Canopy dynamics in unlogged and logged forest stands in the eastern Amazon

Selective logging of tropical forests damages residual trees and creates canopy openings throughout the stand. In the Amazon, reduced-impact logging results in significantly less damage than conventional unplanned logging; yet either logging method leads to substantial fragmentation of the forest canopy. Increased mortality rates of trees damaged in logging have been documented. In this paper, we investigate the effect of logging disturbance on treefall rates.Using repeat inventories of canopy trees (≥35 cm dbh) in six large (≥50-ha) forest stands at two sites in the eastern Amazon, we measured mortality rates in three treatment classes: unlogged, conventionally logged (CL) and logged using reduced-impact methods (RIL). At least 3000 trees were mapped and inventoried per stand prior to timber harvests. In the second inventory, 3 years after harvests in the logged stands, all trees were located and scored as living, standing dead, uprooted or broken.We found significantly higher overall mortality rates for trees in logged forest (both CL and RIL stands) than in adjacent unlogged forest. This effect was largely due to higher rates of treefall (i.e., stems uprooted or broken from natural causes). Moreover, significantly higher treefall rates were recorded for trees in logged forest that were not damaged in the logging than for trees in unlogged stands. Treefall rates were nearly twice as high in conventionally logged forest as in forest logged using reduced-impact methods. We found indirect support for the hypothesis that increased treefall rates in logged forest are related to increased canopy opening and fragmentation through analysis of the locations of fallen trees in relation to canopy disturbance.     

Simulating responses of Northeastern China forests to potential climate change

IntroductionItissurethatpresentelevatiollsofCO2a11dotllergrcc11-housegasesinducedbyhumanactivitiesaren1akli1gglobalclimategothroughinexperielICedcl1anges(Scl1le-subgerl987).Thecurrentquasi-equilibriulllstatesofbio-sphereecosystCm,esPeciallyterrestrialecosystems,wouldbebrokenbecausetl1estructure,fu11ction,distributio11andtlledynamicsofanyexistedecosystemsareIberesultsoflongtermadaptationofbio-systemtocurrentclin1ate.Theec()systemsdistributedinhighlatitlldeareawouldhavemuchbiggerchai1ge(Bona…     

天水市国有林区森林资源变化分析

通过对天水市1979、1989和1996年进行的3次森林资源调查结果的分析，掌握和了解该地区森林资源现状和消长规律，以及造成林分、经济林、森林覆盖率等下降的原因，并据此提出了保护森林生态系统、提高林分质量的措施和对策，对实施天然林保护、恢复和重建天水主森林生态环境具有指导意义。     

美国白蛾卵块及幼虫网幕空间格局研究

在美国白蛾发生区，分别在行道树和林地中对美国白蛾卵块及幼虫网幕的空间格局进行了研究。结果表明，美国白蛾卵块及幼虫网幕的空间格局为负二项分布型，呈聚集分布。对其空间分布型指数进行的计算也表明，美国白蛾卵块及幼虫网幕在行道树上和林地中均为聚集分布。在此基础上，分别计算出了行道树和林地中的卵块及幼虫网幕在不同虫口密度时的理论抽样数，为防治时调查美国白蛾数量，进而确定释放天敌的数量提供了依据。     

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)     

美国白蛾新天敌—蠋敌捕食能力的初步观察

首次报道美国白蛾Hyphantria cunea(Drury)的一种捕食性天敌——蠋敌Arma chinensis(Fallou),简述了蠋敌的生物学特性。在商河县,蠋敌在美国白蛾幼虫网幕枝中的分布率为2.33%～17.86%;记述了蠋敌的捕食习性和规律,经室内饲养,统计出各龄若虫和成虫的捕食量,从若虫到成虫,最大捕食量为2头3龄、7头4龄、5头5龄、23头6龄共37头白蛾幼虫;最小取食量为4头2龄、8头3龄、1头4龄、1头5龄、2头6龄共16头白蛾幼虫;分析并指出蠋敌对美国白蛾具有较强的控制能力,是自然界中影响美国白蛾种群密度的重要因子。     

星天牛行为及控制技术研究Ⅰ.天牛行为及危害木麻黄规律的研究

通过野外调查和室内外人工饲养,结果表明星天牛[Anoplophorachinensis(Forster)]成虫大多在白天活动,在自然条件下有趋向木麻黄防护林带飞翔的行为。雌、雄成虫一生可多次交尾,每天8时和16时为交尾高峰。成虫补充营养最喜欢取食苦楝树(MeliaazedarachL.)。苦楝树饲养雌虫每头产卵156～198粒,平均176 4粒,是木麻黄饲养的3 10倍;取食苦楝树的雌虫寿命72～110d,平均91 8d;雄虫寿命88～125d,平均103d,雌、雄成虫分别比取食木麻黄(Casuarinaequi setifolia)的多存活30 2d、40d。幼虫主要集中在离地面40cm高度内的树干根际附近,占总虫数的94 8%。1年生林分受害株至第2年5月成虫羽化期死亡率最高,达66 7%,3～7年生林分有虫株率最高;7年生以下林分应重点防治。在生境条件相似的同龄林中,星天牛则喜欢危害基径较大的木麻黄,6cm以下的树则较少受害。     

Forest management and forest state in southern Sweden before and after the impact of storm Gudrun in the winter of 2005

About three times the annual cut in southern Sweden (Götaland) was damaged by the storm Gudrun in January 2005, i.e. almost as much as the normal annual cut for all of Sweden. To establish any differences in forest management and state before and after the storm, measures such as growing stock volume, age-class distribution, and species composition were analyzed within the damaged area. As a reference the situation before and after the storm within the area in Götaland not damaged by the storm was also analyzed. For all analyses, sample plots from the Swedish National Forest Inventory were used. Results based on mean values for the years 2000–2004/2005–2009 showed that the total growing stock for the damaged area decreased by approximately 30 million m³ after the storm. This was mainly caused by a decrease in Norway spruce (Picea abies (L.) H. Karst). Annual growth for pine, spruce, and deciduous trees decreased by 1.8 million m³ in the damaged area. This mainly included stands already thinned and not, as expected, in the stands ready for final felling. Also, the proportional area within each of the age classes 21–40, 41–60, and 61–80 years decreased. The storm led to an increased area in immediate need of precommercial thinning. No changes in choice of species when regenerating could be observed. Furthermore, only marginal adaptation by forest owners to future risk of wind throw could be detected.     

Management Strategies and Research Orientations of Forest Diseases and Pests in China

Forest diseases and pests are perceived as a growing hazard to China economy. It is a common conclusion that the actualities of forest pests in china are no effective measures to the old important pests, some secondary pests are ascending to chief pests, increasing devastation from exotic pests, frequent ecological pest eruption induced by environmental detriment and host-leading diseases to threaten the "Western Development Project "in China, which is the most important economical strategy to China; that inducement of current forest pests results from ecological function loss and dangerous exoticpest intruding, On the basis of these cognitions, we suggest that strategies of management pests to natural forest would be stressed to maintain its innate capacities to adjust pests in virgin forest and resume such function in intermpted one, that to artificial forest would establish self-control in afforestated stands and develop resistant tree varieties and species, especially those in landscape trees. In re     

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。     

山核桃新害虫深褐拟叶螽的危害及防治

首次报道深褐拟叶螽在山核桃上的危害。2007—2010年,对危害山核桃的深褐拟叶螽进行野外调查并定株观察,同时开展防治试验。深褐拟叶螽严重危害的林分被害率高达100%,被害次年基部以上枝干死亡的林木达95%,被害3年后整株死亡率达到25%,严重影响山核桃幼林生长。通过使用冬季刻杀卵、伐除林缘算盘子,以及在5月中旬、7月中旬各使用1次3%高效氯氰菊酯微囊悬浮剂等措施进行综合防治,当年冬季该虫有虫株率下降为8%,平均每株卵量下降为4.5粒,次年林分基本恢复正常,完全控制该虫危害。     

Optimal management of a flammable multi-stand forest for timber production and maintenance of nesting sites for wildlife

Decline of cavity-using wildlife species is a major forest management issue. One of the causes of this problem is the loss in cavity tree abundance, resulting from short rotation silviculture, stand-replacing disturbance events and timber harvesting in disturbed stands. Cavity tree availability cannot be guaranteed due to the stochastic nature of disturbance events. We developed a Markov model to predict future cavity tree availability under alternative tree felling and fire protection strategies using information on cavity tree dynamics and fire history. Stochastic dynamic programming was used to find a strategy that maximizes timber revenues less forest management costs, including the cost of an artificial nest-box program that must be implemented whenever cavity trees become critically scarce. The requirement to implement a nest-box program in such circumstances strongly influenced the optimal tree felling strategy and resulted in a higher probability of having cavity trees in the future. This reflected an increase in the retention of old growth forest and stands with fire-killed cavity trees as well as stands of younger trees to provide a future source of cavities. These results demonstrate the need to consider the costs of artificial habitat enhancement and the risk of future cavity tree scarcity in multiple-use forest management planning.     

Forest self-regeneration following clear-felling of dieback-affected Fraxinus excelsior: focus on ash

Due to the dieback caused by invasive fungus Hymenoscyphus pseudoalbidus, ash is threatened in many regions of Europe. In order to predict the situation with ash ecosystems, it is important to examine forest regeneration in areas formerly dominated by ash with long disease history and known management. The main aim of the present study was, therefore, to evaluate forest self-regeneration following clear-felling of ash dieback-devastated stands, focusing on ash. In Lithuania, during 2011, a forest regeneration inventory was performed on twenty clear-cuts, initially dominated by stands of ash, but severely damaged by the dieback caused by H. pseudoalbidus and clear-felled 1–10 years previously. In subsequent forest regeneration, grey alder and birch dominated. Ash regeneration was scarce, and its proportion decreased from 40–100 % in pre-dieback stands to 0–21 % in current stands. Of all observed ash trees (n = 775), 53.9 % were diseased, 16.8 % were dead, and only 29.3 % were visually healthy. Moreover, ash was among the slowest growing species, while grey alder, aspen and birch were the fastest. The regeneration and health condition of ash in forests, where previous to the dieback ash was dominant, demonstrated a sharp decrease in occurrence of this species and a clear shift in species composition towards grey alder and birch.     

Relationship between presence of basidiomes,above‐ground symptoms and root infection by Collybia fusipes in oaks

Collybia fusipes is a common cause of root rot on oak in the north of France. Collybia fusipes basidiomes can be as frequent on oaks in stands where no decline of the trees occurs compared with stands where the decline is chronic. This might be explained by differences in the amount of roots damaged by the parasite. To test that hypothesis, 430 oak trees, Quercus petraea, Quercus robur and Quercus rubra, located in six forests were selected. Half of them showed C. fusipes basidiomes at the trunk base. The association between presence of basidiomes and decline of affected trees depended on the forest. The level of infection of each tree by C. fusipes, as well as the crown appearance, the tree height : diameter at breast height ratio, age and sapwood width were determined. The presence of C. fusipes basidiomes was always associated with significant root infections. The crowns of the trees deteriorated with increasing level of root infection and the decline was severe only when the root damage was heavy. Although the decline of trees that were heavily damaged by C. fusipes was severe in some of the stands, in others, it was only mild, and so the differences in tree decline between the stands could not be attributed solely to differences in root infection severity. Trees damaged by C. fusipes seemed not to be subjected to more competition than their undamaged neighbour as reflected by a similar tree height: diameter at breast height ratio.     

应用地理信息系统进行林木空间模拟分析

把地理信息系统方法引入林分空间结构研究中，对具体指定林分(硬阔叶林和白桦林)的林木空间分布进行模拟分析，获得它们分化度、混交度、聚集度、不同树种潜在生长空间，为研究该区域的森林生态系统修复和空间结构优化决策提供基本信息，为森林经营技术的发展提供有效的支持。     

Dynamic response of tree growth to changing environmental pollution

Long-term investigations of Scots pine (Pinus sylvestris L.) growth were carried out in the vicinity of one of the biggest air pollution sources in Lithuania—mineral fertilizers plant “Achema.” It is detected that initial stages of the dynamic tree response to the external stress factors in the polluted environment with an increased quantity of nitrogen compounds have started with a stimulation stage, followed by a gradual transition to a depression of growth. The recovery of the damaged stands took place along with the reduced environmental pollution, and the overdraft of the “normal” annual increment was a characteristic feature of all the investigated stands. This phase is still continuing for the most damaged stands. A very high individual variability of the tree growth response to the environmental impact is a characteristic feature of the damaged Scots pine stands. The homeostatic mechanisms of the survived trees stipulated reaching approximately the same or even higher growth rate as prior to the depression period, and the tree growth rate before the depression period can serve as the most powerful predictor of tree growth recovery capacity under the reduced environmental pollution. Crown defoliation is the next most important predictor of individual tree recovery capacity. Lower stand density and lower competition cause higher recovery capacity of damaged trees. The conclusion is made that a reduction in the environmental pollution on the local and regional scale and especially a decrease in emissions and deposition of sulfur and nitrogen compounds caused the recovery of damaged forests. These trends should be taken into account while analyzing and modeling forest dynamics. Interaction of environmental pollution and climatic factors is very important for the response of tree growth to the environmental stressors.     

Why do trees decline or dieback after a strong wind? Water status of Hinoki cypress standing after a typhoon

We examined the water status of Hinoki cypress, Chamaecyparis obtusa (Siebold & Zucc.) Endl., trees after a severe typhoon to determine possible causes of the decline and dieback that can occur in what appear, at first, to be healthy trees in typhoon-damaged forest stands. We found that in apparently healthy trees in a storm-damaged stand, the water conducting area of the trunk cross section was greatly reduced compared with that of similarly sized trees in a nearby undamaged stand. Although leaf specific hydraulic resistance (Wl) from soil to leaf and from trunk to leaf was higher in trees from the storm-damaged than the undamaged stand, Wl values from soil to root were similar. Diurnal patterns in the rates of change in trunk diameter differed between trees in the damaged and the undamaged stand. We conclude that increased aboveground hydraulic resistance caused by a reduction in trunk water conducting area could be a major reason for the decline and dieback of apparently healthy trees in typhoon-damaged stands.     

美国白蛾的发生特点及防控措施

美国白蛾（Hlyphantria cunea（Drury））是一种对林木、农作物为害严重的害虫。本文针对滦县美国白蛾为害,从其生物学特性、为害特点等方面对美国白蛾现状进行简要分析,提出有效的预防、防治措施,以期对美国白蛾防治起到指导性的作用。     

Individual-level analysis of damage to residual trees after single-tree selection harvesting in northern Japanese mixedwood stands

Quantifying tree damage and mortality caused by single-tree selection harvesting is critical to understanding postharvest forest dynamics and management. In this study, we quantified the effects of tree size and species and the distance from residual trees to felled trees and skid trails on damage to residual trees and mortality in mixed coniferous–broadleaved stands of Hokkaido, northern Japan. Among the 4,961 trees that we studied, 373 (7.5 %) were damaged, and 148 of these trees (3.0 %) died during or immediately after logging. Hierarchical Bayesian modeling showed that the risk of damage to residual trees increased with increasing size of the felled trees and with increasing proximity to felled trees and skid trails. Smaller residual trees had the greatest risk of damage. Species differed in their susceptibility to damage; Abies sachalinensis (Fr. Schm.) Masters and Picea jezoensis (Sieb. et Zucc.) Carr. were the most susceptible species in our sample plots. Smaller damaged trees had the highest risk of mortality. The damaged trees that did not die at the time of logging had a higher risk of postharvest mortality than undamaged trees. Our results indicate that, to minimize logging-induced damage and mortality: (1) the spatial arrangement of skid trails should be optimized and fixed, (2) the risk of skidding damage should be considered before marking the trees to be harvested and choosing the felling direction, and (3) logging operators should be instructed to avoid damaging small trees, especially those of the species that are most susceptible to damage.     

青钱柳红豆杉混交造林技术试验

进行了青钱柳红豆杉混交林、纯林造林技术试验。经过3年经营管理,对林木生长量进行了调查,幼林林木生长良好。结果显示:青钱柳红豆杉混交林幼林林木生长量,比青钱柳、红豆杉纯林幼林林木树高大于2.89%、29.66%,平均胸径粗于17.07%、23.08%,平均树冠宽于6.02%、19.72%。