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1.
林冠截留模型 总被引:10,自引:0,他引:10
对林冠截留的研究已有近百年的历史。1971年,Rutter等人就推导出了一个具有清楚物理意义的林冠截留模型,结束了以往的林冠截留模型中只有统计模型的历史。1987年,刘家冈用数理方法,对林冠截留的时空演变过程作了很好的描述。但使用他们的模型对林冠截留进行估计时,需要同时对其它多个气象因子进行测定,而且人们普遍关心的不是林冠对次降雨截留的大小,而是林冠对降水的年截留量大小。 1979年,Gash用分析法代替了Rutter模型中的数值法,建立了截留模型,该模型能在只有降雨数据的情况下,对林冠的季节截留进行估计,结果与实测值接近。该模型将林冠截留分成两部分,即树冠截留和树干截留,因而引进了较多的参数。本文从林冠截留的过程出发,推导出一个有清楚物理意义,且含林冠和降雨参数较少的截留模型。 相似文献
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辽宁东部山区主要森林类型林冠截留降水的研究 总被引:3,自引:0,他引:3
本文主要研究了辽宁东部山区主要森林类型林冠层对降雨的截留和树干迳流情况。结果表明,森林对降雨的截留率为17.2% ̄33.1%。其中,油松林为33.1%,落叶松叶26.9%,红松林为23.9%,杂木林为17.5%,柞木林为17.2%。树干迳流较少,占降雨量的1%以内。同时对不同降雨强度和不同月份林冠的截留率也做了对比研究。 相似文献
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毛竹林冠截留雨量的研究 总被引:1,自引:0,他引:1
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。 相似文献
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非均匀林冠降雨截留模型 总被引:5,自引:0,他引:5
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. 相似文献
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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.
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Translated from Scientia Silvae Sinicae, 2007, 43(3): 8–14 [译自: 林业科学] 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):67-74
In this study we applied a theoretical model for determining the projection area of a Scots pine (Pinus sylvestris L.) crown in different directions. The model is based on the assumption that the foliage elements (shoots) are randomly distributed within a symmetrical crown envelope. The model was tested using photographically measured data for three young Scots pine crowns. The compatibility between calculated and measured values was satisfactory. 相似文献
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The functions of canopy interception on energy conversion processes in a Chinese fir plantation ecosystem were studied with
the aid of long-term observation data in Huitong. The results showed that the absorbed, penetrated and reflected amounts of
solar radiation were, respectively, 2.5543 × 109 J/(m2·year) (absorption rate of 0.827), 2.5306 × 108 J/(m2·year) (penetration rate of 0.082), and 2.7432 × 108 J/(m2·year) (reflection rate of 0.091) by the canopy. The conversion of net solar radiation to latent heat in the process of evaporation
from canopy interception amounted to 6.3695 × 108 J/(m2·year) (accounting for 22.9% of total ecosystem net radiation and 30.4% of ecosystem evaporation), which was an important
part of the budget of the energy system. Canopy interception consumed kinetic energy of raindrops in overcoming resistance
of branches and leaves, which collected raindrops, followed with the conversion of potential energy in raindrops to kinetic
energy with falling raindrops. In general, the diameter of raindrops from the canopy is larger than that of the raindrops
above the canopy as a result of the collection effort by the canopy. The kinetic energy of raindrops from the canopy, therefore,
was higher than that of raindrops in the atmosphere. The drop-size distribution from the canopy was affected by the structure
of the canopy layer rather than the amount of precipitation and precipitation intensity. The canopy had no important nor efficient
effects on decreasing the kinetic energy of raindrops in our case study with a first branch height of 7 m and precipitation
amounts over 3 mm. However, the canopy would play a key role in decreasing kinetic energy of raindrops in two cases, that
of a small amount of precipitation and one of heavy precipitation intensity, in which the canopy could intercept the largest
amount of precipitation in the former condition and the canopy could scatter bigger raindrops to smaller raindrops with striking
leaves in the case of heavy precipitation.
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Translated from Scientia Silvae Sinicae, 2007, 43(2): 15–20 [译自: 林业科学] 相似文献
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Felipe Crecente-Campo Peter Marshall Valerie LeMay Ulises Diéguez-Aranda 《Forest Ecology and Management》2009
A crown profile model was developed for radiata pine (Pinus radiata D. Don) in Galicia (northwestern Spain). Data from 443 trees located in 56 permanent plots, established by the Unidade de Xestión Forestal Sostible (UXFS) of the University of Santiago de Compostela in plantations of this species in the region, were used. The crowns of the trees were measured by a visual method based on similar triangles. Both simple geometric shapes and mathematical equations were used to describe the crown profiles. As crown profile models usually require variables that are expensive to measure, equations to estimate the maximum crown radius and the height to the maximum crown radius were also developed, using other easily measured tree and stand variables. Several models were fitted using a system of equations approach and accounting for an autocorrelated, heteroscedastic error structure. The selected crown profile model consists of a system of two allometric equations for the crown below (primarily shade needles) and above (primarily sun needles) maximum crown radius. The model explained 88% of the variability in crown radius with a mean error of 0.24 m. 相似文献
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Analysis of the relationship between DBH and crown projection area using a new model 总被引:1,自引:0,他引:1
Koji Shimano 《Journal of Forest Research》1997,2(4):237-242
Relations of DBH-crown projection area (CPA) were studied for deciduous and coniferous trees with different models, one of
which is newly derived this time. For DBH-CPA relations, a proposed power-sigmoid function was the most suitable one among
four models because of its good fit and mechanistic meaning. This model contains the feature that CPA grows with the second
power relation to DBH, and the increasing rate of CPA slows as DBH increases. With transformation, the power-sigmoid function
for DBH-CPA relation can be applied for individual basal area (IBA)-CPA relations as single-saturate function, and these two
functional models have high compatibility. Next, the differences of DBH-CPA between deciduous and coniferous tree groups were
analyzed with power-sigmoid function. The initial increasing rates of CPA against DBH for each group were similar, though
the CPA's increasing rate for the coniferous group tended to decrease earlier than for the deciduous group. Because the power
sigmoid function has mechanistic meanings, one can separately analyze the attributes of the DBH-CPA relation: the initial
increasing rate of CPA and final tree form. 相似文献
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Chen Dong Chengde Wang Yanrong Guo Yanyun Han 《Scandinavian Journal of Forest Research》2016,31(3):302-313
Crown profile models were developed for Chinese fir (Cunninghamia lanceolata) in Shunchang County, Fujian Province. We used data from 360 trees located in 65 pure, even-aged, and unthinned temporary plots. The data were divided into three groups according to site index. Nine models, including models for upper crown, lower crown, and entire crown, were fit; the optimal ones in each group were validated and chosen to estimate crown shape. The optimal models explained at least 70% variability in crown radius (CR). In addition, models for crown width, height above ground to crown base, and height above ground to largest CR were also developed to facilitate the convenient simulation of crown profile models. These three models explained 85.4%, 85.1%, and 86.9% variability. All models also passed the F-test and residual test. The 3D images of a single tree and stands were presented by OpenGL technology on visual c++ platform based on the proposed models. Tree growth was compared and analyzed using crown profile curves under constrained conditions. The analysis results accorded with plant growth. 相似文献
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通过调查近年来八百里绿色行动造林中大量采用带冠幅绿化大苗进行造林的实际情况,浅述了带冠幅绿化大苗栽植的含义,并对树种的选择以及在栽植过程中对绿化大苗的起运、修剪、栽植和管理等技术进行了分析。 相似文献
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Two models of interception loss have been tested against new field data obtained in widely-spaced stands of Sitka spruce trees. The Gash model and a modified version of the Rutter model, have been used with data from an automatic weather station, to predict interception loss using parameters obtained from observations made in 1988 and 1989. The predictions for an eight-week period during 1987 were compared with measurements of interception loss. Good agreement between observed and predicted interception loss was obtained with both models over the whole period. The modified Rutter model gave better predictions than the Gash model for individual storm events and performed better at the wider spacings. The sensitivity of both models to the major characteristics of the tree stand structure in agroforestry systems was also investigated and it was shown that interception loss was most sensitive to boundary layer conductance and free throughfall coefficient. 相似文献
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【目的】无人机机载激光雷达能够准确地测定单木、林分乃至大尺度森林结构参数(树高和树冠因子)。为应用无人机激光雷达技术准确估测森林蓄积量、生物量和碳储量提供计量依据和技术支撑。【方法】以150株实测马尾松生物量样本数据为研究对象,采用非线性回归估计方法和度量误差联立方程组方法,分析立木材积和地上生物量与树高、树冠因子的相关性,并在此基础上研究建立基于树高和树冠因子的立木材积与地上生物量相容模型。【结果】单株材积和地上生物量与树高因子的相关性最为紧密,其次才是树冠因子;基于树高和冠幅因子的二元材积和地上生物量模型预估精度较高,达到92%以上,再考虑冠长因子的三元模型预估精度改进不大;基于树高和冠幅因子的二元立木材积与地上生物量相容模型估计效果更好,相对于一元相容模型系统而言,二元相容模型拟合效果有较大幅度提高,预估精度达到92%以上。【结论】采用度量误差联立方程组方法可以有效解决基于树高和树冠因子的立木材积与地上生物量相容问题,并且预估精度达到92%以上,所建二元立木材积与地上生物量相容模型可为应用激光雷达技术反演森林蓄积量和生物量提供计量依据。 相似文献
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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. 相似文献