Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi-arid Riparian Ecosystems

摘要

Effective tools to monitor and evaluate ecosystem change are needed to measure the impacts of human activity and determine whether ecosystem protection or restoration are needed or are even reasonable options to minimize continued degradation and loss of natural resources (Karr 1991, 2005; Karr and Chu 1999). The problem is how to accurately measure and monitor human induced impacts in highly complex and continually changing environments. The Index of Biological Integrity. The concept of biological integrity was first introduced in the language of the 1972 Clean Water Act. This legislation was designed to restore or maintain the physical, chemical, and biological integrity of the nation's water resources. The 1997 National Wildlife Refuge System Improvement Act further mandated government agencies to protect the biological integrity, diversity, and environmental health of the refuge system (Karr 1991, 2005; Adler 2003; Fischman 2004). A working definition of biological integrity is the ability to support and maintain a balanced, integrated, adaptive biological system having the full range of parts (genes, species, and assemblages) and processes (mutation, demography, biotic interactions, nutrient and energy dynamics, and metapopulation and fragmented population processes) expected in the natural habitat of a region. (Karr 1996). This definition incorporates the concept of scale and emphasizes that living systems range from individuals and assemblages acting locally to populations operating on the landscape or regional scale. Furthermore, living systems include not just parts of the system, but also the processes that create and maintain them. Living systems are influenced not only by the physical, chemical, and biological context of their environments, but are also subject to ongoing evolutionary processes (Karr 2005). The complex factors impacting ecosystems need to be monitored in a hierarchical approach that includes local and regional impacts.