Land snail assemblages along altitudinal gradients on Mount Semeru, the highest montane forest in Java, Indonesia

We conducted research on land snail diversity on the highest volcanic mountain in Java, Mt Semeru. This research aimed to gain data on the land snail species diversity in the area as well as analyse environmental variables that affect the land snail assemblages along the altitudinal gradients. A total of 40 plots of 10 × 10 m2 were examined in the altitudinal gradient of 800–1,200, 1,201–1,600, 1,601–2,000 and 2,001–2,400 m asl using a timed search method. In total, 788 individuals of land snails were collected, belonging to 22 species from 14 families. Fifteen species were new records for the area. Five endemic species were recorded on Mt Semeru. A single introduced species, Bradybaena similaris was found abundantly on the mountain at an altitude of more than 2,000 m asl. Multiple linear regression analyses showed a unimodal response of species richness for altitude, temperature and precipitation sums on Mt Semeru. In addition to these environmental variables, species richness is influenced by land use type and soil pH. These findings suggest that species and ecosystem management at the altitude 2,001–2,400 m asl is necessary to conserve endemic land snail species, which were found most abundantly at this altitude.