A state-and-transition approach to alpine grasslands under abandonment

The abandonment of the traditional pastoral practices is acknowledged as the main causes of the shrub-encroachment in the alpine semi-natural grasslands. In this paper, we proposed a state-and-transition approach in order to organize pastoral vegetation in a simple management-oriented framework integrating ecological data. The study sites were chosen in an inner alpine territory where the abandonment of pastoral practices was more evident than in other alpine regions. Cluster and fuzzy analysis applied to botanical data allowed the classification of six pastoral types and the assessment of the main overlaps between them. Non-parametric tests on Landolt nutrients indices, slope and distance from farm allowed the identification of a gradient linked with nutrients and pastoral practices intensity from rich pastures to shrub encroached pastures. Moreover, the implementation of the available information in a state-and-transition model (STM) allowed us to hypothesize the presence of an ecological threshold between grass-dominated and shrub-dominated grasslands and the identification of the at-risk pastoral types in the shrub-encroachment dynamics.