Methods for Evaluating Wetland Condition: Number 1. Introduction to Wetland Biological Assessment.

摘要

Biological assessments (bioassessments) evaluate the health of a waterbody by directly measuring the condition of one or more of its taxonomic assemblages (e.g., macroinvertebrates, plants) and supporting chemical and physical attributes. A major premise of bioassessments is that the community of plants and animals will reflect the underlying health of the waterbody in which they live. When a waterbody is damaged by human activities, biological attributes such as taxonomic richness, community structure, trophic structure, and health of individual organisms will change. For example, in disturbed systems the number of intolerant taxa typically decreases and the proportion of tolerant individuals typically increases. The biological community will reflect the cumulative effect of multiple stressors, whether they be chemical (e.g., toxic chemical), physical (e.g., sedimentation), or biological (e.g., non-native species). In recent years, a growing number of State and Federal organizations have started to develop bioassessment methods and Indexes of Biological Integrity (IBI) for wetlands. An IBI is an index that integrates several biological metrics to indicate a site's condition. A common approach among these organizations is to first sample attributes of a taxonomic assemblage in wetlands ranging from good condition to poor condition. The data are reviewed to identify metrics, which are attributes of the assemblage that show a predictable and empirical response to increasing human disturbance. After the metrics are tested and validated, they are combined into an IBI, which provides a summary score that is easily communicated to managers and the public. Once wetland bioassessment methods are developed, wetland managers can use them for a variety of applications. Wetland managers can use bioassessments to evaluate the performance of wetland restoration activities or best management practices, such as buffer strips, in restoring and protecting wetland health. Wetland managers can also use bioassessments to more effectively target resources for restoring, protecting, and acquiring wetlands.