Evaluation of heterogeneity in foliage distribution. How does the complexity of canopy structure affect on the gas-exchanges of forest ecosystem?

林冠中叶片的空间分布是林分结构的一个重要方面，它决定了林分的小气候、森林生态系统的气体交换和茎的形状。随着叶簇的构建，叶片呈不连续分布，冠层内叶片密度呈非均匀分布。林冠的簇状和缝隙镶嵌增强了林冠结构的异质性。尽管它很重要，但由于在高大乔木林分进行测量的困难，关于叶片三维分布格局的定量资料很少。对叶簇结构的定量了解甚少。本研究项目旨在量化叶片分布的异质性，明确叶片结构的复杂性是否在物种和林分阶段发生变化，了解叶片分布的异质性对森林生态系统气体交换的影响。进一步定量分析了粳稻冠内叶片的簇状结构，并考察了该物种冠内叶片的分布是否随着年龄的增长而更加不均一化和块状化。老树冠（78年和88年）比年轻树冠（20年）和中年树冠（40年）具有更多的异质性和破碎性叶簇。叶的分布随着年龄的增长而增加。这种非均质性与冠内间隙比例密切相关。比较了两种常绿阔叶冠层乔木的叶簇结构；通过测量冠内叶片的三维分布，研究了东北栲（Castanopsis cuspidata）和雷杉（Machilus thunbergii）。cuspidata形成紧凑的簇，可能是由于它的茎结构。对油豆冠内叶片的三维分布进行了测量。3 .利用叶片分布参数，通过估算树冠的时空光照变化，建立了单株蒸腾和光合速率的预测模型。林隙镶嵌结构是影响冠层复杂性的重要因素之一。构建了一个估算缝隙镶嵌结构对幼苗光合速率影响的模型。林隙镶嵌对光合势的空间分布和幼苗生态位有较大的影响。少

The spatial distribution of foliage in canopy represents an important aspect of the stand structure for silviculture, with determining the microclimates in the stand, gas-exchanges of forest ecosystems, and the stem shape. Foliage distributed discontinuously with constructing foliage cluster, and the foliage density is heterogeneous in canopy. The cluster formation and gap mosaics in the canopy enhance the heterogeneity of canopy structures. In spite of its importance, little quantitative information on three-dimensional foliage distribution pattern was available, because of the difficulty in making measurements in stands of tall trees. The structure of foliage cluster is poorly understood quantitatively. This study project aims to quantify the heterogeneity of foliage distribution, to clarify whether the complexity of foliage structure changes among species and stand stages, and to know the impact of heterogeneity of foliage distribution on gas-exchanges of forest ecosystem.1. I quant … More ified the cluster structure of foliage within crown of C. japonica, and examined whether foliages within crowns of this species distribute more heterogeneous and clumpy with ageing. Old crowns (78yrs and 88yrs) had more heterogeneous and fragmented foliage clusters than young (20-yrs) and middle-aged crowns (40yrs) did. Foliage distributed more with ageing. These heterogeneities closely related to the gap proportion within a crown.2. The structures of foliage clusters were compared between two evergreen broadleaved canopy trees ; Castanopsis cuspidata and Machilus thunbergii, through measuring three-dimensional distribution of foliages within crowns. C.cuspidata formed compact clusters, possibly due to its shoot architectures.3. We measured three-dimensional foliage distribution within crowns of Fagus crenata. A model for predicting transpiration and photosynthetic rate of single tree was constructed through evaluating temporal and spatial light variance in a crown using parameters of foliage distribution.4. Gap mosaic structure is one of important factor of complexity of canopy. I constructed a model for estimating the effect of gap mosaic structure on photosynthetic rates of seedlings. Gap mosaics had large impacts on spatial distribution of photosynthetic potential, and niches of seedlings. Less