A regional assessment of windbreak habitat suitability

The Environmental Monitoring and Assessment Program was initiated in 1989 b y the United States Environmental Protection Agency to collect, analyze, an d report quantitative, statistically unbiased information about the state o f the nation's environment on a regional basis. During a pilot program in N ebraska we measured a habitat suitability index for a probability sample of 40 windbreaks and expanded the results to estimate the potential value of windbreaks as wildlife habitat in Nebraska. The index estimates the suitabi lity of a windbreak as habitat for wildlife including breeding birds, small mammals, and deer. Index values range from zero to one, where a value of o ne indicates maximal habitat value. We estimated that 50% (+/- 13% at 90% c onfidence) of windbreaks in Nebraska have a habitat suitability index of 0. 25 or less and that no windbreaks have a suitability index greater than 0.6 . Our results indicate that increasing the area of individual windbreaks is the most effective way to improve their value as wildlife habitat. Monitor ing windbreak condition over time would alert wildlife managers to changes in the resource that might affect wildlife populations. Because our data we re highly variable, the power to detect change in habitat condition between two measurement periods was low. A much larger sample would be required to detect small changes in habitat condition. Variability may be reduced, and power increased, by carefully and consistently constructing the sampling f rame, keeping data collection as simple as possible, appropriately stratify ing sample selection, and using a small number of well-trained data collect ion teams. However, we suggest adapting the index for use with aerial photo graphy in future efforts to evaluate windbreaks as wildlife habitat in exte nsive areas.