【作者】 赵东；

【导师】 杨喜田； 樊巍；

【作者基本信息】 河南农业大学 ， 森林培育， 2011， 博士

【摘要】 农田防护林的主要功能是防止自然灾害、调节小气候、护农增产,合理的林带结构能更好地发挥其防护效益。农田防护林结构一直是农田防护林研究的热点,构建结构合理、功能协调、效益显著的防护林体系,是农田防护林学研究的主要目标。研究不同林龄、不同林带宽度防护林带树冠结构的变化,能够深入了解叶、枝条在林带结构水平、垂直空间的分布规律,对于深入了解树冠结构变化机制、不同林带宽度的林带结构变化的机制都具有重要意义,此外,分维疏透度是重要的林带结构因子,能更精确描述林带结构。然而,关于农田防护林树冠结构的研究非常缺乏,限制了树冠结构的变化对林带结构变化机理的理解,也限制了分维疏透度在调控林带结构的应用,成为该研究领域内的一个重要问题。因此,本文以中林46杨和107杨为对象,基于不同林龄、林带宽度林带,采用分级标准木测定法,研究了2个杨树无性系树冠结构变化规律,旨在为农田防护林带结构调控提供依据。主要结论为。（1）叶面积冠层位置对比叶面积影响显著,由上层到下层,比叶面积逐渐增加。相同林带宽度的单木比叶面积随林龄的增加而增加;相同林龄的各林带行数间单木比叶面积单行>两行>三行,三行<四行<宽林带;相同的林龄、林带宽度,单木比叶面积107杨显著高于中林46杨;不同林龄、林带宽度的单木比叶面积中林46杨为109.3-133.8 cm²·g^-1,107杨为135.1-157.8 cm²·g^-1。冠层位置对叶面积影响显著,不同林带冠层的叶面积由内层到外层逐渐增加;单行林带冠层叶面积由上层到下层逐渐增加,而两行、三行、四行、宽林带冠层叶面积中层高于下层、上层。相同林龄,不同林带宽度的单木叶面积均随树木生长空间的降低而降低;相同林龄、林带宽度的单木叶面积中林46杨显著低于107杨。不同林龄、不同林带宽度的单木叶面积中林46杨为35.02-177.75m²,107杨为51.11-212.94 m²。（2）枝面积侧枝比枝面积随年龄级别增加而降低,随分枝级别的增加而增加。相同林龄的单木比枝面积随林木生长空间的降低而增加;相同林带宽度的单木比枝面积随林龄的增加而降低。相同林龄、林带宽度,单木比枝面积表现为中林46杨高于107杨。单木比枝面积中林46杨和107杨分别为11.14-12.79 cm²·g^-1和8.72-11.62 cm²·g^-1。主枝面积受冠层位置的影响,主枝面积由内层到外层逐渐降低;单行、两行林带的主枝面积从上层到下层逐渐增加,三行、四行及宽林带的主枝面积中间层高于上层和下层。各分枝级别侧枝面积随分枝级别的增加而降低。单木枝面积（主枝面积、侧枝面积、总枝面积）与单木叶面积的变化趋势一致。中林46杨、107杨的单木叶面积/树面积的平均值分别为79.25%、82.08%,单木枝面积/树面积平均值分别为13.63%、12.81%。（3）树冠分维度单行、两行及三行林带的树冠分维度,8年生林木高于6年生林木,而四行及宽林带情况与之相反。相同林龄的树冠分维度为单行<两行<三行<四行<宽林带。相同林龄和林带宽度的107杨树冠分维度略高于中林46杨。基于叶量计算的树冠分维度,中林46杨各林带宽度值为2.05-2.39,107杨值为2.18-2.51。（4）林带面积指数林分叶面积指数与单木叶面积的变化趋势相似。相同林龄、不同林带宽度的林分枝面积指数、枝干面积指数及总树面积指数变化趋势不明显。相同林带宽度的林分面积（叶、枝、枝干、树）指数均随林龄的增加而增加;相同林龄、林带宽度,林分面积指数中林46杨均低于107杨。（5）林带分维疏透度将基于枝、叶、干生物量计算的林带分维度作为有叶期的分维度(D_f有),基于枝、干生物量计算的林带分维度作为无叶期的分维度(D_f无),而对应的林带分维疏透度（β_f）为,有叶期:β_f有=3- D_f有、无叶期:β_f无=3-D_f无。建立了林带分维疏透度（β_f）和透光疏透（β）的函数模型（β_f = aβ^b）、与林带固定长度胸高断面积（G,m²/50m）及相对枝下高（h0）的模型（β_f =a+bln G+ch₀）,与林带叶面积、枝面积、枝干面积、总树面积指数的关系模型:β_f =a+bln（ x）+cln（x2 ）+dln（x³）。为定量描述林带结构及对林带结构的调控提供了依据。更多还原

【Abstract】 Shelterbelt is an ecosystem for guarding against natural disasters, adjusting local space micro-climate and improving crops production. It can provide the better preventive function with reasonable forest structure. The structure of shelterbelt is a hot topic in the study of shelterbelt, the main goal of study for shelterbelt is to build shelterbelt system with reasonable structure, functional harmony and remarkable benefit.It could know the variation of leaf and branch characters, tree crown, and shelterbelts to reaseach crown structre in Poplar shelterbelt. Fractal porosity is important index desribed shelterbelt structure and can characterized the structure of shelterbelt more accurately. However, the research about tree crown was just few at present, so, fractal porosity was limited to regulate and manage shelterbelt.to regulate optical porosity of shelterbelt. The optical porosity of shelterbelt was two dimensions index, however, there was deficiency to use the optical porosity express the structure of shelterbelt. With the developing of technical, fractal geometry can characterized the structure of shelterbelt more accurately. It can regulate the structure of shelterbelt and improve protect effect in plain.In this study, Populus×euramericana （Dode） Guinier CL.“zhonglin 46”and Populus×euramericana cv.“74/76”shelterbelts with different age and row were selected in kaifeng country. Thee crown structure were studied based on sample tree selected by different tree order. The main objectives of the paper were to regulate and manage the structrre of shelterbelt. The mainly conclusions as follow:（1） Leaf area Specific leaf area（SLA） was significantly affected by the position in the crown. SLA increased from the top to the bottom of the crown. SAL on individual tree increased with increasing tree age in the same width of shelterbelt, and the order of SLA on individual tree in the same forest age was single row>two rows>triples rows shelterbelts, and triples rows<four rows<stand. This changing might be related to the environmental conditions of tree growth. The results indicated that the SLA of individual tree in P×euramericana cv.“74/76”tree was higher than that in P×euramericana （Dode） Guinier CL.“zhonglin 46”（called Pדzhonglin 46”in short） tree in the same tree age and row. SLA on individual tree in Pדzhonglin 46”forests was 109.3-133.8 cm²·g^-1, and it 135.1-157.8 cm²·g^-1 in P×euramericana cv.“74/76”stands.Leaf area （LA） was also significantly affected by position in the crown. It increased from the interior to the exterior of the crown, and it increased from the top to the bottom of the crown for single row shelterbelt, while, it was higher in the middle than that in the upper and the lower of the crown for two rows, triple rows, four rows and many rows shelterbelts. In addition, LA on individual trees reduced with reducing growth space in the same forest age and row, raised with older forest age in the same row, and it was significantly lower in Pדzhonglin 46”tree than that in P×euramericana cv.“74/76”tree in the same forest age and row. It ranged from 35.02 to 177.75 m² for Pדzhonglin 46”stands, and it varied from 45.35 to 212.94 m² for P×euramericana cv.“74/76”stands.（2） Branch surface area Specific shoot area（SSA） decreased with successively older age classes and increased with sequentially higher branching classes. SSA of individual tree increased with reducing growth space in the same forest age. Furthermore, it decreased with older forest age in the same row. SSA of individual tree in P×euramericana cv.“74/76”tree was higher than in Pדzhonglin 46”tree in the same type. SSA of individual tree in Pדzhonglin 46 and P×euramericana cv.“74/76”shelterbelts ranged from 11.14 to 12.79 cm²·g^-1and 8.72 to 11.92 cm²·g^-1, respectively.Primary branch axis surface area was also significantly influenced by canopy position, and it decreased from the inner to the exterior. But it increased from the top to the bottom in triple rows, four rows and many rows shelterbelts. Lateral shoot surface area decreased with branching order. Moreover, the variation modes for total, primary branch axis, and lateral shoot surface area in individual tree were all the similar as that of LA in a tree. The LA/tree area of Pדzhonglin 46”trees and P×euramericana cv.“74/76”tree were 79.25% and 82.08%, respectively. The branch surface area/tree area of a tree for Pדzhonglin 46”trees and P×euramericana cv.“74/76”tree were 13.63% and 12.81%, respectively.（3） Fractal dimension of the crown The fractal dimension of the crown for 8-year-old tree was greater than that for 6-year-old tree from single, two, and triple rows shelterbelt, conversely, fractal dimension of the crown for 8-year-old tree was lower than that for 6-year-old tree for four rows and more rows shelterbelt. The order of the fractal dimension of the crown in the same forest age was single row<two rows<triples rows< four rows<more rows. Besides, fractal dimension of the crown for P×euramericana cv.“74/76”tree was slightly larger than that for Pדzhonglin46”tree in the same tree age and pattern. Fractal dimension of the crown, calculated based on leaf biomass, ranged from 2.02 to 2.39 for Pדzhonglin46”tree, and ranged varied from 2.18 to 2.63 for P×euramericana cv.“74/76”tree.（4） Shelterbelt structure characters The variation of LAI of stand and LA in a tree was similarly. the variation of branchwood area index, wood area index, and tree area index of stands were also the same, and they all hadn’t remarkably tendency in the same forest age and row, all increased with older shelterbelt age in the same row, and that of Pדzhonglin46”shelterbelt were all lower than that of P×euramericana cv.“74/76”shelterbelt in the same forest age and row.（5） fractal porosity model of Shelterbelt Fractal dimension of Shelterbelt in leafed period(D_f有) was calculate based on total （branch, leaf, and stem） biomass, and that in leafless period(D_f无) was calculate based on branch and stem biomass. Fractal porosity implies occupancy of stands gap to forest volume. Fractal porosity in leafed period and leafless equalβ_f有=3-D_f有 andβ_f无)=3- D_f无 , respectively. Some equations describing the fractal porosity of shelterbelt were developed. Fractal porosity could be described by fractal dimension using the power function model （β_f =αβb） and could be described by stand basal area and relative height to live branch （β_f =α+blnG+ch0）. In addition, some equations for describing the relationship between fractal porosity and LAI, BAI ,WAI ,and TAI were developed（βf =a+bln（ x）+cln（x² ）+dln（x³））. The above model could were used to regulate forest structure.更多还原