黄土高原半干旱区人工林刺槐展叶期树干液流动态分析

应用热扩散式树干茎流计(TDP)于2008年4月26日至5月31日,在黄土高原半干旱区安塞县对人工林刺槐展叶期树干液流及其气象、土壤水分等6个指标进行连续测定。结果表明:刺槐展叶期可分为芽期、展叶初期、中期和全叶期。在芽期,刺槐树干液流速率日变化无明显昼夜波动;在展叶初期至全叶期日变化呈现出从微弱波动逐渐增大到趋于平稳的剧烈波动;在展叶中期以后液流速率表现为上升快、下降缓慢的单峰曲线;在全叶期平均峰值约为0.0027cm.s-1;树干液流速率与光合有效辐射强度、大气温度、水蒸气压亏缺和风速呈极显著正相关,与相对湿度呈负相关,其相关程度依次为光合有效辐射强度>大气温度>水蒸气压亏缺>相对湿度>风速,且可用光合有效辐射强度和大气温度线性表达式来估测;土壤水分在展叶期呈逐渐减少趋势,但对树干液流的胁迫不显著;在展叶期刺槐单株日蒸腾耗水量随直径的增大而增大并与胸径呈良好的线性关系,可用来估算展叶期刺槐人工林蒸腾耗水量。

Thermal dissipation probe(TDP)was applied to measure the sap flow dynamics of Robinia pseudoacacia in Ansai County in semi-arid region of the Loess Plateau from April 26 to May 31,2008.Soil water content,photosynthetic active radiation(PAR),air temperature,relative air humidity,water vapor pressure deficit(VPD)and wind speed were measured at the same time.The results showed that the leaf-flushing period in a R.pseudoacacia plantation was divided into four stages:bud swollen,the beginning of leaf-flushing,th...