Addressing soil protection concerns in forest ecosystem management under climate change

Background: Climate change may strongly influence soil erosion risk, namely through variations in the precipitation pattern. Forests may contribute to mitigate the impacts of climate change on soil erosion and forest managers are thus challenged by the need to define strategies that may protect the soil while addressing the demand for other ecosystem services. Our emphasis is on the development of an approach to assess the impact of silvicultural practices and forest management models on soil erosion risks under climate change. Specifically, we consider the annual variation of the cover-management factor(C) in the Revised Universal Soil Loss Equation over a range of alternative forest management models to estimate the corresponding annual soil losses, under both current and changing climate conditions. We report and discuss results of an application of this approach to a forest area in Northwestern Portugal where erosion control is the most relevant water-related ecosystem service.Results: Local climate change scenarios will contribute to water erosion processes, mostly by rainfall erosivity increase.Different forest management models provide varying levels of soil protection by trees, resulting in distinct soil loss potential.Conclusions: Results confirm the suitability of the proposed approach to address soil erosion concerns in forest management planning. This approach may help foresters assess management models and the corresponding silvicultural practices according to the water-related services they provide.

Forest management for optimizing soil protection:a landscape-level approach

Background:Soil erosion is still identified as the main cause of land degradation worldwide,threatening soil functions and driving several research and policy efforts to reverse it.Trees are commonly associated to some of the most successful land-use systems to achieve soil protection goals,but the extent to which forest ecosystems reduce erosion risks can largely depend on management decisions and associated silvicultural practices.Optimization tools can assist foresters in solving the complex planning problem they face,concerning the demand for different,and often conflicting,ecosystem services.A resource capability model(RCM),based on a linear programming approach,was built and solved for a forest landscape management problem in Northwest Portugal,over a 90-years planning horizon,divided in 10-years periods.Results:Timber provision and soil erosion were found to be in trade-off.The management alternatives included in the model were proven to be sufficiently flexible to obtain the desired level of timber yield,both in volume and even distribution along the planning horizon,while ensuring lower levels of soil loss estimates(below 35 Mg·ha^(−1)·year^(−1)).However,under climate change conditions,compatible with an increasing greenhouse gases emission scenario,potential landscape soil erosion may be enhanced up to 46 Mg·ha^(−1)·year^(−1) in critical periods.Conclusions:Soil conservation concerns in landscape-level forest management planning can be addressed by LPbased optimization methods.Besides providing an optimal management solution at landscape level,this approach enables a comprehensive analysis of the RCM,possible trade-offs and potential changes towards uncertainties.