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Larger Fragments (larger + fragment)
Selected AbstractsForest Fragment and Breeding Habitat Characteristics Explain Frog Diversity and Abundance in SingaporeBIOTROPICA, Issue 1 2010David Bickford ABSTRACT Habitat loss and fragmentation can have severe negative and irreversible effects on biodiversity. We investigated the effects of forest fragmentation on frog diversity in Singapore because of its high rates of deforestation and the demonstration that frogs are some of the most sensitive species to habitat degradation. We surveyed frog species in 12 forest fragments varying from 11 to 935 ha. We compared differences in species richness, abundance, and Shannon's index in relation to forest fragment size, connectivity (distance between fragments), and breeding habitat heterogeneity. A total of 20 species from 12 genera and five families were encountered in 12 fragments. Larger fragments and those closer to larger fragments had higher species richness. Abundance, however, was not correlated with forest area or connectivity, but we found fewer individual frogs in the larger fragments. We also found that breeding habitat heterogeneity best explained frog species diversity and abundance in forest fragments. Fragments with a high diversity of breeding habitats had more species. We found no evidence to suggest that abundance and diversity are strongly correlated, particularly in disturbed areas, but that breeding habitat heterogeneity is an under-appreciated factor that should be considered when prioritizing areas for anuran conservation. Enriching breeding habitat heterogeneity, creating corridors between fragments, and reforesting degraded areas are some of the most beneficial strategies for preserving urban frog biodiversity. [source] Genetic diversity of Y-specific STRs in chimpanzees (Pan troglodytes)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 1 2002L. Gusmão Abstract Using the primers described for humans, sequences for 11 Y-specific microsatellites (DYS434, DYS435, DYS436, DYS437, DYS438, DYS439, GATA A10, A7.1, A7.2, C4, and H4 [Gusmão et al., in press]), previously described in 10 male chimpanzees (Pan troglodytes), were confirmed in nine additional male chimpanzees. Sequences for nine additional microsatellites (DYS19, DYS385I and II, DYS389I and II, DYS390, DYS391, DYS392, and DYS393) were determined in all 19 male chimpanzees; homology to human Y-Short Tandem Repeat (STRs) was confirmed by sequencing. Good amplification results were not obtained for DYS19 and DYS385I/II. Two amplicons were obtained for DYS389I/II, but in contrast to humans, the larger fragment was not Y-specific. Moreover, no polymorphism was observed for DYS434, DYS435, or GATA A10. Consequently, these eight STRs were eliminated from further analyses, and haplotype and allele frequencies were estimated for the remaining 12 STRs. A high haplotype diversity value was found (1.000 ± 0.017), demonstrating the usefulness and informative power of these Y-STRs for future studies on chimpanzee population genetics.Am. J. Primatol. 57:21,29, 2002. © 2002 Wiley-Liss, Inc. [source] Laboratory simulation of the salt weathering of schist: II.EARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2007Fragmentation of fine schist particles Abstract Recent developments in long term landform evolution modelling have created a new demand for quantitative salt weathering data, and in particular data describing the size distribution of the weathered rock fragments. To enable future development of rock breakdown models for use in landscape evolution and soil production models, laboratory work was undertaken to extend existing schist/salt weathering fragmentation studies to include an examination of the breakdown of sub-millimetre quartz chlorite schist particles in a seasonally wet tropical climate. Laser particle sizing was used to assess the impact of different experimental procedures on the resulting particle size distribution. The results reveal that salt weathering under a range of realistic simulated tropical wet season conditions produces a significant degree of schist particle breakdown. The fragmentation of the schist is characterized by splitting of the larger fragments into mid-sized product with finer material produced, possibly from the breakdown of mid-sized fragments when weathering is more advanced. Salinity, the salt addition method and temperature were all found to affect weathering rates. Subtle differences in mineralogy also produce variations in weathering patterns and rates. It is also shown that an increase in drying temperature leads to accelerated weathering rates, however, the geometry of the fracture process is not significantly affected. Copyright © 2006 John Wiley & Sons, Ltd. [source] Forest Fragment and Breeding Habitat Characteristics Explain Frog Diversity and Abundance in SingaporeBIOTROPICA, Issue 1 2010David Bickford ABSTRACT Habitat loss and fragmentation can have severe negative and irreversible effects on biodiversity. We investigated the effects of forest fragmentation on frog diversity in Singapore because of its high rates of deforestation and the demonstration that frogs are some of the most sensitive species to habitat degradation. We surveyed frog species in 12 forest fragments varying from 11 to 935 ha. We compared differences in species richness, abundance, and Shannon's index in relation to forest fragment size, connectivity (distance between fragments), and breeding habitat heterogeneity. A total of 20 species from 12 genera and five families were encountered in 12 fragments. Larger fragments and those closer to larger fragments had higher species richness. Abundance, however, was not correlated with forest area or connectivity, but we found fewer individual frogs in the larger fragments. We also found that breeding habitat heterogeneity best explained frog species diversity and abundance in forest fragments. Fragments with a high diversity of breeding habitats had more species. We found no evidence to suggest that abundance and diversity are strongly correlated, particularly in disturbed areas, but that breeding habitat heterogeneity is an under-appreciated factor that should be considered when prioritizing areas for anuran conservation. Enriching breeding habitat heterogeneity, creating corridors between fragments, and reforesting degraded areas are some of the most beneficial strategies for preserving urban frog biodiversity. [source] Plant Community Structure in Tropical Rain Forest Fragments of the Western Ghats, India,BIOTROPICA, Issue 2 2006S. Muthuramkumar ABSTRACT Changes in tree, liana, and understory plant diversity and community composition in five tropical rain forest fragments varying in area (18,2600 ha) and disturbance levels were studied on the Valparai plateau, Western Ghats. Systematic sampling using small quadrats (totaling 4 ha for trees and lianas, 0.16 ha for understory plants) enumerated 312 species in 103 families: 1968 trees (144 species), 2250 lianas (60 species), and 6123 understory plants (108 species). Tree species density, stem density, and basal area were higher in the three larger (> 100 ha) rain forest fragments but were negatively correlated with disturbance scores rather than area per se. Liana species density, stem density, and basal area were higher in moderately disturbed and lower in heavily disturbed fragments than in the three larger fragments. Understory species density was highest in the highly disturbed 18-ha fragment, due to weedy invasive species occurring with rain forest plants. Nonmetric multidimensional scaling and Mantel tests revealed significant and similar patterns of floristic variation suggesting similar effects of disturbance on community compositional change for the three life-forms. The five fragments encompassed substantial plant diversity in the regional landscape, harbored at least 70 endemic species (3.21% of the endemic flora of the Western Ghats,Sri Lanka biodiversity hotspot), and supported many endemic and threatened animals. The study indicates the significant conservation value of rain forest fragments in the Western Ghats, signals the need to protect them from further disturbances, and provides useful benchmarks for restoration and monitoring efforts. [source] | ||||||||||