人工草地建植对昭苏盆地山地草甸碳水通量特征的影响

摘要

2014年4~10月采用静态箱法对新疆昭苏盆地围封3年的人工草地(LG)和天然草地(NG)的生物量、CO2净生态系统交换量(NEE)、蒸散量(ET)、生态系统呼吸(ER)进行了观测,结果表明:(1)退化山地草甸翻耕重建能有效提高草地的地上生物量.(2)NG年平均NEE要小于LG,全年平均蒸散量NG>LG.NG的碳、水(NEE和ET)之间存在极显著相关关系(P<0.01),而LG相关性不显著.(3)两种草地的NEE与大气温度、土壤温度和土壤含水量之间呈线性负相关关系,与空气湿度呈线性正相关关系,其中LG和NG的NEE与土壤含水量的线性关系均达显著水平.指数模型能够较好地模拟ER对土壤温度变化的响应,天然草地ER的温度敏感系数(Q10值)大于人工草地.天然草地翻耕重建成人工草地,草地CO2净生态系统交换量虽有所升高,但蒸散量降低且同时降低了对温度变化的敏感性,提高了水分利用效率和草地生产力.%The static chamber method was used to observe and measure CO2 net ecosystem exchange (NEE) and evapotranspiration flux (ET) in natural mountain meadow and plowed-sowed mountain meadow (legume-grass mixtures) which were enclosed for 3 years (2011~2014) during the period from April to October 2014.The study plots was located in Horse Farm of Zhaosu, Xinjiang and the field observation was last for seven months.The results showed that:1) The annual average NEE in natural mountain meadow was lower than legume-grass mixtures, with a mean of 0.099μmol/m2·s and 0.263μmol/m2·s respectively.The annual average ET and water use efficiency (WUE) were 0.145nmolH2O/m2·s, 0.222nmolH2O/m2·s and 19.87μmolmol, 14.41μmolmol respectively.They were no significant difference between legume-grass mixtures and natural mountain meadow.2) There were significant correlation relationship in NEE and ET between carbon flux and water flux in natural mountain meadow (P<0.01).3) There were linear and negative correlations between NEE and atmospheric temperature (Ts), the soil temperature and soil water content(SWC), and there was a linear and positive correlation between NEE and air humidity.Especially, the negative correlation between NEE and SWC was significant in legume-grass mixtures (P<0.05), the negative correlation between NEE and SWC was significant in natural mountain meadow (P<0.01).The correlation relationship between ER and Ts was significant (P<0.01), and the exponential model could simulate the response of ER to soil temperature changes.The temperature sensibility coefficient (Q10)values of ER ranked in the order: natural mountain meadow (4.362)>legume-grass mixtures(3.370).Therefore, plowing and sowing(legume-grass mixtures) would not improve effectively hydrothermal conditions of grassland ecosystem, but it could reduce dependence on water, improve WUE, decrease carbon emission from grassland ecosystem, and improve the forage production capacity.