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Analysis of spatial-temporal variations of desert vegetation under the background of climate changes can provide references for ecological restoration in arid and semi-arid areas. In this study, we used the Global Inventory Modeling and Mapping Studies (GIMMS) NDVI data from 1982 to 2006 and Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI data from 2000 to 2013 to reveal the dynamics of desert vegetation in Hexi region of Northwest China over the past three decades. We also used the annual temperature and precipitation data acquired from the Chinese meteorological stations to analyze the response of desert vegetation to climatic variations. The average value of NDVImax (the maximum NDVI during the growing season) for desert vegetation in Hexi region increased at the rate of 0.65×10 -3 /a (P<0.05) from 1982 to 2013, and the significant increases of NDVImax mainly appeared in the typical desert vegetation areas. Vegetation was significantly improved in the lower reaches of Shule and Shiyang river basins, and the weighted mean center of desert vegetation mainly shifted toward the lower reaches of the two basins. Almost 95.32% of the total desert vegetation area showed positive correlation between NDVImax and annual precipitation, indicating that precipitation is the key factor for desert vegetation growth in the entire study area. Moreover, the areas with non-significant positive correlation between NDVImax and annual precipitation mainly located in the lower reaches of Shiyang and Shule river basins, this may be due to human activities. Only 7.64% of the desert vegetation showed significant positive correlation between NDVImax and annual precipitation in the Shule River Basin (an extremely arid area), indicating that precipitation is not the most important factor for vegetation growth in this basin, and further studies are needed to investigate the mechanism for this phenomenon.

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Financial returns of forest plantations are an important concern around the world. In this research, we focused on South China's timber investments, collected data from the Pingxiang, Guangxi Province, China, which is the demonstration zone of Fast-growing and High-yielding Timber Plantation Base Construction Program and National Timber Strategic Storage and Production Bases Construction Program, and used capital budgeting analysis method and sensitivity analysis to compare different scenarios of planted forest management. The results showed that excluding land costs, (1) the financial returns of Eucalyptus forest managed by small business were excellent, having an IRR of 28% per year and a LEV of $7555 per ha, but it had a high risk with fluctuations of cost, timber price and timber yield; (2) the results for the Experimental Center of Tropical Forests indicate that the Eucalyptus forest and Castanopsis hystrix forest returns were greater than those for Cunninghamia lanceolata forest and Pinus massoniana forest, with having IRRs of 24%, 21%, 13% and 10% per year respectively. The mixed planted forest of Castanopsis hystrix × Eucalyptus and Castanopsis hystrix × Pinus massoniana had the features of high profits and low risks; (3) the forest farmers had lower levels of returns for Eucalyptus forest management in South China, but were still in the middle rank of global comparisons. This study gave a view of China's timber investment and provided more options of improving the economic returns of planted forest management to both small businesses and forest farmers in South China.