【作者】 王霞；

【导师】 陆元昌；

【作者基本信息】 北京林业大学 ， 森林可持续经营， 2013， 博士

【摘要】 马尾松(Pinus massoniana)作为我国南方的主要用材与造林树种,在保持水土、涵养水源、园林绿化以及保持生物多样性方面发挥着重要作用,主要以人工林形式大面积进行培育。但是由于人工针叶纯林树种单一、结构过于简单以及中幼龄林的比重较大,导致林分抵御有害生物的能力较差,易受到外来因素的干扰与侵害。此外,马尾松人工纯林难以满足市场对不同层次、特别是高质量大径材的需求。本文以中国林科院热带林业实验中心(简称热林中心)伏波林场内1993年春季杉木采伐迹地更新造林的马尾松人工纯林为研究对象,于2007年进行4种不同模式的近自然化改造设计和作业,并保留了对照林分和样地,总体目标是把结构简单的针叶纯林改造为结构丰富、功能多样的异龄混交林。每种模式分别建立4块面积为400平米的圆形样地,共设20块,对样地林分信息进行持续观测。本文以2008年、2010年和2012年三期观测数据为基础,从树种组成、林分结构、生长动态、土壤化学性质等方面,对马尾松近自然改造效果进行综合分析。初步研究结果表明：近自然改造的林分树种组成丰富,其直径分布从最初的近正态分布逐步过渡为倒J形分布,并且已经形成上层、中层和下层复层垂直结构。近自然化后的林分,混交度有了明显的提升,林木空间分布格局从最开始的均匀分布逐渐过渡为聚集分布或随机分布。近自然化改造林的土壤化学性质与有机质含量较对照林分表现出明显的优势。同时,本文对不同等级的林木生长过程进行分析,分析结果表明优势木生长具有绝对的优势,其总生长量远远高于中庸木和被压木。由于以纯林为应用对象的传统生长收获表,不能满足改造后的异龄混交林生长收获预估的需要,本研究通过逐步回归的方法分析,构造基于林木大小、竞争指数、立地条件的单木生长模型,为改造后的异龄混交林的预估及经营方案的制定提供了决策依据。总之,分析表明近自然化改造丰富了林分的树种组成、优化了林分结构、促进了土壤的良性发展,形成了较为稳定且持续覆盖的森林生态系统。初步结果展示出人工林的近自然化改造是实现我国森林多功经营的一个有效途径。更多还原

【Abstract】 Pinus massoniana is a main timber and afforestation tree species widely used in South China. It also played an important role in soil and water conservation, biodiversity protection and so on..However, these coniferous pure forest standshave many problems, such as poor species composition, simple stand structure, and large proportion of young and middle-aged stands, resulting in poor vulnerability tonature and human disturbance.Besides, the current Pinus massonianaplantation can not meet the multiple demands from the markets, especially the timber of large size.In2007, we employed4different models for transforming the pure Pinus massoniana plantation into close-to-nature forests, and reserve stand and control, which was reforested in1993on the clear-cutting sites in Tropical Forestry Research Center, Chinese Academy of Forestry. Our total objective was to convert the simple construction pure stands into uneven-aged mixed foreststands which are of rich species diversity, multiple functions and stable forest structure. In each transformation model, we installed4permanent circular plots with the size of400m2for continuous monitoring purposes. In this study, based on the montoring data that we abtained in2008,2010and2012, we evaluated the transformation effects in terms of species composition, stand structure, stand growth dynamics and soil chemical characteristics. The initial results suggested that the transformed stands have significant advantage over the pure stands. For example, the transformed stands have rich tree species, and the diameter distribution is approaching reverse J-shaped distribution, and the vertical structure was gradually developed and now the distinte canopy layeres were formed. In terms of spatial structure, the species mixture was greatly improved and the spatial point distribution is changing to random distribution or cluster distribution from the even distribution. In addition, the soil chemical property was greated enhanced. In addition, we analyzed the growth difference amongst dominate tree, intermediate tree, suppressed tree. The results of growth comparison indicated that the dominate trees have great advantage over the intermediate trees and suppressed trees. Given that the classical yield table which was developed for the pure plantation can not be efficiently used for prediction for the mixed irregular forest stands, we used step-wise regression to produce individual tree growth model for support the decision making process of making forest management regimes. In a word, transforming pure plantation into close-to-nature forest had greatly diversified species composition, opimazied stand structure and improved the soil quality and hence resulted in a sustainable and continuous cover forest ecosystem.As a result, we drewan initial conclusion that the close-to-natural transformation that transforming pure conifer plantation into mixed-species forests is a possible solution to multi-purpose forest management.更多还原