnár et al 2007). Material and method Region of Külső-Somogy (Fig. 1) is located south from Lake Balaton, bordered by Kapos River, Sió Channel and Pogány Valley in the territory of Somogy and Tolna counties. Its total extension is 3000 km2, mean altitude is 186 m a.s.l., 200-300 m a.s.l. especially on the ridges of the hills. The bedrock is limestone covered by loess on the surfaces of the crests trended to north-south direction. In the western part of the area (West Külső-Somogy) the ridges of the hills are exposed to erosion and derasion. The eastern part of the region (East Külső-Somogy) is dissected with valleys parallel to Lake Balaton and the south part of it (South Külső-Somogy) is a horizontal loess plateau with moderate slope to Kapos River. Running through the main north-south valleys, Jaba Stream and Koppány Stream flow from west to east. According to the data of regional meteorological stations (Szabadhídvég, Kaposvár) the mean temperature is -2.5 C° in January, +20.5 C° in July, the sum of precipitation is 650 mm per year. There are some cities and many small villages, so Külső-Somogy is not a frequent region from an economical point of view (Marosi and Somogyi 1990). On the basis of drought-sensitivity index several vegetation types existing in the south-eastern part of the region could be endangered in climatically dry periods (Németh et al 2004). Data collection and analyses Field data collection was executed between 2003-2006 as a grid-based, satellite-image supported (SPOT4), multi-attributed, large-scale mapping method so called MÉTA (Molnár et al 2007). It is based on Á-NÉR2003 mapping and habitat guide (Bölöni et al 2007). The goals of the research were: 1) to collect data of all natural and semi-natural
