Effects of converting natural grasslands into planted grasslands on ecosystem respiration: a case study in Inner Mongolia, China

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• 作者：Meng Zhang ; Xiaobing Li ; Hong Wang ; Fei Deng ; Xu Li ; Xue Mi
• 关键词：natural grasslands ; planted grasslands ; ecosystem respiration ; soil respiration ; vegetation autotrophic respiration ; Inner Mongolia
• 刊名：Journal of Arid Land
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：9
• 期：1
• 页码：38-50
• 全文大小：
• 刊物主题：Physical Geography; Plant Ecology; Sustainable Development;
• 出版者：Science Press
• ISSN：2194-7783
• 卷排序：9

文摘

With increasingly intensifying degradation of natural grasslands and rapidly increasing demand of high quality forages, natural grasslands in China have been converted into planted grasslands at an unprecedented rate and the magnitude of the conversion in Inner Mongolia is among the national highest where the areal extent of planted grasslands ranks the second in China. Such land-use changes (i.e., converting natural grasslands into planted grasslands) can significantly affect carbon stocks and carbon emissions in grassland ecosystems. In this study, we analyzed the effects of converting natural grasslands into planted grasslands (including Medicago sativa, Elymus cylindricus, and M. sativa+E. cylindricus) on ecosystem respiration (F_eco) in Inner Mongolia of China. Diurnal F_eco and its components (i.e., total soil respiration (F_ts), soil heterotrophic respiration (F_sh) and vegetation autotrophic respiration (F_va)) were measured in 2012 (27 July to 5 August) and 2013 (18 July to 25 July) in the natural and planted grasslands. Meteorological data, aboveground vegetation data and soil data were simultaneously collected to analyze the relationships between respiration fluxes and environmental factors in those grasslands. In 2012, the daily mean F_eco in the M. sativa grassland was higher than that in the natural grassland, and the daily mean F_va was higher in all planted grasslands (i.e., M. sativa, E. cylindricus, and M. sativa+E. cylindricus) than in the natural grassland. In contrast, the daily mean Fts and Fsh were lower in all planted grasslands than in the natural grassland. In 2013, the daily mean F_eco, F_ts and F_va in all planted grasslands were higher than those in the natural grassland, and the daily mean F_sh in the M. sativa+E. cylindricus grassland was higher than that in the natural grassland. The two-year experimental results suggested that the conversion of natural grasslands into planted grasslands can generally increase the F_eco and the increase in F_eco is more pronounced when the plantation becomes more mature. The results also indicated that F_sh contributed more to F_eco in the natural grassland whereas F_va contributed more to F_eco in the planted grasslands. The regression analyses show that climate factors (air temperature and relative humidity) and soil properties (soil organic matter, soil temperature, and soil moisture) strongly affected respiration fluxes in all grasslands. However, our observation period was admittedly too short. To fully understand the effects of such land-use changes (i.e., converting natural grasslands into planted grasslands) on respiration fluxes, longer-term observations are badly needed.