Search

Himalayan hemlock (Tsuga dumosa) experienced a recolonization event during the Quaternary period; however, the specific dispersal routes are remain unknown. Recently, the least cost path (LCP) calculation coupled with population genetic data and species distribution models has been applied to reveal the landscape connectivity. In this study, we utilized the categorical LCP method, combining species distribution of three periods (the last interglacial, the last glacial maximum, and the current period) and locality with shared chloroplast, mitochondrial, and nuclear haplotypes, to identify the possible dispersal routes of T. dumosa in the late Quaternary. Then, both a coalescent estimate of migration rates among regional groups and establishment of genetic divergence pattern were conducted. After those analyses, we found that the species generally migrated along the southern slope of Himalaya across time periods and genomic makers, and higher degree of dispersal was in the present and mtDNA haplotype. Furthermore, the direction of range shifts and strong level of gene flow also imply the existence of Himalayan dispersal path, and low area of genetic divergence pattern suggests that there are not any obvious barriers against the dispersal pathway. Above all, we inferred that a dispersal route along the Himalaya Mountains could exist, which is an important supplement for the evolutionary history of T. dumosa. Finally, we believed that this integrative genetic and geospatial method would bring new implications for the evolutionary process and conservation priority of species in the Tibetan Plateau.

Using NOAA/AVHRR normalized difference vegetation index (NDVI) data, the impact of vegetation cover on surface air temperature change is investigated by subtracting the reanalysis from the observation (observation minus reanalysis, OMR). The results show that the temperature OMR trend is inversely correlated to the surface vegetation index and the strong (weak) surface warming corresponds to the surface barrenness (greenness). Areas with NDVI less than 0.1 show a large warming trend of more than 0.2 degrees C/10a, but areas with NDVI larger than 0. 5 show little surface warming and even decreasing trends of temperature. Moreover, the OMR trend sensitively responds to the seasonal vegetation cover change. Atmosphere-land feedbacks over areas with different vegetation covers can alter the response of regional surface air temperature to global warming induced by the increase in anthropogenic greenhouse gases concentrations. Thus, it is suggested that projection of future surface climate of China should incorporate the impacts of spatio-temporal variability in vegetation cover.