Remediating degraded ecosystems: Complications of scale

Title	Remediating degraded ecosystems: Complications of scale
Publication Type	Conference Paper
Year of Publication	2002
Authors	Havstad K, Brown JR
Conference Name	17th Annual Symposium, US-International Association for Landscape Ecology
Date Published	April 23-26, 200
Conference Location	Lincoln, NE
ARIS Log Number	144837
Abstract	Anthropogenic disturbances that result in degradation of ecosystems often are initiated at relatively small scales. These disturbances can disrupt small-scale processes and cascade to affect processes at larger spatial scales. Eventually, degradation is expressed at landscape, regional or larger scales and any reasonable prospects for effective remediation are poor. An example of these phenomena is the scaled response to livestock overgrazing of and rangelands in the Southwest USA. Initial (late 19th century) overgrazing impacts were at relatively small spatial scales around points of livestock and affected only smaller scale plant community processes. Eventually, the impacts of these disturbances expanded and resulted in larger-scale degradation. By the beginning of the 20th century, the extent was regional as overgrazing, compounded by periodic drought, affected larger-scale processes such as plant dispersal, fire regimes and annual productivity. In addition, changes in regional climatic patterns, continued livestock grazing and introduction of nonnative forage species complicated remediation efforts. Areas where degradation has been remedied are generally small in scale and are the result of resilient soil/vegetation systems or responses to costly practices. As yet, we have not observed the reversal of degradation at large scales due to cascading effects of remediation practices implemented at small scales. Landscape remediation will require either extensive small-scale practice application and/or improved understanding of landscape dynamics that will trigger large-scale processes.