Causes of outbreak of the larch caterpillar (Dendrolimus superans Butler) in Daxingan Mountain and its control strategy

In 1991, in Daxingan Mountain, an outbreak of larch caterpillar (Dendrolimus superans Butler) happened on large areas of more than one million hectares, where stands of larch were seriously damaged because needles on the trees were almost eaten up by the pest, causing enormous economic losses. Analysis of data collected indicated that the main cause of the outbreak of larch caterpillar on large areas was that, after thirty years of exploitation, mature and overmature forests decreased rapidly, middle-aged and young forests incresed in large amount, significant changes occurred in individual ecological conditions of stands, especially those tended, with decreasing canopy density and better light condition in the forest, and all these were adventageous to the outbreak of the pest. In addition, in recent years, the climatic condition in Daxingan Mountain changed significantly. The yearly average temperature raised gradually and the soil surface temperature in April and October increased year by year, which were advantageous to the outbreak of larch caterpillars. In short, the significant changes in the ecological conditions in Daxingan Mountain provided suitable conditions for the outbreak of the larch caberpillar, and after several years of increase in population number, the larch caterpillar outbroke into a serious disaster on vast areas. In the paper, composite control strategy was also discussed.     

Quantitative dynamics of larch caterpillar (Dendralimus superans [Buller]) and the biological control

The relationship between pest population and other factors is rather complex within the forest ecosystem. A number of environmental factors, such as extreme climatic conditions, infection of natural enemies, may cause the death of pest insects directly. The effect of these factors reflects basically the situation and cause of death of insects at different stages of entire process of growth and development, so that they may be employed as the basic records of the quantitative dynamic of the population, and are of important value to the study of population quantitative dynamics of pests. Since Morris and Miller (1954) applied the life table technique to study natural population of insects, the insect life table technique has becoming an important means for the study of quantitative dynamics of pest populations. In foreign countries, the study of the life table of forest pest began in 50 year’s already. Moreover, the results of investigation were applied to the productive practice, such as the spruce budworm (Chorisloneura fumiferana Clemens), winter moth (Opperophlera brumata Linnaeus), while in our country, the quantitative dynamics of many forest pests were not investigated. The larch caterpillar is one of the great pest of larch plantation in China. Every year, the outbreak of this pest occur in some places, causing large economic loss. Many studies were performed on the biological and chemical controls, but the investigation on quantitative dynamics of the natural population of larch caterpillar was lacking. Since 1980, we studied the quantitative dynamics of the natural population of larch caterpillar in Shangzhi County, Heilongjiang Province and worked out life tables of two generations.     

马尾松毛虫预测预报系统的研究*

本文应用系统分析方法总结有关马尾松毛虫的科研成果和实际经验，建立了反映了马尾松毛虫，松林、自然条件与环境状况，人类社会行之间本质关系的结构模型，通过对影响马尾松毛虫种群动态因子的分析，提炼及数量化表示，建立了马尾松志虫时间域及空间域种群动态模型，两者结合可以对松毛虫群种动态进行系统模拟，预测松毛虫的发生量、发生面积及分布状况，以安徽省潜山县黄铺试验区调查数据验证此模型，与松毛虫实际发生规律吻合。     

QUANTITATIVE DYNAMICS OF LARCH CATERPILLAR (DENDRALIMUS SUPERANS [BULLER]) AND THE BIOLOGICAL CONTROL

METHoDSoFlNVESTIGATIONIna24yearso1dlarchp1antation,asampleplotwassetup,inwhichloosam-pletreeswereselected.ThenumberoflarchcaterpillarsoneachsampletreewerecountedperiodicaI1y,whilethesameinves-tigationswerea1sodoneinlarchplanta-tionswithsameecologica1conditionssur-roundingthesamplep1ot.Asacontrol,ac-cordingtothedeve1opmentalprogressandlivinghabitsoflarchcaterpiIIar,thewholegenerationwasdividedintosevendevel0pmentaIstages:egg,firstinstar,thirdinstar(beforeoverwintering),fourthinstar(aft…     

Carbon storage in old-growth and second growth fire-dependent western larch (Larix occidentalis Nutt.) forests of the Inland Northwest,USA

There is limited understanding of the carbon (C) storage capacity and overall ecological structure of old-growth forests of western Montana, leaving little ability to evaluate the role of old-growth forests in regional C cycles and ecosystem level C storage capacity. To investigate the difference in C storage between equivalent stands of contrasting age classes and management histories, we surveyed paired old-growth and second growth western larch (Larix occidentalis Nutt)–Douglas-fir (Pseudostuga menziesii var. glauca) stands in northwestern Montana. The specific objectives of this study were to: (1) estimate ecosystem C of old-growth and second growth western larch stands; (2) compare C storage of paired old-growth–second growth stands; and (3) assess differences in ecosystem function and structure between the two age classes, specifically measuring C associated with mineral soil, forest floor, coarse woody debris (CWD), understory, and overstory, as well as overall structure of vegetation. Stands were surveyed using a modified USFS FIA protocol, focusing on ecological components related to soil, forest floor, and overstory C. All downed wood, forest floor, and soil samples were then analyzed for total C and total nitrogen (N). Total ecosystem C in the old-growth forests was significantly greater than that in second growth forests, storing over 3 times the C. Average total mineral soil C was not significantly different in second growth stands compared to old-growth stands; however, total C of the forest floor was significantly greater in old-growth (23.8 Mg ha⁻¹) compared to second growth stands (4.9 Mg ha⁻¹). Overstory and coarse root biomass held the greatest differences in ecosystem C between the two stand types (old-growth, second growth), with nearly 7 times more C in old-growth trees than trees found on second growth stands (144.2 Mg ha⁻¹ vs. 23.8 Mg ha⁻¹). Total CWD on old-growth stands accounted for almost 19 times more C than CWD found in second growth stands. Soil bulk density was also significantly higher on second growth stands some 30+ years after harvest, demonstrating long-term impacts of harvest on soil. Results suggest ecological components specific to old-growth western larch forests, such as coarse root biomass, large amounts of CWD, and a thick forest floor layer are important contributors to long-term C storage within these ecosystems. This, combined with functional implications of contrasts in C distribution and dynamics, suggest that old-growth western larch/Douglas-fir forests are both functionally and structurally distinctive from their second growth counterparts.     

Functional analysis of vegetation on alpine treeline ecotone in the Julian and Kamnik-Savinja Alps in Slovenia

Our study focused on the functional aspects of plant species and vegetation at the transition from larch (Larix decidua Mill.) forest to mountain pine (Pinus mugo Turra) stands on the alpine treeline ecotone. With increasing elevation, living conditions grow harsher, which is reflected in the plant species and functional trait composition of plant communities. At four different localities in the Slovenian Alps, relevés along an altitudinal gradient and according to vegetation type were made (European larch forests, larch trees-mountain pine shrubs, mountain pine shrubs), using standard Central European phytocoenological method. In the upper mountain pine belt, few differential species were found, since most species represented in mountain pine stands also occurred in the lower two vegetation belts, while there were many differential species in the lower forest belt. Species with considerable competitive ability and moderate stress tolerance dominated the upper treeline ecotone, whereas ruderality is poorly expressed. The importance of stress tolerance in plant strategies increased slightly in the mountain pine belt. Changes in the representation of some functional traits attributes were detected by vegetation belts, but complete species turnover did not occur. Changes in dominant life form involved greater cover of chamaephytes and nanophanerophytes in the upper mountain pine belt. Species with evergreen leaves dominated mountain pine stands and deciduous forest stands. The share of species with scleromorphic leaves increased in the direction of the mountain pine belt while the share of species with mesomorphic and hygromorphic leaves declined. Mountain pine stands create good conditions for the regeneration of tree species and colonisation by ecologically more demanding forest species while species of alpine grasslands withdraw on open areas. Since today’s treeline is lowered due to past human activity, an upward shift is expected. Also, considering the great importance of competition strategy, current conditions in mountain pine stands are favourable for future forest succession.     

大面积治理森林害虫的实践与展望

近20年来,对害虫防治提出了害虫综合治理(IPM)、全部种群治理(TPM)、大面积种群治理(APM)和合理害虫治理(RPM)等策略,这些策略代表了害虫防治领域里各种不同的学说。实践表明,IPM未必是完美无缺、放之四海而皆准的策略;TPM还不是目前多数害虫所宜采取的策略,但很可能是未来的害虫防治策略;APM是IPM和TPM两个防治策略的折衷办法。目前我国大面积治理森林害虫的实践,在一些原则上采用了IPM的做法,而在具体防治方法上又偏重于TPM的技术,基本思路符合APM的对策,RPM是针对APM的不足而改进的策略。     

基于加权信息量模型的油松毛虫灾害发生危险性评价

【目的】充分考虑影响灾害发生及灾害等级的气象、地形地貌等多种因素,实现多因子灾害发生危险性评价和制图,以期为灾前的防控和预警提供依据。【方法】以辽宁省西部的油松人工林为研究区,基于Landsat影像提取油松分布范围,以高程、坡向、坡度、降雨量、活动积温、日照时数、上一年灾害程度和距离上一年重灾区远近8个危险性评价因子,采用层次分析法确定各因子权重,建立加权信息量模型,结合GIS空间分析方法,将油松的受灾危险性划分为5个等级:极低危险区、低危险区、中危险区、高危险区和极高危险区,实现危险区划制图,并与实际灾害程度监测结果对比进行精度验证。【结果】1)根据信息量法原理,信息量值越大代表发生灾害的危险性越大。本文计算得到的各因子类别信息量值均与油松毛虫的生物学特性相吻合。2)研究区2017年虫灾极高和高危险区主要分布在建平县北部,中危险区主要分布在北部部分地区和建平县与凌源市交汇处,其他地区发生虫灾危险性较低,与实际调查结果相吻合。3)最终划分等级中的中低危险区和实际受灾油松失叶率大小对应关系明显,实际成灾油松林地中有90.32%被划分至高危险区和极高危险区。【结论】基于加权信息量模型的油松毛虫灾害发生危险性评价充分考虑了不同评价因子对灾害发生影响程度的差异,得到的风险区划结果较为准确,具有应用价值,可为大区域的森林病虫害危险性评价及风险评估提供技术依据。     

Studies on bionomics and occurrence regulation of Phigalia djakonovi Moltrecht

lntroductionlnrecentyears,PhigaIi8djakOnoViMoltrecht(LepidopterafGeometridae)occurredseriouslyinDaxing'anMount8infOrestareaofInnerMongoIia.Forexample,in1983,theoccurredareaofthispestwasover333oohm2andhundredshectaresofbi,.hfOreststandswaredamagedinthearea.Shu(1987,1988)studiedthelifecycIeandbionomicsofPhigah8djbkOnovI.From1997to1999,wemadefurtherstud-iesonbionomicsandoccurrencereguIationofthepestinYakeshiForestryAdministration,InnerMon-goIia.StudymethodFourfixedsamplepIotswereestabI…     

松树皮象生物学、生态学特性及综合控制对策

为了有效控制松树皮象对河北省塞罕坝林区落叶松、云杉、樟子松的为害，对松树皮象的生物学特性及生态学特性进行了研究。结果表明，在塞罕坝地区松树皮象主要为害落叶松、云杉幼树，1a1代，以老熟幼虫或成虫在地下越冬。调整选林时问以及幼树喷施绿色威雷药剂均可有效控制松树皮象的为害。     

The influence of mountain pine beetle outbreaks and drought on severe wildfires in northwestern Colorado and southern Wyoming: A look at the past century

Outbreaks of bark beetles and drought both lead to concerns about increased fire risk, but the relative importance of these two factors is the subject of much debate. We examined how mountain pine beetle (MPB) outbreaks and drought have contributed to the fire regime of lodgepole pine forests in northwestern Colorado and adjacent areas of southern Wyoming over the past century. We used dendroecological methods to reconstruct the pre-fire history of MPB outbreaks in twenty lodgepole pine stands that had burned between 1939 and 2006 and in 20 nearby lodgepole pine stands that were otherwise similar but that had not burned. Our data represent c. 80% of all large fires that had occurred in lodgepole pine forests in this study area over the past century. We also compared Palmer Drought Severity Index (PDSI) and actual evapotranspiration (AET) values between fire years and non-fire years. Burned stands were no more likely to have been affected by outbreak prior to fires than were nearby unburned stands. However, PDSI and AET values were both lower during fire years than during non-fire years. This work indicates that climate has been more important than outbreaks to the fire regime of lodgepole pine forests in this region over the past century. Indeed, we found no detectable increase in the occurrence of high-severity fires following MPB outbreaks. Dry conditions, rather than changes in fuels associated with outbreaks, appear to be most limiting to the occurrence of severe fires in these forests.     

THE INFLUENCEN OF STAND STATE ON THE OCCURRENCE OF DENDROLIMUS SUPERANS (BUTLER) IN DAXING'AN MOUNTAINS

DendlxilinIIisSIIPeIWlsbrokeoutil1theforestofDaxil1g'anMountainsregio111nl99O.Tlleligl1tandheatydal11agedareaisone111iI-llollhln=Tlledan1agedegreeofD.SItPeIwhlsnoteve11lntheregion.Thestandsdal11agedbyDendIxihnIIissIIPeIunlnsenous'i11ten11ediateandligl1tdegreeaPpearedaspatchshaPedis-tribuholl.Thereaso11thatthedifferentresu1tsaboveapPearedisstandenviro11l11e11tclearly.Therefor,undertl1eco11dihol1oflargeareaweatl1er.Itwasnotclearlythatwhichfactor1sllla1ninthestandenviroIUnent.n1eoccu…     

采伐强度对林分蓄积生长量与更新影响的研究

通过对大兴安岭、小兴安岭和长白山部分林区不同林型的调查，分析了不同采伐强度对林分蓄积生长量和更新效果的影响，并应用统计学原理，对不同采伐强度与林分年平均蓄积生长量和年平均更新株数进行拟合分析，得出不同林型不同采伐强度与林分蓄积年平均生长量和年平均更新株数的相关关系。结果表明：采伐强度与林分年平均蓄积生长量和更新株数间呈抛物线关系。     

金佛山方竹笋用混交林混交树种选择试验

文章试验研究了金佛山方竹纯林、方竹针叶混交林、方竹阔叶混交林在竹林生长及竹笋产量方面的差异。结果表明,方竹混交林能够促进竹林生长,增加竹笋产量,其中,方竹阔叶混交林的效果更加明显。     

红脂大小蠹形态学特征及生物学特性研究

红脂大小蠹又名强大小蠹 (DendroctonusvalensLeConte) ,为国内新纪录种 ,是油松 (PinustabulaeformisCarr.)的毁灭性害虫 ,可导致几十年生的油松在较短期内死亡。越冬虫态以成虫和老熟幼虫为主 ,占 77 5 % ,2～ 3龄幼虫为辅 ,占 2 1 7% ,少数以蛹越冬 ,占 0 8%。其生活史以成虫越冬的 1a 1代 ,以老熟幼虫越冬的需跨年度才能完成 1个世代发育 ,以小幼虫越冬的需 3a完成 2代或 2a完成 1代。在种群密度较低时 ,危害生长衰弱的过火木、新伐倒木及新的伐桩 ,种群密度大时 ,能迅速入侵胸径≥ 10cm、树龄在 2 0a生以上的健康木。在郁闭度较低的油松林分中 ,红脂大小蠹的危害明显高于郁闭度高的林分     

Summer Forest Fire Meteorological Environment in the North of Daxingan Mountains

In recent years, especially in the summer of 2002, the most serious forest fires occurred in the Daxingan Mountain of Heilongjiang province and Inner Mongolia. There has been long time serious forest fire environment in summer in Daxingan Mountain. The grass in the forest is scorched for long time drought and the moisture content of litter and turf layer decrease rapidly. The accumulation and dryness of fuel build the summer forest fire environment, which are major caused by Meteorological environment. Human are lack of the right recognition of summer fires, and can not achieve the goal of detecting and fighting in time. Also summer fires have the tendency to increase in some areas of the world and human have to pay much more attention to how to prevent and control summer fires.     

基于灰色系统理论的森林火灾预测模型研究

依据灰色系统建模的基本理论，在系统分析内蒙古大兴安岭林区森林火灾发生规律的基础上，建立了森林火灾高火险及重灾年景灰色灾变GM（1，1）预测模型。模型模拟检验精度达到Ⅰ水平，发展系数-α小于0.3，可用于该地区森林火灾灾变中长期预测。预测结果显示，2001-2010年间，该林区将出现3个森林火灾高火险年，5个森林火灾重灾年，二者出现的间隔期均为2-3a，平均相对精度达98%以上；预测2007年将是高火险、重灾年份，前者预测精度为98.05%，后者预测精度为99.78%。     

南京紫金山毛竹景观林维护与质量提升

毛竹林是南京紫金山国家森林公园景观的重要组成部分,其健康状况关系着该区域森林景观效益和生态效益的发挥。文章调查分析了紫金山毛竹林的起源、林分结构及经营管理现状,提出了改善毛竹林质量的经营措施,包括：调整竹林结构、混交阔叶树种、生态防治病虫害等生态培育措施,垦复、施肥、劈山除灌、疏伐等退化竹林复壮措施,以及控制竹林扩张、改造荒芜竹林等措施。这些经营措施为紫金山毛竹林的可持续经营提供了技术支撑。     

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.     

Comparison of stand structure and growth between artificial and natural forests of Pinus sylvestiris var, mongolica on sandy land

Mongolian pine (Pinus sylvestiris Linnaeus var. mongolica Litvinov) as a valuable conifer tree species has been broadly introduced to the sandy land areas in “Three North” regions (North, northwest and northeast of China), but many prob-lems occurred in the earliest Mongolian pine plantations in 7hanggutai, 7hangwu County, Liaoning Province (ZZL). In order to clarify the reason, comprehensive investigations were carried out on differences in structure characteristics, growth processes and ecological factors between artificial stands (the first plantation established in ZZL in 1950s) and natural stands (the origin forests of the tree species in Honghuaerji, Inner Mongolia) on sandy land. The results showed that variation of diameter-class distributions in artificial stands and natural stands could be described by Weibull and Normal distribution models, respectively.Chapman-Richards growth model was employed to reconstruct the growth process of Mongolian pine based on the data from field investigation and stem analysis. The ages of maximum of relative growth rate and average growth rate of DBH, height, and volume of planted trees were 11,22 years, 8, 15 years and 35, 59 years earlier than those of natural stand trees, respectively. In respect of the incremental acceleration of volume, the artificial and natural stands reached their maximum values at 14 years and 33 years respectively. The quantitative maturity ages of artificial stands and natural stands were 43 years and 102 years respectively. It was concluded that the life span of the Mongolian pine trees in natural stands was about 60 years longer than those in artificial stands. The differences mentioned above between artificial and natural Mongolian pine forests on sandy land were partially attributed to the drastic variations of ecological conditions such as latitude, temperature, precipitation, evaporation and height above sea level. Human beings‘‘ disturbances and higher density in plantation forest may be ascribed as additional reasons. Those results may be potentially useful for the management and afforestation of Mongolian pine plantations on sandy land in arid and semi-arid areas.