Pastoral management vs. land abandonment in Mediterranean uplands: impact on land snail communities

Abstract

The aim of the study was to assess the impact of a pastoral management chosen to limit the recent expansion of woodland on a Mediterranean mountain on land snail diversity. An additional aim was to acquire quantitative data that could be used to identify pasture environments from Holocene molluscan assemblages. The work was undertaken at the Luberon mountain, Provence, south of France. We used a stratified quantitative sampling scheme according to altitude and vegetation structure. A total of 80 sites were studied. Large species were collected within a 5 × 5-m plot. Small species were extracted from litter and surface soil. A standard procedure for site description was used based on 35 environmental variables. Grazing pressure was estimated according to the impact of grazing on the herb layer. Correspondence analysis and canonical correspondence analysis were performed using canoco 4.0 software. The distribution of land snails is related to altitude and grazing intensity. Large patches of grazed grassland harbour open country and mountain snail species. Thermophilic open ground species are located in grazed grasslands at lower altitude. Shade-loving species are present in ungrazed scrublands or in small clearings on the upper slopes. The lowest species richness, diversity and equitability are associated with large patches of grazed grassland, the presence of a continuous cover of short grass reinforcing this negative impact on snail diversity. Our study is consistent with similar works on land snails or other invertebrates but discordant with vegetation studies. A homogeneous grazed herb layer significantly reduces snail diversity and abundance. Heterogeneity seems to favour snail diversity both at the local and landscape scales. However, sheep grazing contributes to the expansion of suitable habitats for rare snail species.

Gastropod communities in alpine grasslands are characterized by high beta diversity

“…At a regional scale, terrestrial gastropod diversity of various habitats decreased with increasing elevation in Val Müstair in the Eastern Alps (Baur et al 2014). Grazing intensity has been found to negatively affect land snail diversity and abundance in nutrient-poor calcareous grassland in the Swiss Jura mountains (Boschi and Baur 2007a,b), in Mediterranean uplands in France (Labaune and Magnin 2002) and in alpine grasslands in the Southern Carpathians in Romania (Baur et al 2007). The aim of our study was to investigate how environmental variables (elevation, slope, soil pH, etc.…”

Long-Term Forest Dynamics and Land-Use Abandonment in the Mediterranean Mountains, Corsica, France

“…The intensity of this mountain area revegetation has had several negative consequences, including greater risk of fire and an increase in the speed at which wildfires spread (Vázquez and Moreno 1998), reduced water availability (Gallart and Llorens 2004), a reduction in landscape quality and agricultural value (Vos and Meekes 1999), a reduction in the extent of pastoral areas (Molinillo et al 1997), and a reduced spatial distribution of rare or endemic species (Farina 1997, Preiss et al 1997, Labaune and Magnin 2002, Kiss et al 2004.…”

Intensified grazing affects endemic plant and gastropod diversity in alpine grasslands of the Southern Carpathian mountains (Romania)

“…As indicators of biodiversity we used vascular plants and terrestrial gastropods, which both have been shown to be sensitive indicators of habitat change (Ellenberg 1996;Labaune & Magnin 2002). We assessed the species diversity and species abundance of vascular plants and terrestrial gastropods in both intensively grazed sites and in sites only occasionally grazed by chamois in two areas in the Southern Carpathians, Romania.…”