Search

Little has been published to describe or interpret Asian biodiversity hotspots, including those in the East Himalayan Mountains of Southwest China (HMSC), thus making necessary a review of the current knowledge. The Pliocene and Pleistocene geological and glacial histories of the Asian continent differ from those of Europe and North America, suggesting different mechanisms of speciation and extinction, and, thus, different responses to climate changes during the Quaternary glaciations. This short review summarizes potential drivers in shaping and maintaining high species richness and endemism of birds in the HMSC. The geographical location at the junction of different biogeographical realms, the wide range of habitats and climates along the extensive elevational range, the complex topography and the distinct geological history of this region have probably contributed to the evolution of an exceptionally species-rich and endemic-rich, specialized montane avian fauna. The Mountain systems in the HMSC may have provided refugia where species survived during the glacial periods and barriers for preventing species dispersal after the glacial periods. More studies are required to further test this refugia hypothesis by comparing more cold-tolerent and warm-tolerent species. [ABSTRACT FROM AUTHOR]

Abstract: Both porosity and deformation properties of porous media are dependent on stress. For geological media, the stress-dependent porosity and deformation properties can be shown to be depth related. Unfortunately, both in situ porosity and in situ deformation properties are difficult to measure. In the current study, a method is developed to evaluate the changes in porosity and bulk modulus with depth by using in situ measurements of permeability, which can be easily obtained by employing packer tests. In the case study, the change in permeability of a shear in the Baihetan hydropower station in Southwest China is estimated. Then, the permeability–depth correlation is utilized to calculate the porosity and the bulk modulus at different depths. The results clearly show that the porosity decreases with depth while the bulk modulus increases with depth. Based on the proposed model, the bulk modulus is calculated to increase from 4–6MPa on the ground surface to 18–30MPa at the depth of 160m. The Young''s modulus of the shear estimated with this depth-dependent bulk modulus is consistent with in situ measurement. [Copyright &y& Elsevier]