ABSTRACT
Quantitative study on effects of roads on suitable breeding habitats of wildlife is one of topics that need in-depth research in road ecology. Crested ibis (Nipponia nippon), a first class nationally protected bird species, is the species of interest in this research. Using the Maximum Entropy Models (MaxEnt) in the Species Distribution Model (SDM) toolbox of ArcGIS, autocorrelation of environmental variables were analyzed and environmental variables with r>0.8 were removed. Ten environmental variables were chosen as impact factors for the breeding habitat of crested ibis, including mean temperature of coldest quarter, landscape type, normalized difference vegetation index(NDVI), slope, aspect, distance to waters, distance to paddy field, distance to high-grade roads (expressway, national way, provincial way), and distance to low-grade roads (country road). By analyzing the contribution rate of each environmental variable, the results showed that the mean temperature of coldest quarter, landscape type, distance to paddy field, and distance to high-grade roads were the main factors determining breeding habitat of crested ibis. The suitable distribution of crested ibis' nesting area was under the following scenarios: variable road present (scenario1), high-grade road absent (scenario2), and low-grade road absent (scenario 3). The results showed that the presence of roads affected suitable nesting areas of crested ibis with high-grade roads showing a larger influence than low-grade roads. The presence of high-grade roads and low-grade roads decreased the suitable nesting areas of crested ibis by 66.23 and 35.69 km2, respectively. The crested ibis preferred to nest in areas distant from high-grade roads, with an average road avoidance distance of 1500 m. This study was of great significance for formulating management measures to protect crested ibis and provide a reference for quantitative assessment on impacts of engineering and construction projects on wildlife.
Subject(s)
Birds , Breeding , Animals , EcosystemABSTRACT
There are few reports on the vertical distribution of water quality and its influence on underwater light field. In our study, we analyzed the vertical distribution of water quality based on the in situ data in Lake Chaohu, and studied their influence on diffuse attenuation coefficients of downwelling irradiance Kd via Hydrolight simulation. It was indicated that the suspended matter and colored dissolved organic matter (CDOM) were relatively vertical-uniform in Lake Chaohu; excluding algae scums at the surface, the vertical profiles of chlorophyll-a conformed to Gaussian distribution; the complex Kd in vertical was affected by chlorophyll-a and inorganic suspended matter. The analysis on vertical distributions of water quality and its influence on Kd could be the basis for further studying the influence of algae vertical heterogeneity on underwater light field in Case II waters.
