大兴安岭北部兴安落叶松林穿透雨延滞效应

Time lag effects of throughfall in natural Larix gmelinii forest in the north of Great Xing'an Mountains,China

以黑龙江漠河生态站兴安落叶松天然林为研究对象,对林外雨、穿透雨和树干茎流进行定位观测,分析大兴安岭北部兴安落叶松林穿透雨延滞效应.结果表明:穿透雨量、树干茎流量和林冠截留量分别占同期降雨总量的76.5%、2.6%和20.9%.降雨发生后,穿透雨与林外雨在产生和终止时间上均存在一定延滞性;随降雨量级增大,穿透雨滞后时间表现出逐渐缩短的趋势,变动范围为(67.8±7.8)^(17.2±3.9)min(穿透雨)和(112.0±38.8)^(48.3±10.6)min(树干茎流);相同降雨量级下,穿透雨滞后时间随降雨强度增大而逐渐降低,且降雨强度>2 mm·h-1时延滞时间显著缩短,同时随雨前干燥期的增加而增长,而当雨前干燥期≥48 h时,降雨量则是影响滞后时间的主要因素;降雨终止时,降雨量>5.0 mm,穿透雨终止时间也存在延滞性,且随降雨强度增加而增大,但与雨前干燥期关系不明显;树干茎流终止时间先于林外雨终止时间,且主要与降雨量级有关,降雨量级越小,终止时间越早.

Based on a natural Larix gmelinii forest from Mohe Ecological Station,located in north of Great Xing＇an Mountains,time lag effects of throughfall inside the Larix gmelinii forest were analyzed by measuring rainfall,throughfall and stemflow with the method of location observation. The result showed that forest throughfall,stemflow and canopy interception accounted for 76.5%,2.6%and 20.9% of total rainfall,respectively. Time lag of rainfall inside L. gmelinii forest was found both in beginning and termination of rainfall compared to outside,and the higher the rainfall level,the shorter the time lag of throughfall. For throughfall and stemflow,variations of time lag were（ 67.8±7.8）-（ 17. 2 ± 3. 9） min and（ 112. 0 ± 38. 8）-（ 48. 3 ± 10. 6） min,res-pectively. The time lag of throughfall decreased with the increasing rainfall intensity under the same rainfall level. When the rainfall intensity was greater than 2 mm·h^-1,the time lag of throughfall was shortened significantly,but it increased with prolonging the antecedent dry period before rainfall. Rainfall would be the critical factor to affect the time lag of throughfall when the antecedent dry period was longer than48 h. Termination of throughfall also lagged when rainfall termination happened with a rainfall greater than 5.0 mm. The time lag of throughfall termination increased with increasing the rainfall intensity,but it had no significant relationship with the antecedent dry period before rainfall. However,the termination of stemflow occurred prior to rainfall,which was relevant to the rainfall level,and the smaller the rainfall level,the sooner the stemflow terminated.