Key interactions between nutrient limitation and climatic factors in temperate forests: a synthesis of the sugar maple literature

Mineral stress (nutrient deficiency and (or) ion toxicity) is a widespread phenomenon in forests around the world. However, with the exception of N limitation, its significance is often under appreciated. On weathered, acidic soils that support many of the world's forests, P, Ca, and Mg deficiencies and toxicities of Al and Mn are important constraints to forest productivity. Nutrient resources are a primary controller of forest function and structure and have important trophic implications, because foliar nutrient status is an important determinant of leaf palatability and consumer fitness. Nutrient acquisition and utilization in forest ecosystems is strongly influenced by environmental factors, which are changing at unprecedented rates with regional and global climate shifts. Here we examine nutrient limitations common to temperate, sugar maple (Acer saccharum Marsh.) dominated forests as a model for understanding how climatic factors influence the acquisition and utilization of nutrient resources in forest ecosystems. In general, foliar nutrient imbalances created by soil weathering and acidification impair sugar maple physiology and correlate with health decline symptoms. Extremes in light environment, temperature, precipitation, pathogen attack, and herbivory tend to induce and (or) negatively interact with nutrient imbalances in sugar maple. A conceptual model is presented that characterizes abiotic and biotic interactions influencing sugar maple health and fitness in the context of nutrient limitation.