Implications of Soil Nitrogen Levels for Soil Erosion and Revegetation in the High Sierras

摘要

Revegetation and restoration of degraded wildland ecosystems depends upon an adequate, long-term supply of nitrogen from a variety of nitrogen pools. Site disturbance often reduces or removes the soil organic matter, soil microbes and plant litter that are the sources of these nitrogen pools. This is especially true in the thin, nutrient poor, relatively young high elevation soils of the Sierra Nevada Mountains. This paper describes an ongoing study intended to characterize several aspects of this nitrogen supply. These aspects include: (1) the amount of nitrogen in various pools that support plant growth for extended periods of time (and delineates sustainable from non-sustainable), (2) the seasonal release rate or turnover of nitrogen required for a healthy, dynamic plant community, (3) the soil sampling depth required to adequately characterize the condition of a disturbed site and (4) the estimated nitrogen release rate of various fertilizers, organic soil amendments including composts and mulches that might be used to "bootstrap" disturbed soil ecosystems to approximate predisturbance conditions.