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Zhang G.,Tianjin Normal University | Zhang G.,Tianjin Key Laboratory of Cyto Genetical and Molecular Regulation | Li X.,Tianjin Agricultural University | Kang Y.,Kochi University | And 3 more authors.
Journal of Food, Agriculture and Environment | Year: 2012

Understanding how the net primary production (NPP) of arid and semiarid ecosystems of the world responds to variations in climate factors is crucial for assessing the impacts of climate change on ecosystems. Here we investigated the spatial and temporal change of NPP and its key driving factors based on climate data over the past half century and a long-term data set from 9 natural arid and semiarid ecosystem sites across the Inner Mongolia steppe region in northern China. Our results showed that climate warming and drying strongly influenced ecosystems productivity, and NPP decreased gradually with decreasing mean annual precipitation from east to west in Inner Mongolia of China. NPP with lower values were distributed in the west part, while in the east part, high NPP values were found. At the same time, the areas of high values of NPP region were decreasing, and the areas of low values of NPP region were increasing from 1956 to 2006. Moreover, decreased precipitation and the subsequent increase in temperature and potential evapotranspiration caused a severe water deficiency, simultaneously, the allocation model of precipitation changed and rain-use efficiency (RUE) decreased, which may be the main climate factors limiting ecosystem productivity in Inner Mongolia. Our findings have important implications for understanding and predicting ecological impacts of global climate change and for management practices in arid and semiarid ecosystems region. Source


Zhang G.,Tianjin Normal University | Zhang G.,Tianjin Key Laboratory of Cyto Genetical and Molecular Regulation | Li X.,Tianjin Agricultural University | Kang Y.,Kochi University | And 3 more authors.
Journal of Food, Agriculture and Environment | Year: 2013

Drylands occupy more than 50% of the Earth's land surface, and Inner Mongolia grassland is highly representative of a classical arid and semiarid ecotype. In this study, we reviewed the history of grassland degradation in Inner Mongolia of China, the current measures for recovering degraded grassland and the existing shortages in current measures. Our suggestions have important implications for restoration the degraded grassland. First, the large population and growing standards of living that have placed great demand on the grasslands, some constant inputs can be easily negated. Thus, to enhance the grassland productivity, farmer must improve the mode of the grassland management and increase inputs. Second, government investment and national programs for restoring the degraded grassland focused too many attentions on the common pasture, whereas the pasture of household farm was neglected. Therefore, a landscape-level framework, based on sustainability science, must be developed to integrate ecological, economic, and social dimensions in both research and management policies. Source


Mei H.,Inner Mongolia Agricultural University | Zhang G.,Tianjin Normal University | Zhang G.,Tianjin Key Laboratory of Cyto Genetical and Molecular Regulation | Gan X.,Inner Mongolia Agricultural University | And 2 more authors.
Journal of Food, Agriculture and Environment | Year: 2013

Grassland degradation not only results in soil degradation and severe decreases in land productivity, but also can promote the emission of soil carbon and nitrogen compounds as greenhouse gases into the atmosphere. The primary objective of this study was to characterize the impact of grassland degradation on carbon and nitrogen budgets in Inner Mongolia, China. We investigated the changes of total carbon and total nitrogen (including in aboveground biomass, litter, roots, and soil, i.e. top 100 cm soil layer) that occur in meadow, typical and desert steppe ecosystem as affected by grassland degradation. The results revealed that the degraded grassland had become a very weak C source and a strong N source. Total carbon stored in the grassland ecosystem was reduced by up to 13 and 38% in the meadow and typical steppe, respectively, depending on the severity of the degradation. Total nitrogen storage was reduced by almost 17%, 20% and 33% under severe degradation plots in the meadow, typical and desert steppe, respectively. Meanwhile, over 90% of the total carbon and nitrogen stored in the grassland ecosystem were bound in the soil which provides the dominant and most stable carbon and nitrogen pool in the ecosystem. Moreover, the carbon and nitrogen storages in grass (including in aboveground biomass, litter and root) decreased with increasing grassland degradation. In conclusion, the carbon sequestration capacity of the vegetation decreased significantly, and substantial proportions of soil carbon and nitrogen were lost as affected by grassland degradation, resulting in unbalanced carbon and nitrogen budgets. Therefore, strategies to restore degraded grassland must be designed to increase the carbon and nitrogen storage potential of grassland ecosystems. Source


Liu L.,Tianjin Normal University | Liu L.,Tianjin Key Laboratory of Cyto Genetical and Molecular Regulation | Wang Y.,Tianjin Normal University | Wang Y.,Tianjin Key Laboratory of Cyto Genetical and Molecular Regulation | And 6 more authors.
Molecular Biotechnology | Year: 2013

Chlorella ellipsoidea is a single-celled eukaryotic green microalgae with high nutritional value. Its value may be further increased if a simple, reliable and cost-effective transformation method for C. ellipsoidea can be developed. In this paper, we describe a novel transformation method for C. ellipsoidea. This system is based on treatment of C. ellipsoidea cells with cellulolytic enzymes to weaken their cell walls, making them become competent to take up foreign DNA. To demonstrate the usefulness and effectiveness of this method, we treated C. ellipsoidea cells with a cell wall-degrading enzyme, cellulase, followed by transformation with plasmid pSP-Ubi-GUS harbouring both the zeocin resistance gene and the beta-glucuronidase (GUS) reporter gene that serve as selective makers for transformation. Transformants were readily obtained on zeocin selection medium, reaching transformation efficiency of 2.25 × 103 transformants/μg of plasmid DNA. PCR analysis has also demonstrated the presence of the GUS reporter gene in the zeocin-resistant transformants. Histochemical assays further showed the expression of the GUS activity in both primary transformants and transformants after long-term growth (10 months) with antibiotic selection on and off. Availability of a simple and efficient transformation system for C. ellipsoidea will accelerate the exploration of this microalga for a broader range of biotechnological applications, including its use as a biologic factory for the production of high-value human therapeutic proteins. © 2012 Springer Science+Business Media, LLC. Source

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