How is the nitrogen cycle changing at high elevations?
Before looking at trends in discharge (amount of water leaving the Green Lakes Valley) and nitrogen concentrations, first we look at trends in climate. Records of temperature from 1985-2009 show a steadily warming temperature with an increase of 0.5 °C per decade at the D1 site. Precipitation has declined over the same period by 1.66 mm per year at D1, in large part due to a regional drought from 2000 to 2007.
Concentrations of dissolved inorganic nitrogen significantly increased from 1985-2009. This means that rain and snow contain more nitrogen now than it did twenty years ago.
Annual nitrate concentrations in surface water throughout Green Lakes Valley vary spatially. A general pattern shows that nitrate concentrations increase with elevation, with Navajo the highest stream site and Albion the lowest elevation stream site.