Threshold of potential concern: an early way to identify the ecosystem structural thresholds in a grazing gradient

Identification of ecosystem thresholds is a way to predict future changes and taking the best management practices in restoration processes. Thresholds are an integral part of nonlinear responses of ecosystems to disturbances such as climate change or human activities. In this study, structural threshold of the total patch area and mean patch width in a grazing gradient were identified using the nonlinear function and the concept of threshold of potential concern. Other structural features including number of grass, shrub and forb patches were also measured. The result showed that three-parametric sigmoid functions had the highest ability to predict structural changes in ecosystem structure within a grazing gradient radiating out from the livestock stock night corral (camp). The result also showed that 1 to 2 Km radius from the livestock camp is the critical threshold in ecosystem structure based on total patch area, landscape organization index and mean patch width fitting to a sigmoid function. Generally, the area within 2 Km from the camp needed to receive emergency remedial management actions. The present study showed that the concept of threshold of potential concern is a useful and early way to predict the thresholds in the ecosystem for management actions. Also, the present study revealed that threeparameter sigmoid function provides a much better fit to structural data than other nonlinear functions.