Sensitivity testing of the gap intercept method, a simple, rapid indicator of changes in vegetation, soil erosion and hydrologic function

Title	Sensitivity testing of the gap intercept method, a simple, rapid indicator of changes in vegetation, soil erosion and hydrologic function
Publication Type	Conference Paper
Year of Publication	2002
Authors	Herrick JE, Gillette D.E, Remmenga M.D.
Conference Name	Eco-Hydrology of Semiarid Landscapes: Interactions and Processes, Chapman Conference
Date Published	September 9-13,
Conference Location	Taos, NM
ARIS Log Number	139202
Abstract	The spatial structure of vegetation is widely recognized as a key factor controlling soil erosion and hydrology in arid and semiarid ecosystems at multiple spatial scales. At the plant-interspace scale, shrub invasion of grasslands may cause little or no change in total plant canopy cover but dramatically increases the area susceptible to wind erosion and reduces resistance to overland water flow. At the patch scale, the development of vegetation bands has been shown to dramatically change both hydrology and primary production. The gap intercept method is designed to detect changes in the proportion of the soil surface covered by gaps between plants larger than a minimum size. Cumulative area and frequency distributions can also be generated from the data. Gaps between both plant canopies and plant bases are recorded along the same line transect. Sensitivity tests completed in relatively degraded and undegraded areas in southern New Mexico showed the method is sensitive to vegetation change and to related changes in wind erosion and can be completed at relatively low cost by individuals with little or no botanical knowledge. We will also present the results of a comparison with a semi-quantitative ¿boot-gap¿ technique designed for use by land managers in conjunction with step-point methods of estimating plant cover and composition.