长江中上游低质低效次生栎林的分类与评价

对林分的生长过程、形成原因和功能特征进行了分析 ,建立了栎类低质低效林综合等级的判别函数 ,将林分划分为四种类型 :极低质低效型、生长潜力型、低质型、综合低质低效型。对林分立地因子的逐步回归分析表明 ,影响栎林生长的主导立地因子依次为海拔、土层厚度和坡向 ,它们的组合可以构成不同的立地条件类型。根据对各等级的林分生长过程及其立地特征的分析 ,提出了划分栎类低质低效林的技术参数标准     

低质低效杉木次生林的分类与评价

对林分的生长过程、形成原因和功能特征进行了分析,建立了杉木低质低效林综合等级的判别函数,将林分划分为四种类型极低质低效型、生长潜力型、低质型、综合低质低效型.对林分立地因子的逐步回归分析表明,影响杉木生长的因子根据其影响大小排序依次为坡位、土壤厚度、坡度和坡向.它们的组合可以构成不同的立地条件类型.根据对各等级的林分生长过程及其立地特征的分析,提出了划分杉木低质低效林的技术参数标准.     

低质低效冷杉林的分类与评价

对冷杉林分的生长过程、形成原因和功能特征进行了分析 ,建立了冷杉低质低效林综合等级的判别函数 ,将林分划分为4种类型 :极低质低效型、生长潜力型、低质型、综合低质低效型 .对林分立地因子的逐步回归分析表明 ,在其分布区域内 ,影响冷杉生长的主导立地因子除了海拔和坡向外 ,依次为土壤名称、土层厚度和坡位 ,而坡度对其影响较小 .它们的组合可以构成不同的立地条件类型 .根据对各等级的林分生长过程及其立地特征的分析 ,提出了划分冷杉低质低效林的技术参数标准     

马尾松低质低效次生林分类技术研究

对林分的生长过程、形成原因和功能特征进行了分析,建立了马尾松低质低效林综合等级的判别函数,将林分划分为4种类型极低质低效型、生长潜力型、低质型、综合低质低效型.对林分立地因子的逐步回归分析表明,在不同的区域范围内,影响马尾松生长的主导立地因子有所不同,但海拔、土层厚度和坡度是影响马尾松生长排在前三位的3个主要因子,它们的组合可以构成不同的立地条件类型.根据对各等级的林分生长过程及其立地特征的分析,提出了划分马尾松低质低效林的技术参数标准.     

红皮云杉人工林立地分类与经营方向选择

1　材料与方法在绥棱、通化、南岔、美溪、东京城、桦南等地调查红皮云杉人工林临时标准地 130余块 ,标准地分布在各种立地类型上 ,每种立地至少有 3个重复 ,林龄为 2 2～ 35年 ,样地面积 0 .0 4～ 0 .1hm2 ,样地林分为郁闭度均在 0 .7以上的纯林 ,株数不少于 80株 ,林分只采用过下层抚育伐。调查时记载立地因子 ,进行树干解析 ,采用样地内 5株优势木进行平均高计算。通过数量化 理论对影响红皮云杉的主导立地因子进行相关分析 ,筛选出主导立地因子 ,进行立地类型的划分。以理查德生长函数对各立地类型生长进行模拟 ,建立生长模型及有关参…     

大庆市森林立地类型划分与评价

文章通过对大庆典型林分和宜林地土壤理化性质分析,结合环境因子调查,采用灰色关联度分析方法筛选出影响立地的主导因子,利用聚类分析方法,将大庆市森林立地划分为3个立地类型小区、8个立地类型组和15个立地类型,同时结合植被生长状况和土壤理化性质,对各个立地类型进行了综合生产力等级评价,为指导全市今后造林绿化选择适宜树种提供了科学依据。     

太行山低质低效林类型划分及其改造技术

在四种质效类型的基础上，按照树种组成和坡度、坡向、土层厚度等立地因子把太行山低质低效林划分为108个类型，就一些主要类型提出了经营改造技术。     

江西省赣州市低质低效林成因与特征分析

从历史、立地、粗放经营及自然灾害等方面分析了赣州市低质低效林形成的原因,并根据森林资源调查结果,分析、总结了现有低质低效林的几大特征,以期为实施低质低效林改造提供理论依据。     

福建省低质低效红树林类型划分及改造技术研究

由于生物入侵、人为破坏、海洋污染、病虫危害等原因,福建沿海的红树林面积呈下降态势,已有的红树林也出现了不同程度的衰退现象,林分质量下降,形成低质低效林分,其生态功能及经济价值不能得到充分发挥。文章根据福建省目前低质低效红树林的实际状况和形成原因,将低质低效红树林划分为:低生长量类型、稀疏类型、病虫危害类型、生物入侵类型、老龄林类型等5种类型。再运用生态学原理和方法,提出了每个类型相应的改造技术。     

云南松低质低效林的成因及其分类

低质低效林的成因和分类是对其林分作出评价和改造的基础。在从生态学和森林培育学的角度出发，提出低质低效林概念的前提下，结合恢复生态学对低质低效林的定义，分析了云南松低质低效林的自然和非自然（人为）成因，结合起源并采用其生态公益林和用材林的功能的分类方法对云南松低质低效林进行了宏观的分类，为其低质低效林的评价和改造、更新提供了依据。     

低效林的近自然经营技术

探讨了低效林的概念与类型,分析了低效林的成因及其改造方法,并针对我国长江上游大面积低效林的现状,试图通过引进近自然经营技术理念,为大面积地改造低效林,实现森林的可持续经营提供指导.     

湖南省低质低效马尾松次生林改造技术研究Ⅱ改造措施筛选和改造成效综合分析评价

在湖南省茶陵县设置了低质低效马尾松次生林改造试验基地,面积为10hm2.根据多项改造技术措施及改造措施因素的对比筛选试验结果,确定了最优改造经营技术模式.通过5a的定位观测研究,试验林在林分结构、林分生产力、林分涵养水源、固持土壤等方面均比对照林分有较大幅度的提高,改造成效非常显著.     

安徽亳县泡桐立地质量评定

本文在分析林木直径和树高的相关性的基础上,结合平原农区地形地貌特征,以林分内最大径阶木的平均胸高直径代替优势木的平均树高作因变量,以林分平均林龄和土壤种类、土层厚度、地下水位、株距等定性因子作为自变量,分别编制出安徽省亳县泡桐人工林地位指数表和数量化地位指数表,并在此基础上将泡桐人工林划分为14个立地类型。该项研究对于探讨平原农区主要树种有关经营数表的编制方法、立地类型划分和林木生长预估等具有普遍意义。     

Belowground carbon pools and processes in different age stands of Douglas-fir

Forest floor material and soil organic matter may act as both a source and a sink in global CO2 cycles. Thus, the ecosystem processes controlling these pools are central to understanding the transfers of carbon (C) between the atmosphere and terrestrial systems. To examine these ecosystem processes, the effect of stand age on temporal carbon source-sink relationships was examined in 20-year-old, 40-year-old and old-growth stands of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in the Cascade Mountains of south-central Washington State. Belowground C and nitrogen (N) storage and soil respiration were measured. In addition, nylon mesh bags containing homogenized soils from each site were buried at the respective sites to quantify root ingrowth and potential C sequestration and loss. The sites supporting the 20- and 40-year-old stands had soil C stores reflecting the C contributions from logging residue, coarse woody debris and stumps left after harvest. Because the N-fixer red alder (Alnus rubra Bong.) comprised 33% of the 40-year-old stand, this site had significantly greater concentrations and pools of N in the forest floor than sites without red alder. This N-rich site had consistently lower soil CO2 efflux rates during the growing season than the sites supporting the 20-year-old and old-growth stands. Estimated annual soil C efflux was 1367, 883 and 1194 g m-2 for the sites supporting the 20-, 40- and old-growth stands, respectively. These values are higher than previously reported values. Root ingrowth was significantly less in the 40-year-old stand than in the 20-year-old stand, and both young stands showed markedly less fine root growth than the old-growth stand. At the sites supporting the young stands, C and N were lost from the soil bags, whereas there was an increase in C and N in the soil bags at the site supporting the old-growth stand. The fine root growth and soil respiration data support the hypothesis that belowground C allocation decreases with increasing fertility. Quantification of the source-sink relationship of soil C at the three stands based on litterfall, relative root ingrowth and soil respiration measurements was compromised because of significant CO2 flux from decaying organic matter in the young stands.     

国内低效林研究综述

本文通过文献综合阐述了低效林概念及其成因，分析了自然地理因素和非自然因素在我国低效林形成中所起的作用，提出了树种选择、层次结构的改善、培育措施及封山育林等四种低效林分改造技术，并阐述了改造后的效益变化状况。     

White spruce foliar nutrient concentrations in relation to tree growth and soil nutrient amounts

Concentrations of foliar N, P, S, K, Ca, and Mg were studied in relation to stand age, tree growth, site index, and soil nutrient amounts for natural white spruce stands on a wide range of site conditions in the sub-boreal spruce zone of British Columbia, Canada. While Ca was sufficient in every sampled stand, relatively widespread deficiency in N was diagnosed. Deficiencies of other nutrients were diagnosed only on wet to very wet sites. Foliar N, P and K were negatively correlated with stand age and positively correlated with height and diameter growth. White spruce site index was positively correlated with foliar nutrients, and their relationships were quantified using a quadratic function. Foliar nutrients, except Ca, are positively correlated with soil nutrients measured in routine chemical analysis, and their relationships were quantified using Mitscherlich's function. It is recommended that the existing standards need to be modified should they be applied to nutrient diagnosis in natural white spruce stands. These standards appear too high for N and too low for P, K, and Ca.     

Species Interactions in the Dynamics of Even- and Uneven-Aged Boreal Forests

Many boreal tree stands are neither clearly even-aged nor clearly uneven-aged. The stands may undergo a series of stages, during which an even-aged stand is transformed into two-storied mixed stand, and finally to multistoried or uneven-aged stand structure. The species composition often changes during the succession of stand stages. This study developed models for stand dynamics that can be used in different stand structures and species compositions. The model set consists of species-specific individual-tree diameter increment and survival models, and models for ingrowth. Separate models were developed for Scots pine, Norway spruce, and hardwood species. The models were used in a growth simulator, to give illustrative examples on species influences and stand dynamics. Methods to simulate residual variation around diameter increment and ingrowth models are also presented. The results suggest that mixed stands are more productive than one-species stands. Spruce in particular benefits from an admixture of other species. Mixed species improve diameter increment, decrease mortality, and increase ingrowth. Pine is a more beneficial admixture than birch. Simulations showed that uneven-aged management of spruce forests is sustainable and productive, and even-aged conifer stands growing on medium sites can be converted into uneven-aged mixed stands by a series of strong high thinnings.     

北京海坨山典型林分土壤有机碳含量及有机碳密度垂直分布特征

目的 探讨海坨山不同林分类型下土壤有机碳含量和有机碳密度的垂直分布特征及其与土壤性质相关关系,为华北地区森林土壤碳库准确评价及森林生态服务功能评估提供科学依据。 方法 选择不同5种典型林分（油松林、核桃秋林、蒙古栎林、针阔混交林、山杨林）分别设置3块标准样地,采集0～100 cm不同土层土样,并分析相关土壤理化性质,分析不同土壤理化因子对土壤有机碳含量的影响,研究该林区不同林分土壤碳含量及密度的分配特征。 结果 不同林分类型下土壤各层次有机碳含量为9.35～50.25 g·kg−1,均值为27.42 g·kg−1。林分类型对不同土层土壤有机碳含量影响显著（p < 0.05）,不同林分类型土壤有机碳平均含量由小到大排序：山杨林 < 针阔混交林 < 核桃楸林 < 蒙古栎林 < 油松林。不同林分类型土壤有机碳含量垂直变化趋势相同：从表层向下逐渐降低,表聚性明显,表层（A+AB）占土壤总有机碳含量约57%。不同林分类型100 cm深度土壤有机碳密度为21.4～76.6 t·hm−2,均值为45.7 t·hm−2。各林分间土壤总有机碳密度大小为：山杨林 > 核桃楸林 > 针阔混交林 > 蒙古栎林 > 油松林。单位cm厚度土壤有机碳密度的垂直变化规律与土壤有机碳含量相同,从表层向下逐渐降低,表层（A+AB）土壤有机碳密度占土壤总有机碳密度的35%～40%。不同林分土壤有机碳含量与全氮含量呈极显著正相关(r=0.923～0.985),与土壤密度呈极显著负相关(r=−0.971～−0.996)。 结论 林分类型是影响土壤有机碳垂直分配的重要因素之一,且其影响程度随土壤深度的增加而下降;仅山杨林下土壤有机碳含量与土壤黏粒含量呈极显著正相关,其它林分与黏粒含量相关性不显著。