Throughfall drop sizes suggest canopy flowpaths vary by phenophase
Throughfall drop sizes suggest canopy flowpaths vary by phenophase
复制标题
穿过落差的水滴大小表明冠层流动路径因物候期而异
DOI：
10.1016/j.jhydrol.2022.128144
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发表时间：
2022
影响因子：
6.4
通讯作者：
Levia Delphis F.
中科院分区：
文献类型：
--
作者：
Nanko Kazuki;Keim Richard F.;Hudson Sean A.;Levia Delphis F.
森林冠层表面上的入射降雨造成的水流路径有一个显着的影响，对水分收支和化学的森林生态系统。这项研究揭示了不同的冠层流动路径和停留时间在事件内的规模和整个物候过渡，从有叶到无叶状态的一组三个美国山毛榉（山毛榉Ehrh。）有多层树冠的树。同时测量的雨滴和穿透雨下降的15个激光disdrometers超过5个降雨事件进行了分析，在过渡过程中，从叶到无叶的物候期。降雨分为自由穿透雨、飞溅穿透雨和冠层滴雨四种类型。每种穿透雨类型的雨滴尺寸分布和体积在事件内和事件间尺度上都有所不同。较小的冠层滴水，直径<5.5毫米，在降雨事件中开始较早，而更多的降雨积累是必要的，以产生较大的冠层滴水，直径>5.5毫米。较小的冠层滴水更占主导地位的叶物候期时，一些结构介导的木质表面滴点更静音。这些结果表明，从叶面穿透产生较小尺寸的冠层滴水与较短的停留时间，而穿透从结构介导的木本表面滴点产生较大尺寸的冠层滴水与较长的停留时间。也有一个增加自由穿透雨和飞溅液滴从有叶到无叶状态，一致的冠层间隙增加，并在无叶状态下与木质表面的直接相互作用。在此基础上，提出了冠层中叶和分支流路发生和发展的概念。
Water flowpaths caused by incident rainfall onto forest canopy surfaces have a notable effect on the water budgets and chemistry of wooded ecosystems. This study revealed varying canopy flowpaths and residence times at the intra-event scale and across the phenological transition from leafed to leafless states for a set of three American beech (Fagus grandifoliaEhrh.) trees in a multilayered canopy. Simultaneous measurements of raindrops and throughfall drops by fifteen laser disdrometers over five rain events were analyzed during the transition from leafed to leafless phenophases. Throughfall was partitioned into free throughfall, splash throughfall, and canopy drip with four drop size classes. Throughfall drop size distributions and volume of each throughfall type varied at both intra-event and inter-event scales. Smaller canopy drips, <5.5 mm in diameter, were initiated earlier in rain events, whereas more rainfall accumulation was necessary to generate larger canopy drips, >5.5 mm in diameter. Smaller canopy drips were more dominant in the leafed phenophase when some structurally-mediated woody surface drip points were more muted. These results suggested throughfall from foliar surfaces generated smaller-sized canopy drip with shorter residence time, whereas throughfall from structurally-mediated woody surface drip points generated larger-sized canopy drip with longer residence time. There was also an increase in both free throughfall and splash droplets from leafed to leafless states, consistent with increased canopy gaps and direct interaction with woody surfaces in the leafless state. Based on the results, a conceptualization of the genesis and development of leaf and branch flowpaths in canopies is proposed.