Ecohydrological and biogeochemical consequences of forest degradation in tropical montane systems: interactive effects of land use and precipitation variability

Abstract:

In tropical montane regions, the interactive effects of land use and climate change affect the capacity of forests to provide ecosystem services. Particularly important among these effects are the consequences of forest transformation in soil and water resources, as the runoff-erosion-nutrient loss progression, affects the provision of key services to largely populated areas. Systematic evaluations of the progressive effects of human intervention in this progression are key to managing these systems. We established a space for time substitution experiment in the Colombian Andes, where four types of vegetation cover were selected to represent different stages of human intervention. The dynamics of precipitation were related to nutrient loss in both runoff and sediment loss. In all vegetation cover types (natural forests, transitory crops, permanent crops and pasturelands) we measured weekly totals of precipitation and its properties, forest internal precipitation components, runoff and sediment loss for a year. Monthly measurements of elemental concentrations in all fluxes and sediments were determined. Overall, our results highlight the role of natural forests in the retention of dissolved nutrients in the rain, whereas more intervened cover types, such as pastures and transitory crops, are more prone to induce nutrient loss via runoff and sediments, respectively (Fig. 1). In addition, when related to precipitation properties, our results indicate the potential for amplified effects of disturbance on the loss of ecosystem functions in response to increased variability in precipitation. Collectively our results illustrate a fundamental interactive effect of ecosystem degradation via land use and projected climate change on fundamental ecosystem services.

Image: "Fig. 1, from Suescún et al., submitted"