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Dong J.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Dong J.,University of Chinese Academy of Sciences | Dong J.,Key Laboratory of Resources Remote Sensing and Digital Agriculture | Tao F.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 2 more authors.
Environmental Earth Sciences | Year: 2011

Extensive studies have investigated the relationships between climate change and vegetation dynamics. However, the geographic controls on vegetation dynamics are rarely studied. In this study, the geographic controls on the trends and variation of vegetation greenness in middle and eastern Inner Mongolia, China (mid-eastern Inner Mongolia) were investigated. The SPOT VEGETATION 10-day period synthesis archive of normalized difference vegetation index (NDVI) from 1999 to 2007 was used for this study. First, the maximum value compositing (MVC) method was applied to derive monthly maximum NDVI (MNDVI), and then yearly mean NDVI (YMNDVI) was calculated by averaging the MNDVIs. The greenness rate of change (GRC) and the coefficient of variation (CV) were used to monitor the trends and variation in YMNDVI at each raster grid for different vegetation types, which were determined from a land use dataset at a scale of 1:100,000, interpreted from Landsat TM images in 2000. The possible effects of geographic factors including elevation, slope and aspect on GRC and CV for three main vegetation types (cropland, forest and steppe) were analyzed. The results indicate that the average NDVI values during the 9-year study period for steppe, forest and cropland were 0.26, 0.41 and 0.32, respectively; while the GRC was 0.008, 0.042 and 0.033 per decade, respectively; and CVs were 10.2, 4.8 and 7.1%, respectively. Cropland and steppe shared a similar trend in NDVI variation, with both decreasing initially and then increasing over the study period. The forest YMNDVI increased throughout the study period. The GRCs of the forest also increased, although GRCs for cropland and steppe decreased with increasing elevation. The GRCs of cropland and steppe increased with increasing slope, but the forest GRCs were not as closely related to slope. All three vegetation types exhibited the same effects in that the GRC was larger on north-facing (shady) slopes than south-facing slopes due to differences in water conditions. The CVs of the three vegetation types showed different features to the GRC. The CVs for all three vegetation types were not affected by aspect. The CVs for forest and cropland showed minor effects with changes in elevation and slope, but the CV for steppe decreased with increasing slope, and increased with increasing elevations to 1,200 m, before decreasing at higher elevations. Our findings suggest that the role of geographic factors in controlling GRC should also be considered alongside climate factors. © 2010 Springer-Verlag. Source

Liu X.-R.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Dong Y.-S.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Ren J.-Q.,Key Laboratory of Resources Remote Sensing and Digital Agriculture | Ren J.-Q.,Chinese Academy of Agricultural Sciences | Li S.-G.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research
Nutrient Cycling in Agroecosystems | Year: 2010

Soil net nitrogen mineralization (NNM) of four grasslands across the elevation and precipitation gradients was studied in situ in the upper 0-10 cm soil layer using the resin-core technique in Xilin River basin, Inner Mongolia, China during the growing season of 2006. The primary objectives were to examine variations of NNM among grassland types and the main influencing factors. These grasslands included Stipa baicalensis (SB), Aneulolepidum Chinense (AC), Stipa grandis (SG), and Stipa krylovii (SK) grassland. The results showed that the seasonal variation patterns of NNM were similar among the four grasslands, the rates of NNM and nitrification were highest from June to August, and lowest in September and October during the growing season. The rates of NNM and nitrification were affected significantly by the incubation time, and they were positively correlated with soil organic carbon content, total soil nitrogen (TN) content, soil temperature, and soil water content, but the rates of NNM and nitrification were negatively correlated with available N, and weakly correlated with soil pH and C:N ratio. The sequences of the daily mean rates of NNM and nitrification in the four grasslands during the growing season were AC > SG > SB > SK, and TN content maybe the main affecting factors which can be attributed to the land use type. © 2009 Springer Science+Business Media B.V. Source

Suramaythangkoor T.,King Mongkuts University of Technology Thonburi | Li Z.,Key Laboratory of Resources Remote Sensing and Digital Agriculture | Li Z.,Chinese Academy of Agricultural Sciences
Renewable and Sustainable Energy Reviews | Year: 2012

Cane trash could viably substitute fossil fuels in heat and power generation projects to avoid air pollution from open burning and reduce greenhouse gas (GHG) emission. It is competitive with bituminous and other agro-industrial biomass. Using cane trash for heat generation project could provide a higher reliability and return on investment than power generation project. The heat generation project could be viable (Financial Internal Rate of Return, FIRR = 36-81%) without feedstock subsidy. With current investment and support conditions, the capacity of 5 MW option of power generation project is the most viable (FIRR = 13.6-15.3%); but 30 MW, 1 MW and 10 MW options require feedstock subsidy 450-1100 Baht/t-cane trash to strengthen financial viability. Furthermore, the revenue from carbon credit sales could compensate the revenue from current energy price adder and increases 0.5-1.0% FIRR of power generation project. Using cane trash for 1 MW power generation could reduce GHG emission 637-861 t CO 2eq and avoid air pollutant emissions of 3.35 kg nitrogen oxides (NO x), 0.41 kg sulfur oxides (SO x) and 2.05 kg volatile organic compounds (VOC). Also, 1 t steam generation from cane trash could avoid pollutant emissions of 0.6 kg NO x, 0.07 kg SO x, and 0.37 kg VOC. The potential of cane trash to cause fouling/slagging as well as erosion are not significantly different from other biomass, but chlorinated organic compounds and NO x could be higher than bituminous and current biomass feedstock at sugar mill (bagasse and rice husk). © 2012 Elsevier Ltd. All right reserved. Source

Yin H.,Peking University | Li Z.,Peking University | Li Z.,Key Laboratory of Resources Remote Sensing and Digital Agriculture | Wang Y.,Peking University | Cai F.,Institute of Atmospheric Environment
Acta Geographica Sinica | Year: 2011

Desertification is one of the serious threats to the environment in arid and semi-arid northern China. In order to understand inter-annual vegetation dynamics, vegetation indicators have been widely used in desertification assessment. In this study, rain use efficiency (RUE) derived from hyper-temporal remote sensing images has been used for desertification assessment. Based on time-series analysis, this study focused on how the desertification developed in Inner Mongolia and how the desertification reversed in the extremely arid environment. Results showed that during the past 11 years, there was no significant desertification development in Inner Mongolia. Parts of area showed a significant increase trend of RUE, especially in the eastern part of Ordos Plateau and southern Daqing Mountain, as well as the region from the Greater Hinggan Mountains to northern Yanshan Mountains. It is indicated that the ecological conditions in these areas have tended to be much better than before. The reason may be that the vegetation protection policies adopted in northern China have exerted a positive effect on the local environment. The results also showed that there was a significant relationship between rainfall and vegetation restoration, areas with more precipitation tend to be more easily restored, especially in the areas with more 300 mm precipitation. In addition, the research on desertification reversion showed that the desert edge region in western Inner Mongolia have changed intensively, and desertification reverse assessment needs to be further examined. Source

Yan Z.,Chinese Academy of Agricultural Sciences | Peng Y.,Key Laboratory of Resources Remote Sensing and Digital Agriculture
Proceedings - 4th International Conference on Intelligent Computation Technology and Automation, ICICTA 2011 | Year: 2011

With global warming and increasing of extreme climate evens, climate change may impose positive or negative effects on crop growth and yield. The traditional crop productivity simulations based on crop models are normally site-specific. In this study, the spatial crop model is developed by integrating Geographical Information System (GIS) with Erosion Productivity Impact Calculator (EPIC) model to simulate regional crop growth and yield. Data are exchanged using ASCII or binary data format between GIS and EPIC model without a common user interface. The GIS-based EPIC model is applied to simulate the average corn and wheat yield of 1980s in North China. Compared with the statistical yields, the crops yield of Shandong and Beijing is underestimated by the GIS-based EPIC model, especially for Beijing. However, the errors are mostly less than 10%, except that in Beijing and Shandong. Thus, the simulation accuracy of the GIS-based EPIC model is acceptable. The simulation accuracy can be improved by using the detailed field management information, such as irrigation, fertilization and tillage. © 2011 IEEE. Source

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