林冠对降雨截留过程的研究

在天然降雨情况下，利用自制自记装置，对油松、侧柏和灌木林的林冠截留降雨过程及截留量进行了观测。结果表明：油松林的截留量最大，灌木林次之，侧伯林最小。年截留率为２０％～３３％，截留强度与降雨强度呈正相关。林冠截留过程表示为：Ｉｔ＝Ｉｃ＋（ｆＩ０兄－Ｉｃ）ｅ－αｔ　（ｆ≠０）。用实测数据确定出截留公式的特征值及参数，经检验与实际过程有良好的一致性。     

非均匀林冠降雨截留模型

考虑由彼此间有间距的树冠组成的非均匀林冠内的降雨截留过程,将以前的林冠截留理论模型从水平均匀随机分布林冠推广到非均匀林冠,导出相应的偏微分方程和截留量的计算公式,并以实例运行该模型,以揭示非均匀林冠在降雨截留过程中的一些细节特征.     

黄土高原半干旱区油松人工林林冠截留模型及其参数特征研究

利用2008—2011年定位观测数据,采用回归分析方法对黄土高原半干旱区油松人工林林冠截留与林外降雨之间的关系进行建模研究,并运用Bootstrap方法,对模型参数特征进行分析。结果表明:林冠截留量(I)与林外降雨量(P)可用非线性模型I=a Pb进行回归模拟,回归方程为I=0.584P0.576;该模型不仅具有较高的拟合精度,且拟合方程参数稳定性良好,经检验,方程均达到显著性要求,可在该区域油松人工林应用。     

基于修正的Gash模型模拟缙云山毛竹林降雨截留

为了验证修正的Gash模型对缙云山毛竹林林冠截留模拟的适用性,基于2009年4—7月的气象和林分特征资料以及实测的穿透雨和树干茎流等资料,分析缙云山毛竹林林外降雨、穿透雨和树干茎流特征,并应用修正的Gash模型对林冠截留量进行模拟,对比分析周降雨累计截留量和单次降雨截留量的模拟值和实测值,采用敏感性分析法分析模型参数对截留量的影响程度。结果表明:研究期间共29次降雨,总降雨量为531.1mm,平均降雨强度为2.11mm·h-1,大部分为低雨强、低雨量级、长历时的降雨;穿透雨量、茎流量和林冠截留量的实测值分别为463.2,6.5和61.4mm,模拟值分别为461.1,6.1和63.9mm,模拟的截留量约高出实测值4.07%,模型计算的周累积截留量和单次降雨截留量与实测值相比的相对标准差分别为5.02%和7.13%,模拟效果较好,模型适用于缙云山毛竹林;以林冠郁闭度(c)对模拟结果影响最大,其次为平均降雨强度()、林冠持水能力(S)和林冠平均蒸发速率(),树干茎流系数(Pt)和树干持水能力(St)这2个参数对林冠截留总量影响很小。     

水曲柳林冠的降水截留特征

对水曲柳林冠在2003年5-9月的降水截留特征进行了野外测定与统计分析,结果表明:水曲柳林分林冠截留量为68.77 mm,占同期降水量的17.41%;降水约按以下比例被再次分配:穿透降水72.50%,林冠截留17.41%,树干茎流10.08%.模拟分析结果表明:Horton改进模型模拟精度高,参数物理意义较明确,水曲柳林冠吸附容量为0.84 mm,区域降雨蒸发能力的参数值为11.83%,水曲柳林冠截留率随降水变化的曲线可分为快变期(截留率大于19.0%,降水量小于10 mm)、渐变期(截留率19.0%～12.8%,降水10～30 mm)和稳定期(截留率小于12.8%,降水大于30 mm),水曲柳林冠稳定截留率为12.8%.     

亚热带杉木、马尾松人工林的林内降雨、林冠截留和树干茎流*

本文用统计分析方法对江西分宜县山下林场杉木、马尾松人工林的林内降雨、林冠截留和树干茎流进行了研究。结果表明:在该林分中林内降雨量和树干茎流量随降雨量的增加而以直线形式增加;林冠截留量随降雨量的增加呈幂函数关系上升。在杉木林内,随郁闭度的增大,林内降雨率和树干茎流率减少,而林冠截留率增大,马尾松林和杉木林相比,林内降雨率和树干茎流率较大,而林冠截留率较小。     

林冠降水截留效应国内研究进展

林冠对降雨截留再分配过程的影响,涉及到森林生态、森林水文、森林气象及水土保持等诸多方面,是森林涵养水源、减少地表径流的重要生态水文过程,对林地水分平衡和养分循环具有重要意义。近年我国对林冠截留、穿透雨、树干流的降水截留效应研究有较多报道,本文对近几十年来我国林冠对降水截留效应研究进展和现状进行简要整理     

侧柏栎类混交林林冠截留模拟研究

林冠截留能力是反映森林与水关系的一个重要指标,该研究充分考虑林冠结构特征与降雨特性,采用机械布样的方法,对侧柏栎类混交林林分内的3种主要水源保护林树种生长季的降雨再分配特点进行了研究。结果表明:3种树种生长季场降雨的林冠截留量都表现出随降雨量的增大而增大,截留率随降雨量的增大而减少,在降雨初期下降幅度最大,以后趋于平稳。干流量在低雨量级时随降雨量的增加而增大,但其增加幅度有限,干流率起初也均随林外降雨量的增加而呈增加的趋势。透雨量随林外降雨量的增大而增大,透雨率逐渐增大,但当林外降雨量增大到一定时透雨率基本不变。3个树种的截留量、干流量、穿透降雨量林外降雨量均呈线性相关。该文采用谢春华等的林冠截留模型对3种水源林树种进行模拟,模拟误差为11%左右,基本上可以满足林冠截留模拟需要。     

毛竹林冠截留雨量的研究

毛竹林冠枝叶密布,能有效地阻截降雨流失。截留量随降雨量的大小、降雨的性质、降雨形成的原因和不同坡向、坡位、林冠枝叶湿润状况等因子而异。研究这种规律,对于控制毛竹林冠截留量,调节林下土壤的水分状况,涵养水源,提供理论依据。     

流溪河小流域针阔混交林林冠降雨截留模型研究

以流溪河流域针阔混交林为研究对象,对林分样地进行降雨截留实测与模拟研究.结果表明:林内穿透雨量与降雨量呈线性相关;穿透系数与降雨量呈对数相关;林冠截留量与降雨量呈幂函数相关;截留率与降雨量呈对数相关.以降雨强度、穿透系数和树干茎流率数据为基础,进行了林冠截留量模型模拟,实测表明该模型能较准确地估算针阔混交林分的林冠截留量.     

A rainfall interception model for inhomogeneous forest canopy

The process of rainfall interception by an inhomogeneous forest canopy composed of tree crowns with some gaps among them were considered, and the previous theoretical models of rainfall interception were modified to model an inhomogeneous canopy instead of a statistically homogeneous canopy. The paper deals with the following. First, the process of rainfall interception in tree crowns and that of rainfall in the gaps among them are studied respectively to acquire the average rainfall interception of a forest canopy. Based on the model derived by Liu (1987) and setting the canopy density value, both the relevant partial equations and a formula to estimate rainfall interception were derived. Moreover, the new model was solved through a numerical method and was illustrated with typical values of some ecological factors; three groups of curves were acquired by calculation with the VisualBasic program. A model of rainfall interception by an inhomogeneous forest canopy is classified as a multi-layer model, which is different from previous models (models where all the parameters represent the whole canopy). The results from the model in this paper could be used to determine the relationship between interception and each ecological factor in detail. __________ Translated from Scientia Silvae Sinicae, 2007, 43(3): 8–14 [译自: 林业科学]     

Relationship between annual rainfall and interception ratio for forests across Japan

Several previous studies in Japan have examined differences in rainfall interception amounts induced by differences in forest properties by comparing the annual rainfall interception ratios (annual rainfall interception divided by annual rainfall) from various sites without considering variations in meteorological conditions between sites. Rainfall interception actually depends on meteorological conditions as well as forest properties. This study examined variations in the annual interception ratio relating to the variation in annual rainfall, which would be the primary factor relating to the interception ratio, across Japan with the use of a rainfall interception model assuming the same forest properties (i.e., the canopy storage capacity, canopy closure, leaf area index (LAI), and the bulk coefficient for sensible heat transfer). The ratio ranged between 0.12 and 0.24 across Japan and was highly correlated to annual rainfall. This indicates that considering the variation in annual rainfall is critical for assessing the difference in rainfall interception amounts induced by forest properties. We reconsidered the results of previous studies in Japan that compared annual interception ratios between sites with different forest properties: (i) there is no clear difference in interception amounts between broadleaf and coniferous forests and (ii) there is a positive correlation in stem density and interception amounts for coniferous forests. These results still held when considering differences in annual rainfall between sites.     

Predicted models for potential canopy rainfall interception capacity of landscape trees in Shanghai,China

This study aimed to build urban green space with environmental functions (e.g., canopy interception of rainfall) and adjust hydrographic balance to some extent for forecasting the potential canopy rainfall interception capacity of landscape trees and the effects on rainfall distribution. The effects of urban green space on interception and runoff reduction have been conceptualized, but not quantified. Therefore, the leaf area index and the water storage abilities of 17 kinds of landscape trees in common use were measured, at Shanghai, and canopy rainfall interception capacity was calculated using the interception formula. The predicted rainfall interception capacity models were established choosing tree morphological characteristics (diameter at the breast height, height, and crown width) as variables. The model test showed that the errors of 12 models were less than 5% between the predicted and the measured data and the errors of four models were within 5 and 10%, with the error for only one model being between 10 and 11%. Also, the study indicated that conifer trees were able to hold more rainfall compared with broad-leaved trees per unit area (k). The results showed that these models could effectively predict the potential capacity of canopy rainfall interception for landscape trees in Shanghai area and were beneficial for species selection in constructing plant communities, aiming to improve the rainfall interception capacity of urban green space.     

森林乔木冠层雨水再分配特征及机制研究综述

森林乔木冠层对降雨的再分配具有重要的水文生态意义,有助于定量评价不同区域、尺度、类型的森林冠层雨水利用效率,可为深入研究森林冠层变化对区域水分循环的调节作用提供科学依据。文中从森林冠层雨水截留、林内穿透雨、树干茎流和林下凋落物截留4个方面评述了近20年来国内外对森林乔木冠层影响雨水再分配的研究最新进展。研究认为,由于森林冠层雨水再分配的生态机理仍未明晰,因此建立精确度高的截留模型仍将作为此类研究的重难点之一;引入激光雷达技术获得森林冠层三维结构,以及多角度、多通道的多种传感器观测垂直空间多层次的森林冠层雨水再利用规律将会成为未来的研究方向之一;目前林冠雨水截留研究缺乏其与区域水文变化之间的关联性研究,将林冠雨水再分配研究的成果转化为区域水文问题的解决方案也将会是未来研究的趋势之一。     

植被护坡水文机制模型的构建

植被护坡主要是依靠坡面植被地下根系的力学效应和茎叶的水文效应来实现的。本文通过对乔木层、灌木层、草本层和枯枝落叶层的降雨截留、削弱溅蚀等水文作用机制的研究,构建了公路边坡植被降雨截留和所消减的降雨动能的理论模型。     

Rainfall interception and drop size-development and calibration of the two-layer stochastic interception model

This paper reviews the development of the stochastic interception model from the original, single-layer, drop-size-dependent model to the two-layer model that recognizes that vegetation canopies are wetted through both the primary impact of raindrops to the top layer of the canopy and secondary impacts from drops falling from the vegetation to lower layers of the canopy. It is shown that drop volumes of primary raindrops can be calculated from the Marshall-Palmer distribution and drop volumes of secondary drops can be estimated from disdrometer measurements of the characteristic volume appropriate to the particular vegetation species. It is recognized that, in addition to the volume-dependent stochastic wetting effect, there is also another drop-size-dependent wetting effect that is related to the kinetic energy of the raindrops, which reduces the maximum storage that can be achieved on the canopy. The predicted wetting functions for canopies of different density are described and compared with observations made with the use of a rainfall simulator. It is also shown that the species-dependent model parameters can be determined from measurements made with the rainfall simulator. The improved performance of the model compared with conventional interception models is demonstrated for a tropical forest in Sri Lanka. Application of the two-layer model may explain why interception losses from coniferous, fine-leaved forests in the temperate, low-intensity rainfall climate of the uplands of the U.K. are among the highest in the world, whereas interception losses from tropical broad leaved forest in high-intensity rainfall climates of the tropics are among the lowest.     

北京九龙山不同结构侧柏人工纯林降水的再分配

[目的]基于华北石质山区侧柏人工林2014年(3—10月)降水数据进行量化分析,探究其降水的再分配规律。[方法]采用野外定位研究方法,对不同结构(郁闭度、枝下高)侧柏人工林林冠层降水再分配特征进行分析。[结果](1)1/2枝下高0.4、0.6、0.8郁闭度林内穿透雨总量分别为181.1、168.1、147.1 mm,穿透雨率分别为78.8%、73.1%、64.0%;树干径流总量分别为6.0、5.9、3.9 mm;总树干径流率分别为4.2%、2.6%、1.7%;林冠截留总量分别为39.5、56.1、79.1 mm;林冠截留率分别为17.2%、24.4%、34.4%。(2)1/3枝下高0.4、0.6、0.8郁闭度林内穿透雨总量分别为175.6、154.8、136.0 mm,穿透雨率分别为76.4%、67.3%和59.2%,树干径流总量分别为8.3、4.9、3.3 mm,总树干径流率分别为3.6%、2.1%和1.4%,林冠截留总量分别为46.3、70.4、90.7 mm,林冠截留率分别为20.1%、30.6%和39.5%。[结论](1)侧柏人工林同一枝下高不同郁闭度林分林内穿透雨量差异不显著。2种枝下高郁闭度为0.4和0.8之间的树干径流量均存在显著差异,郁闭度0.4和0.6以及0.6和0.8之间差异不显著。(2)郁闭度为0.4、0.6、0.8时,冠厚占树高2/3(即枝下高为1/3)的林分林冠截留量分别是1/2的1.17、1.25和1.14倍。(3)2种枝下高各自不同郁闭度间林冠截留量均存在显著差异。(4)同等降雨量情况下雨强越大,林冠截留量越小;2次降雨间隔时间越长,林冠层越干燥,林冠截留能力越强;枝下高越低(即冠层厚度越大),林冠截留量越大,且随着郁闭度的增加,林冠截留量逐渐增大。     

长白山北坡阔叶红松林林冠对降雨及其养分的影响

在2001年森林生长季(6-9月),通过测量降雨各分量,分析了中国吉林省长白山北坡红松阔叶林冠层对降水分配各分量的影响。结果表明:干流量(37.39 mm),透流量(326.02 mm)和截留量(105.67 mm),分别占同期降雨量(469.08 mm) 的7.97%、69.50%和22.53%。林冠对降雨的月份分配规律是:树干茎流率的月变化为七、八月份大于其它月份,穿透率从6-9月份有逐渐减少的趋势,而截留率的变化正好与穿透率相反,从19.43%增加到31.02%。林内降雨中的养分元素浓度发生显著变化,除Ca、Mg外,其它元素的浓度都有所增加。经分析得出,大气降雨中养分元素的浓度序列为:Ca> Mg> N> K> Fe > P> Cu > Mn;而穿透雨中养分元素的浓度序列为:K>N>Mg>Ca>P>Fe>Mn>Cu;在林冠淋溶中各养分元素的浓度序列为:Mn> P>K>Cu>Fe>N>Mg>Ca。图1表5参13。     

Characteristics of canopy interception and its simulation with a revised Gash model for a larch plantation in the Liupan Mountains,China

Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological impact evaluation. In this study, throughfall, stemflow and interception were measured in a pure Larix principis-rupprechtii Mayr.(larch) plantation in the Liupan Mountains of northwestern China during the growing season(May–October) of 2015, and simulated using a revised Gash model. During the study period, the total precipitation was499.0 mm; corresponding total throughfall, stemflow and canopy interception were 410.3, 2.0 and 86.7 mm,accounting for 82.2, 0.4 and 17.4% of the total precipitation, respectively. With increasing rainfall, the canopy interception ratio of individual rainfall events decreased initially and then tended to stabilize. Within the study period, the simulated total canopy interception, throughfall and stemflow were 2.2 mm lower, 2.5 mm higher and0.3 mm lower than their measured values, with a relative error of 2.5, 0.6 and 15.0%, respectively. As quantified by the model, canopy interception loss(79%) mainly consisted of interception caused by canopy adsorption, while the proportions of additional interception and trunk interception were small. The revised Gash model was highly sensitive to the parameter of canopy storage capacity,followed by the parameters of canopy density and mean rainfall intensity, but less sensitive to the parameters of mean evaporation rate, trunk storage capacity, and stemflow ratio. The revised Gash model satisfactorily simulated the total canopy interception of the larch plantation within the growing season but was less accurate for some individual rainfall events, indicating that some flaws exist in the model structure. Further measures to improve the model's ability in simulating the interception of individual rainfall events were suggested.     

林冠对降雨截留的半理论模型

在林冠对降雨截留过程的研究中,将理论模型的考虑方法和经验模型的模拟方法结合起来,提出一种新的半理论模型。这个半理论模型既具有理论模型把过程与机理紧密联系的优点,又具有经验模型计算相对简单的长处,新模型与实验数据很好地符合,也和理论模型的结果一致。