Determining Spatial Relationships between Landscape Structure and Avian Diversity in the Edwards Plateau of Texas

The Edwards Plateau of Texas (USA) is an area of high biological diversity.However, the biodiversity of the Edwards Plateau has been endangered by shifts in the landscape mosaic resulting from continued fragmentation of rural properties.As a contribution to understanding the relationship among landscape structure and biodiversity, the objective of the present study was to investigate specific linkages between landscape structure at two levels (landscape mosaic or cluster of ecosystems and class or types of ecosystems in the landscape), and avian breeding alpha and beta biodiversity ( -diversity and -diversity) within the Edwards Plateau.The study area was bounded by a circle with a radius of 300 km located at the geographical center point of the Edwards Plateau Ecoregion.Avian data from 31 North American Breeding Bird Survey (BBS) transects were collected from 1990 to 1994.Highly significant positive spatial correlations at the Class level (mean patch size (MN) and -diversity (abundance and richness) and proximity (PROX) showed that habitats in the Live Oak-Mesquite Savannah sub-region, the less fragmented subecoregion of the Edwards Plateau, were highly suitable for birds.The landscape structure analysis at class level showed that maintaining minimum mean patch size around 8 ha for woodland and 49 ha for scrubland, and a high proximity between patches is important to preserve suitability of habitat for permanent resident species, short-distance migrants, and the woodland and scrubland bird species richness in the Edwards Plateau ecoregion.