永安市巨尾桉人工林生长的区位效应初步研究

依据调查样地资料,分别对永安市巨尾桉人工林在不同小地形、不同坡位和不同坡向上的生长进行了研究,结果表明:山脊和山坡的林分生长量相差不大;山洼林分生长最好,其次为山脊和山坡,山顶林分生长最差;不同年龄、不同坡向的林分中,不同坡位的生长差异不大;巨尾桉在阳坡上生长明显优于半阴半阳坡的林分。     

祁连山水源涵养林天然更新状况调查

在祁连山天然林区，选择林分的不同郁闭度、龄级、地位级、林木组成、坡向、海拔高度等生态因子，进行了天然更新状况的调查。结果表明：林分郁闭度在0．4～0．7时幼树数量最多，0．8～0．9郁闭度次之，1．0、0．3以下郁闭度时最少；中郁闭度林分更新中等，过密和过稀林分更新不良；云杉在海拔2800m左右的阴坡、半阴坡更新最好。     

元江县干热河谷引种柚木生长情况初探

在1965年引种自缅甸的元江县干热河谷柚木林分中设置4个调查样地,对在不同小地形、不同坡向和不同土壤质地上的样木生长情况进行了研究.结果表明:位于山坡的林分生长差,位于山凹的林分生长最好;在半阴坡上的样木生长状况明显优于半阳坡,同坡向相比,水土条件好的地方树木生长优于水土条件差的地方.     

坡向、坡位对水曲柳中龄林生长与生物量分配的影响

水曲柳(Fraxinus mandshurica Rupr.)是我国东北林区珍贵的阔叶用材树种,研究其适宜生长的立地条件具有重要的生态和经济价值。本研究在帽儿山地区水曲柳中龄人工林不同坡向、坡位设置样地,进行胸径、树高的测定,并通过异速生长方程,估计总生物量、地上与地下生物量的分配。结果表明:坡向和坡位对水曲柳中龄林林分的生长有重要影响。坡向对林分平均胸径和优势树高的影响要大于坡位,但双因素方差分析表明,仅坡向对优势树高有显著的影响(P<0.05)。总体而言,西向坡林分生长状况好于东向坡,而且坡下与坡上林分生长状况的优劣,强烈地受到坡向的影响,并且在不同坡向上表现出相反的关系。     

不同坡向落叶松人工林林分生长模型差异的研究

本文利用红石林业局2016年森林资源调查小班数据库，对落叶松人工林不同坡向的林分生长模型进行了构建，并分析了模型参数差异。结果表明：不同坡向落叶松人工林公顷株数、公顷蓄积量、平均胸径和年龄等主要林分因子差异较小。落叶松人工林林分生长模型为理查德方程，不同坡向模型参数a差异显著，参数b和参数c差异不显著。阳坡、半阴半阳坡和阴坡模型参数a分别为207.7、207.6和181.5,参数b均为0.051 3,参数c均为2.761 6。     

家参野化立地条件的初步调查

家参野化适宜立地条件是:林分以柞、椴、楸等阔叶混交的天然次生林,地形为陡坡,坡向为半阳坡,郁闭度为0.65,土壤质地为轻砂暗棕壤。     

腾冲县秃杉人工林立地条件与林分生长关系分析

根据样地调查数据,采用方差分析法、显著性分析和多重比较分析法,分析不同坡向、坡位、坡度、土壤等立地因子下的秃杉人工林树高、胸径平均生长量状况。结果表明:不同坡向、坡位、土壤厚度对秃杉人工林林分生长均有显著影响;影响秃杉人工林林分生长的最主要立地因子为坡位、坡向和土壤厚度;秃杉最适生的立地条件为坡下部、阴坡、土壤深厚。     

不同立地因子对马占相思人工林的影响

以闽东南地区3个立地条件不同的8年生马占相思人工林为研究对象，运用方差分析、多重比较等方法，分析出马占相思林分的生长状况及其影响因素。结果表明，坡向对马占相思存活率影响很大，林分密度和混交程度对林分的胸径、单株材积无显著影响，但对树高生长量有显著影响。3个样地中，坡向为南坡、林分密度最大、无混交的林分蓄积量最大。     

适宜改建核桃楸果材兼用林的立地因子特征

从坡向、坡位、坡度、土层厚度等立地因子角度,分别调查统计分析了新宾地区核桃楸天然次生林自然生长的分布状况,并研究了立地因子对核桃楸资源生长分布情况产生的影响,总结了天然核桃楸林分改建果材兼用林的选林技术。     

马占相思人工林生长影响因子的分析

通过对闽南不同坡向、不同坡形、不同造林密度6年生马占相思人工林生长状况的调查分析,结果表明：6年生马占相思人工林生长阴坡优于阳坡,山洼优于山脊,密度为750株／hm^2的林分优于密度为1500株／hm^2的林分;坡形和造林密度对6年生马占相思人工林的生长影响显著,而坡向对6年生马占相思人工林的生长影响不显著。     

永顺万坪乡植被生态系统模型研究

通过对永顺万坪乡30个不同类型群落的实地调查,结合TWINSPAN来进行梯度分析和分类,识别了7种天然林植被类型:楠竹(Phyllostachys heterocycla'Pubescens')林,落叶阔叶林,常绿落叶阔叶林,常绿阔叶林,针叶林,针、阔混交林和灌木林;从而制作出万坪乡天然林植被生态系统模型,揭示其演替规律,预测天然林群落的演替发展方向,以便于更好地对万坪乡天然林进行生态系统模式的经营、管理与保护。     

Population dynamics of herbivorous insects and potential arthropod natural enemies on Alnus species in Kabale district, Uganda

Monitoring populations of pests and their natural enemies under different management situations and seasonal weather parameters provides extremely useful information for taking preventive measures against pest outbreaks. The abundance, spatial and temporal distributions of herbivorous insects and arthropod natural enemies on Alnus species were monitored at four sites in Kabale district, Uganda between June 1999 and August 2000. Chewing insects, dominated by Coleoptera (75%), constituted the majority of insect herbivores sampled. Dominant and potentially serious pests of Alnus included Apion globulipenne, an unidentified Chrysomelidae (Coleopt. 27), Phymateus viridipes, Coloborrtics corticina and a Cacopsylla species (Homoptera: Psyllidae). Spiders were the predominant natural enemies accounting for 64% of the total natural enemies encountered, followed by parasitic Hymenoptera (30%). There were marked spatial and temporal variations in arthropod abundance. Among sites, mean abundance of total insect herbivores and total natural enemies on A. acuminata over 15 months ranged from 3.8–8.5 and 3.3–4.7 individuals per 1-m branch length respectively. Over the same period, mean number of total insect herbivores and total natural enemies on A. nepalensis that was studied at only one site were 11.9 herbivores and 4.2 natural enemies per 1-m branch length. Populations of most insect orders increased in the wet season although the greatest herbivore abundance was evident in the dry season. Further studies are necessary on the impact and management strategies of the potentially important insect pests and natural enemies on Alnus.This revised version was published online in November 2005 with corrections to the Cover Date.     

Plant diversity patterns in different forests in Aershan, Inner Mongolia

Taking the communities of the sample sites in Aershan of Inner Mongolia as an investigation object, the indices affecting plant diversity were studied. The investigation was carried out in three different forest types (natural forests, plantations and regenerated forests after fire). Results show that 95 plant species belonging to 19 families and 50 genera were identified in total. Of these species, nine were arbors, six were shrubs and the other 80 were herbs. We found some differences in the dominant species of different layers in three forest types. Natural forests had the largest importance value for the total number of species, followed by plantations and regenerated forests after fire. Plantations and natural forests had a similar change in richness indices. The largest value of richness indices was obtained in natural forests, while the lowest value was in regenerated forests after fire. Three diversity indices (Simpson’s, Shannon-Wiener and Pielou’s indices) indicate a similar trend in all sample plots. With an increase in elevation, values of diversity indices first increased and then decreased. In different forest types, similarity between natural forests was largest, while similarity between the regenerated forests and plantations was lowest.     

四川米仓山国家级自然保护区生态环境变化及其驱动力分析

国家级自然保护区是推进生态文明、构建国家生态安全屏障、建设美丽中国的重要载体。为给保护区生态环境保护和自然资源合理利用提供一个示范案例,本文以四川省米仓山国家级自然保护区(以下简称米仓山保护区)为研究区,利用该地区2016年和2017年获取的两期遥感数据,采用人机交互解译方法,在ArcGIS平台上分别圈定耕地、建设用地、未利用地(人工因子)和林地、草地、水域湿地(自然因子),监测保护区土地利用/覆盖现状,分析保护区生态环境变化及其驱动力。结果表明:2016—2017年间保护区土地利用/覆盖类型转换趋势为人工因子转自然因子,主要类型为耕地转林地。通过选定与生态环境密切相关的岩性坚硬度,坡度,水资源,气候降水和人文因素进行驱动力分析发现,米仓山保护区生态环境的变化是自然因素和人文因素等驱动力共同作用的结果,政策推动下的人口减少是直接动因。该成果可为保护区相关监管部门的生态环境保护工作提供重要依据。     

Seed Biology,Stand Characteristics,and Regeneration of Fraxinus rhynchophylla Hance

Fruit size and seed moisture content were measured and seed production and dispersal were monitored to understand the seed biology of the Korean ash (Fraxinus rhynchophylla Hance) in two Korean ash forests. A combination of four ground treatments and four crown closure levels were created in a natural forest to understand the site conditions needed for seedling emergence in natural stands and to determine practical regeneration methods for direct seeding. The seed size of Korean ash increased until late May and its moisture content decreased rapidly in early November. Prolific seed bearing occurred every 3 yr. The distance of seed dispersal by wind was about 30 m, but more than 90% of the seeds dispersed within 10 m from the seed trees. Twenty-five seed trees per hectare provided for successful natural regeneration. The seedling emergence in the natural stands was best with scarification treatment and 25～50% of crown closure.     

国家农业部原部长何康同志与云南天然橡胶业

国家农业部部长何康同志是我国天然橡胶业的创业者和领导者之一,文章通过有关重大史实的记述,展现出何何康同志一直在关心和指导云南天然橡胶业的创造和发展的至深情怀。     

广东江门地区雷林1号桉的自然更新与扩散

调查了雷林1号桉单株的扩散情况及雷林1号桉林缘在广东江门地区主要植被类型(杉木人工林、红花荷人工林和灌木丛)中的扩散情况,采用小样方法调查了雷林1号桉林下乡土乔木树种的自然更新情况.调查发现:15年生雷林1号桉单株在45°扇形样地单向扩散的最大距离为17.82 m,扩散苗最多22株,平均树高4.72 m;雷林1号桉不能扩散进入20年生杉木人工林,可以扩散进入红花荷幼林,但实生苗数量很少,还可以扩散进入地被物较少的灌木丛,且更新苗数量较多.分析表明:雷林1号桉在引种栽培地能自然更新;雷林1号桉种子落地接触土壤、光照充足是其更新的主要条件;有5种乡土树种能在雷林1号桉林下自然更新且正常生长,因此,目前雷林1号桉对乡土树种的自然更新没有影响.     

广西西南桦天然居群的表型变异

以广西壮族自治区的西南桦天然分布区为研究对象 ,调查了 11个居群 190个单株的 12个表型性状指标 ,运用变异系数和巢式方差分析研究了居群间和居群内的表型变异 ;应用相关分析揭示了表型性状间及其与地理、气候因子间的相关性以及表型变异的地理格局 ;并且运用聚类分析进行了居群分类。结果表明 ,西南桦天然居群内的变异远大于居群间的变异 ,居群分化较小 ;侧脉数、叶片基部至最宽处距离与经度、纬度显著相关 ,叶片长与经度相关显著 ,种翅宽与海拔显著相关 ,存在较明显的地理变异趋势。而表型性状的Mahalanobis距离与地理距离间相关不显著。研究结果为西南桦的遗传改良工作奠定了基础 ,为制定西南桦育种策略和天然林持续利用对策提供了科学依据     

Soil and litter fauna of cacao agroforestry systems in Bahia,Brazil

Agroforestry systems deposit great amounts of plant residues on soil and this leads to high levels of soil organic matter content and has increased soil biodiversity and improved its conservation. This study compares the distribution of meso and macrofaunal communities in soil and litter under cacao agroforestry systems and in a natural forest in the southern Bahia state of Brazil. Soil and litter samples were obtained in September 2003, February 2004, and August 2004 in five cacao agroforestry systems. The systems evaluated included: cacao renewed under Erythrina sp. (Erythrina poeppigiana) (CRE); cacao renewed under natural forest (Cabruca, CRF); an old cacao system under Erythrina sp. (OCE); an old cacao system under a natural forest system (Cabruca, OCF) and a cacao germplasm collection area (CGC). As a reference soil and litter under a natural forest (NF) was included. Organisms were collected over a 15-day period with a Berlese–Tullgren apparatus. The density and richness of total fauna varied distinctly according to sites, sampling time and material sampled (soil and litter). 16,409 of fauna were recovered from soil and litter samples and the density of total fauna was 2,094 individuals m⁻² in the litter and 641 individuals m⁻² in the soil. The richness was 11.8 in the litter and 7.5 in the soil. The cacao agroforestry systems adopted for growing cacao in the southern Bahia region of Brazil have beneficial effects on the soil and litter faunal communities, and such systems of cacao cultivation could be considered as a conservation system for soil fauna. The development of a litter layer resulted in higher abundance and diversity of soil fauna.     

水曲柳、胡桃楸等天然次生林生长情况调查

通过标准地调查,对现有天然次生林水曲柳、胡桃楸和黄菠萝幼龄林林分特征、优良单株径级分布、生长过程进行研究,指出相应的抚育技术措施,为小兴安岭天然次生林中水曲柳、胡桃楸和黄菠萝等珍贵阔叶树种单株定向培育提供科学依据。