闽北天然异龄林林分结构规律的研究

本文对现有闽北天然异龄林的林分结构进行分析和模拟研究，得出了林分内部的树种及林分层次结构、林分直径分布结构、林分蓄积分布结构等规律，并对现有异龄林的合理经营和结构调整提出几点建议。     

用林分结构分析法检验天然异龄林择伐作业质量

单层或复层林相的异龄林分，适于择伐主伐方式。从森林永续利用观点出发，择伐作业成败的标准应当是：在完成主伐任务的同时，使保留木仍保持异龄合理结构。这种基本结构是林分株数（空间）和径级（时间）的相关结构，是连续均匀的反抛物线分布，这是异龄林植物群落存在的基本形式。 目前，黑龙江省许多林场对天然异龄林的择伐方式极不一致，且又各不完善，尤其对择伐作业质量检验标准不统一。用林分结构分析法检验择伐作业质量较为可行。 一个可以永续择伐作业的异龄林分。应当至少包括由幼龄至老龄各龄组齐备的林木，以使择伐作业不间断，…     

落矶山异龄颤杨林的结构和生长

在落矶山，许多颤杨林是异龄的。这种年龄结构使许多不耐荫的下层木受压。科罗拉多西北部的林道中，被压木的胸高直径和树高分别比主林层和亚林层林木低２２％－４４％和２５％和２８％，某些状况下，被压木腐烂的百分比是上层木的两倍多。     

试论大窝铺天然油松异龄林林分结构及经营对策

本文根据对平泉县柳溪乡大窝铺村第17小班天然油松林的调查结果,认为该小班达到了法正异龄林标准,株数按径级分布基本是倒“J”形分布,小、中、大径级组蓄积量之比大体为1:1:1,小班平均每公顷蓄积量为190m~3,连年生长量5.1m~3,单位面积蓄积量接近法正异龄林标准;提出经营措施应着眼于维护并改善复层异龄结构,可采用经营择伐作业,或综合疏伐作业。     

兴安落叶松林分直径结构研究

通过对大兴安岭原始兴安落叶松林分直径结构进行研究,分析兴安落叶松林和白桦林木株数和蓄积按径阶分布的特点。分析结果表明:兴安落叶松林分总体上表现出较明显的原始天然异龄林特点,直径分布结构符合原始天然林的自然生长规律,总体上呈波动的倒"J"字型曲线,这可能是由于该林分中林木的生物学特性和生境共同作用的结果。该研究为科学经营提供理论依据。     

岷江冷杉林分的直径结构

<正> 本文试图通过岷江冷杉林分的直径结构分析,研究异龄林的直径分布规律,探讨不划森林分子直接编制异龄林株数分布序列表和出材量表的可能性,改进异龄林的调查和出材量计算方法。     

根据树种组成和直径结构的天然异龄林样地资料分类方法

本文介绍根据树种组成和直径结构对天然异龄林的样地资料分类方法,分步从各径阶组的各树种组的株数百分数、针阔蓄积百分数指标两方面进行控制。第一步应用系统聚类方法。第二步根据针阔蓄积组成进一步分类。并且本文对来自长白山林区的140个2次至4次复测的天然异龄林样地资料进行分类。     

朝阳地区油松毛虫重度危害林分近自然恢复关键技术研究

对油松毛虫重度危害林分近自然恢复关键技术的研究结果表明:采取清除油松死亡木,全面割除林下多年生灌木,搂散枯枝落叶层等关键技术措施,即可达到近自然恢复的目的。近自然恢复的新一代油松林已将第一代人工油松单层纯林演变成复层异龄林,与林下灌木和草本植物合理利用立体生长空间,通过自然选择形成了密度合理的共生环境,提高了抵御松毛虫等自然灾害的能力。     

关于异龄林大小等级划分标准的探讨

在森林资源调查中,对异龄林用平均年龄和龄组进行归类,会缩小不同林分之间的结构差异,并造成林分年龄的偏低估计。利用海南省热带天然林样地资料。在对异龄林结构进行分析的基础上,提出用占总株数20％的大径级林木来计算异龄林的平均直径、平均树高等林分特征因子,并根据平均直径大小按“径组”（或粗度级）将异龄林分为5级,基本与同龄林的5个龄组相对应。便于对森林资源的统计和汇总分析。提出的径组划分标准可为异龄林的调查和统计提供参考,也为开展这方面的进一步研究提供借鉴。     

辽西半干旱地区不同林型对油松天然更新生长的影响

通过调查裸岩油松林、禾草油松林、山杏油松林、蒙古栎油松林、胡枝子油松林5种林型内天然更新后生长幼树的品种、数量和林龄所占比例,判定不同林型对油松天然更新的影响,再对更新后的油松进行位置调查。分别在阳坡、阴坡、林窗下、林窗边缘和树冠下所生长的油松数量进行对比,从而得出油松在无林地内的天然更新决定于下种条件、环境特点和人为干扰因素,林冠下死亡地被物的厚薄是影响油松天然更新数量的主要因子,通过带状皆伐更新,带宽30 m,带距50 m较为适宜油松天然下种更新。     

Thirty Year History of Even-Aged Management

Abstract

Forests of Turkey were severely degraded and depleted as a result of mismanagement particularly during the application of uneven-aged management periods. With the beginning of a national call for planning, all forests except fir-dominated stands are planned for management under even-aged management methods. This paper explains and discusses the results of application of even-aged management on Calabrian pine forests and Eastern spruce forests in Turkey. As shown in 1973 with the first timber inventory, the implementation of even-aged management failed in the first planning period to create an optimal forest structure. It was observed, however, that even-aged management is beginning to accomplish an optimal forest structure in Calabrian pine forests with successful silvicultural treatments. In contrast, implementations of the even-aged management method on spruce forests was found unsuccessful so far. It is concluded that the method would be implementable in spruce-dominated forests and the other light-demanding commercial tree species as well if the silvicultural plans are prepared carefully based on site classification, and if the welfare system of the forest villagers in Eastern Black Sea region is improved.     

A density management diagram for Norway spruce in the temperate European montane region

Norway spruce is one of the most important conifer tree species in Europe, paramount for timber provision, habitat, recreation, and protection of mountain roads and settlements from natural hazards. Although natural Norway spruce forests exhibit diverse structures, even-aged stands can arise after disturbance or as the result of common silvicultural practice, including off-site afforestation. Many even-aged Norway spruce forests face issues such as senescence, insufficient regeneration, mechanical stability, sensitivity to biotic disturbances, and restoration. We propose the use of Density Management Diagrams (DMD), stand-scale graphical models designed to project growth and yield of even-aged forests, as a heuristic tool for assessing the structure and development of even-aged Norway spruce stands. DMDs are predicated on basic tree allometry and the assumption that self-thinning occurs predictably in forest stands. We designed a DMD for Norway spruce in temperate Europe based on wide-ranging forest inventory data. Quantitative relationships between tree- and stand-level variables that describe resistance to selected natural disturbances were superimposed on the DMD. These susceptibility zones were used to demonstrate assessment and possible management actions related to, for example, windfirmness and effectiveness of the protective function against rockfall or avalanches. The Norway spruce DMD provides forest managers and silviculturists a simple, easy-to-use, tool for evaluating stand dynamics and scheduling needed density management actions.     

乌拉山自然保护区不同森林群落土壤化学性质的比较研究

对乌拉山自然保护区的3个森林类型(天然油松林、人工油松林、白桦林)不同层次(O～5 cm,5～10cm,10～20 cm,20～40 cm)土壤的化学性质进行了测定、分析与对比.结果表明:(1)不同森林类型土壤化学性质存在明显的差异.土壤有机质、全N、全P含量在不同森林类型下表现出相对一致的规律,即其含量大小顺序为:白...     

Influence of fire and mountain pine beetle on the dynamics of lodgepole pine stands in British Columbia,Canada

An outbreak of the mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB), currently affecting over 10.1 million hectares of lodgepole pine forests (Pinus contorta Dougl.) in British Columbia, Canada, is the largest in recorded history. We examined the dynamics of even-aged lodgepole pine forests in southern British Columbia, which were undergoing this MPB outbreak. Using dendroecology and forest measurements we reconstructed the stand processes of stand initiation, stand disturbances, tree mortality, and regeneration, and explained the current stand structure and the potential MPB impacts in selected stands. Our results indicate that stand-replacing fires initiated even-aged seral lodgepole pine stands in this region. In the absence of fire in the 20th century, multiple MPB disturbances, which each resulted in partial canopy removal, modified the simple one-layer structure of the fire-origin stands by the initiation of post-MPB disturbance regeneration layers, transforming the stands into complex, multi-aged stands. Despite high overstory mortality due to the current MPB outbreak, regeneration layers, which are likely to survive the current outbreak, will provide important ecological legacies and will contribute to mid-term timber supply.     

How to quantify forest management intensity in Central European forests

Existing approaches for the assessment of forest management intensity lack a widely accepted, purely quantitative measure for ranking a set of forest stands along a gradient of management intensity. We have developed a silvicultural management intensity indicator (SMI) which combines three main characteristics of a given stand: tree species, stand age and aboveground, living and dead wooden biomass. Data on these three factors are used as input to represent the risk of stand loss, which is a function of tree species and stand age, and stand density, which is a function of the silvicultural regime, stand age and tree species. Consequently, the indicator consists of a risk component (SMI_r) and a density component (SMI_d). We used SMI to rank traditional management of the main Central European tree species: Norway spruce (Picea abies [Karst.] L.), European beech (Fagus sylvatica L.), Scots pine (Pinus sylvestris L.), and oak (Quercus robur L. and Quercus petraea L.). By analysing SMI over their whole rotation period, we found the following ranking of management intensity: oak<beech<pine?spruce. Additionally, we quantified the SMI of actual research plots of the German Biodiversity exploratories, which represent unmanaged and managed forest stands including conifer forests cultivated outside their natural range. SMI not only successfully separate managed from unmanaged forests, but also reflected the variability of forest management and stand properties across the entire sample and within the different management groups. We suggest using SMI to quantify silvicultual management intensity of stands differing in species composition, age, silvicultural system (even-aged vs. uneven-aged), thinning grade and stages of stand conversion from one stand type into another. Using SMI may facilitate the assessment of the impact of forest management intensity on biodiversity in temperate forests.     

不同森林植被下土壤微生物量碳和易氧化态碳的比较

土壤碳库平衡是土壤肥力保持的重要内容[1].不同森林类型,由于其凋落物数量、类组及分解行为不同,因而形成的土壤碳库大小与特征将存在较大差别.常绿阔叶林、马尾松(Pinus massoniana Lamp.)林、杉木(Cunninghamia lanceolata (Lamb.)Hook.)林和毛竹(Phyllostachys edulis(Carr.)H.de Lehaie)林是我国亚热带最主要的4种森林类型.     

灵空山主要森林类型枯落物生物量及持水性能

通过对太岳灵空山四种主要森林类型 :油松纯林、辽东栎林、松栎混交林、油落桦栎混交林的枯落物生物量及其持水性能的调查分析 ,总结出不同森林类型的生物量、最大持水量、分解率的大小排序。为研究森林的水土保持、水源涵养功能以及进一步综合评价该区的森林生态功能提供了科学依据     

马尾松天然林病虫害调查

通过对马尾松Pinus massoniana Lamb天然林及其速丰试验林、针阔混交天然林的调查，计有病虫19种，其中病害6种，害虫13种，天敌昆虫15种。调查表明，病虫种类和被害率，试验林较低，施肥区最低，混交林明显比纯林少。     

太行山低质低效林改造后的水文效益

在示范林内选取了几种有代表性的森林植被类型,即分别代表太行山的主要乡土树种油松、辽东栎,及经改造形成的主要混交林类型松栎混交林和油落桦混交林。用标准木法和样方法分别测定了林分单位面积各森林植被层的生物量及总生物量,用浸水法测定了各森林植被层的日最大持水量。观测了油松示范林林冠截留降雨能力。