The Swiss Mountain Wooded Pastures: Patterns and Processes

Abstract

Influenced by the combined action of grazing and forest management, wooded pastures represent a traditional form of multiple use of natural resources in some European mountains. This fragile semi-natural ecosystem is characterized by the coexistence of high biodiversity and extensive land use. Based on experimental and observational studies carried out at various spatial scales in the Swiss Jura Mountains, this chapter provides an insight into patterns and processes occurring in this typical silvopastoral ecosystem. Summer grazing by cattle is the main driving force affecting vegetation dynamics. Large herbivores influence vegetation in three ways: grazing and browsing, dung and urine deposition and trampling. Field observations reveal a high heterogeneity of cattle activities at both fine and large scales. Cattle habitat use controls the dynamics of plant species and functional groups in the herb layer. Natural tree regeneration is also closely affected by cattle activity and related to the heterogeneous environment. Distribution of tree seedlings is spatially associated with specific physical structures or nurse plants that facilitate their survival in the herb and the shrub layers. Moreover, the growth of tree saplings is related to grazing intensity. Knowledge of ecological functioning of wooded pastures has allowed the development of a novel, spatially explicit, mosaic compartment model of the dynamics of silvopastoral ecosystems. This model is able to explain some aspects of the origin of vegetation heterogeneity in pasture-woodland landscapes. The conservation of such ecosystems is an important challenge considering its complexity and the present change in agricultural practices in mountain regions. A better integration of ecological and socio-economic processes into predictive multi-level models will permit the exploration of the conditions for sustainable management schemes compatible with biodiversity conservation.