Abstract:

Over the past half century the development of ecosystem models which quantify material and energy flows through forest ecosystems have led ecologists to identify and characterize the various sources, sinks, and flux rates of mineral nutrients and how these are affected by disturbance. The “Vernal Dam" hypothesis suggests that during the early spring months when nutrient susceptibility to loss is highest, an ephemeral herbaceous community takes up nutrients in biomass as a mechanism to retain nutrients in the system. This paper evaluates evidence from several studies regarding the “Vernal Dam" hypothesis. The uptake of nutrients in plant biomass during the early spring months is highly variable across ecosystems, and microbial immobilization is a more important mechanism for retaining nutrients than traditionally thought. Suggestions are made for future research which considers the role of plants and microbes as a “Vernal Dam", and how the roles of plants and microbes change under different climatic conditions and ecosystem types.