【作者】 余林；

【导师】 范少辉；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2011， 博士

【摘要】 毛竹（Phyllostachys edulis）是我国亚热带主要的生态经济竹种,不仅具有较高的经济价值和社会价值,而且发挥着重要的生态功能。密度管理一直是毛竹林培育的关键技术,合理的密度管理不仅是提高竹林生产力的重要途径,而且是充分发挥竹林生态功能的必要手段。以往关于毛竹林密度的研究常侧重于生产力方面,而随着人们对生态需求的不断增强,毛竹林经济效益和生态效益兼顾将成了竹林培育的重要发展方向,因此探讨毛竹林的密度效应对毛竹林可持续经营具有重要的意义。本研究通过在皖南地区设置具有代表性且环境条件基本一致,林分密度分别为1 200株?hm-2（D1）、1 800株?hm-2（D₂）、2 400株?hm-2（D₃）和3 000株?hm-2（D₄）的毛竹纯林,比较研究了不同密度毛竹林的生长特征、土壤质量、生物量格局、营养元素积累与分配、水源涵养功能的差异,旨在揭示林分密度对毛竹林生产力及主要生态功能的作用机理,探讨经济效益和生态效益兼顾的毛竹林经营密度,为皖南地区毛竹林丰产培育和可持续经营提供理论依据和技术指导。研究结果表明:（1）不同密度毛竹林的胸径、竹高、枝下高、冠幅、基径、胸径处壁厚、总节数和枝盘数等指标差异不显著,而毛竹林的出笋成竹、受害程度及叶面积指数差异显著。毛竹林的出笋率和成竹率随着密度的增大而降低,而退笋率不受密度的影响。密度影响着毛竹林病虫害率和雨雪冰冻受害率,竹林总受害率大小排序为D（316.67 %）>D（413.33%）>D1（10.19 %）>D₂（9.26 %）,在竹林经营中可以通过密度管理来降低毛竹林的受害率。构建了皖南地区毛竹林叶面积指数的估算模型LAI=0.000588 N 0.9519 D 0.7136,不同密度毛竹林叶面积指数表现为D₄（6.83）>D₃（5.38）>D₂（4.21）>D1（2.96）。毛竹生长因子之间存在着不同程度的相关关系,其中毛竹的胸径和竹高与其他指标的相关关系更密切。（2）应用加权综合指数法对毛竹林土壤物理性状、化学性质和酶活性进行了综合评价,毛竹林土壤质量综合指数排序为D（10.5086）>D（20.5084）>D（30.4943）>D（40.4781）。试验区土壤较适合毛竹的生长,但是土壤氮磷钾比值与毛竹生长所需氮磷钾比值存在差异,其中土壤磷元素含量是毛竹生长的主要限制因子。随着林分密度增大,毛竹林土壤脲酶、蔗糖酶、蛋白酶、过氧化氢酶、酸性磷酸酶活性总体呈现先增加后趋于稳定的规律性变化。土壤酶之间及其与土壤理化性质密切相关,可以用土壤酶活性作为评价毛竹林土壤质量的指标。（3）林分密度显著影响着毛竹林生物量格局。不同密度毛竹林生态系统生物量表现为D₄(118.02 t·hm^-2)>D₃(98.42 t·hm^-2)>D₂(67.84 t·hm^-2)>D₁(58.27 t·hm^-2),其中乔木层生物量所占比例最大,大小排序为D(4111.45 t·hm^-2)>D(391.44 t·hm^-2)>D(260.54 t·hm^-2)>D₁(50.14 t·hm^-2)。林下植被生物量占毛竹林生态系统生物量的比例较小,其中灌木层所占比例为0.23 %～4.60 %,草本层所占比例为0.25 %～2.53 %,灌木层和草本层的生物量与竹林密度呈显著负相关。毛竹林枯落物储量的大小排序为D(46.00 t·hm^-2)>D₃(5.56 t·hm^-2)>D₂(5.02 t·hm^-2)>D₁(3.98 t·hm^-2),占生态系统生物量的5.08 %～7.40 %。通过线性逐步回归拟合发现,对毛竹林生态系统生物量的直接影响力排序依次为林分密度>土壤有机质>土壤pH值>平均胸径>土壤容重。（4）林分密度对毛竹不同器官和毛竹林生态系统各层次氮、磷、钾元素积累与分配有着深刻的影响。毛竹林营养元素的总积累量表现为D(354 019.59 kg·hm^-2)>D(446676.53 kg·hm^-2)>D₂(44 548.81 kg·hm^-2)>D₁(25 650.10 kg·hm^-2),各元素占总积累量比例大小依次为钾>氮>磷。毛竹林对林地土壤中营养元素的累积程度存在显著差异,表现为主要累积氮元素和磷元素,而对钾元素的生物吸收较少。毛竹林林下植被的营养元素含量均高于乔木层,富集系数呈现随密度增大而减小的趋势。（5）林分密度显著影响毛竹林水源涵养功能的发挥,试验区1 200株·hm^-2的毛竹林水源涵养功能最强。毛竹林的水源涵养量表现为D₁(722.20 t·hm^-2)>D₃(720.71 t·hm^-2)>D₄(655.96 t·hm^-2)>D₂(616.04 t·hm^-2)。毛竹林植冠层截留量的大小排序为D₄(7.93 t·hm^-2)>D₂(6.34 t·hm^-2)>D₃(6.33 t·hm^-2)>D₁(5.30 t·hm^-2),乔木层枝叶持水量随密度增大而增加,林下植被持水量则与密度负相关。毛竹林枯落物层最大持水量与其储量密切相关,大小排序为D₄(20.70 t·hm^-2)>D₃(17.71 t·hm^-2)>D₂(17.04 t·hm^-2)>D₁(13.56 t·hm^-2)。枯落物层最大拦蓄量和有效拦蓄量均随着竹林密度增大而增加,枯落物层持水量和吸水速率与浸泡时间之间的拟合模型为S=aInt+b和V=ctd。土壤是毛竹林水源涵养的主体,占毛竹林水源涵养量的95.64 %～97.39 %。随着林分密度增大,毛竹林土壤层水源涵养功能呈降低趋势。不同密度毛竹林土壤渗透性能高低排序为D₁>D₃>D₂>D₄,模型f=at-n可以模拟毛竹林土壤水分入渗过程。（6）在研究区,2 400株·hm^-2为毛竹林最优的经营密度。不同密度毛竹林的生产力、改良土壤、维持生物循环平衡、水源涵养功能等主要生态功能优劣次序不尽相同。应用加权综合指数法对毛竹林的生长特征、土壤质量、生物量格局、营养元素积累与分配、水源涵养功能进行综合评价,不同密度毛竹林生产力及生态功能综合指数大小依次为D₃（0.4995）>D₂（0.4803）>D₁（0.4662）>D₄（0.2602）。皖南地区2 400株·hm^-2毛竹林不仅具有较好的经济效益,而且能够很好地发挥竹林改良土壤、维持生物循环平衡、水源涵养等生态功能。更多还原

【Abstract】 Moso bamboo （Phyllostachys edulis） is the most important eco-economic bamboo species in subtropical region of China. It has not only relatively high economic value and social value, but also other important ecological functions. For now, as a key technology, density management is always used in P. edulis silviculture, because a reasonable density can express a vital function not only in improve productivity, but also in ecological function. It is important to study density effect from the aspect of sustainable management for P. edulis forest. Previously, the research of density was focus on the aspect of productivity, but with the continuous enhancement of the ecological requirements, more and more people took the balance of economic and ecological benefits as the new direction. In this research, four kinds of densities （D₁, D₂, D₃, D₄, represent the stand density of 1 200, 1 800, 2 400, 3 000 tree·hm-2 respectively） had been chosen at the southern Anhui province, and the characters of representativeness and environment condition were all contained in the samples. Through the study on different aspects of P. edulis forest, such as growth characteristics, soil quality, biomass, nutrient accumulation and distribution, and water conservation function, the mechanisms of forest density for productivity and ecological function were exposed, and the reasonable density was chosen as well. The aiming is to provide theoretical and technical guidance for P. edulis silvilcuture and sustainable management in the mountainous areas of southern Anhui province. The main results of this study are as follow:（1） There were no obvious differences in the grown factors under different densities, such as DBH, height, height under branch, crown width, basic diameter, wall thickness, number of internodes and branch, while significant difference was found in shooting, harmed and leaf area index （LAI） under all four stands. Sprouting rate and survival rate decrease with the increasing of stand density, but stand density had no significant influence on shooting mortality rate. The harmed rates of diseases, pests, freezing rain and snow were affected by stand density, the sequence of harmed rates were D₃ （16.67%）>D₄ （13.33%）>D₁ （10.19%）>D₂ （9.26%）, therefore, the harmed rate can be reduced by density management of P. edulis forest. The sequence of LAI under different stands was D₄ （6.83）>D₃ （5.38）>D₂ （4.21）>D₁ （2.96）. LAI=0.000588 N 0.9519 D 0.7136 can be used as LAI estimation models of P. edulis in the areas of southern Anhui province. The grown factors had various relationships between each other; furthermore, DBH and height had closer relationships than the other growth factors.（2） A weighted composite index method was used to make a comprehensive evaluation of soil quality of P. edulis forest with different density, and the order was D₁ （0.5086）>D₂ （0.5084）>D₃ （0.4943）>D₄ （0.4781）. In the study area, soil condition is suitable for the growth of P. edulis, but there is a different between the N, P, K ratio in the soil and the N, P, K ratio needed for growth, and the content of P in soil is the main limiting factor for the growth of P. edulis. With the increasing of stand density, the overall activity of urease, invertase, protease, catalase and acid phosphatase in the soil showed that an increasing was found at the first beginning and then became stable under different density stands. The relationship among the soil enzymes were closely related to each other, as well as the relationship between soil enzymes and soil properties, so, the soil enzymes can be used as the indicators to evaluate soil quality.（3） Stand density had significant effect on biomass pattern of P. edulis forest. In the experimental area, the ecosystem biomass of P. edulis stands have been shown as D₄ (118.02 t·hm^-2)>D₃ (98.42 t·hm^-2)>D₂ (67.84 t·hm^-2)>D₁ (58.27 t·hm^-2). The max proportion of total biomass was the biomass of tree layer, which the range was D₄ (111.45 t·hm^-2)>D₃ (91.44 t·hm^-2)>D₂ (60.54 t·hm^-2)>D₁ (50.14 t·hm^-2). The biomass of undergrowth plant had less proportion of total biomass, the proportion of shrub ranged from 0.23 % to 4.60 %, the proportion of herb ranged from 0.25 % to 2.53 %. The biomass of shrub and herb had a significant negative correlation with stand density. The ratio of litter amount under various stands ranged from 5.08% to 7.40%. The litter amount order of P. edulis forest was D₄ (6.00 t·hm^-2)>D₃ (5.56 t·hm^-2)>D₂ (5.02 t·hm^-2)>D₁ (3.98 t·hm^-2). The stepwise multiple regression analysis showed that, the sequence of direct influence of biomass were stands density>soil organic matters>soil pH value>average DBH>soil bulk in P. edulis forest.（4） The nutrients accumulation and distribution had influence in some extent by stand density in different organic of bamboo body and different layer of bamboo forest eco-system. The arrangement order of total accumulation of nutrient under different stands was D₃ (54019.59 kg·hm^-2)>D₄ (46 676.53 kg·hm^-2)>D₂ (44 548.81 kg·hm^-2)>D₁ (25 650.10 kg·hm^-2), and the ratio of each element was potassium>nitrogen>phosphorus. Accumulation of different nutrient elements from soil had significant differences in P. edulis forest, and it was mainly enriched in nitrogen and phosphorus, but low in potassium. The nutrient contents of understory vegetation were higher than the tree layer, and the accumulation coefficients to nutrient element in soil decrease with the increasing of stand density.（5） Stand density had significant effect on water conservation of P. edulis forest. In the experimental area, the P. edulis stand with 1 200 tree·hm^-2 was the best stand which conserves water and soil. The arrangement order of the total water conservation of P. edulis stands was D₁ (722.20 t·hm^-2)>D₃ (720.71 t·hm^-2)>D₄ (655.96 t·hm^-2)> D₂ (616.04 t·hm^-2). The arrangement order of water-holding capacity of plant canopy layer of P. edulis stands was D₄ (7.93 t·hm^-2)>D₂ (6.34 t·hm^-2)>D₃ (6.33 t·hm^-2)>D₁ (5.30 t·hm^-2). With the increase of density, the water-holding capacity of branch and leaf of tree layer increase, while the water-holding capacity of undergrowth vegetation reduced. The maximal water holding capacities of litter layer was closely related to the litter amount, and the range was D₄ (20.70 t·hm^-2)>D₃ (17.71 t·hm^-2)>D₂ (17.04 t·hm^-2)>D₁ (13.56 t·hm^-2). The modified and maximal interception amount of litter increase with the increase of density, S = a In t+b and V = c t d were expressed in the relation between water holding capacity, water absorption rate and immerse time respectively. With the increase of density of P. edulis stands, the maximum water holding capacity of soil reduced, and the arrangement order was D₁>D₃>D₄>D₂. Model f = a t -n can simulate the process of soil water infiltration of P. edulis stands.（6） In the experimental area, 2 400 tree·hm^-2 was the reasonable management density of P. edulis forest. The order of productivity and main ecological function such as improve soil fertility, maintain the balance of ecosystem nutrient circulation and conserve water were different under different densities. A weighted composite index method was used to make a comprehensive evaluation of productivity, soil quality, nutrient accumulation and distribution, water conservation of P. edulis forest with different density. The comprehensive index of productivity and ecological function of P. edulis stands with different density were in the order of D₃ （0.4995）>D₂ （0.4803）>D1 （0.4662）>D₄ （0.2602）. In southern Anhui province, P. edulis stand with 2 400 tree·hm^-2 not only bring about better economic benefit, but also improve soil fertility, maintain the balance of ecosystem nutrient circulation, conserve water, etc.更多还原