| 北京山区侧柏林林内降雨的时滞效应 |
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| 作者姓名： | 史宇 余新晓 张佳音 |
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| 基金项目： | 林业公益性行业科研项目(201104005) |
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| 摘 要： | 林内降雨通常在开始和结束的时刻上都要迟于林外降雨,这种作用可称之为林内降雨的时滞效应,目前对该方面的研究尚处于探索阶段。研究地点设在北京妙峰山林场,利用侧柏林样地林内和林外的两台全自动激光雨滴谱仪在2010年雨季自动观测获取的数据,研究了典型场降雨的林内降雨时滞效应特征以及主要影响因素。研究结果表明,在观测的18场完整降雨中林内降雨在开始时间上均晚于林外降雨,平均延滞时间为21 min;而降雨结束的时间绝大部分也出现了明显的延滞现象,平均延滞时间为46 min。通过回归分析得出,林内降雨延滞开始时间随延滞期的雨强增大呈对数曲线递减,延滞结束时间随场降雨量增大而呈对数曲线递增。林冠层对林内降雨的延滞作用可有效的削减洪峰流量和延长汇流时间,对减少山洪、泥石流和滑坡等地质灾害产生具有积极的生态意义。
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| 关 键 词： | 时滞效应 林冠截留 侧柏 北京山区 |
Time lag effects of rainfall inside a Platycladus Orientalis plantation forest in the Beijing Mountain Area, China |
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| Authors: | SHI Yu YU Xinxiao and ZHANG Jiayin |
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| Abstract: | Rainfall interception by the forest canopy not only consumes a portion of rainfall but also changes the timing of rainfall inside a forest. Rainfall inside a forest always starts and ends later than it does outside a forest, an effect called the time lag effect. This time lag effect can influence the ecological and hydrological functioning of forest ecosystems, but the study of this relationship is only in its infancy. This study, performed at the Miaofeng Mountain forest farm in Beijing, used two laser raindrop spectrometers to synchronously monitor precipitation both inside and outside a Platycladus orientalis plantation. Based on these monitoring data, this paper analyzed the characteristics and major factors influencing the lag effect of rainfall inside a forest for 18 complete rainfall events. The results show all the start times of rainfall inside the forest were later than those outside the forest, with lag times ranging between 2 and 88 minutes (average 21 minutes). Most of the ending times of rainfall inside the forest were also later than those outside the forest except two light rainfalls of less than 0.1mm; the lag time averaged 46 minutes and was as long as 158 minutes. Additionally, using a size-based analysis of large, medium and small typical rainfall events both inside and outside the forest, we found that the forest canopy delayed the peak rainfall intensity inside the forest, and rainfall intensity inside the forest was occasionally greater than outside the forest at same time during a rainfall event. Based on regression analysis, the delays of both the beginning and ending of rainfall occurring inside the forest decreased as rainfall intensity increased, which could be plotted as logarithm curves. This time lag effect of rainfall inside a forest may reduce flood peaks and effectively prolong conflux time, and it has positive ecological significance for land managers attempting to control flash floods, debris flows, landslides and other geologically related disasters. |
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| Keywords: | time lag effect canopy interception Platycladus orientalis Beijing mountain area |
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