Survey of diseases and insects of Fraser fir and red spruce in the southern Appalachian Mountains

Disease and insect surveys of three Southern Appalachian spruce-fir ecosystems were conducted between 1985–1988. Visual tree decline was correlated with the presence of fungal pathogens and insect pests. Fungi were isolated from tree cankers, necrotic roots and diseased foliage; while insect incidence and impact was assessed visually. With the exception of damage to Fraser fir inflicted by the balsam wooly adelgid, little significant pathology or insect infestation was noted. This survey indicates that major diseases and insect damage, particularly on red spruce, appear not be primarily causal in the observed forest decline.     

Change in forest structure in the boreal montane ecosystem of Mount Mitchell,North Carolina1

Surveys were undertaken on Mt. Mitchell, N. C. (USA) from Spring 1984 through 1987 to determine the extent and rate of decline and mortality of red spruce and Fraser fir ecosystems. Data indicate that regardless of cause and effect mechanisms the physical structure and integrity of the boreal montane forest has greatly deteriorated over the past 4 years. Along ridges, and particularly on west facing aspects greater than 80% of all mature stands are dead. No definitive conclusions can be made concerning etiological agents; however, current hypotheses include biotic factors, climatic abberations, and/or the acute or chronic stress from anthropogenic pollutants.     

Feinstrukturelle Untersuchungen an Nadeln geschädigter Tannen und Fichten aus Waldschadensgebieten im Schwarzwald

Fine structural studies on the needles of damaged fir (Abies alba Mill.) and spruce [Picea abics (L.) Karst.] trees from forest dieback areas in the Black Forest . The fine structural changes in the variously damaged needles of fir and spruce trees from forest dieback areas have been investigated with special reference to cytoplasmie organization in the vascular bundles, mesophyll tissue and cuticle. The results are compared with those available for a few plants affected both by natural and artificial stress factors, especially air pollutants.     

The potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest

With the expected rising temperatures, outbreaks of insect pests may be more frequent, which can have large consequences on forest ecosystems and may therefore negatively affect the forestry sector. In order to be better able to predict where, but not if, outbreaks may occur in future we investigated the potential future (2070) geographical distribution of 30 prospective insect pest species (Coleoptera and Lepidoptera) by applying species distribution modelling. We also assessed the geographical extent to which the boreal forest in Sweden may be affected. We found that numerous species may experience large increases in their potential distribution in future, which may result in outbreaks in “new” areas. It is therefore likely that more trees will be infested by pests in future, which may have large implications for the Swedish forestry sector.     

Growth patterns and sensitivity to climate predict silver fir decline in the Spanish Pyrenees

Patterns in radial growth have often been used to predict forest decline since they are regarded as indicators of the tree responses to long-term stressors. However, the sensitivity of tree growth to climate, as a proxy of the trees’ adaptive capacity to short-term climatic stress, has received less attention. Here, we used retrospective tree-ring analyses to determine whether growth patterns and sensitivity to climate are related to Abies alba (silver fir) decline in the Spanish Pyrenees. We used regional climatic data to calculate normalised temperatures and drought indexes. Basal-area increment (BAI) was measured for declining (defoliation >50%) and non-declining (defoliation <50%) silver firs in four stands with contrasting decline levels. A dynamic factor analysis (DFA) was applied to test the hypothesis that declining and non-declining trees have experienced different long-term growth trends. Growth sensitivity to climate was computed as the average change in BAI per unit of change in a given climate variable. Declining trees showed a negative growth trend during the last 20?years. Trees with lower relative BAI and negative BAI trends showed stronger growth sensitivity to climate and higher defoliation than trees with the opposite characteristics. Our findings underscore the idea that long-term climatic warming seems to be a major driving factor of growth decline in Pyrenean silver fir forests. Ongoing growth reduction and enhanced growth sensitivity to climate may promote vegetation shifts in these declining forests located near the xeric edge of the species distribution area.     

Synergistic effects of past historical logging and drought on the decline of Pyrenean silver fir forests

The causal factors and effects of forest declines are not well understood in temperate conifer forests. Most studies have focused on climatic and environmental stressors and have obviated the potential role of historical forest management as a predisposing factor of decline. Here, we assess if the recent silver fir (Abies alba) decline observed in the Spanish Pyrenees was predisposed by historical logging and incited by warming-induced drought stress. We analysed a dataset of environmental, structural, and historical variables at the tree and stand level including 32 sites with contrasting degrees of defoliation distributed over 5600 km². We followed a dendroecological approach to reconstruct historical logging and to infer the effects of warming-induced drought stress on growth. The silver fir decline was more severe and widespread in western low-elevation mixed forests dominated by trees of small size and slow growth. These sites were subject to higher water deficits than eastern sites, where late-summer rainfall as the key climatic variable controlling silver fir growth was higher. Declining sites showed more frequent growth releases induced by historical logging than non-declining sites. Historical logging and warming-induced drought acted as long-term predisposing and short-term inciting factors of silver fir decline in the Pyrenees, respectively. We suggest that biomass increases caused by past intense logging affected the vulnerability of silver fir against late-summer water deficit. Future research in declining temperate conifer forests should consider the interacting role of predisposing historical management and inducing climatic stressors such as droughts.     

Changing patterns in insect pests on trees in The Netherlands since 1946 in relation to human induced habitat changes and climate factors—An analysis of historical data

In The Netherlands, insect pests on trees and shrubs are being monitored continuously since 1946. During these years, almost all insect pest populations showed marked changes, which may be the result of changes in forest management, shifts in forest composition, climate change and the arrival of new pests from the Mediterranean region or from other continents. In order to generate hypothesis about possible relationships between species ecology and environmental factors, we have analyzed 61 years of population development of the 98 most abundant species in the database while paying attention to life history traits and preferred host plants. The 22 species with infestations lasting a few years only were excluded from the analysis. Of the remaining 76 species, 18 were present over the entire observation period of 61 years. Of the other species, 27 showed a decline and 31 showed an increase. On coniferous trees most species showed decreasing populations. Increasing populations were found most on deciduous trees. Not directly climate-related factors such as changes in forest age, tree composition and forest management were identified as the most important causes for the fluctuations in pest insect populations. Climate change is a possible driver of the population increase in Thaumetopoea processionea, Haematoloma dorsatum and of the population decrease in Euproctis chrysorrhoea. The recently increasing exotic species Eupulvinaria hydrangeae and Pulvinaria regalis were exclusively found on trees in cities, presumably in relation to the higher temperatures of the urban habitat.     

Response of arthropod biodiversity to foundation species declines: The case of the eastern hemlock

Widespread declines of foundation species, such as many corals, kelps, and overstory trees, are of grave concern because, by definition, these species create and maintain habitat that supports other species. Nevertheless, past responses to their declines, many of which were caused by invasive species, have been late and ineffective, underscoring the need to predict changes in biodiversity and ecosystem function associated with species invasions and foundation species losses. One predictive, but under-used, approach is to compare the species and functions associated with the afflicted foundation species to its projected replacement communities. The taxa associated with the foundation species and subsequent successional stages would be expected to decline and increase, respectively. We used this approach to generate hypotheses for how arthropod diversity might change in response to extensive losses of eastern hemlock trees caused by the invasive, hemlock woolly adelgid (insect: Hemiptera, Adelgidae). Our all-strata survey of the arthropods in an eastern hemlock forest and its expected replacement climax community in the mid-Atlantic region of the United States, mixed hardwood forest, suggests that eastern hemlock losses might initiate increases in arthropod abundance, alpha diversity, and 23 arthropod taxa, might produce no change in evenness or composition of arthropod functional groups, but might trigger decreases in beta diversity and seven hemlock indicator taxa. These predictions are consistent with observed trends in arthropod responses to hemlock losses in other studies, and thus might be useful for targeting early monitoring, management, and conservation efforts. This research is exploratory, however, and tests of these predictions across larger spatial scales will be necessary to determine the generality of the findings.     

近10年我国林木抗虫性研究概述

过去10年里,为了有效地解决我国人工林大范围严重的害虫危害,人们对林木的抗虫性问题,从概念、分类分级方法,到林木抗虫机制、抗虫力与耐害力、个体抗性与群体（林分）抗性等各个方面,进行了大量的研究,取得了许多成果。文中对此进行了分类整理,同时对一些相关概念做了初步的界定。     

森林病虫害发生与生态环境变化

文章论述了我国森林病虫害发生的情况及分析了发生的原因,并对森林病虫害的发生与生态环境变化之间的相互关系进行了分析,提出森林病虫害的发生与生态环境这两者之间是相辅相成、互相影响的。     

Long-term growth trends of red spruce and fraser fir at Mt. Rogers,Virginia and Mt. Mitchell,North Carolina

Cross-sectional area growth and height growth of Fraser fir and red spruce trees growing in Virginia and North Carolina were analyzed to identify possible long-term growth trends. Cross-sectional area growth provided no evidence of growth decline. The individual discs were classified according to parameter estimates of the growth trend equation. The predominant pattern of growth was a steady increase followed by fluctuation about a horizontal line. Other cross-sections exhibited a steady increase throughout the series. The only discs that represent declining growth patterns were from trees in subordinate crown position or which had previous top damage. No unexplained growth decline was present in any disc. The results regarding height growth were uncertain. A slight decline in height growth was present although we suggest that this observation was due to problems with the data or the model used to fit height growth. These findings contradict other studies suggesting that a recent growth decline has occurred in red spruce in the southern Appalachians.     

特大雨雪冰冻天气对林业有害生物的影响及防控对策

本文使用线路踏查和样地调查相结合的研究方法,研究了雨雪冰冻天气对林木寄主植物、林业有害生物的影响,并讨论了应对因灾而引起的次生性林业有害生物的预防性措施。结果表明雨雪冰冻天气对林木寄主植物造成了严重机械损伤,同时还产生了严重的生理性冻害,为后期次生性林业有害生物的发生埋下了隐患;对林业有害生物的直接影响是“双刃剑”效应：一方面,对各种以相对裸露方式生存的有害生物的发生是极其不利,另一方面,对弱寄生侵染性病害和大多数以隐蔽方式生存的害虫的发生是十分有利的,间接影响是造成次生性林业有害生物的发生量增加．发生种类增多,并随雨雪冰冻天气受灾程度的增强而逐渐增多。     

浅谈园林绿化树木病虫害的防治

文章分析了城市园林绿化树木病虫害发生的主要原因,提出了以生态学为基础,充分考虑园林绿化树木、病虫害及天敌三者之间的关系,以农业防治为主,从而控制有害生物,以保护园林绿化树木。     

尤溪世行项目幼林主要病虫害调查及发生原因分析

通过病虫害普查，初步摸清尤溪县世行项目林主要病虫种类有１５种，其中杉木缩顶病、杉木炭疽病、马尾松赤枯病及微红梢斑螟为害最为严重。病虫的发生与森林结构、立地条件、林分状况、森林采伐和苗木带病等因子有关。     

福建省速生丰产林病虫害发生现状及其治理策略

概述了福建省速生丰产林主要病虫害发生种类、危害情况,分析了病虫害发生的严重形势及发生原因,据此提出了病虫害可持续治理策略,为速生丰产林发展提供依据。     

高大林木病虫害防治技术研究进展*

在分析国内外高大林木病虫害防治技术与设备的基础上 ,研究了开发多元化高大林木病虫害防治技术及设备的设计思路 ,并提出了高新技术应用于高大林木病虫害防治技术的建议与解决方案。     

黄河三角洲盐碱地林木衰退原因及对策

林木衰退是黄河三角洲盐碱地防护林生态功能退化甚至逐步丧失的主要原因.文中在调研黄河三角洲土壤盐分时空变异特征的基础上,分析该区域土壤盐分反复表聚、树种选择适应性不强、栽培技术针对性不够、抚育管理缺位及干旱和病虫害等因素对林木生长的影响,明确了引起黄河三角洲盐碱地林木衰退的原因,并提出解决林木衰退问题的对策:1)因地制宜...     

Tree spatial patterns of Abies alba and Fagus sylvatica in the Western Carpathians over 30 years

The decline of Abies alba (fir) in natural fir–beech forests in Europe has fascinated scientists for over a century. During this period, Fagus sylvatica (beech) became the dominant species in this forest type. We hypothesised that (1) the success of beech over fir is significantly connected with the fact that beech suffers less than fir from the presence of conspecific neighbours; that (2) shade tolerance is not a factor which favours beech over fir; and that (3) this is due to a significantly reduced proportion of litter treethrow mounds with suitable conditions for the successful regeneration of fir. We investigated these hypotheses by means of tree spatial pattern analysis. Eight rectangular plots (2–8 ha) were analysed in mountain fir–beech forests of the Outer Western Carpathians, Czech Republic. Various types of the pair correlation function and L function were used to describe the tree density variability of trees with DBH ≥10 cm. The analyses were carried out on datasets from the 1970s, 1990s and 2000s. Our results suggest that negative density dependence is not responsible for the current decline of fir. It seems that a higher shade tolerance of the advanced regeneration could be one of the factors which favour beech over fir. It is evident that fir trees have a markedly stronger positive association to mounds than beech trees.     

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.