论文部分内容阅读
在全球气候变化条件下,全球陆地区域的降水量及其空间/时间分布模式将发生明显改变,这种变化将对中国的陆地生态系统,尤其是干旱地区的温带草地生态系统碳收支产生重要影响．作为中国陆地生态系统通量观测研究网络(ChinaFLUX)的一部分,本研究利用2003至2004年在内蒙古羊草草原的涡度相关通量观测数据,初步探讨了水分胁迫对羊草草原生态系统光合和呼吸作用的影响．研究发现温度和水分是影响该生态系统在生长季(5～9月)的光合和呼吸作用的主要因子．在土壤水分适宜条件下,生态系统呼吸对温度变化的敏感性较大(Q10=2．0),而当土壤含水量降低时生态系统呼吸对温度的敏感性明显降低(Q10=1．6)．高温和干旱会显著降低生态系统的光合生产力．生长季的降水量及其季节分配模式的不同对草地生态系统的生物物候有明显的影响,在2003年6月初生态系统就开始净吸收CO2、在7月初出现最大净生态系统CO2吸收量,而因随后发生的干旱和高温胁迫使其在8月就提早进入休眠期;2004年春季的严重干旱导致生态系在7月初才开始净吸收CO2,并在降水丰沛气温适宜的8月出现最大CO2吸收量,水分胁迫导致该草地植物生长发育比2003年推迟1个多月．观测结果显示该草地生态系统在2004年5～9月比2003年同期多吸收30 g CO2·m-2．我国温带草原植被类型复杂多样,要准确估算我国草地生态系统碳收支还需要开展更多的长期联合观带研究．
Under global climate change, the pattern of precipitation and its spatial / temporal distribution in the global land area will change significantly, and this change will have an important impact on the terrestrial ecosystem in China, especially in the temperate grassland ecosystem in arid regions influences. As part of the China Terrestrial Ecosystem Flux Observational Network (ChinaFLUX), this study analyzed the vorticity-related fluxes of Leymus chinensis grasslands in Inner Mongolia from 2003 to 2004 and discussed the effects of water stress on the photosynthesis and Respiratory effects. The study found that temperature and moisture are the main factors affecting the photosynthesis and respiration of the ecosystem during the growing season (May-September). Under suitable soil moisture regimes, ecosystem respiration was more sensitive to temperature changes (Q10 = 2.0), while ecosystem respiration had a significantly lower temperature sensitivity (Q10 = 1.6) when soil moisture content decreased . High temperatures and droughts significantly reduce the photosynthetic productivity of ecosystems. The precipitation in the growing season and its seasonal distribution pattern have obvious effects on the grassland ecosystem bio-phenology. In early June 2003, the ecosystem started to absorb CO2, and the largest net ecosystem CO2 absorption occurred in early July. However, Due to subsequent drought and high temperature stress, it entered early dormancy in August; severe drought in spring 2004 caused the ecosystem to start net absorption of CO2 at the beginning of July and maximum CO2 uptake in August when the precipitation was abundant The amount of water stress led to the grass plant growth and development than in 2003 delayed more than 1 month. Observations show that the grassland ecosystem absorbed 30 g CO2 · m-2 more during May-September 2004 than the same period in 2003. The types of vegetation in temperate steppe in China are complex and diverse. To accurately estimate the carbon budget of grassland ecosystem in China, we need to carry out more long-term joint observation.