How is the nitrogen cycle changing at high elevations?
A major question that alpine hydrologists have is how nutrients travel through a watershed. This is important because the concentrations of nutrients like nitrogen, carbon, and phosphorous in water and soils effect water quality, fish habitat, and plant and animal communities in the mountains and landscape downstream.
Nitrogen is a nutrient that has been spotlighted by research at Niwot Ridge, due to a phenomenon called nitrogen deposition. Nitrogen deposition occurs due to a combination of increased atmospheric concentrations of nitrogen from agriculture and fossil fuel from nearby sources in Colorado, and orographic precipitation (higher elevations receive higher amounts of precipitation). As a result of these two factors, more nitrogen is deposited in rain and snow at high elevations. Consequently, forests are reaching nitrogen saturation, resulting in an increase of nitrogen export from high elevations in rivers and streams. Once nitrogen is deposited in rain, snow, and dust, it can go many different places within the watershed. Plants can use it directly from the soil for growth, microbial communities can assimilate or nitrify nitrogen, or it can be leached into surface and groundwater. Nitrogen may travel in different pathways due to the specific location, plant abundance, or climate.