Topography and human disturbances are major controlling factors in treeline pattern at Barun and Manang area in the Nepal Himalaya

The alpine treeline ecotone is an important component of mountain ecosystems of the Nepal Himalaya; it plays a vital role in the livelihood of indigenous people,and provides ecosystem services. However,the region faces a problem of paucity of data on treeline characteristics at the regional and landscape scales. Therefore,we used Remote Sensing(RS),and Geographic Information Science(GIS) approaches to investigate cross-scale interactions in the treeline ecotone. Additionally,European Space Agency land cover map,International Center for Integrated Mountain Development(ICIMOD) land cover map,ecological map of Nepal,and United States Geological Survey Shuttle Radar Topography Mission-Digital Elevation Model were used to analyze treeline pattern at the regional scale. Digital Globe high-resolution satellite imagery of Barun(eastern Nepal) and Manang(central Nepal) were used to study treeline patterns at the landscape scale. Treeline elevation ranges from 3300-4300 m above sea level. Abies spectabilis,Betula utilis,and Pinus wallichiana are the main treeline-forming species in the Nepal Himalaya. There is an east to west treeline elevationgradient at the regional scale. No slope exposure is observed at the regional scale; however,at the landscape scale,slope exposure is present only in a disturbed area(Manang). Topography and human disturbance are the main treeline controlling factor in Barun and Manang respectively.

高效液相色谱法检测食品中食品添加剂的探究

本文详细介绍了高效液相色谱法在食品添加剂检测中的应用,包括对食品甜味剂、防腐剂 和色素添加剂的检测。文章首先强调了样品前处理的重要性,包括选择合适的提取方法和去除杂质的 方法。然后,文章阐述了如何严格、合理地设置参数,包括色谱柱和流动相的选择、流速和进样量的控 制、检测波长和检测器类型的选择。最后,文章讨论了如何加强对干扰因素的控制,以获得更准确和可 靠的检测结果。