土壤营养元素对杉阔混交林杉木及其伴生树种优势度的影响

不同资源维度对杉阔混交林中主要建群种的功能地位产生较大的影响 ,同一资源维度不同资源位对杉阔混交林中主要建群种的功能地位也产生较大的影响。可以根据不同树种在不同资源维度不同资源位中的功能地位 ,选择杉木适宜的伴生树种。     

Assessment of technologies and dogs for detecting insect pests in timber and forest products

Abstract

Lack of accurate tools for detecting insect infestation in timber remains a big challenge for pest management authorities. Seven non-destructive insect detection technologies were used to assess their effectiveness in detecting insect borers and termites in timber samples. These technologies were: Termatrac®; Tramex Moisture tester; Acoustic Emission Device (AED-200L®); X-ray, thermal imaging camera; a termite detector dog; and trained quarantine inspectors using standard visual inspection (VI). The timber samples of Acacia parramattensis and Acacia decurrens used for the trial were naturally infested timber branches; timber blocks inoculated with lyctine beetles; timber blocks naturally infested with termites; and un-infested controls. All timber samples used were destructively sampled at the end of the trial to confirm the presence or absence of insects. The detector dog was 100% effective in detecting natural infested termite colonies but was totally ineffective in detecting termites on artificially inoculated timber blocks. The moisture metre and the thermal image camera were 100% effective in detecting large termite colonies but ineffective in detecting other insects in dry timber samples. The effectiveness of other methods of detecting insects or termites varied considerably. The AED was 79% effective, Termatrac 70%, X-ray 40% and VI 35%. Implications of these findings for quarantine and inspection purposes are discussed.     

Potential effects of climate change on insect herbivores in European forests—General aspects and the pine processionary moth as specific example

The nature of “climate change” will differ with geographical regions and its final impact on ecosystems vary with the extent of temperature increase, changes in irradiance and levels of UVB, amount and patterns of precipitation and humidity, and alterations in the incidence and nature of abiotic disturbances. Despite many uncertainties, there is consensus in the fact that global warming already has and will have impact on the temporal and spatial dynamics of insect herbivores. Ectothermic organisms are affected by the changes in environmental conditions directly in dispersal, reproduction, development and mortality, and indirectly through altered plant nutritional quality, resistance and via community interactions. Ambiguous consequences are to be expected depending on the individual host plant and herbivore species, probably involving altered incidence and intensity of pest outbreaks and changes in distributional ranges. Regions that represent northern or upper limits of occurrence, such as the Alps or the boreal zone, are likely to be affected most by an increase in stability and population density of certain pest species, such as defoliating insects or bark beetles. At the same time, temperature increase and drought will render areas of distribution in southern and continental parts of Europe less suitable for heat susceptible species, which will probably not only result in northwards shifts, but range contractions. The review is based on chapters of the “Study on impacts of climate change on European forests and options for adaptation” led by the European Forest Institute (Efi) and on results of the EU project “PROMOTH - Global change and pine processionary moth: a new challenge for integrated pest management”. Thaumetopoea pityocampa serves as illustrative example for insect herbivores whose latitudinal and altitudinal distribution is mainly controlled by temperature and already modified by global warming.     

林木病虫害化学防治中的农药污染与综合治理对策

该文探讨了施用农药防治林木病虫害对林木、人畜和环境的影响，污染现状和原因，以及林木病害的特点，提出了防治林木病虫害和减少农药污染的综合治理对策。     

Short-term effects of a nun moth suppression programme (Lymantria monacha), (Lepidoptera: Lymantriidae) on epigeic non-target arthropods

The short-term responses of non-target soil arthropods to insecticides (Nomolt: Teflubenzuron, Karate: lambda-Cyhalothrin) applied against the nun moth (Lymantria monacha L.) were investigated in 2003. This phytophagous pest infested 30–40-year-old monocultures of Scots pine (Pinus sylvestris L.) located at an active military training area in northeast Saxony (Germany). According to the non-target epigeic arthropods, extinction of a higher systematic taxon (family, order) was not observed. Activity densities of soil macroarthropods were lower on plots treated with Karate, while those of necrophagous ground beetles increased considerably. Nomolt revealed no distinct impact on soil invertebrate density. Statistical analysis did not prove any consistent insecticidal effects on non-target arthropods. Adjacent open-heathland arthropods were not affected by a possible drift of the agents.     

A soil seed bank in a mature conifer plantation and establishment of seedlings after clear-cutting in southwest Japan

Compositions and spatial distribution patterns of buried viable seeds, and demographic transition from buried viable seeds to seedlings after clear-cutting were examined in a 75-year-old conifer plantation in southwest Japan. A part of the plantation was cleared in December 1997 and study plots were set up on a cleared site and a preserved site. Soil samples (a total of 105 l for the preserved plot and 90 l for the cleared plot) were collected from surface soils in spring 1998 and were incubated in a greenhouse for 120 days. There were an estimated 1064 buried viable seeds per square meter from 67 species in the preserved plot and 1754 seeds/m² from 53 species in the cleared plot. The soil seed bank was from mostly low density species with some high density species, and contained many pioneer species that were absent in the floor vegetation. Buried viable seeds were clumped together, especially in gravity-dispersal species. Although plenty of buried viable seeds were pooled in the soil, few seedlings emerged on the forest floor. In contrast, a number of seedlings, including many pioneer species, emerged in the cleared plots, showing a positive correlation between seed weight and germination rate. It is assumed that dominance of the seedlings established after clear-cutting depends on germination rates and/or growth rates of the seedlings rather than the initial density of buried viable seeds. These results suggest strong contribution of the soil seed bank to the establishment of the secondary vegetation after disturbance in a mature conifer plantation.     

Leakage of forest harvest changes in a small open economy: case Norway

The effect of changes in roundwood harvests in Norway on the harvests in rest of the world is examined using a global forest sector model. About 60–100% of the harvest change in Norway is offset by an opposite change in the rest of the world. Such leakage rates vary over time, wood category, background scenario, and the size of the harvest change. Asymmetries between the effects of increasing and decreasing the harvests also exist. Hence, the magnitude of leakage rate is case specific, though considerable. Under tightening wood supply there is less need/room to respond to harvest increase/decrease in Norway with incremental/reduced harvests elsewhere. When the use of global forest resources intensifies with increasing wood demand in the future, leakage rates can be smaller than today. It is important to account for harvest leakage in order to avoid overestimating the climate benefits of policies that decrease or increase roundwood harvests. For instance, for full carbon sequestration benefits of increasing harvests for harvested wood products, creating fresh additional demand for these products should be prioritized. Else the origin of raw material and the place of production for these products may change instead of their stock.     

汕头市城市绿地土壤调查

通过对市区主要绿地进行地下水位及土壤理化性状的调查,结果表明:本市常年地下水位偏高,平均雨季(0.83m)高于旱季(1.20m),越近海受大潮期的影响越大;土壤容重高于正常值0.12~0.42g/cm3,总孔隙度比正常值低近10%;土壤的pH值以微酸性为主,有机质含量极低。对本市园林土壤的主要特征有了较明确的了解,确定了土壤地下水位是影响绿化树种抗风性能的主要外因。       

Using multitemporal satellite imagery to characterize forest wildlife habitat: The case of ruffed grouse

Like many similar forest species, ruffed grouse (Bonasa umbellus; hereafter grouse) populations in the central and southern Appalachians (CSA) are strongly affected by forest composition at the landscape scale. Because these populations are in decline, managers require accurate forest maps to understand how stand level characteristics affect the survival and reproductive potentials of individual birds to design management strategies that improve grouse abundance. However, traditional mapping techniques are often labor-intensive and cost-prohibitive. We used a normalized difference vegetation index (NDVI) from each of 8 Landsat images and the digital elevation model (DEM)-derived variables of elevation and aspect in discriminant analyses to classify 7 study areas to 3 overstory classes (evergreen, hardwoods, and oak) and distinguish evergreen and deciduous understories in the CSA, 2000–2002. Overall accuracy was 82.08%, varying from 83.59% for oak to 79.79% for hardwoods overstories. Periods with large phenological differences among classes, particularly early and late spring, were most useful for discriminating overstory vegetation types. Alternatively, winter NDVI in combination with elevation was critical for differentiating evergreen and deciduous understories. Multitemporal image sets used in concert with DEMs provided a cost-effective alternative to hyperspectral sensors for improving wildlife habitat classification accuracy with Landsat imagery. This allowed for enhanced understanding of grouse-habitat relationships and habitat affects on grouse populations that allowed for improved management. With the incorporation of simple adjustments for local forest plant species phenology into the model, it may be used to better classify wildlife habitat of similar species in areas with comparable forest communities and topography. Multitemporal images can also be used to differentiate grassland communities, monitor wetlands, and serve as baseline data for detecting changes in land use over longer temporal scales, making their use in forest wildlife habitat studies cost-justifiable.     

Comparison of statistical tests for habitat associations in tropical forests: A case study of sympatric dipterocarp trees in a Bornean forest

Habitat difference is an important mechanism for maintenance of tree diversity in tropical forests. The first step in studies of habitat difference is to statistically analyze whether the spatial distributions of tree populations are skewed to species-specific habitats; this is called a habitat association test. We propose a novel habitat association test on the basis of the probability of tree occurrence along a continuous habitat variable. The test uses torus shift simulations to obtain a statistical significance level. We applied this test to 55 common dipterocarp species in a 52-ha plot of a Bornean forest to assess habitat associations along an elevation gradient. The results were compared to those of three existing habitat association tests using the same torus shift simulations. The results were considerably different from one another. In particular, the results of two existing tests using discrete habitat variables varied with differences in habitat definitions, specifically, differences in elevation break points, and the number of habitat classes. Thus, definitions of habitats must be taken into account when habitat association tests with discrete habitat variables are used. Analyses of artificial populations independent of habitat showed that all of the tests used were robust with respect to spatial autocorrelation in tree distributions, although one existing test had a higher risk of Type I errors, probably due to the use of multiple tests of significance. Power analysis of artificial populations in which distributions were skewed to certain elevations showed that the novel test had comparable statistical power to the most powerful existing test. Statistical power was affected not by the total number of a given tree but by the number of clumps in a plot, suggesting that >5 clumps were required for a reliable result.     

土著植物产品对印度森林病虫害防治的生物功效：综述

讨论了苦楝树和其他热带树种天然产品在印度森林病虫害防治中的生物功效。这些树木产品可起到拒食素、防护剂、不育诱导剂、毒素等作用,可以调控害虫生长,具有效力高、价格低廉和对环境无公害的特点。将这些树木产品整合到森林虫害管理策略中,会增强森林的可持续性,防止木材质量衰退。表3参61。     

Land tenure and farm management efficiency: The case of smallholder rubber production in customary land areas of Sumatra

This study assesses the impact of land tenure institutions on the efficiency of farm management based on a case study of rubber production in customary land areas of Sumatra, Indonesia. Using the modes of land acquisition as measures of land tenure institutions, we estimated tree planting, revenue, income, and short-run profit functions, and internal rates of return to tree planting on smallholder rubber fields. We find generally insignificant differences in the incidence of tree planting and management efficiency (defined as residual profits) of rubber production between newly emerging private ownership and customary ownership. This is consistent with our hypothesis that tree planting confers stronger individual rights, if land rights are initially weak (as in the case of family land under customary land tenure systems). On the other hand, short-term profits are higher on land that is rented through share tenancy. This result indicates that rubber trees are over-exploited under renting arrangements due partly to the short-run nature of the land tenancy contracts and partly to the difficulty landowners face in supervising tapping activities of tenants in spatially dispersed rubber fields. This revised version was published online in June 2006 with corrections to the Cover Date.     

A comparison of biodiversity values in boreal forest regeneration areas before and after forest certification

Abstract

In this study, 236 regeneration areas (mostly clear-cuts) in southern Norway were selected by random stratified selection: 118 of the study units were cut before and 118 after the introduction of forest certification in 1998. The degree of compliance with biodiversity measures established in the prevailing certification standard (ISO 14001 and the Norwegian standard “Living Forests”) was compared in a field study, and the differences were analysed. In some aspects, a clear difference could be seen, most clearly in an increasing number of green retention trees and an increasing mean width of buffer-strips left along rivers, bogs and lakes in the postcertification units compared with the precertification units. Even though there was a significant increase in the mean number of retention trees, as much as 21% of the postcertification regeneration areas still did not have sufficient retention trees to comply with the certification standard and 41% had either too few retention trees or too few spruce trees according to the standard. Concerning the management of small swamp forests, and the damage done to terrain and prelogging coarse dead wood by off-road transport, little improvement was seen. The discussion examines whether it is probable that the changes seen are a result of forest certification in Norway.     

Forecasting landscape-scale,cumulative effects of forest management on vegetation and wildlife habitat: A case study of issues,limitations, and opportunities

Forest landscape disturbance and succession models have become practical tools for large-scale, long-term analyses of the cumulative effects of forest management on real landscapes. They can provide essential information in a spatial context to address management and policy issues related to forest planning, wildlife habitat quality, timber harvesting, fire effects, and land use change. Widespread application of landscape disturbance and succession models is hampered by the difficulty of mapping the initial landscape layers needed for model implementation and by the complexity of calibrating forest landscape models for new geographic regions. Applications are complicated by issues of scale related to the size of the landscape of interest (bigger is better), the resolution at which the landscape is modeled and analyzed (finer is better), and the cost or complexity of applying a landscape model (cheaper and easier is better). These issues spill over to associated analyses that build on model outputs or become integrated as auxiliary model capabilities. Continued development and application of forest landscape disturbance and simulation models can be facilitated by (1) cooperative efforts to initialize more and larger landscapes for model applications, (2) partnerships of practitioners and scientists to address current management issues, (3) developing permanent mechanisms for user support, (4) adding new capabilities to models, either directly or as compatible auxiliary models, (5) increasing efforts to evaluate model performance and compare multiple models running on the same landscape, and (6) developing methods to choose among complex, multi-resource alternatives with outputs that vary over space and time.     

杉木观光木混交林土壤腐殖质组成及特性

1999年1月对福建三明莘口教学林场杉木观光木混交林及对照杉木纯林土壤腐殖质的有机碳和胡敏酸(HA)含量、HA/FA、可见光谱、红外光谱特性等进行研究。结果表明,与杉木纯林相比,混交林各土层土壤有机碳、胡敏酸含量及胡敏酸的E4值均有显著增加,HA/FA比值亦有所增加(不显著),而E4/E6值略有降低,胡敏酸红外光谱在1650 cm-1处出现明显的吸收峰。可见混交林中土壤腐殖质腐殖化程度和芳香度较纯林的高,这对土壤结构改良和有效养分供应有利,土壤肥力有一定程度的提高。图1表1参17。     

云南松林区的林火与火险等级分区初探

云南松林区发生的森林火灾是多种自然因素和人为活动综合作用的结果。通过对四川省云南松分布区不同区域与林火有关的主要气候因子分析及综合值的比较,结合地形地貌、植被状况和人为活动等多种因素,将我省云南松分布区划分成5个不同等级的火险区,并提出了相应的护林防火对策。     

Early-stage impacts of sika deer on structure and function of the soil microbial food webs in a temperate forest: A large-scale experiment

Modification of forest vegetation caused by an overabundance of mammalian herbivores has been reported in temperate and subarctic regions all over the world. However, the indirect effects of these herbivores on the structure and functions of soil decomposer systems are not fully understood, especially in temperate forests. We investigated the early effects of sika deer invasion on soil decomposer systems in a Japanese temperate forest using two large-scale experimental enclosures with low and high densities of deer (LD: 25 ha, 4 deer km⁻²; HD: 6.25 ha, 16 deer km⁻²) including control plots without deer (WD). Three years after deer introduction the understory cover of dwarf bamboo (Sasa nipponica) declined due to deer browsing in both enclosures. At the same time, measurements were made of the soil microbial community, soil nematode community, soil nitrogen (N) mineralization rate, and carbon (C) and N content in dwarf bamboo leaves. In LD, soil microbial biomass was lower from WD, probably due to the decrease of fresh aboveground litter from dwarf bamboo. Surprisingly, there were no cascading effects on total abundance of soil nematodes and soil total N mineralization potential which were unaffected by deer in the LD treatment, while soil NH₄⁺-N content was lower and soil nematode community structure was different (abundance of 4 families was higher and that of 3 families was lower, but the functional structure was not different) from WD. Specifically, the responses to deer introduction varied between microbes and nematodes, and the change of balance in the microbial food webs may have altered N mineralization processes. In contrast, in the HD treatment, all the variables measured were not significantly different from those of WD treatment. Intensive browsing by deer may have cancelled out the effects of the decrease in aboveground litter input on the soil decomposer systems through other pathways, such as a transitory increase in belowground litter input caused by induced changes in allocation patterns of bamboo. No changes in total N mineralization potential, leaf N, and composition of understory vegetation in both enclosures indicated that deer introduction did not facilitate nor retard N cycling regardless of deer density. This study showed that sika deer browsing can affect soil decomposer systems at an early stage of invasion even at low density, which contrasts with previous studies on the subject. Linking our findings of early-stage effects of deer on soil decomposer systems to longer-term dynamics of understory vegetation and tree regeneration will be needed to evaluate the adequacy of deer management practices with respect to the sustainability of soil nutrient supplies.     

Carbon storage of a subtropical forest ecosystem: a case study of the Jinggang Mountain National Nature Reserve in south-eastern China

The carbon cycle of forest ecosystems plays a key role in regulating CO2 concentrations in the atmosphere. Research on carbon storage estimation of forest ecosystems has become a major research topic. However, carbon budgets of subtropical forest ecosystems have received little attention. Reports of soil carbon storage and topographic heterogeneity of carbon storage are limited. This study focused on the Jinggang Mountain National Nature Reserve as an example of a mid-subtropical forest and evaluated soil and vegetation carbon storage by field sampling combined with GIS, RS and GPS technology. We classified the forest into nine forest types using ALOS high-resolution remote sensing images. The evergreen broad-leaved forest has the largest area, occupying 26.5% of the total area, followed by coniferous and broad-leaved mixed forests and warm temperate coniferous forest, occupying 24.2 and 22.9%, respectively. The vegetation and soil carbon storage of the whole forest ecosystem were 1,692,344 and 5,514,707 t, with a carbon density of 7.4 and 24.2 kg/m^2, respectively, which suggests that the ecosystem has great carbon storage capacity. The topographic heterogeneity of the carbon storage was also analysed. The largest vegetation storage and soil storage is at 700–800 and 1000–1100 m, respectively. The vegetation carbon storage is highest in the southeast, south and southwest.     

A functional analysis of streamside habitat use by southern Appalachian salamanders: Implications for riparian forest management

The appropriate management of streamside forests and use of riparian strips is poorly resolved for many systems because of a lack of understanding of the extent to which riparian forests function as environmental buffers for aquatic species versus core (essential) habitat for semi-aquatic and terrestrial species. We studied streamside forests in western North Carolina and eastern Tennessee, USA, to help delineate their functional value for plethodontid salamanders. We established 30 m × 40 m plots at 17 sites (823–1716 m in elevation) in unmanaged forests with closed canopies. Plots contained a portion of a seep or first-order stream along one edge and typically extended 36–38 m into the adjoining forest. We examined use of stream and streamside habitats based on captures during area-constrained searches of cover objects. We observed 6423 plethodontid salamanders belonging to 7 terrestrial-breeding and 12 aquatic-breeding species. Terrestrial-breeders (primarily Plethodon spp.) comprised 37% of terrestrial specimens and were more abundant at higher elevations. Aquatic-breeders (primarily Desmognathus spp.) increased their proportionate use of terrestrial habitat, but declined in overall abundance with elevation. Catches of aquatic-breeders were greatest within 8 m of aquatic habitats (49% of total terrestrial catch of aquatic-breeders), particularly at low elevation sites. The terrestrial zone provided core habitat for one terrestrial-breeder (D. wrighti) and six semi-aquatic species (Desmognathus spp., Gyrinophilus porphyriticus and Eurycea wilderae) that were broadly distributed throughout plots, and acted as an aquatic buffer for four highly aquatic species (Desmognathus spp.). The remaining species were terrestrial-breeders (Plethodon spp.) that were evenly distributed across plots, suggesting that riparian strips would function as important source populations for recolonization following timbering on adjoining land. Because of the vulnerability of plethodontid salamanders to edge effects, effective management of southern Appalachian streamside habitats may require the addition of a terrestrial buffer to protect terrestrial core habitat that immediately adjoins streams and seeps.     

改善林区无线寻呼信号与调制域特性的一种新方法

本从调制域角度分析了基于ＰＬＬ激励的无线寻呼信号的数字调频特性;发现ＰＬＬ锁定状态下的频率跟踪特性对数字调频有一定影响。阐述了这种影响造成无线寻呼系统误码的机理。最后,本提出了“动态调整ＰＬＬ中心频点”的方法。