Modeling soil quality thresholds to ecosystem recovery at Fort Benning,GA,USA

摘要

The objective of this research was to use a simple model of soil carbon (C) and nitrogen (N) dynamics to predict nutrient thresholds to ecosystem recovery on degraded soils at Fort Benning,Georgia,in the southeastern USA.Artillery,wheeled,and tracked vehicle training at military installations can produce soil disturbance and potentially create barren,degraded soils.Ecosystem reclamation is an important component of natural resource management at military installations.Four factors were important to the development of thresholds to recovery of aboveground biomass on degraded soils: (1) initial amounts of aboveground biomass,(2) initial soil C stocks (i.e.,soil quality),(3) relative recovery rates of biomass,and (4) soil sand content.Forests and old fields on soils with varying sand content had different predicted thresholds for ecosystem recovery.Soil C stocks at barren sites on Fort Benning were generally below predicted thresholds to 100% recovery of desired future ecosystem conditions defined on the basis of aboveground biomass.Predicted thresholds to ecosystem recovery were less on soils with more than 70% sand content.The lower thresholds for old field and forest recovery on more sandy soils were apparently due to higher relative rates of net soil N mineralization.Calculations with the model indicated that a combination of desired future conditions,initial levels of soil quality (defined by soil C stocks),and the rate of biomass accumulation determine the predicted success of ecosystem recovery on disturbed soils.