林木种子的正态分布曲线分级方法

云南有近千种林木种子用于绿化造林,而国家已制定出种子等级标准的仅１１５种,许多常用树种还未制定标准,林木种子分级方法较多,用于制定国家种子分级标准的方法有４种,均有缺欠。此法有严谨的理论依据,数据可经检验,能增强人为控制种子质量的因素。     

《林木种子质量分级》国家标准的研制及其实用价值

介绍了《GB 7908-1999林木种子质量分级》国家标准的研究和制定过程,介绍了我国149个主要造林绿化树种种子质量分级标准及数值,说明了新国家标准比旧的有哪些提高,吸收了那些国际先进的科技及其实用价值。     

回归分析在种子检验中的应用

1 前言现行的国家或地方林木种子质量分级标准,大部分采用发芽率划分等级,只有发芽困难或尚无法解决发芽技术的种子,才用生活力作为质量分级的指标。林木种子发芽率的测定。一般需要十几天甚至几十天的时间,如华山松需40多天发芽才能结束。这种状况极不适应种子调拨和现场收购的需要,给种子经营和造林事业造成严重影响。而测定种     

林木种子等级的划分

林业部1982年制定的林木种子等级办法实施方案(讨论稿)中规定,在服从正态分布情况下,以样本内种子样品品质指标的平均数X,标准差S来形成分级界限,将种子分成Ⅰ、Ⅱ、Ⅲ级和不及格四个等级,并规定计算时每个树种要有30～50份样品的检验结果。对于多项品质指标,在划定分级     

山东省林木种子质量分级地方标准的制定

山东省《林木种子质量分级》已经山东省技术监督局批准分布并且实施。为了较好地实施该标准，该文介绍了种子主要质量指标的检验方法，分级方法和省内３４个主要栽培树种种子质量指标的分级。     

闽楠轻型基质苗木质量分级标准研究

为了提高闽楠造林质量,采用主成分、聚类分析、正态分布等方法研究了闽楠轻型基质苗木质量分级标准。结果表明:苗高和地径可作为闽楠轻型基质苗木质量分级指标,采用聚类分析方法与正态分布分级法,得到2种闽楠轻型基质苗木质量的分级标准。通过调查统计不同育苗圃地闽楠轻型基质苗木的生长情况,确定1年生闽楠轻型基质苗木质量分级标准为Ⅰ级苗,H≥35cm、D≥0.35cm;Ⅱ级苗,35H≥20cm、0.35D≥0.25cm。     

聚类分析法在苗木质量分级中的应用

聚类分析法在苗木质量分级中的应用徐金光，解孝满，刘和风（山东省林木种苗站）聚类分析法在林业资源调查中应用较多，但用于种苗方面的报道还比较少。以往苗木质量一般按照“概率的正态分布”进行分级。由于苗木地径和苗高的实际分布频率与正态分布有偏差，所以，依此制...     

林木种子de质检操作流程

种苗质量是林业工程建设成败的关键。林木种子质量检验是林业工程质量管理的第一道关口。在此介绍一套节时高效的林木种子质量检验操作流程。林木种子质量检验是用随机抽取的样品质量代表种批整体质量的分析方法。根据林木种子质量检验规程 (GB722-1999)主要检验项目有净度分析、发芽测定、生活力测定、优良度测定、种子健康状况测定、含水量测定、重量测定,依据林木种子质量分级标准 (GB7908-1999)应检测净度、发芽率、生活力、优良度、含水量的五项或部分指标。送检样品实验室分析过程中该五项指标检测流程,主要是净度测定结束后其余四项测定交替进行的统筹安排。     

防风种子品质检验及质量标准研究

对全国不同地区防风种子的品质进行测定,研究防风种子的检验方法和分级标准,测定了不同产地的防风种子的净度、千粒重、含水量、生活力、发芽率,并初步制定了防风种子的质量分级标准。     

林木种子介电分选试验研究

通过对林木种子介电特性的研究,分析了影响林木种子介电特性的因素和种子介电常数与种子活力之间的相关性。通过林木种子介电分选机分级,分别测试出各级种子的介电常数和活力指数,结果表明,活力高的种子介电常数较小,活力低的种子介电常数较大。     

增强创新理念发展江西林木种业经济

绿化美化城市环境以及营造工业原料林都需要大量林木种苗，江西地处亚热带，树种资源丰富，发展林木种业经济前景十分可观，就推进林木种苗产业化经营，提升种苗产品档次，实现技术创新，把林木种苗当作一项产业来建设，以及创新机制发展林木种业经济进行探讨，并提出建议。     

古永林场云南松母树林群体子代测定的初步研究

１９９２年在腾冲县古永林场开展白马河林场、古永林场和保山林场３片部省合建的云南松母树林子代测定。对６年生子代林的测定结果表明：古永林场和保山林场母树林树高的遗传增益分别为１３４９％和２０２３％;树高、分枝数和冠幅的遗传力较高,而地径的遗传力较低;诸性状间存在着较紧密的遗传相关,性状间受基因连锁或共效基因的作用较多,相对受环境的影响较小。在种子调拨上应注意种源分区,最好采用本区的优良种子。白马河林场母树林基地因和试验地的气候差异较大,所产种子在试验区的适应性较差,生产力较低,而来自同一种源区滇西古永林场和保山林场母树林的种子对该区的气候具有较强的适应性,其生长力较高。     

林木种子裹衣强度的研究

通过林木种子裹衣试验研究,以搅动法为基础,研究与裹种破碎关系密切的强度,为实施林木种子裹衣技术奠定基础。     

沈阳城市森林结构与生态效益

用样方调查方法对沈阳市建成区163.5km2范围的树木进行实地调查,并建立了基于Arc View 3.2以及CITYgreen模型的城市森林信息管理系统。应用该系统分析了沈阳市土地利用及树木分布的格局、树种柏成、树木密度、树高等级分布、胸径等级分布、健康状况等指标。     

结构化森林经营技术要点与应用

利用结构化森林经营技术对蛟河林业实验区管理局所属红松阔叶林进行经营,并对经营前后林分的基本特征与状态特征进行比较分析,结果表明:郁闭度由0.85下降到0.80,林分密度由1 186株·hm-2下降到992株·hm-2;林分平均角尺度为0.490,仍为随机分布;林分平均混交度为0.792,较经营前略有上升;直径分布仍为倒"J"型。顶级树种红松的相对显著度明显上升,由经营前的8.26%上升到经营后的9.57%,优势度从经营前的0.230上升到经营后的0.264;珍贵树种黄檗及主要伴生树种的优势度均呈上升状态。     

桂花林场苦槠林分空间结构规律研究

利用混交度、大小比数和角尺度3种结构参数,结合树种组成,对湖北桂花林场4块苦槠混交林样地的林分空间结构进行分析。结果表明,苦槠为优势树种,多单种聚集生长,其他树种强度混交、极强度混交的比例大;枫香在大小分化上占有一定的优势,其他树种则分化严重;从林木水平空间格局上来看．该试验地树种分布格局以团状分布为主。     

Effects of seed traits on the success of direct seeding for restoring southern Thailand’s lowland evergreen forest ecosystem

The success of direct seeding, as a low-cost approach to forest restoration, varies with tree species and seed characteristics. A system to predict which tree species are likely to be suitable for direct seeding would therefore be useful for improving forest restoration projects. Therefore, this study aimed to determine the effects of seed traits on the success of direct seeding to restore tropical forest in southern Thailand. Seeds of 19 indigenous lowland tropical forest tree species were collected, from both the east and west sides of the Thailand peninsular and the following parameters measured: seed size, shape, coat thickness and moisture content. Field trials were established to determine seed germination rates and to calculate a “direct seeding suitability score” for each species, which combined seedling establishment and growth rates. Seed size, shape and moisture content were associated with germination percentage. Species with higher seedling survival tended to have large or intermediate-sized seeds, round or oval seeds and seeds with low or medium moisture content. Only seed coat thickness was significantly correlated with the suitability score (r = 0.65, p < 0.01). Seed coat thickness >0.4 mm coincided with higher rank suitability score. These conditions successfully predicted the success or failure of direct seeding for 15 out of 19 species tested. Eight tree species are recommended as suitable for restoring lowland evergreen forest ecosystems in southern Thailand, by direct seeding.     

生态疏伐对华北落叶松林分结构和生物多样性的影响

森林抚育对调整林分结构、促进林木生长都具有极大作用。为了解抚育对华北落叶松林分结构和林下物种多样性的影响,以承德市第三乡林场华北落叶松—白桦混交林为研究对象,采用对比分析的方法,对生态疏伐前后的林分结构、径阶分布和生物多样性进行了探讨。结果表明:生态疏伐后林分平均胸径增加2.1cm,平均树高稍有变化,林分密度从疏伐前的1 365株/hm~2下降到900株/hm~2;生态疏伐前,直径分布曲线呈左偏,6~16径阶林木数量占总数的42.6%;疏伐后,6~16径阶林木株数占总株数的21.3%,直径分布稍向右偏,更趋于正态分布;疏伐后,林下物种的Simpson和Shannon-Wiener指数均有所增加,Pielou均匀度指数在1号、4号、5号样方内有所下降,2号、3号样方内呈增加趋势,且3号样方的Simpson、Shannon-Wiener和Pielou均匀度指数涨幅均最大,分别比抚育前增加了0.373、0.834和0.203。     

Effects of seed quality and seed location on the removal of acorns and beechnuts

We examine whether different guilds of foragers remove seeds differentially according to seed quality (seed size and insect infestation) and seed location (habitat and microhabitat) in a mixed oak-beech forest. Video recordings indicated that the wood mouse (Apodemus sylvaticus) was first to encounter seeds. Foragers preferred acorns to beechnuts, large to small size and sound to infested. Nevertheless, infested seeds were removed by rodents even when sound seeds were present. Seeds that were not preferred by scatter-hoarding rodents remained longer on the ground and were more vulnerable to predation and desiccation (4% moisture loss per day). However, seeds that were removed by scatter-hoarders were moved away from their mother trees (96%) and cached individually (32%), increasing their moisture content (3% per day). Buried seeds, simulating scatter-hoarding behavior, experienced only a 17% removal after 4 months. Seed removal differences among habitats were not due to habitat attributes but to the spatial distribution of rodent-preferred microhabitats. Thus, a significant lower seed removal was observed under the tree canopy with no shrubs. However, seed removal in forest gaps with deadwood cover was not significantly different from the preferred microhabitat (under shrub cover). In pure beech forests, seed removal by rodents only occurred under Ilex aquifolium (the only perennial cover) and under woody debris. This study concludes that seed quality and seed location determine the contribution of different removers (predators vs. dispersers), their seed selection and their removal speed, leading to different seed fates which will eventually affect tree regeneration.     

Modeling frequency distributions of tree height,diameter and crown area by six probability functions for open forests of <Emphasis Type="Italic">Quercus persica</Emphasis> in Iran

The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus persica in open forests in Iran. To investigate the probability distribution of trees in natural stands, 642 trees were selected for measurement using a systematic random sampling method. Selected trees were measured and data were analyzed. Gamma, beta, normal,lognormal, exponential and Weibull probability distributions were fitted to the height distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov–Smirnov and Anderson–Darling tests. Beta, Weibull and Weibull probability distributions explained the distributions of tree height, DBH and crown area.