- IMPACT OF LAND USE CHANGES ON MOUNTAIN VEGETATION - 173 Applied Vegetation Science 5: 173-184, 2002 © IAVS; Opulus Press Uppsala. Abstract. In this study the impact of land use changes on vegetation in the sub-alpine-alpine belt is analysed. The study sites (4.7 km 2 ) are located in the Passeier Valley (South Tyrol, Italy), at an elevation of 1500-2300 m a.s.l. The whole study area was used for hay-making ca. 60 yr ago. Today, part of the meadows are more intensively used, while other parts have been converted to pasture or have been abandoned. We analysed the reasons for these land use changes and the effects on vegetation with a Geographical Information Sys- tem and geostatistical analysis. The result of these analyses are: (1) Current land use is mainly controlled by the degree of accessibility for vehicles. Accessible areas are being used more and more intensively, while poorly accessible areas are being abandoned or used as pasture. (2) Current vegetation is highly determined by current land use. Particular vegetation units can be assigned to each form of land use. (3) Succession starts immediately after abandonment. De- pending on altitude, succession proceeds at different speeds and with different numbers of stages. Hence the type of vegetation indicates the time passed since abandonment. (4) Land use changes lead to characteristic changes in vegetation; they are considered to be the most important driving force for vegetation change. (5) Measures of intensification and abandonment of exten- sively used areas both lead to a decrease in the number of species. Keywords: Land use history; Meadow; Pasture; Secondary succession; Species richness; Sub-alpine belt; Vegetation change. Nomenclature: Adler et al. (1994). Introduction Variation in environmental factors leads to a patchy distribution of vegetation in sub-alpine and alpine re- gions. Superimposed on this distribution pattern there has been an impact of land use for centuries (e.g. Dietl 1995; Giacomini & Pignatti 1955; Hruska & Maggi 1993; Schaminée & Meertens 1992; Spatz 1994; Wegener & Reichhoff 1989). Depending on the type (mowing, grazing) and intensity (frequency of annual mowing, fertilization, irrigation, number of grazing ani- mals) of land use, characteristic vegetation communi- ties develop (Gómez-Sal et al. 1992; Grootjans et al. 1996; Hruska & Maggi 1993; Jutila 1999; Linusson et al. 1998; Stampfli & Zeiter 1999; Tasser et al. 1999). Termination of anthropogenic disturbance is followed by secondary succession, which generally ends in the climax stage of the vegetation adapted to the site. This could vary from alpine grassland to forest. Such devel- opments in the vegetation can be observed everywhere. For the purpose of this study we were especially inter- ested in similar studies from the Alps and other moun- tain regions such as the Pyrenees, the Highlands of Scotland and mountain areas in Finland (Bischof 1981b; Cernusca et al. 1997b; Linusson et al. 1998; Spatz 1994a; Stampfli & Zeiter 1999; Zoller et al. 1984). In all these regions the pattern of vegetation change is deter- mined by local factors related to elevation, aspect, incli- nation and water and nutrient regimes (Cernusca et al. 1997b; Spatz et al. 1978; Spatz & Springer 1987; Tappeiner et al. 1998; Tasser et al. 1998). Succession studies in mountainous areas are trig- gered by the obvious structural changes in agriculture over the last few decades. This paper deals with the case of the sub-alpine and alpine meadows known as the Waltner Mähder in the Passeier Valley (South Tyrol, Italy). Agriculture here is predominantly cattle farming, dairying is the main source of income. A characteristic feature of mountain meadows in this region is the small size of ownership units. A shift in socio-economic con- ditions in the region during the last few decades, how- Impact of land use changes on mountain vegetation Tasser, Erich 1* & Tappeiner, Ulrike 1,2 1 European Academy of Bolzano/Bozen, Drususallee 1, I-39100 Bozen, Italy; 2 Institute of Botany, University of Innsbruck, Sternwartestr. 15, A-6020 Innsbruck, Austria; Corresponding author; Fax +1390471306099; E-mail erich.tasser@eurac.edu