Synoptic climatological approaches to assessing subcanopy hydrologic and nutrient fluxes in eastern deciduous forests.

摘要

Deciduous temperate forests comprise over 280 million hectares in North and Central America, and provide vital ecosystem services through the cycling of water and nutrients. During storm events, water moves through the forest canopy and exchanges nutrients and pollutants with vegetation and deposits the chemically altered precipitation to the forest floor. Both storm characteristics (e.g., intensity, duration, and magnitude) and canopy structural parameters have a significant control on the quantity and quality of such water. How these may be influenced by altered precipitation regimes as a result of changing climates is largely uncertain. This dissertation employs weather classification techniques from the discipline of synoptic climatology to explore the cycling of nutrients and other solutes within a forest canopy through hydrologic pathways that are ultimately controlled by atmospheric circulation and precipitation patterns at a forested catchment in the Mid-Atlantic region.;The research presented in this dissertation adds to this growing body of knowledge with a focus on categorizing the inputs to forest ecosystems using weather map classification methods from the field of synoptic climatology. In the Mid-Atlantic, annual precipitation increased since 1946, which was strongly associated with significant increases in autumn precipitation. In the autumn, storm types like the Weak Coastal Low (L2) increased in frequency and were associated with the highest average enrichment ratios and nutrient cycling rates for many solutes including major cations, dissolved organic carbon, and dissolved organic nitrogen. If autumn precipitation trends persist in the future, rates of nutrient cycling in Mid-Atlantic temperate forests are expected to increase.;A novel approach for assessing forest nutrient cycling was demonstrated in this dissertation and provides valuable insights into how the inputs to biogeochemical cycles are changing and how they may be modeled for future predictions. A more thorough understanding of the movement of water, nutrients, and pollutants in forest ecosystems improves management capabilities and climate change mitigation efforts.