安吉毛竹林生态系统大小年水气通量变化特征

利用涡度相关技术对安吉毛竹(Phyllostachys edulis)林生态系统进行观测,获得2014年(小年)和2015年(大年)毛竹林水气通量数据,并结合相关气象数据,对毛竹林大、小年水气通量变化特征进行对比分析。结果表明:毛竹林生态系统无论在大年还是小年水气通量值都为正值,月平均日变化和季节日变化都呈现单峰曲线;2015年8月份水气通量值最高(0.038 g·m~(-2)·s~(-1)),大于2014年7月份最高值(0.032 g·m~(-2)·s~(-1)),2014年水气通量值最低值出现在12月份,为0.009 6 g·m~(-2)·s~(-1),2015年水气通量值最低值出现在1月份,为0.011 g·m~(-2)·s~(-1);季节尺度上,具有明显的季节变化特征,水气通量值都是夏季最高,冬季最低,春秋季次之。大年毛竹春季受发笋抽叶的影响虽然大于秋季,但蒸散量却小于秋季;而小年春季降水量与蒸散量都小于秋季;大小年毛竹林各季节净辐射日变化都表现为单峰曲线,且水气通量与净辐射都表现出显著的相关性,但是受大小年差异的影响,大年春季的R2大于秋季R2,而小年则秋季R2大于春季R2。

Variation Characteristics of Water Vapor Flux over Anji Phyllostachys edulis Forest Ecosystem in on-and-off Years

We compared the water vapor flux in on-and-off years of Phyllostachys edulis using the eddy covariance (EC) technique and related meteorological data in Anji Country of Zhejiang Province, China.The value of water vapor flux value of P.edulis plantations was positive, and the diurnal variation of monthly and seasonal average showed a single peak curve in on-and-off years.The highest value (0.038g·m-2·s-1) of on-year appeared in August, which was higher than July of off-year.The minimum value of the two year appeared in January.We observed obviously the water vapor flux for seasonal variation, and the highest value appeared in summer and lowest in winter.The rainfall of the spring was higher than the autumn in on-year, the evapotranspiration showed opposite trend.The rainfall and evapotranspiration in spring was higher than that in the autumn in off-year.The diurnal variation of net radiation in each season of P.edulis plantations showed a single peak curve in on-and-off years.The water vapor flux was closely related to the net radiation.Due to the effect of on-and-off years, the determination coefficients (R2) of the spring was higher than that of the autumn in on-year, while that in off-year expressed opposite trend.