Grassland bird communities and environmental health: the role of landscape features
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Geology topics
S.F. Browder
Publications and source records attributed to S.F. Browder.
Assemblages of breeding birds as indicators of grassland condition
We developed a measure of biological integrity for grasslands (GI) based on the most influential habitat types in the Prairie Pothole Region of North Dakota. GI is based on proportions of habitat types and the relationships of these habitat types to breeding birds. Habitat types were identified by digital aerial photography, verified on the ground, and quantified using GIS, We then developed an index to GI based on the presence or abundance of breeding bird species. Species abundance data were obtained from 3 min roadside point counts at 889 points in 44, 4050 ha study plots over a 2-year period. Using a modified North American Breeding Bird Survey protocol, species were recorded in each of four quadrants at each point. Fifty species selected for analysis included all grassland species that occurred in at least 15 quadrants and all other bird species that occurred in at least 1 % of quadrants. We constructed preliminary models using data from each of the 2 years, then tested their predictive ability by cross-validation with data from the other year. These cross-validation tests indicated that the index consistently predicted grassland integrity. The final four models (presence and abundance models at 200 and 400 m scales) included only those species that were statistically significant (P ??? 0.05) in all preliminary models. Finally, we interpreted the components of the indices by examining associations between individual species and habitat types. Logistic regression identified 386 statistically significant relationships between species and habitat types at 200 and 400m scales. This method, though labor-intensive, successfully uses the presence of grassland-dependent species and absence of species associated with woody vegetation or cropland to provide an index to grassland integrity. Once regional associations of species with habitat types have been identified, such indices can be applied relatively inexpensively to monitor grassland integrity over large geographic areas. Indices like the ones presented here could be applied widely using bird abundance data that are currently being collected across the United States and southern Canada through the North American Breeding Bird Survey. ?? 2002 Elsevier Science Ltd. All rights reserved.
Ecological Indicators↗
Grassland bird communities and environmental health: The role of landscape features
Ecosystems throughout the world are imperiled by myriad anthropogenic factors. It is critical to develop tools for evaluating and monitoring the health or integrity of various ecosystems. Because of the broad scale of the problem, the urgency to address informational needs, and the limited financial resources committed to the problem, relatively inexpensive tools that encompass large areas are especially desirable. Remote sensing offers possibilities for such large-scale evaluation and monitoring. With aerial or satellite imagery, vast quantities of information from very large areas can be collected periodically.
Book chapter↗