海南岛橡胶林生态系统水汽通量及其影响因子研究

Water Vapor Flux Exchange and Its Environmental Factors in a Tropical Rubber Plantation Ecosystem in Hainan Island

以海南岛儋州地区橡胶林为研究对象,基于涡度相关法对橡胶林水汽通量进行长期观测,获得2010年全年橡胶林水汽通量观测数据,分析全年水汽通量变化特征及其影响因子。结果表明：（1）橡胶林全年水汽通量基本为正值,水汽由生态系统进入环境,即橡胶林为水汽源;水汽通量日变化特征为单峰型,在12：00-14：00达到最大值,夜间水汽通量保持平稳,且接近0;白天水汽通量雨季（橡胶林主要生长季）远大于旱季,且变化规律性强;2010年全年总降雨量为1 763.8 mm,蒸散总量为999.6 mm,蒸散量占降雨量的56.67%;雨季8-10月降雨量远大于蒸散量,降水严重剩余;旱季蒸散量接近降雨量的2倍。（2）水汽通量与净辐射呈现正相关,且达到显著水平;雨季相关性最好,5-10月R2为0.760 4,其次是旱季,11-12月R2为0.614 3,1-4月相关性最差（R2为0.290 3）。（3）橡胶林水汽通量与气温呈现正相关,雨季相关性高于旱季。（4）水汽通量与饱和水汽压差正相关,雨季相关性最好,R2为0.362 1。（5）不同月份,影响橡胶林水汽通量的主要环境因子不同,净辐射、饱和水汽压差是水汽循环最主要的驱动力,无论在旱季还是雨季都是影响水汽通量最主要的影响因子。

A rubber plantation in Danzhou, Hainan was used as the study object with the eddy covariance（EC）technique for long-term water vapor flux observations in 2010. The water vapor flux dynamic characteristics and the responses on the environmental factors were analyzed in the research. The results showed as follows：（1） The water vapor flux of rubber forest ecosystem was a positive value. The characteristic for water vapor flux diurnal variation was a single-peak, the maximum value was all around 12：00-14：00. The water vapor flux was close to 0and remained stable at night. During the day, the water vapor flux in the rainy season（the main growing season of the rubber plantation） was larger than in the dry season. In 2010, the annual precipitation was 1 763.8 mm, the annual evapotranspiration was 999.6 mm. The annual evapotranspiration of rubber forest accounted for 56.67% of the annual precipitation. The precipitation of August to October was larger than the evapotranspiration, the precipitation was seriously surplus. The evapotranspiration was approximately twice the precipitation in the dry season, and the moisture controled the rubber trees＇ growth.（ 2） There was a high correlation between water vapor flux and net radiation（Rn）, and the square of correlation coefficients（R2） was 0.760 4 in rainy season. The correlation coefficient was small in dry season, in the January to April R2 was 0.290 3, in the November to December the R2 was 0.614 3.（3） The water vapor flux was positively correlated with air temperature（Ta）, and the correlation coefficient of rainy season was larger than dry season.（ 4） The water vapor flux was positively correlated with vapor pressure deficit（ VPD）. The R2 was 0.362 1 in the rainy season.（ 5） In different month, the main environmental factors which affecting the water vapor flux were different, net radiation（ Rn） and vapor pressure deficit（ VPD） were the most important factors, and they were the main driving force of water circulating.