Tree species preferences for foraging site and ways in which the preferences affect the distribution, abundance and species composition of arboreal woodland avifauna

The tree species preferences by six arboreal bird species and their role in structuring the bird communities in woodland were investigated in two sites in County Durham. Each bird species showed a preference or avoidance for most of the tree species in both study sites. The patterns of tree preference were different for each bird species, and were the basis for efficient partitioning of the foraging niches in woodland. Bird species showed significantly less overlap in tree species choice than in any of the other four niche dimensions examined, making it the most important dimension of the foraging niche. The tree species preferences of the bird species were reflected in the distribution of the birds within the woods. For each pair of bird species the degree of similarity in tree species choice and birds' distribution in the wood were identical. Bird species richness was predictable from tree species richness. There were significant positive correlations between all pairs of the following factors: bird species diversity, tree species diversity, bird species richness, tree species richness, bird density, and the percentage of broadleaved trees. Bird density was negatively correlated with the size of the wood (or compartment), apparently due to an edge effect. Seasonal and year to year changes in the tree preference by birds were explicable in terms of changes in the relative abundance of arthropod prey and other foods available in the trees

Response of Bird Populations to Long-term Changes in Local Vegetation and Regional Forest Cover

We analyzed data from a woodland site for a 59-year period to determine whether changes in bird populations are related to changes in the diversity and relative abundance of woody plant species even when vegetation structure, degree of forest fragmentation in the surrounding landscape, and regional changes in bird populations are taken into account. Principal component analyses generated vegetation factors encompassing variables such as total basal area, shrub density, basal area of common tree species, and measures of tree and shrub species diversity. We also calculated a forest edge/ forest area index based on GIS analysis of the landscape within 2 km of the study site. Poisson regression models revealed relationships between these covariates and population changes for 19 bird species and for seven groups of species characterized by similar migration strategies or habitat requirements. All groups of habitat specialists showed a positive relationship with the first vegetation factor, which indicates that they declined as total basal area and dominance of oaks and maples increased and as tree and shrub diversity decreased. This suggests that floristic diversity may be important for determining habitat quality. Bird species associated with the shrub layer and with hemlock stands showed positive relationships with the second vegetation factor, suggesting that the recent decline in eastern hemlocks (Tsuga canadensis) because of hemlock woolly adelgid (Adelges tsugae) had an adverse impact on these species. Forest migrants, shrub-layer specialists, long-distance migrants and permanent residents showed negative relationships with the forest edge/forest interior index, indicating that conservation efforts to protect bird communities should take the wider landscape into account. The strongest relationship for most species and species groups was with the first vegetation factor, which suggests that species composition and diversity of trees and shrubs may be especially important in determining abundance of many forest bird species

Relationship Between Tree Canopy Cover, Impervious Surfaces, & Bird Biodiversity in Urban Parks in Nashville, Tennessee​

Bird diversity is an indicator of the overall biodiversity in urban green spaces. Identifying factors associated with urban green spaces that strongly influence bird biodiversity can inform the development and management of urban green spaces. Parks with larger areas of impervious surfaces were predicted to have lower bird diversity than those with more tree canopy coverage. This study used iTree Canopy to determine the percentage of tree canopy and impermeable surfaces for four different areas of urban parks in Nashville, Tennessee. Two parks were closer to the urban core and two were farther away. Tree canopy and impermeable surface cover were compared to biodiversity of bird species determined from acoustic song meter recordings within the parks. Preliminary analysis of the data suggests that parks with higher percentages of impermeable areas relative to tree canopy had lower overall bird biodiversity. Managing parks for more tree canopy coverage can enhance urban bird diversity

HUBUNGAN KEANEKARAGAMAN JENIS BURUNG DAN KOMPOSISI POHON DI KAMPUS 2 UIN WALISONGO SEMARANG

Various species of birds can be used as bio-indicators of the environmental quality of an area. The diversity of tree species is directly proportional to the diversity of bird species. The purpose of this study was to determine the environmental quality of campus 2 Walisongo UIN Semarang through parameters related to the diversity of bird species with tree composition. This study uses a census method to collect tree composition data, and the number of counting points is used as a bird species data collection technique. The research sites are in four campus areas 2 of UIN Walisongo, namely: zone A in the Taman Fuhum area (east of the Faculty of Usuluddin and Humanities), zone B in the Faculty of Science and Technology area, zone C in the Unyil Park area of the Faculty of Tarbiyah and Teacher Training (FITK) and zone D in the North forest area of the Faculty of Science and Mathematics Technology. The results show zone D has the highest level of tree variation and bird species variation. Consists of 81 species of trees and 13 species of birds. In contrast zone, C has the lowest level of tree variation and lowest variation of bird species. The number of tree species is related to variations in the number of bird species. It can be concluded that the best environmental quality on campus 2 of UIN Walisongo is in zone D. The lack of diversity of bird and tree species in several areas on campus 2 of UIN Walisongo Semarang shows that there is a need for reforestation and tree planting to increase the diversity of bird species as parameters of environmental quality in campus 2 UIN Walisongo Semarang

On the irreducible core and the equal remaining obligations rule of minimum cost spanning extension problems

Minimum cost spanning extension problems are generalizations of minimum cost spanning tree problems in which an existing network has to be extended to connect users to a source. This paper generalizes the definition of irreducible core to minimum cost spanning extension problems and introduces an algorithm generating all elements of the irreducible core. Moreover, the equal remaining obligations rule, a one-point refinement of the irreducible core ispresented. Finally, the paper characterizes these solutions axiomatically. The classical Bird tree allocation of minimum cost spanning tree problems is obtained as a particular case in our algorithm for the irreducible core.Networks;Cost Allocation;costs and cost price