Gash模型在热带季节雨林林冠截留研究中的应用

为了验证Gash林冠截留解析模型在西双版纳热带季节雨林中的适用性,基于2003年的热带季节雨林气候及林冠特征观测数据、采用Gash模型对林冠截留进行了模拟.结果显示,西双版纳热带季节雨林样地年降雨量为1244.4mm,穿透降雨为867.3mm,树干径流为114.4mm,树冠截留量为262,7mm,林内穿透降雨量和林外降雨量之间存在显著的正相关关系;降雨过程中饱和林冠的蒸发强度为0.12mm/h,使林冠饱和的降雨为0.6mm,林冠枝叶部分持水能力为0.41mm,树干持水能力为0.18mm;模型模拟的年林冠截留量为274.9mm,干季为71.7 mm,雨季为203.1 mm;模拟的相对误差年值为4.3%,干季为0.1%,雨季为6.9%,模拟与实测有很好的一致性,显示了Gash模型适用于西双版纳地区热带季节雨林林冠截留计算.

Modeling canopy rainfall interception of a tropical seasonal rainforest in Xishuangbanna, Southwest China

Gash analytical model has been widely used for estimating rainfall interception of forest canopy.In order to verify its applicability,we compared the modeling results of the Gash model with those of field data collected from a tropical seasonal rainforest of Xishuangbanna in 2003.Field measurements showed that annual rainfall was 1244.4 mm in the rainforest with throughfall,stemflow, and canopy interception amounted to 867.3,114.4,and 262.7 mm,respectively.Throughfall correlated positively with the weekly rainfall.Using the Gash analytic model,the estimated canopy interception was 274.9 mm with canopy water storage capacity reaching 0.59 mm(0.41 mm for leaves and branches and 0.19 mm for tree trunks).With an average evaporation rate of 0.12 mm h~(-1) from the saturated canopy and a rainfall intensity of 3.37 mm h~(-1),the amount of rainfall needed to saturate the canopy was 0.6 mm.Evaporation after rainfall ceasing was the greatest within 5 components in Gash model and it accounted for 46.2% of total interception,and evaporation from trunks accounted for about 15% so it was another component that could not be neglected.Relative differences between the Gash modeling results and field measurements were 4.3% with dry season as 0.1% and rainy season as 6.9%.We conclude that the Gash analytic model can be used for estimating canopy water interception in the tropical seasonal rainforest.