The influencen of stand state on the occurrence ofDendrolimus superans (Butler) in Daxing’an Mountains

Dendrolimus superans (Butler) occurred in the vast areas of Daxing’an Mountains forest, in Heilongjiang Province, in 1990. Stands damaged byI). Superans seriously, intermediately and lightly show patch shape distribution within damaged area. By ordination analysis and correlation analysis between ordination factors and coordinate axis. It was found that occurrence ofD Superans in different extent is owing to the effect of forest age, composition and exposure. The tended young pure forests grown on the sunward slopes are most seriously damaged and non-tended middle-age mixing stands grown on the sunless slopes are most lightly damaged. Therefore, in order to preventD. superans from seriously damaging larch forests, relatively large crown density (P > 0. 7) should be kept, and broadleaf trees should be also properly preserved. This research project was supported by Scientific and Techndogical Committee of Heilongjiang Province     

Population Characteristics of Dendrolims Superans in Daxing'an Mountains

CollectionofdataFiveI1tlndredf1eadsofD..`IIl,L;l-I;(Ilt`crecoIlectedilltIletbrest.oraroul1dtbrestarcadtIril1gtl1epeakofap-pearancetYol11I99lloI992.TI1el1tlInberoftb111aIca11dlllaIeaduItst`ererecorded.T``/ostal1dardpIotsucrecI10seninYol1gqingandHa[1jiayuan…     

The effect of Dendrolimus superans breakout on growth of trees

IntroductionDendFOHffiussuPeransbrokeOutinShibazhanForestBureau,Daxing'anMount8insRegion,inJuneOf199o.TheinfeCtedareareachedo.8miIlionhm',takingup7o%offorestareaoftheBureau.AcCoFdingtotheinvestigation,DendFOhinussuPeransoccurredinnaturaIhaIfm8tureoryounggrowthforestmainIycomposedoflarch-TheaveragepopuIationdensityoflarvaereached283.5insectAree,andatthemoSt2256inseCts/treeinheaviIydestroyedstands-Den-dFOHmussuPeranshasonelif6circleovertWoyearsinthisarea.StandaFdplOtswereseIected…     

CAUSES OF OUTBREAK OF THE LARCH CATERPILLAR(Dendrolimus superans Butler) IN DAXINGAN MOUNTAIN AND ITS CONTROL STRATEGY

Inl99o,intheDaxinganMountainfOrestregion,anoutbreakoflarchcaterpil1aroccurredona1argeareaofmorethanonemillionh.2,mainlydistributinginEighteenthStationForestryService,HumaCounty,HanjiayuanForestryServiceandotherForestryServices'Song1ing,Tahe,andAmuer.Duringl99o-l992,wesystematicallysurveyedthesituationoftheoutbreakofthelarchcaterpil1arandc0ntr0llingmeasuresweretaken,sothatitsdamagewaseffective1yc0ntrol1ed.THESITUATIONOFTHE0UTBREAK0FLARCHCATERPILLARINDAXINGANM0UNTAIN…     

陕北黄龙山森林植物群落的初步研究

水文对森林植物群落的类型、结构、生活型谱、排序和动态做了初步研究。结果表明:森林植物群落分2个植被型,4个群系,19个群丛组;群落垂直结构分乔术、灌木、草本3层,植物组成分属于34科、76属108种;群落生活型谱反映了气候条件;群落排序结果满意;顶极植物群落为松栎林,山杨、白桦林将为辽东栎林演替,油松林与山杨林、白桦林之间的动态演替关系值得进一步研究。     

Spatial pattern of Siberian silkmoth outbreak and taiga mortality

Abstract

The latest catastrophic Siberian silkmoth (Dendrolimus superans sibiricus Tschetw.) outbreak occurred in central Siberia during 1994–1996. The relationship between forest stand mortality from insects and topographic features (azimuth, elevation, slope steepness) was analyzed based on a high-resolution digital elevation model, a pest damage map and Terra/MODIS data. It was found that pest-induced forest mortality patterns depend on topographic features. Before the outbreak the major part of host forest species was found within the elevation zone of 150–500 m. After the outbreak, surviving dark-needle stands were found mainly at elevations higher than 400 m. The greatest damage was observed at elevations between 210 and 320 m, whereas maximum mortality was observed at elevations of about 200 m and minimal mortality at elevations of 300 m. With respect to slope steepness, maximum damage for all categories was observed for slopes of 5–20°. Slightly damaged stands were most common at low slope angle (about 5° or less), whereas the highest proportion of stands with high tree mortality was found on steeper slopes. With respect to azimuth, insect damage is mostly uniform, with a small increase in damage on the south-west-facing slopes. The spatial pattern of the silkmoth outbreak can provide a basis for prioritizing Siberian silkmoth outbreak monitoring.     

混交林抑制纵坑切梢小蠹危害作用研究

８０年代以来，云南全省云南松林区遭受纵坑切梢小蠹的猖獗危害，造成大量林木死亡。１９９２年在昆明市现有的云南松与栎类、云南松与华山松、云南松与滇油杉混交林及云南松纯林中，设置１１块定位观察样地，观察云南松混交林蠹害发生情况，１９９２～１９９５年经过４年的观察，混交林平均株受害率１０．９％，纯林平均株受害率４８．９％。混交林比纯林降低纵坑切梢小蠹危害率３８．０％。混交林内由于乔、灌、草种类的多样性，带来纵坑切梢小蠹天敌种类的多样性，有效地抑制纵坑切梢小蠹的发生与发展，形成有虫不成灾的生态环境     

安徽省潜山县竹类植物分布和生态环境的关系

通过竹类植物分布与环境的关系之研究,了解潜山县皖河以北的黄柏山区,限制竹类分布的主要因子,植被被破坏,水土流失严密,土壤沙化,因蒸发量过大,导致水分不足。所以,本县内的竹林分布规律是:依山傍水,山坞和山脚缓坡的局部地段呈块状或条状间断性分布。今后,黄柏区应首先恢复植被,保护土壤,改善生态条件的前提下,方能发展竹林生产。     

Age distribution patterns in open boreal Dahurican larch forests of Central Siberia

Tree age distribution determines stand size structure and is related to disturbance history and stand dynamics. Data are presented from 40 pure larch stands from six locations on the Taimyr peninsula and Evenk region in the northern open forests of Russian Siberia. A Weibull density function was used to describe actual age distribution and to simulate age distribution. Larch age distributions have similar patterns in different locations over the study area. All stands were found to have a multi-aged structure. The average coefficient of variation for age is about 48%. The range of tree ages exceed 400 years in the oldest forests. The patterns of age distribution change for different age groups. For the youngest stands (40–80 years old) the age distribution was leptokurtic and positively skewed, whereas for middle-aged forests (80–180 years old) it tended to be more mesokurtic and symmetric. In the oldest stands (more than 180 years old) the distribution had a platykurtic form. A high correlation was found between the Weibull function coefficients and the coefficient of age variation and for the mean age. The oldest forests were found in river valleys. Middle-aged forests occur more commonly on middle slopes and the youngest forests occupy top slopes and uplands. A more normal tree age distribution assumes a study area less damaged by forest fires than in the more southern parts of the boreal forest.     

2种火烧强度对大兴安岭偃松落叶松林粗木质残体的影响

比较了大兴安岭地区的偃松落叶松原始林和2种不同火烧程度森林类型(轻度火烧林、重度火烧林)之间粗木质残体(Coarse Woody Debris,CWD)组成的差异。结果表明:原始林、轻度火烧林、重度火烧林的CWD蓄积分别为59.92m3/hm2,199.77m3/hm2,217.73m3/hm2,原始林和火烧林之间CWD材积之间有差异,而2种火烧林之间没有差异,说明火灾干扰改变了偃松落叶松林的CWD的组成结构,但是不同的火烧程度对森林CWD的影响程度差不多。原始林和重度火烧林CWD径级大部分为2～20cm,其中立枯木、倒木和伐桩分别占各自总蓄积量的34%,64%,2%和94%,5%,1%,轻度火烧林CWD大部分径级2～10cm,其中立枯木、倒木和伐桩分别占总蓄积量的47%,50%,3%,由此可看出3种不同林型的CWD都集中在小径级的立枯木和倒木中,即小径级的立枯木和倒木是3种林分CWD的主要来源。火烧后偃松落叶松林的蓄积量增加明显,因此可认为火烧可以增加森林CWD的输入量。     

海南岛尖峰岭热带林型的主分量排序

一、林地概况 尖峰岭林区位于北纬18°23′13″—18°52′30″,东经108°46′04″—109°02′43″,在中国植被区划中属琼南丘陵山地季雨林湿润雨林区。植被种类极其丰富,野生高等植物有1500多种,植被可分为四个垂直带,六个类型:1.稀树草原带:(1)稀树草原,(2)砂生植被,2.常绿季雨林带:(3)常绿季雨林,(4)沟谷雨林,3.山地雨林带:(5)山地雨林,4.山顶苔藓矮林带:(6)山顶苔藓矮林。     

华北地区经济树种蚧害研究

对华北地区经济树种蚧虫的种类区系、发生和分布规律及为害特点进行了系统研究。据调查，现已知华北经济树种蚧虫共有９科１２２种。随纬度增高、立地条件恶化、植物群落简单、人为活动频繁、管理水平粗放，蚧虫种类增多，为害严重。一般情况下，观赏树木受害普遍，温室植物受害严重，果树及平原地区林木部分受害，山地森林受害轻微。     

Forest Structure Under Different Management Regimes in the Western Lowlands of Nepal

ABSTRACT

For landscape level conservation and rural sustenance, forests outside of protected areas are becoming increasingly important. Since most outside forests in the lowlands of Nepal are under government control and utilized as open access resources, their feasibility to achieve these objectives is questionable. We compared forests inside (with three decades of strict protection) and outside of protected areas (under government control and proposed as community forests) to assess the ecological sustainability of outside forests and to provide baseline data on structure of outside forests so that effectiveness of community forestry (after implementation) can be evaluated in the future. Our results indicate that outside forests were in a degraded condition with low tree, sapling and seedling densities and lower species diversity. Trees in lower dbh (diameter at breast height) classes were absent in these forests. Although the canopy layer was not significantly different, the ordination of plots and species showed that species composition of understory and the ground layer were different than protected forests. The present condition of outside forests is not only ecologically unsustainable but also cannot fulfill the demands for forest products of local people. The inefficiency of government to monitor against exploitation has been responsible for present conditions. We recommend that community forestry programs, which are successful in improving conditions of degraded forests in the mountains of Nepal, should be widely implemented in lowland areas (Terai) and proposed community forests should be handed over to local communities as soon as it is practicable.     

The effect ofDendrolimus superans breakout on growth of trees

The effect ofDendrolimus superans on growth of trees was investigated after the breakout in Shibazhan forest area in 1990. Stem analysis was conducted for determining the tree increment loss. The result showed that the current annual increment for extreme heavily damaged, heavily damaged, moderately damaged and lightly damaged stands is 14%, 39.8%, 64% and 82% of that of the control forest respectively. (Responsible Editor: Chai Ruihai)     

先秦两汉时期中国北方天然林木分布探究

孢粉、考古及历史文献等资料显示,先秦两汉时期中国北方地区林木分布广泛,种类繁多。春秋以后北方多数地区气温有所波动,树种结构也相应地发生了变化。春秋至东汉时期,东北地区受气候变冷影响,乔木植被中针叶林比率有所增加,落叶阔叶林减少,同时森林分布范围缩小;黄淮海平原地区针、阔叶乔木随气候变化互有消长;黄土高原区未有森林生长,河谷及山地植被以阔叶树种占优的混交林为主。除气候因素外,人类活动也影响着天然植被的变化。受秦汉时期经济、政治、军事等活动的影响,除东北地区天然林木保存较好外,北方其余地区林木破坏较为严重。     

THE CALCULATION OF PROFITS IN FORESTRY

The Nature of profits within the framework of the economic theory is discussed. The difficulties which are met in the calculation of profits in forestry are briefly described and the underlying assumption that the relative difference between prices and production costs will not change with time is discussed. The forest economist should distinguish between a normal forest and a periodic forest. A periodic forest gives intermittent yields; a normal forest produces a regular annual flow of income and expenditures. The equations which should be used for the estimation of profits in these types of forests are derived and illustrated with a practical example. The consequences of the formative period elapsing between the time of initial planting and attainment of the normal forest are discussed.     

杉木短穗扦插苗与实生苗生长对比研究

为了培育杉木速生丰产林，用杉木优质短穗扦插苗与实生苗进行更新造林试验。通过3、9和15a期的观测，结果表明，杉木优质短穗扦插苗表现为林相整齐、速生丰产的特点。平均胸径、立木材积比实生苗高，均超过极显著的水平。说明采用杉木优质短穗扦插苗造林是解决杉木连栽产量低，保持杉木速生丰产的有效途径。     

黄土高原次生林改造林地鼢鼠与林木关系动态分析

对渭北高原及陕北高原的一些林分进行次生林改造.经模型和ANOVA分析证明:改造后,林木被害程度随定植年限的变化总体遵从Logistic模型.其中,全面清坡模式林木被害程度最高,林下更新模式最低.鼢鼠对油松、侧柏和刺槐的危害年限依次为林木定植后11、9和6年,其中油松定植2～6年,侧柏1～4年,刺槐1～2年被害最严重.单个鼢鼠对油松和刺槐的危害强度主要取决于林木的定植年限,与改造模式和林地鼢鼠密度关系不大;而对侧柏的危害强度不仅取决于林木定植年限,也与林地鼢鼠密度和改造模式密切相关.林木定植年限和单个鼢鼠的危害强度是影响林木被害死亡率的关键因素,林地鼢鼠密度和改造模式是主要因素.     

太白山林木真菌病害的垂直分布

我们对秦岭主峰太白山的林木真菌病害的分布规律进行了多年的探讨,结果表明,太白山林木真菌病害可划分为四个垂直分布带。即低山、低中山阔叶林叶点霉病和白粉病分布带;中山、高中山阔叶林锈病和立木腐朽分布带;中高山针叶林散斑病分布带;高山灌丛漆斑病分布带。     

Herb layer vegetation of south Swedish beech and oak forests—effects of management and soil acidity during one decade

Effects of forest management and soil acidity on herb layer vegetation were studied after 10 years on 190 permanent plots in south Swedish beech (Fagus sylvatica) and oak (Quercus robur) forests. Species richness generally increased with management intensity, mainly due to establishment of ruderal species from the seed bank. Species richness of the typical forest flora was unaffected by management. Moderate management of oak stands favoured several species which are commonly found in semi-natural pastures. Classification and ordination of the data showed that the main floristic gradient within Swedish beech and oak forest vegetation is related to soil acidity. Species richness of the typical forest flora was strongly positively correlated with soil pH in beech forests, but this correlation was weaker in oak forests. The number of herbaceous plants with a broader habitat range increased with pH only in the oak forest plots. Long term changes in the forest environment, which may affect the vegetation, are the decline of grazing 150-50 years ago and soil acidification mainly caused by atmospheric pollutants during the last 50 years. In the one-decade perspective of this study, however, we did not find a general trend towards a more acid-tolerant flora. Neither could we find a general decrease of pasture species in currently ungrazed oak stands. The results indicate that most typical forest plants are well adapted to and partly depend on occurrence of canopy gaps and soil disturbance. If canopy thinning is followed by periods of canopy closure the characteristic shade tolerant flora of Swedish beech and oak forests may be able to persist as long as soil chemical limits of existence are not exceeded.