Hydrologic Nutrient Cycle Interactions in Undisturbed and Manipulated Ecosystems (Watersheds)

Nutrient cycling studies have proven valuable in explaining the presence, abundance, and seasonal variation of elements in stream water. The long term objectives of this project are to understand mineral cycling and stream water chemistry of forested watersheds in New Mexico as influenced by vegetational communities, climatic conditions, weathering of soil minerals, and man.

Studies to date show water quality changes over elevation, with the lowest concentrations of elements occurring at the highest elevations. This trend is consistent throughout the year; however, actual concentration values vary due to the source of water (e.g. snow melt at high or low elevations) and seasonal patterns of biological activity. Variation in concentration is greatest at lower elevations. The reasons for the higher concentrations at lower elevations are increased evapotranspiration and a combination of biological controls and bedrock weathering differences. For nitrate, variation in concentration is a result, primarily, of biological activity and climatic factors (precipitation, temperature). Research needed to identify mechanisms of biological control involve transfer of materials within the system. A limited number of these results are presented. The information gathered from natural areas is essential in evaluating man’s activities. The only land use activity evaluated to date has been minor: replacing a poma ski lift on the border of a watershed. An additional loss of Ca and Mg did occur during September and October and which was attributed to the construction of the new lift. Additional ski area development is currently being evaluated.

Project No. A-039-NMEX