Future provision of soil erosion protection by Mediterranean forests under global change pressures.

Mediterranean forests are biodiversity-rich and complex ecological systems, with a long history of close interaction with human societies to which they provide a wide range of ecosystem services. These systems are particularly affected by ongoing global change, especially by the increase in both the frequency and the intensity of disturbances associated to climate and land-use change (e.g. fires, droughts and extreme rainfall events; Stocker et al. 2014).

In this study we evaluate the effects of climate change and management strategies (through fire suppression) on the provision of soil erosion protection by Mediterranean forests, using the forests of Catalonia (Spain) as a case study. We calculate the provision of the service ‘soil erosion protection’ following the framework proposed by Guerra et al. (2016), where the service of soil protection by woody vegetation is calculated as a function of vegetation cover, intrinsic soil properties, rainfall patterns and topographic conditions (the Universal Soil Loss Equation). Future provision of the service is estimated under two different climate change scenarios (RCP 8.5 and RCP 4.5; these have a direct influence in fire regimes) and two different fire suppression management strategies (being fire one of the main drivers of forest loss and forest compositional change in Mediterranean environments) for the 2050 horizon. To estimate changes in forest cover under these two scenarios we use the spatially-explicit landscape dynamics model MEDFIRE (Brotons et al. 2013). This model simulates, on a yearly basis, changes in forest composition at the landscape level as a function of fire regimes, post-fire regeneration, and afforestation processes. Using this evaluation we identify the fire suppression strategies that allow to minimize potential future soil loss linked to increasing fire risk. We also identify the areas at most threat of irreversible soil loss where management efforts (through fire suppression or forest management) should focus in the coming years.here