The Qomolangma Mountain region within the Central Himalayas is characterized by obvious altitudinal variation, habitat complexity, and land cover diversity. This region is therefore one of the most sensitive areas to climate change in the world. Besides, because this region has the most complete natural vertical spectrum in the world, it is ideal for studying the vertical structure of alpine land cover. Utilizing land cover data for 2010 (30 m resolution) along with digital elevation model outputs, three division methods were defined that encompass the northern and southern slopes of Qomolangma Mountain. These comprised the ridgeline method, the sample transect method, and the sector method. The study investigated altitudinal distributions, similarities and differences, and changes in the degree of land cover on the northern and southern slopes of the Himalayas area using the software ArcGIS and MATLAB tools and division models. The main results of this analysis are listed as follows:
Firstly, the distribution of land cover in mountainous areas was characterized by an obvious vertical spectrum structure, with the south-six and north-four pattern of vertical spectrum of land cover in the Central Himalayas marked by the influence of human activities. Secondly, zonal distribution was exhibited by forests, grasslands, sparse vegetation, barren land, glaciers, and snow covers from low to high altitudes. It was markedly different in the composition and structure of land cover vertical spectrum between the northern and southern slopes of this mountain area. The vertical spectrum of land cover types on the southern slope was complete and diverse, but it was relatively simple on the northern slope. The study shows that given the same land cover type, the amplitude of elevation distribution on the southern slope was wide, while that on the northern slope was narrow. The distribution of land cover types on the southern slope was low. Thirdly, the results show that the area distribution ratio of each land cover type varied with elevation according to change mode. Vertical distribution patterns of land cover types on the southern and northern slopes were therefore divided into four categories, with glaciers, snow, sparse vegetation, and grasslands conforming to unimodal distribution patterns. The bare land also followed a unimodal distribution pattern on the southern slope, but it followed a bimodal one on the northern slope. Fourthly, all kinds of vertical belt structures and land cover divisions on the southern slope were similar, but they were different from one another on the northern slope due to division methods. In comparison with field survey data, results reported here for the sector method were more in line with the actual situation.

The Loess Plateau is the core region of the "Green to Grain" Program, which makes it become the most successful example of ecological restoration in China. It is the common demand of both academic research and management practice to analyze the effects of vegetation restoration on ecosystem service and identify the threshold effects of vegetation restoration. However, there still is a research gap in related studies, especially for the thresholds of vegetation in the ecosystem service change at regional scale. In this study, we chose the fractional vegetation cover (FVC) as an index to indicate the vegetation coverage change in the Loess Plateau in 2000-2015, and took soil conservation service, water yield service and carbon sequestration service as indexes to exhibit the ecosystem service changes. The spatiotemporal changes of vegetation coverage and ecosystem services and their interaction were quantitatively analyzed. On such a basis, we further assessed the effects of vegetation coverage change on ecosystem services and quantitatively identified their thresholds. The results indicated that: (1) The vegetation coverage significantly improved in 2000-2015. Meanwhile, the differences of ecosystem service changes were prominent, with the carbon sequestration service getting significant enhancement, soil conservation service getting certain improvements and the water yield service maintaining steady. (2) There are differences among the correlations between vegetation restoration and changes of ecosystem service. The correlation of vegetation coverage-carbon sequestration service was the strongest, followed by that of vegetation coverage-soil conservation service. (3) The vegetation restoration could promote the improvement of the overall level of regional ecosystem service. Furthermore, we revealed the threshold effect in the promotion. The threshold occurrence resulted in the decrease of promotion efficiency of vegetation restoration, with vegetation coverage reaching 44%, 32%, 34% and 34% in forest zone, forest-grass zone, grass zone and grass-desert zone, respectively.

Based on the observed daily temperature and precipitation of the land surface of 603 meteorological stations in China, the Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) 3rd generation dataset, the changing patterns of NDVI in China during 1982-2015 were investigated and the corresponding contributions of the main driving forces, climatic change and human activities, to these changes were distinguished using the methods of trend analysis and multiple regression residuals analysis. The results showed that vegetation recovered in whole China in research period significantly. Shanghai was the single case with a decrease in growing season NDVI in the selected 32 provincial-level administrative regions, while the growing season NDVI in Shanxi, Shaanxi, and Chongqing increased much faster compared with other regions. The climatic change and human activities drove the NDVI change jointly as main forces in China and induced both a rapid increasing trend on the whole and a huge spatial difference. The impacts of climatic change on NDVI change in the growing-season ranged from -0.01×10 ^-3 a ^-1 to 1.05×10 ^-3 a ^-1, while the impacts of human activities changed from -0.32×10 ^-3 a ^-1 to 1.77×10 ^-3 a ^-1. The contributions of climatic change and human activities accounted for 40% and 60%, respectively, to the increase of NDVI in China in the past 34 years. The regions where the contribution rates of human activities were more than 80% were mainly distributed in the central part of the Loess Plateau, the North China Plain, and the northeast and the southwest of China. There were 22 provincial-level regions where the contributions of human activities were more than 50%, and the shares of contribution induced by human activities in Shanghai, Heilongjiang, and Yunnan were much greater than those of any other regions. The results suggest that we should focus more on the role of human activities in vegetation restoration in the whole country.

Forest ecosystem service trade-offs and synergies are important research topics for several disciplines. The multi-scale analysis of service trade-offs and synergies assists in the implementation of more effective forest resource management. Based on multi-source data including forest distribution, topography, NDVI, meteorology and soil conditions, key forest ecosystem services, including total forest volume, carbon storage, water yield, soil retention and habitat quality were mapped and evaluated for the Funiu Mountain Region through integrated deployment of the CASA model, the InVEST3.2 model and the ArcGIS10.2 software. The characteristics of trade-offs and synergies among different ecosystem services were then mapped and considered across multiple spatial scales (i.e., by region, north and south slopes, vertical belt) using the spatial overlay analysis method. The main results are as follows: (1) Mean forest volume is 49.26 m ³/hm ², carbon density is 156.94 t/hm ², water supply depth is 494.46 mm, the unit amount of soil retention is 955.4 t/hm ², and the habitat quality index is 0.79. (2) The area of forests with good synergy is 28.79%, and the area of forests with poor synergy is 10.15%, while about 61.06% of forests show severe trade-offs and weak trade-offs. The overall benefits of forest ecosystem services in the study area are still low. In the future, bad synergy and severe trade-off areas should be the focus of forest resource management and efficiency regulation. (3) Synergy between ecosystem services is better for forest on south slope than that on north slope. Deciduous broad-leaved forest belt at moderate elevations on south slope in the mountains (SIII) has the highest synergies, while that at low elevations on north slope (NI) exhibits the lowest synergy levels.