The Application of the QBR Index to the Riparian Forests of Central Ohio Streams
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Date
2007-03
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The Ohio State University
Abstract
Riparian forests are one of the most threatened ecosystem types in the world. There is a need to develop an ecological index of the quality of riparian habitats. The QBR index (‘Qualitat del Bosc de Ribera’, or in English, ‘Riparian Forest Quality’) was developed to score the quality of the habitat in Mediterranean riparian areas, and we have modified the QBR index for use in Central Ohio. The specific objectives of this project were to alter terminology and requirements of the index that are region-specific to Spain, to develop lists of native and non-native tree and shrub species found in riparian forests in Central Ohio, to test the altered index in three study watersheds in Ohio (Big Darby, Little Darby, and Walnut Creek watersheds), and to access the management implications of the index. There are four parts to the QBR index: total riparian cover, cover structure, cover quality, and channel alterations. Only a few changes were made to the original QBR index in order to adapt it for use in Central Ohio. These included increasing the number of tree and shrub species for higher scores due to the increased diversity in the United States compared with Mediterranean areas, adding non-natives shrubs as a negative factor along with non-native trees, adding categories for streambanks with only one side modified, and format changes. All of these alterations resulted in scores that more accurately reflected the habitat quality of riparian forests along Central Ohio streams than the original index would have. Sixty study sites were chosen for testing this index, 20 within each watershed. In these sixty sites, a total of 39 tree species were recorded. One non-native tree species, 23 common native shrub species, and four non-native shrub species also were identified. With our modified index, the Big Darby had the most high-quality sites (with scores ≥95), while the Little Darby had the most poor-quality sites (with scores of ≤50). All sites were placed into habitat quality categories based on their scores. These categories are riparian habitat in natural condition and of excellent quality (scores ≥95), some disturbance but good quality (75-90), disturbance important with fair quality (55-70), strong alteration and poor quality (30-50), and extreme degradation with very poor quality (≤25). Only twelve sites fell below good quality, while 48 sites were of good or excellent condition. The QBR index, with the changes made to the original, adapted well for use in Central Ohio, and could be used in the future for assessing the progress of restoration and rehabilitation projects, for determining high quality riparian areas for conservation projects, or to assess the quality of habitat throughout entire watersheds or study areas.
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Keywords
Riparian Forests, QBR Index