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Gao Q.,Chinese Academy of Agricultural Sciences | Gao Q.,Key Laboratory for Agro Environment and Climate Change | Gao Q.,Beijing Normal University | Kang M.,Beijing Normal University | And 3 more authors.

The semi-arid loess hilly-gully region in China has an extremely vulnerable ecological environment. Inappropriate land use - crop farming, overgrazing, and plantation forestry - has worsened soil erosion, intensified water shortage, and hence impeded the ecological conservation and agricultural development of the entire region in the past. Optimizing land use and vegetation cover and spatial pattern is conducive to achieving both ecological and economic goals in terms of controlling soil erosion, using water resources rationally and raising agricultural productivity. Changchuan Watershed, a typical small catchment in the semi-arid loess hilly region, was selected as the case study area to analyze the impacts of land use and land cover structure and associated spatial pattern on soil erosion and water consumption in the Watershed, through field investigation and model simulation. Land use structure was optimized by multi-objective programming, using remote sensing (RS) and geographical information system (GIS) techniques, analytic hierarchical programming (AHP) and expert consultancy. The digitized optimumspatial patternembodying rationally-proportioned land use structure was obtained through GIS-aided redistribution of land use types. The optimized land use structure reapportioned woodlands, shrublands, grasslands, and croplands at 3.7%, 38.6%, 49.4%, and 6.3% of the land area respectively, compared to the current land use structure of 2.4%, 38.6%, 24.0%, and 12.6%, respectively, in the Changchuan Watershed. In the optimized land use spatial pattern, croplands are mainly located in the riverside plain and check-dammed valleys and grasslands are widely distributed in the lower reaches of the basin, while shrublands are appropriately established in the middle and upper reaches of the river. A comparative analysis shows that the optimized land use structure, with well-designed spatial pattern is able to reduce soil erosion, enhance the utilization of water resources and raise agricultural productivity. © 2010 Elsevier B.V. Source

Fang H.,CAS Institute of Geographical Sciences and Natural Resources Research | Cheng S.,University of Chinese Academy of Sciences | Lin E.,Key Laboratory for Agro Environment and Climate Change | Yu G.,CAS Institute of Geographical Sciences and Natural Resources Research | And 6 more authors.

Carbon dioxide (CO2) enrichment and increased nitrogen (N) deposition can change microbial activity and dissolved organic carbon (DOC) turnover, consequently affecting carbon sequestration in soils. However, we do not have much available information on the relationship between soil DOC and microbial activity under CO2 enrichment and N addition in semi-arid agroecosystems. Using free air CO2 enrichment (FACE), soybean and winter wheat were grown in the field under ambient CO2 (350 μmol mol−1) and elevated CO2 (550 μmol mol−1) conditions subjected to two N fertilizer regimes (132 and 306 kg N ha−1 year−1). Rhizosphere soils and bulk soils at three depths, 0–10, 10–20 and 20–40 cm, were collected to determine water extractable organic matter (WEOM) characteristics with fluorescence spectroscopy and parallel factor analyses of excitation/emission matrix, as well as five extracellular enzymes activities. All significant effects were observed in the topsoil (0–10 cm): elevated CO2 decreased water extractable organic carbon concentration of the rhizosphere soils and bulk soils by 8.5 and 10.1 %, respectively. Furthermore, elevated CO2 changed the composition and structure of soil WEOM by increasing the plant- and microbial-derived components in the rhizosphere and solubilizing soil organic matter (SOM). The activities of β-1,4-glucosidase, cellobiohydrolase, phenol oxidase, and peroxidase were stimulated by elevated CO2 in the rhizosphere soils and bulk soils. Our findings suggest that the stimulation of microbial activity elicited by elevated CO2 increased the turnover of labile WEOM and the solubilization of SOM in the topsoils, which could be adverse to the accumulation and stability of soil carbon in the semi-arid agroecosystems in northern China. © 2014, Springer International Publishing Switzerland. Source

Gao Q.-Z.,Chinese Academy of Agricultural Sciences | Gao Q.-Z.,Key Laboratory for Agro Environment and Climate Change | Wan Y.-F.,Chinese Academy of Agricultural Sciences | Wan Y.-F.,Key Laboratory for Agro Environment and Climate Change | And 5 more authors.
Quaternary International

Northern Tibet is the headstream region for the Yangtze, Nu (Salween River), and Lancang (Mekong River). Sustaining the environmental conditions in the region is vital for Tibet and, as the source of many rivers, the whole of China and much of Asia. The study combines remote sensing data with data from other sources and national standards of grassland degradation index to assess alpine grassland degradation index between 1981 and 2004 in Northern Tibet. A Geographical Information System (GIS) was used to examine trends in grassland degradation index and its response to climate variability, including precipitation, temperature, and solar radiation. The results show that degradation has been very serious. The areas with a significant grassland degradation index trend accounted for 23.3% of the total grasslands in Northern Tibet. During 1981-2004, precipitation variability has benefited the recovery and protection of the grasslands, while temperature and solar radiation variability exacerbated grassland degradation index in Northern Tibet. The impact of regional climate change on grassland degradation index was on the balance more detrimental than positive from 1981 to 2004. © 2009 Elsevier Ltd and INQUA. Source

Gao Q.-Z.,Chinese Academy of Agricultural Sciences | Gao Q.-Z.,Key Laboratory for Agro Environment and Climate Change | Li Y.,Chinese Academy of Agricultural Sciences | Li Y.,Key Laboratory for Agro Environment and Climate Change | And 4 more authors.
Mitigation and Adaptation Strategies for Global Change

Northern Tibet is the headstream region for the Yangtze, Salween River, Mekong River, and numerous other inflowing rivers and high mountain lakes. Sustaining the environmental conditions in the region is of vital importance for Tibet and the whole of China. The alpine grassland ecosystem in Northern Tibet is the most important ecosystem and extremely sensitive to climate change and human activity. In this study, we analyzed the characteristics of climate variability based on observed meteorological data and future climate scenarios, and reviewed the impact of climate variability and to explore adaptation strategies of alpine grassland in Northern Tibet. The result showed that the annual mean temperature has increased by 0.31 °C·10a-1 while the annual total precipitation has increased by 14.6 mm·10a-1 with high inter-annual and inter-seasonal fluctuations in Northern Tibet from 1961 to 2008. The rising trends of temperature and precipitation would be continued and the aridity indices showed a decreasing trend in the future, which potentially predicts that the climate in Northern Tibet becomes warmer and dryer. The climate variability results the melting of glaciers, the expansion of inland high mountain lakes and the negative impacts on alpine grassland in recent years. In order to adapt to such possible future climate changes, the alpine grassland water-saving irrigation was recommended as key adaptation measure and also rational grazing management, alpine grassland fencing and artificial grass planting were selected as adaptation measures, to lower the negative impacts of climate variability on the alpine grassland ecosystem in Northern Tibet. © 2012 Springer Science+Business Media Dordrecht. Source

Fang H.,Chinese Academy of Agricultural Sciences | Fang H.,Key Laboratory for Agro Environment and Climate Change | Yang Q.,Chinese Academy of Agricultural Sciences | Yang Q.,Key Laboratory for Agro Environment and Climate Change | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering

In this study, the solar energy was used as heat source, the water was used as heat storage medium and the shallow soil in greenhouse was used for heat storage. The heat was collected and stored in shallow soil through water circulation during daytime, and the greenhouse temperature increased at night due to the soil heat releasing. The results showed that this method could increase the heat storage of greenhouse. The temperature difference of the experiment greenhouse and normal greenhouse began to increase after covered the insulation. The average air temperature in experiment greenhouse is 4.0°C higher than in normal greenhouse. The soil temperature at 0, 30, 60 cm in the experiment greenhouse was 3.0°C, 3.0°C, 5.0°C higher than in the normal greenhouse respectively. Therefore the method can not only increase the air temperature, but also increase the temperature of soil around crops. Source

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