Effects of large-scale land consolidation projects on ecological environment quality: A case study of a land creation project in Yan'an, China.

Large land consolidation projects modify the structures and functions of regional ecosystems through the reshaping of the territorial spatial pattern, thereby affecting the ecological environmental quality (EEQ). To investigate the effects of large-scale land consolidation projects on EEQ, this study takes the major land consolidation project of "bulldoze mountains to create land" (BMCL) in Yan'an City as a research object and evaluates the change of EEQ based on Remote Sensing Ecological Index (RSEI). The consolidated area and the control area were set up to comparatively analyze the EEQ change processes and spatial distribution characteristics of these two areas in the full life cycle of BMCL. According to the results, the mean RSEI of the consolidated area was 0.128 lower than that of the control area, and the EEQ of the consolidated area was always lower than that of the control area. BMCL had a strong negative impact on the EEQ grade of the consolidated area, especially in the early stage. However, the positive effect of BMCL on EEQ gradually emerged in the late stage of the large land consolidation project. The overall EEQ grade of the consolidated area has also improved. The results of the stepwise regression analysis indicated that the wetness component and the normalized differential vegetation index played key roles in improving the EEQ of the BMCL. Overall, the local BMCL strongly affected the EEQ of the consolidated area but would not cause the EEQ of the whole region to experience any dramatic, abrupt change in the short term. This study provided references for the evaluation and analysis of the ecological effects of land consolidation at the regional scale, offering a feasible way to evaluate the spatio-temporal change of EEQ in BMCL.

Advance in cross species transmission of avian influenza virus H6N1 subtype / 中国人兽共患病学报

Avian influenza virus H6N1 subtype has been circulating in aquatic bird and terrestrial bird,and is the most frequently detected subtype of influenza A virus in those hosts.Genetic analysis results suggested that this virus might be the progenitor of the highly pathogenic avian influenza H5N1 virus,as seven of eight gene segments of those viruses had a common source.As continuing evolution of H6N1,it could spread across species barriers to mammals and had strong infection ability in mice,swine and ferrets.Serological epidemiological survey showed that a few people were positive for H6 avian influenza virus antibody and then the world's first human infection with influenza virus H6N1 subtype was reported in May 2013.Therefore,with the expansion of the host range of the virus,gene mutation and gene reassortment of H6N1 virus can occur in these hosts,and then it may evolve into novel variant strain with infected human potential.