Effects of mountain resort development on streamwater nitrogen export: Importance of spatial location of land use / land cover change

Human alteration of the patterns of land use/land cover (LULC) on the earths surface is one of the most profound impacts on the functioning of natural ecosystems. At the watershed scale, we hypothesize that not only the amount and type of landscape alteration, but also the spatial distribution and corresponding watershed characteristics, will dictate the impact on streamwater nitrogen (N) export. We are developing a method to examine the impact of watershed location and spatial distribution of LULC change on the spatial, seasonal, and temporal patterns of streamwater N export and its consequent speciation. LULC and topography will be mapped with high resolution imagery (QuickBird) and elevation data (Airborne Laser Swath Mapping - ALSM) and combined with streamwater chemistry data analyzed from quarterly synoptic streamwater sampling initiatives (>60 locations) and high temporal resolution streamwater sampling at eight locations beginning prior to watershed development in the 1970s. We will further trace N sources by incorporating isotopic analysis of 15N and 18O of nitrate. We seek to define the relationships between streamwater chemistry, LULC, and watershed geomorphology and geology though development of a N export coefficient model. Here, we present preliminary results of this research.