Stemflow (SF) has been recognised as an important process that can exert considerable effects on the hydrology, biogeochemistry, and ecology of wooded ecosystems. The aim of this study was to quantify the relationship between SF (yields and funnelling ratios, FRs) of beech (Fagus orientalis) trees and rainfall characteristics, to evaluate the effects of tree traits on SF yield and the magnitudes of FRs in differing rainfall classes. Event‐based measurements were carried out from April 2016 to November 2017 during the leafed‐out periods in a natural uneven‐aged beech stand located in the Hyrcanian forest of Iran. Tree density in the studied plot was 188 trees ha⁻¹ with a basal area of 51 m² ha⁻¹. SF volume was measured in three diameter classes (10–40, 40–70, and >70 cm; n = 3 per class). During the 25 rainfall events SF, SF%, and FR were 3.22 mm, 0.41%, and 1.11 on average, respectively. The linear regression analysis revealed that gross rainfall had the strongest correlation with SF yield and FR (P value <.01). The linear regression with the trees structural traits indicated that canopy projected area, diameter at breast height (DBH), and mosses cover percentage, respectively, strongly influence SF yield for rainfall <15 to >50 mm. FR significantly decreased with increasing tree height, DBH, and mosses cover percentage (all P values <.05). Smaller trees concentrated more SF than tall and large DBH trees. Pearson correlation analysis indicated tree height, canopy projected area, and MCP were positively and significantly correlated to DBH (P value <.01; r ≥ .87). Therefore, SF generation in the present study is more associated with DBH. Our findings could assist managers to optimise the management strategies of deciduous forest via promotion of some large DBH trees along with small DBH trees to optimise water inputs via SF in water‐limited forest ecosystems.

中文翻译：

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天然山毛榉林（Fagus Orientalis Lipsky）的茎流产生与降雨和树木性状的变化

干流（SF）已被认为是一个重要过程，可以对树木繁茂的生态系统的水文，生物地球化学和生态学产生重大影响。本研究的目的是量化SF（收率和漏斗比率，FR）的山毛榉的（之间的关系山毛榉侧柏）树和降雨特征，以评估对SF产量树性状在不同降雨类的影响和FR的大小。在2016年4月至2017年11月期间，基于事件的测量是在伊朗Hyrcanian森林中天然不规则年龄的山毛榉林中进行的。研究小区的树木密度为188公顷ha ^-1，基础面积为51 m ² ha ^-1。在三个直径级别（10–40、40–70和> 70 cm；n = 3 /每个级别）中测量了SF体积。在这25次降雨事件中，平均SF，SF％和FR分别为3.22毫米，0.41％和1.11。线性回归分析表明，总降雨量与SF产量和FR的相关性最强（P值<.01）。树木结构性状的线性回归表明，冠层投影面积，胸高直径（DBH）和苔藓覆盖率分别强烈影响降雨<15至> 50 mm的SF产量。FR随树高，DBH和苔藓覆盖率的增加而显着降低（所有P值<.05）。较小的树木比高大的DBH树木更集中SF。Pearson相关分析显示树高，树冠投影面积，和MCP是到DBH正和显著相关（P值<0.01; [R ≥0.87）。因此，本研究中的SF生成与DBH更相关。我们的发现可以帮助管理者通过推广一些大型DBH树和小型DBH树来优化落叶林的管理策略，从而通过有限水域森林生态系统中的SF优化水输入。