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Results for “General Technical Report”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 73 records · Page 4Linked to original sources
USGS1996

A land manager's guide to point counts of birds in the Southeast

Current widespread concern for the status of neotropical migratory birds has sparked interest in techniques for inventorying and monitoring populations of these and other birds in southeastern forest habitats. The present guide gives detailed instructions for conducting point counts of birds. It further presents a detailed methodology for the design and conduct of inventorial and monitoring surveys based on point counts, including discussion of sample size determination, distribution of counts among habitats, cooperation among neighboring land managers, vegetation sampling, standard data format, and other topics. Appendices provide additional information, making this guide a stand-alone text for managers interested in developing inventories of bird populations on their lands.

General Technical Report↗
USGS1995

Point count length and detection of forest neotropical migrant birds

Comparisons of bird abundances among years or among habitats assume that the rates at which birds are detected and counted are constant within species. We use point count data collected in forests of the Mid-Atlantic states to estimate detection probabilities for Neotropical migrant bird species as a function of count length. For some species, significant differences existed among years or observers in both the probability of detecting the species and in the rate at which individuals are counted. We demonstrate the consequence that variability in species' detection probabilities can have on estimates of population change, and discuss ways for reducing this source of bias in point count studies.

General Technical Report↗
USGS2000

Relationship of Eastern hemlock ( Tsuga canadensis ) to the ecology of small streams in Delaware Water Gap National Recreation Area

Hemlock ravines in Delaware Water Gap National Recreation Area (DEWA) are highly valued because of their distinctive aesthetic, recreational and ecological qualities. We conducted a comparative study designed to determine the potential long-term consequences to aquatic communities of the suspected transition from hemlock-dominated forests to mixed hardwood forests as a result of hemlock woolly adelgid (HWA; Adelges tsugae) induced mortality. A landscape analysis of DEWA using Geographic Information Systems (GIs) was used to select 14 hemlock and hardwood site-pairs that were similar in topography (i.e., slope, terrain shape, aspect, light levels) and stream size (first or second order) but differed in forest composition. This paired watershed approach provided a powerful means to discern the influence of hemlock forests on stream communities. This study was designed to provide an aquatic perspective on potential losses of biological diversity should hemlock forests die.

New Jersey;Pennsylvania↗
USGS1998

Natural establishment of woody species on abandoned agricultural fields in the lower Mississippi Valley: first- and second-year results

The natural establishment of woody seedlings on abandoned agricultural fields was investigated at sites in Louisiana and Mississippi. Series of disked and undisked plots originating at forest edges and oriented in cardinal directions were established on fields at each site. During the firest 2 years, seedling recruitment was dominated by sweetgum, sugarberry, and elms at both sites. Seedling establishment was strongly affected by direction from mature forest and disking, and to a slightly lesser degree by distance from mature forest. Slightly under half of the variation in seedling numbers per plot was explained by the effects of direction, distance, and disking, indicating that other factors also may play an important role in seedling recruitment.

General Technical Report SRS↗