Nitrogen balance in forest soils: nutritional limitation of plants under climate change stresses

Abstract

Forest ecosystems with low soil nitrogen (N) availability are characterized by direct competition for this growth‐limiting resource between several players,i.e.various components of vegetation, such as old‐growth trees, natural regeneration and understorey species, mycorrhizal fungi, free‐living fungi and bacteria. With the increase in frequency and intensity of extreme climate events predicted in current climate change scenarios, also competition for N between plants and/or soil microorganisms will be affected. In this review, we summarize the present understanding of ecosystem N cycling in N‐limited forests and its interaction with extreme climate events, such as heat, drought and flooding. More specifically, the impacts of environmental stresses on microbial release and consumption of bioavailable N, N uptake and competition between plants, as well as plant and microbial uptake are presented. Furthermore, the consequences of drying–wetting cycles on N cycling are discussed. Additionally, we highlight the current methodological difficulties that limit present understanding of N cycling in forest ecosystems and the need for interdisciplinary studies.