【作者】 富丰珍；

【导师】 徐程扬；

【作者基本信息】 北京林业大学 ， 森林培育学， 2010， 博士

【摘要】 论文对不同栽植配置方式和不同密度三倍体毛白杨林木冠层结构的特点、叶片光合特性、光合产物在树冠内的分配规律、冠层内二氧化碳同化物质分配的机理以及树冠整形与修枝措施等进行了研究,得到以下结论：(1)树冠下层叶面积指数分别比中层、上层高0.82、0.69；树冠下层的消光系数为0.89,分别比中、上层高0.07和0.005。在生长旺盛期,三倍体毛白杨冠层不同部位叶片的光饱和点变化幅度在600～1350μmol～m-2～s-1之间,光补偿点变化幅度在12～33μml·m-2·s-1之间,暗呼吸的速率变化范围为0.08-2.95μmol·m-2·s-1,同时表观量子效率的值在0.109 molCO2·mol-1内变化；西向枝条叶片的平均LSP、LCP和Pmax都较其它方向高,中层枝条叶片的平均LSP依次高于上层枝条叶片和下层枝条叶片；枝条外部叶片LSP和LCP平均值均达到最大；叶片水分利用效率在树冠的朝向和冠层的垂直层次上,随着叶片气孔导度的增大而增大,但不因叶片着生位置的不同而存在差异性。(2)三倍体毛白杨比叶重随着叶片的发育,呈现增大—降低—增大的趋势,随着树冠垂直层次的加深,比叶重逐渐减少；比叶面积在整个生长期呈现下降-升高-下降的趋势；叶片氮随着树冠垂直距离的加大而降低,生长期的推延先增大后降低,在树冠的水平部位,枝条中部叶片含有叶片氮的量最高,在生长旺盛期冠层各位置叶片氮含量与叶片的最大净光合速率之间存在着显著的正相关关系；同时树冠不同位置叶片的非结构性碳水化合物含量在林木的生长末期达到最大。(3)三倍体毛白杨林木生长量的大小及生长速率因栽植配置方式的不同而不同,胸径、树高和材积在林木生长到了第5a时都减弱；均匀配置林分比带状配置林分的叶面积指数和消光系数在整个生长季都高,而带状配置林分叶片的含氮量高于均匀配置栽植林分的叶片；一级侧枝的分枝角度随着林分密度的减小而增大,林分密度较小时,枝条的长度增大,当林分密度减小到一定的程度时枝条的长度反而降低；光合作用对光的响应受林分密度的影响,低密度林分的叶片能获得更多的光照,叶的阳生特性更强,表现出高的光饱和点、光补偿点,同时非结构性碳水化合物也均随着林分密度的降低,在叶片中的积累量呈现先降低后增加的趋势。(4)环剥处理的林木其光合作用明显的小于未进行环剥的林木,其LSP变化幅度在815μmol·m-2·s-1～1529μmol·m-2·s-1,对林木的韧皮部进行环剥处理截断了光合同化产物从源到库的运输,造成光合产物在源叶中的积累,尤其是淀粉的积累增加。(5)三倍体毛白杨1／2和1／3修枝处理林木的东向枝条叶片,在生长旺盛期时比叶重均比对照的低,且随着冠层层次的上升和叶片在枝条上生长位置的外延,比叶重越大,当冠形率为1／4时,枝条的生物量在树冠内各个部分的分配达到最大,胸径及树高的生长幅度、枝条的生物量、树干和根生物量均高于对照和其它修枝处理。更多还原

【Abstract】 This paper was studied on the structural characteristics of Triploid Chinese White Poplar canopy and photosynthetic characteristics of leaves in the canopy with differents planting configuration and stand densities;Studied on carbon dioxide assimilation source/sink relation mechanism after girdling on phloem;Meanwhile, in order to get a reasonable canopy structure management technology, according to canopy structure characteristics, pruning the canopy of Triploid Chinese White Poplar; The main results as follows:(1) Leaf Area Index(LAI) and Extinction Coefficient (K) of the buttom canopy were reache maximum, K of the buttom canopy was arrived 0.89, more 0.07 than middle and top 0.005.In the growing period, the different layers in the canopy, Light Saturation Point (LSP) changed from 600μmol·m-2·s-1 to 1350μmol·m-2·s-1, Light Compensation Point (LCP) from 12μmol·m-2·s-1 to 33μmol·-2·s-1, the dark respiration(Rd) and apparent quantum yield (a) were changes within 17.4μmol·m-2·s-1 and 0.109 molCO2·mol-1, respectively; Leaves in east branch, the top of canopy and outside of branch, the LSP, LCP and maximum net photosynthetic rate(Pmax) were highest.The leaves of WUE were increase with stomatal conductance(Gs) increasing, but there were no difference between leaves in the different canopy positions.(2) Specific Leaf Weig(SLW) was changed with leaf development, showed increase-reduce-increase trend, with the depth in the vertical canopy, SLW decreased; Specific Leaf Area (SLA) was reduce-increase-reduce in the whole growing season;With the depth in the vertical canopy, leaf nitrogen increased;With the tree grow, leaf nitrogen was increase, then decrease, meanwhile, leaves in the utter was highest.In the growing period, leaf nitrogen and Pmax exists significant positive correlation.The non-structural carbohydrate (NSC) of leaves in different positions of canopy while its content was maximum in the mature period.(3) The tree growth and growth rate of Triploid Chinese White Poplar were different due to different planting configurations, diameter、height and volume had grow slowly during the first 5 years.Leaf area index and extinction coefficient of Uniform planting configuration higher than strip planting configuration in the whole growing season;But leaf nitrogen in strip configuration was more.Branches’angle and length increased with decreased stand density.Low-density tree could receive more light, had higher LSP and LCP; NSC of leaves was decrease then increase with decreasing stand density.(4) Leaf photosynthesis was lower after girdling tree, LSP changed from 815μmol·m-2·s-1 to 1529μmol·m-2·s-1.Girdling tree was cut off production from source to sink and caused the accumulation in the source leaves, especially starch.(5) In the growthing period, pruning tree to 1/2 and 1/3, SLW is lower than control and increase with canopy layer rise and the branch extension.Diameter, height, branch and stem biomass were higher than control when canopy shape ration was 1/4.更多还原