太行山石灰岩区侧柏人工林蒸腾耗水及其与环境因子的关系

Transpiration of Platycladus orientalis plantation and its relationship with environmental factors in limestone area,Taihang Mountains

为阐明太行山石灰岩区干旱瘠薄立地侧柏人工林的蒸腾变异及其与环境因子的关系,采用自动观测技术对边材液流速率、气象与土壤因子进行高时间分辨率的同步测定,经统计分析与模型模拟,表明:1)不同月份,蒸腾速率的昼夜变化均为单峰曲线,昼夜均值为0.025～0.041 mm/h,峰值为0.078～0.150 mm/h。2)除风速(vw)(P>0.05)外,相对湿度(Hr)、气温(ta)、光合有效辐射(Par)、土壤体积含水量(Wv)均对蒸腾速率昼夜变化有显著影响(P<0.05),可共同解释其变异的87.7%,相关程度从大到小依次为Par、Hr、ta与Wv;林分日蒸腾量为0.2～1.6 mm,平均为0.7 mm,除日降雨量(R)与vw外,Par、Hrt、a与Wv均对日蒸腾量有显著影响(P<0.05),可共同解释其季节性变异的64.3%,相关程度大小依次为Par、Hr、Wv与ta;观测期多数时段,日蒸腾量受Par的影响最为强烈,其次为ta,仅在干湿交替比较剧烈时段,Hr与Wv才明显发挥作用;林分月蒸腾量为18.3～28.8 mm,平均为21.8 mm,变化趋势为单峰曲线,6月最高,仅与Par月(月均值)有显著的相关关系(P<0.05)。3)观测期林分总蒸腾量为130.5 mm,占同期降雨量(306.8 mm)的42.5%。

In order to ascertain the transpiration variation of oriental arborvitae（Platycladus orientalis（L.） Franco）plantation and its relationship with environmental factors in limestone area of Taihang Mountains,flow-based transpiration was measured simultaneously with environmental variables,including soil volumetric water content（Wv）,photosynthetically active radiation（Par）,relative humidity（Hr）,air temperature（ta）,wind speed（vw） and rainfall（R）. Transpiration rate showed unimodal diurnal variations with diurnal mean value 0.025-0.041 mm/h and maximum value 0.078-0.150 mm/h over the experiment period.Diurnal transpiration rate was significantly affected by Hr,ta,Par and Wv（P0.05）,which could give 87.7% variation together. The descending order of correlation degree was Par,Hr,ta and Wv. Accumulative and mean daily transpiration of stand mean was 0.2-1.6 mm and 0.7 mm respectively.They were significantly affected by Hr,ta,Par and Wv,which could give 64.3% seasonal variation together.The descending order of correlation degree was Par,Hr,Wv and ta over the experiment period.Par had the most significant effects on daily transpiration,followed by ta in most of period intervals.Hr and Wv had significant effects on daily transpiration only during the wetting and drying alternation intervals.Accumulative and mean monthly transpiration were 18.3-28.8 mm and 21.8 mm respectively.The seasonal variation of accumulative monthly transpiration occurred unimodal pattern with peak value observed in June.Accumulative monthly transpiration only greatly correlated with Par（P0.05）.The seasonal（1 April to 30 September）total transpiration amounts to 130.5 mm,representing 42.5% of rainfall over the period.