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Research about Washington D.C., Maryland, Virginia

Source-linked reports with geographic coverage including Washington D.C., Maryland, Virginia.

3 recordsLinked to original sources
USGS2021

Effectiveness of a distance sampling from roads program for white-tailed deer in the National Capital Region parks

We evaluated the effectiveness of a distance sampling from roads program for estimating population sizes of white-tailed deer (Odocoileus virginianus) from 2001 to 2015 in parks of the National Capital Region (NCR), National Parks Service. Distance sampling is a method for estimating the density of organisms using a distribution of distances to observed individuals. Re-analysis of survey data for 9 of 11 NCR parks found that although the original park analyses likely estimated deer densities correctly, the uncertainties (coefficients of variation or CV) of the original estimates were likely underestimated. Power analyses based on the current analysis methods showed that survey effort at some parks was likely insufficient to reach the NCR target of a 20% CV. We simulated 7 different types of deer populations and 3 survey designs to assess how violations of the assumptions of distance sampling might have impacted population estimates. A significant interaction between survey type and population type explained most of the variation in population estimates across simulations. Simulation results suggested that (1) non-road surveys were more robust to bias in seven deer population distributions than were road surveys, (2) effectiveness of each of 3 survey types was dependent on the way deer were distributed across the landscape, and (3) non-road surveys produced unbiased estimates of populations affected by roads, whereas, road surveys did not. Based on this study, we recommend revisions of the NCR distance sampling program, including additional sampling effort for some parks and suggest alternative survey strategies to ameliorate potential assumption violations of distance sampling.

Maryland, Virginia↗
USGS1978

An evaluation of errors in mapping land use changes for the Central Atlantic Regional Ecological Test Site

Land use change maps prepared from high-resolution, high-altitude aerial photographs for the period 1970 to 1972 of the CARETS (Central Atlantic Regional Ecological Test Site) project were analyzed for accuracy. To test for errors of commission, all outlined areas (polygons) of land use change on five l:100000-scale maps were examined for accuracy. An estimate of the errors of omission was obtained by comparing the land use change polygons mapped for the Norfolk SMSA (Norfolk and Virginia Beach Standard Metropolitan Statistical Area) with the changes mapped in a more detailed study of the same area. The results of these studies showed that the largest number of errors was caused by misregistration of the land use change map to the 1970 land use map; however, only a very small percentage of the total land area of the land use change was affected by misregistration. In the Norfolk SMSA, which is an area of rapid urban growth, many of the land use changes had not been mapped. The conclusion is that quality control checks are necessary both during and after map compilation. The experience of the CARETS and other land use mapping experiments conducted in the early 1970's has resulted in the development of carefully designed quality-control procedures implemented in the nationwide mapping of land use and land cover currently being carried out by the U.S. Geological Survey.

Maryland, Virginia↗