Soil type modifies the impacts of warming and snow exclusion on leachate carbon and nutrient losses

Abstract

The varied and wide-reaching impacts of climate change are occurring across heterogeneous landscapes characterized by a broad diversity of soil types. Despite the known importance of soils in mediating biogeochemical nutrient cycling, there is little experimental evidence of how soil characteristics may shape aqueous nutrient losses from forest ecosystems under climate change. Our objective was to clarify how soil characteristics modify the impact of climate changes on carbon and nutrient leaching losses in temperate forests. We therefore conducted a field-based mesocosm experiment with replicated warming and snow exclusion treatments on two soils in large (2.4 m diameter), in-field forest sapling mesocosms. We found that nutrient loss responses to warming and snow exclusion treatments frequently varied substantially by soil type. For example, warming and snow exclusion increased nitrogen (N) losses on fine textured soils by up to four times versus controls, but these treatments had no impact on coarse textured soils. Generally, the coarse textured soil, with its lower soil-water holding capacity, had higher nutrient losses (e.g., 12–17 times more total N loss from coarse than fine textured soils), except in the case of phosphate, which had consistently higher losses (23–58%) from the finer textured soil. Furthermore, the mitigation of nutrient loss by increasing sapling biomass varied by soil type and nutrient. Our results suggest that potentially large biogeochemical responses to climate change are strongly mediated by soil characteristics, providing further evidence of the need to consider soil properties in Earth system models for improving nutrient cycling and climate projections.