Isolation of endophytes from leaves of <Emphasis Type="Italic">Neolitsea sericea</Emphasis> in broadleaf and conifer stands

Endophytic fungi were isolated from leaves of Neolitsea sericea, a major lauraceous tree in the laurel forests of southern Kyushu, collected from the understory layer of broadleaf and conifer stands. Cytosphaera sp. and a species of Ascomycetes in leaf blade segments, plus a xylariaceous species and Phomopsis spp. in petiole segments, were isolated at relatively high frequency. In general, isolation frequencies of endophytes were higher in petiole than blade segments. In blade segments, patterns of endophyte isolation were quite different among stands, while relatively similar in petiole segments. Significant effects of sampling sites or canopy vegetation were rarely detected. the understory layer of laurel forests. Neolitsea sericea is an evergreen broadleaf lauraceous tree, widely distributed in areas of eastern Asia. In southern Kyushu, it is one of the most common trees, growing both as canopy and understory species. In this study, endophytes were isolated from the leaves of N. sericea growing in the understory layer of conifer and broadleaf forest stands to survey the endophytes of N. sericea leaves and to examine the effect of the canopy layer on endophytic mycobiota in understory plants.     

Increasing the Efficiency of Microsatellite Discovery from Poorly Enriched Libraries in Coniferous Forest Species

Microsatellites are PCR based markers widely applicable in many plant species. Although the discovery and development of new microsatellites is a costly and technically demanding process, they are widely used in many plant systems. In coniferous tree species, the large genome size and repetitive DNA regions further aggravate the process, often resulting in libraries with very low enrichment efficiencies. Such species have proven intractable to efficient microsatellite discovery. For example, enriched microsatellite libraries produced for seven angiosperm species had enrichment efficiencies up to 50%, whereas libraries for three conifers, generated concurrently, under identical conditions, all had enrichment efficiencies below 10%. This report describes a simple strategy for recovering useful microsatellites from two of these conifer libraries, Pinus elliottii and Araucaria cuninghamii. Enrichment efficiencies increased from 0% to 100% and 1.5% to 98%, respectively. The strategy utilised DIG labelled oligo probes to identify clones containing microsatellite inserts. The technique is cost effective and rapid, utilising basic techniques and equipment that are widely available.     

黑龙江省大兴安岭林区火烧迹地森林更新及其影响因子

林火干扰是大兴安岭森林更新的影响因子之一,研究火烧迹地森林更新的影响因子(立地条件、火前植被、火干扰特征)对理解生态系统的结构、功能和火后演替轨迹具有重要意义。选取呼中及新林林业局55个代表性火烧样地,利用增强回归树分析法分析了火烧迹地森林更新的影响因素。结果表明:(1)立地条件是影响针、阔叶树更新苗密度的主要因素;海拔对针叶树更新苗密度的影响最大;坡度对阔叶树更新苗密度影响最大;(2)距上次火烧时间对针叶树更新苗比重影响最大,其次是林型;(3)中度林火干扰后森林更新状况好于轻度和重度火烧迹地。根据火烧迹地森林更新调查分析可知:林型影响火后演替模式,火前为针叶树或阔叶树纯林,火后易发生自我更新(火后树种更新组成与火前林型相同),而针阔混交林在火干扰影响下易于发生序列演替(火后初期以早期演替树种更新为主)。     

Early colonization of red alder and Douglas fir by ectomycorrhizal fungi and Frankia in soils from the Oregon coast range

The potential for mycorrhizal formation and Frankia nodulation were studied in soils from six sites in the Pacific Northwest. The sites included young and old alder stands, a 1-year-old conifer clear-cut, a young conifer plantation, and rotation-aged and old-growth conifer stands. A bioassay procedure was used with both red alder and Douglas fir seedlings as hosts. After 6 weeks growth, seedlings of both hosts were harvested every 3 weeks for 21 weeks and numbers of nodules and ectomycorrhizal types estimated. Nodules formed on red alder and ectomycorrhizae formed on both alder and Douglas fir in soil from all sites. Nodulation potential was highest in soil from the alder stands and the conifer plantation. Seven morphologically distinct ectomycorrhizal types were recovered on Douglas fir and five on alder. Only Thelephora terrestris, a broad-host-range mycobiont, formed mycorrhizae on both hosts. New ectomycorrhizal types formed on both hosts throughout the bioassay. Ectomycorrhizal colonization of alder was greatest in the alder and clear-cut soils. Low ectomycorrhizal colonization on alder was found in soils from sites where conifers were actively growing. Ectomycorrhizal colonization of Douglas fir was highest in the young alder and conifer plantation soils and was low in the rotation-aged conifer soil. The highest diversity of ectomycorrhizal types was found on alder in the conifer clear-cut soil and on Douglas fir in the rotation-aged conifer soil. Effects of host specificity, nodulation and mycorrhiza-forming potential and nodule-mycorrhiza interactions on seedling establishment are discussed in relation to seral stage dynamics and attributes of pioneer ectomycorrhizal fungal species.     

Environmental correlates of tree alpha-diversity in New Zealand primary forests

Correlations between environment and tree alpha-diversity in New Zealand's primary forests were examined using an extensive quantitative dataset (14 540 plots). Generalised additive models were used to examine relationships between species richness and temperature, solar radiation, root-zone moisture deficit, relative humidity, lithology, drainage, and plot size for all trees (112 species), and separately for broadleaved trees (88 species), conifers (17), and the genus Nothofagus (4). Diversity both for all tree species and for broadleaved trees was predicted to be highest on sites with high temperatures, high solar radiation, and high soil and atmospheric moisture, and on sedimentary and basaltic substrates. Highest conifer diversity was predicted on sites with intermediate temperatures, low solar radiation, high root-zone and atmospheric moisture, and rhyolitic and Quaternary substrates, particularly where drainage was impeded. Highest Nothofagus diversity was predicted for sites combining low temperatures, high solar radiation, high root-zone moisture but low atmospheric moisture, and on granitic substrates. Differences in diversity between the species groups on different lithologies are interpreted as rejecting both the effects of variation in large-scale disturbance histories, and the effects of confounding environmental factors associated with particular substrates. There were also significant interactions between species groups: both broadleaved tree and conifer richness were predicted to be lower on sites where one or more Nothofagus spp. — all of which have marked patchiness in their distribution — are present. Although these results are consistent with the hypothesis that tree diversity is highest on sites conducive to high productivity, history is also indicated as an important determinant of tree diversity in New Zealand.     

Effect of Trichoderma Fungi on Soil Micromycetes That Cause Infectious Conifer Seedling Lodging in Siberian Tree Nurseries

Soils in the tree nurseries studied were characterized by a lower species diversity of fungi than adjacent virgin soils. In particular, the relative abundances of representatives of the genera Mucor, Chaetomium, and Trichoderma in the nursery soil were two times lower than in adjacent virgin soils. On the other hand, the nursery soil exhibited greater abundances of fungi of the genus Fusarium, which are causative agents of many diseases of conifer seedlings. To appreciate the efficiency of biocontrol of the infectious diseases of conifer seedlings, we introduced several indigenous Trichoderma strains into the nursery soil and found that this affected the species composition of soil microflora considerably. Changes in the species composition of mycobiota beneficially influenced the phytosanitary state of soils and reduced the infectious lodging of conifer seedlings.     

Community structures of Mesostigmata, Prostigmata and Oribatida in broad-leaved regeneration forests and conifer plantations of various ages

The community structures of Mesostigmata, Prostigmata, and Oribatida in the soil of broad-leaved regeneration forests and conifer plantations of various ages were assessed alongside soil and plant environmental variables using three response metrics (density, species richness, and species–abundance distribution). The density and species richness of mites recovered swiftly after clear-cutting or replanting. Oribatid mites dominated the soil mite communities in terms of densities and species richness for both forest types. Soil mite communities in broad-leaved forests was related to forest age, the crown tree communities index, and forest-floor litter weight. In contrast, soil mite communities in the conifer plantation sites were related to various indices of understory plants. The development of the understory plants was synchronized with the silvicultural schedules, including a closed canopy and thinning. Such a conifer plantation management may affect indirectly the community of mites.     

An evaluation of the impact of Melaleuca quinquenervia invasion and management on plant community structure after fire

Two questions were asked in this study: after a fire, does the choice of invasive plant management strategy, namely herbicidal or biological, alter (1) plant community assemblages and (2) the re-invasion potential of the Australian tree Melaleuca quinquenervia? Plant species richness was highest in the non-invaded and herbicide sites compared to the biological site with 10.5, 10.8, and 8.25 species m⁻² found in each site, respectively. Although the total count of live and dead seedlings was highest in the biologically controlled site at 22.8 and 13.6 plants m⁻², respectively, M. quinquenervia seedlings were recruited in all sites. While the ultimate goal of management programs is to restore ecosystem integrity, this work provides evidence that passive restoration may not be enough to restore plant community structure in this system.     

Aspen (<Emphasis Type="Italic">Populus tremuloides</Emphasis>) stands and their contribution to plant diversity in a semiarid coniferous landscape

We conducted a field study to determine the relative contributions of aspen (Populus tremuloides), meadow, and conifer communities to local and landscape-level plant species diversity in the Sierra Nevada and southern Cascade Range, northeastern California, USA. We surveyed plant assemblages at 30 sites that included adjacent aspen, conifer, and meadow communities across a 10,000-km² region. We statistically investigated patterns in local and landscape-scale plant diversity within and among the three vegetation types. Summing across sites, aspen stands supported more plant species overall and more unique plant species than either meadow or conifer communities. Local richness and diversity did not differ between aspen and meadow plots; conifer forest plots were significantly lower in both measures. Heterogeneity in species composition was higher for aspen forest than for meadows or conifer forest, both within sites and between sites. Plant communities in aspen stands shared less than 25% of their species with adjacent vegetation in conifer and meadow plots. Within aspen forest, we found a negative relationship between total canopy cover and plant diversity. Our results strongly support the idea that plant communities of aspen stands are compositionally distinct from adjacent meadows and conifer forest, and that aspen forests are a major contributor to plant species diversity in the study region. Current patterns of aspen stand succession to conifer forest on many sites in the semiarid western US are likely to reduce local and landscape-level plant species diversity, and may also have negative effects on other ecosystem functions and services provided by aspen forest.     

树种及多样性组配对南亚热带人工林早期树木生长的影响

为科学筛选提升南亚热带人工林生产力的树种配置模式,选择南亚热带8个乡土树种,采用随机区组的试验设计,建立了树种多样性梯度(1、2、4、6个树种)人工新造林试验平台,研究树种多样性及不同功能特性树种混交对人工林早期树木生长的影响。结果表明: 在树木生长第5年,树木生长并没有随树种多样性增加而增加;速生树种马尾松和米老排纯林生长量是珍贵树种红椎和格木纯林的2.5～4.5倍;2个树种混交和4个树种混交情况下,针阔树种混交、速生树种与固氮树种混交显著提高树木生长量51.5%～132.8%,而当6个树种混交时,不同树种组配对生长量没有显著影响。不同树种配置模式下土壤氮、磷养分是影响树木早期生长的主要因素。针阔树种混交、速生和固氮树种混交能显著提高南亚热带人工林树木的早期生长。     

Influence of bioclimatic variables on tree-line conifer distribution in the Greater Yellowstone Ecosystem: implications for species of conservation concern

Aim Tree‐line conifers are believed to be limited by temperature worldwide, and thus may serve as important indicators of climate change. The purpose of this study was to examine the potential shifts in spatial distribution of three tree‐line conifer species in the Greater Yellowstone Ecosystem under three future climate‐change scenarios and to assess their potential sensitivity to changes in both temperature and precipitation. Location This study was performed using data from 275 sites within the boundaries of Yellowstone and Grand Teton national parks, primarily located in Wyoming, USA. Methods We used data on tree‐line conifer presence from the US Forest Service Forest Inventory and Analysis Program. Climatic and edaphic variables were derived from spatially interpolated maps and approximated for each of the sites. We used the random‐forest prediction method to build a model of predicted current and future distributions of each of the species under various climate‐change scenarios. Results We had good success in predicting the distribution of tree‐line conifer species currently and under future climate scenarios. Temperature and temperature‐related variables appeared to be most influential in the distribution of whitebark pine (Pinus albicaulis), whereas precipitation and soil variables dominated the models for subalpine fir (Abies lasiocarpa) and Engelmann spruce (Picea engelmannii). The model for whitebark pine substantially overpredicted absences (as compared with the other models), which is probably a result of the importance of biological factors in the distribution of this species. Main conclusions These models demonstrate the complex response of conifer distributions to changing climate scenarios. Whitebark pine is considered a ‘keystone’ species in the subalpine forests of western North America; however, it is believed to be nearly extinct throughout a substantial portion of its range owing to the combined effects of an introduced pathogen, outbreaks of the native mountain pine beetle (Dendroctonus ponderosae), and changing fire regimes. Given predicted changes in climate, it is reasonable to predict an overall decrease in pine‐dominated subalpine forests in the Greater Yellowstone Ecosystem. In order to manage these forests effectively with respect to future climate, it may be important to focus attention on monitoring dry mid‐ and high‐elevation forests as harbingers of long‐term change.     

Community structure of ectomycorrhizal fungi across an alpine/subalpine ecotone

In order to assess changes in the community structure of ectomycorrhizal fungi across the tree line, data on distributions of fungi and their host plants, as well as on edaphic factors and stand age, were collected at two montane sites in the Front Range of the Canadian Rockies. Canonical correspondence analysis (CCA) was used to explore relationships between fungal species composition and environmental factors. Richness and diversity of ectomycorrhizal fungi decreased with elevation, in spite of the fact that host plant diversity was highest at the ecotone between the subalpine forest and the alpine zone. Both host plant distribution and edaphic factors were important in explaining the observed changes in fungal species diversity and composition. The majority of ectotnycorrhizal fungi found in the subalpine forest and at the ecotone were conifer associates, while a large proportion of those in the alpine zone were non-host specific and able to form mycorrhizae with both angiosperms and gymnosperms. The abundance of non-host specific fungi in the alpine zone is expected to provide a favorable environment for the establishment of conifer seedlings above the present tree line.     

Regional‐scale directional changes in abundance of tree species along a temperature gradient in Japan

Climate changes are assumed to shift the ranges of tree species and forest biomes. Such range shifts result from changes in abundances of tree species or functional types. Owing to global warming, the abundance of a tree species or functional type is expected to increase near the colder edge of its range and decrease near the warmer edge. This study examined directional changes in abundance and demographic parameters of forest trees along a temperature gradient, as well as a successional gradient, in Japan. Changes in the relative abundance of each of four functional types (evergreen broad‐leaved, deciduous broad‐leaved, evergreen temperate conifer, and evergreen boreal conifer) and the demography of each species (recruitment rate, mortality, and population growth rate) were analyzed in 39 permanent forest plots across the Japanese archipelago. Directional changes in the relative abundance of functional types were detected along the temperature gradient. Relative abundance of evergreen broad‐leaved trees increased near their colder range boundaries, especially in secondary forests, coinciding with the decrease in deciduous broad‐leaved trees. Similarly, relative abundance of deciduous broad‐leaved trees increased near their colder range boundaries, coinciding with the decrease in boreal conifers. These functional‐type‐level changes were mainly due to higher recruitment rates and partly to the lower mortality of individual species at colder sites. This is the first report to show that tree species abundances in temperate forests are changing directionally along a temperature gradient, which might be due to current or past climate changes as well as recovery from past disturbances.     

A comparison of diversity and species composition of ground beetles (Coleoptera: Carabidae) between conifer plantations and regenerating forests in Korea

Ground beetles were collected by pitfall trapping to compare their species richness between conifer plantations (14 sites) and regenerating forests (14 sites) and among forest ages and to examine how different functional groups responded to forest type, forest age, patch size, elevation, and geographic location in terms of abundance and richness. Ground beetles were collected from middle August to late October, 2008. A total of 34 species were identified from 3,156 collected ground beetles. Individual-based rarefaction curves showed greater species richness in regenerating forests, especially in 40–50-year-old forests, than in conifer plantations. Stepwise multiple regression analysis showed that patch size and elevation were major predictors of species richness and/or abundance of forest specialists, brachypterous species, and large- and medium-bodied species. A multivariate regression tree indicated that patch size and elevation were major predictors of assemblage structure. Although our results suggest that maintaining forest areas adjacent to agricultural landscapes may be essential to preserve ground beetle assemblages irrespective of forest types, further study is necessary to clarify the effects of habitat quality and amount on ground beetles in forests.     

Genomic diversity in forest trees

Forest trees in general are out-crossing, long-lived, and at early stages of domestication. Molecular evolution at neutral sites is very slow because of the long generation times. Transferring information between closely related conifer species is facilitated by high sequence similarity. At the nucleotide level, trees have at most intermediate levels of variation relative to other plants. Importantly, in many species linkage disequilibrium within genes declines within less than 1000 bp. In contrast to the slow rate of neutral evolution, large tree populations respond rapidly to natural selection. Detecting traces of selection may be easier in tree populations than in many other species. Association studies between genotypes and phenotypes are proving to be useful tools for functional genomics.     

长白山主要生态系统地面藓类植物的生态位研究

应用王刚提出的生态位重叠值公式,计测了长白山主要生态系统中41个样点42种主要地面藓类的生态位重叠值。以此为指标,分别应用主坐标排序、图论聚类及系统聚类分析方法,作出了反映42种地面藓类的种间生态关系的二维投影图、最小生成树和动态聚类图。3种方法相结合,能够对生态位重叠值矩阵进行直观地表达,并使所表达的藓类种间关系具有确切的生态学含义。研究表明,按生态位重叠值大小,长白山主要生态系统中地面主要藓类可区分出落叶松-沼泽藓类、高山苔原藓类和暗针叶林-岳华林藓类3大类。42种藓类中,生态位宽度(B)与种数(N)符合公式N=38.1985×e     

A comparison of fungal endophytic community diversity in tree leaves of rural and urban temperate forests of Kanto district,eastern Japan

To clarify the effects of forest fragmentation and a change in tree species composition following urbanization on endophytic fungal communities, we isolated fungal endophytes from the foliage of nine tree species in suburban (Kashiwa City, Chiba) and rural (Mt. Wagakuni, Ibaraki; Mt. Takao, Tokyo) forests and compared the fungal communities between sites and host tree species. Host specificity was evaluated using the index of host specificity (Si), and the number of isolated species, total isolation frequency, and the diversity index were calculated. From just one to several host-specific species were recognized in all host tree species at all sites. The total isolation frequency of all fungal species on Quercus myrsinaefolia, Quercus serrata, and Chamaecyparis obtusa and the total isolation frequency of host-specific species on Q. myrsinaefolia, Q. serrata, and Eurya japonica were significantly lower in Kashiwa than in the rural forests. The similarity indices (nonmetric multidimensional scaling (NMS) and C_MH) of endophytic communities among different tree species were higher in Kashiwa, as many tree species shared the same fungal species in the suburban forest. Endophytic fungi with a broad host range were grouped into four clusters suggesting their preference for conifer/broadleaves and evergreen/deciduous trees. Forest fragmentation and isolation by urbanization have been shown to cause the decline of host-specific fungal species and a decrease in β diversity of endophytic communities, i.e., endophytic communities associated with tree leaves in suburban forests were found to be depauperate.     

Nest Site Selection by Western Gray Squirrels at Their Northern Range Terminus

ABSTRACT The western gray squirrel (Sciurus griseus) in Washington, USA, is limited to 3 disjunct areas and is a state threatened species. Information is lacking for the North Cascades population, which is the northernmost population for the species. Squirrels in this population exist without oaks (Quercus spp.) that provide forage and cavities for maternal nests elsewhere in their range. During May 2003 to August 2005, we studied selection of nest sites and nest trees by 18 radiocollared squirrels in Okanogan County, Washington. Without oak cavities, females reared their young in dreys. General nest-tree characteristics were similar to characteristics of western gray squirrel nest trees in Southeastern Cascades: relatively tall ponderosa pines (Pinus ponderosa) ≥ 40 cm diameter at breast height. Results from conditional logistic models determined that the odds of a squirrel selecting a tree for nesting increased with greater diameter at breast height and with infection by dwarf mistletoe (Arceuthobium spp.). Nest sites with high selection probability by squirrels had greater basal area and number of tree species than available unselected sites. Retention of forest patches that include a mix of conifer species or conifer and deciduous trees and moderate to high basal area could promote nesting opportunities, connectivity for arboreal travel, as well as abundance and diversity of hypogeous fungi. Experiments to test the efficacy of retaining untreated patches of varying size (including trees infected with mistletoe) on nesting by western gray squirrels within stands managed for fire suppression and forest health would provide important information about the effects of forest fuel management on arboreal wildlife.     

Dynamics of forests with Araucariaceae in the western Pacific

Abstract. Several species of Araucaria and Agathis (Araucariaceae) occur as canopy emergents in rain forests of the western pacific region, often representing major components of total stand biomass. New data from permanent forest plots (and other published work) for three species (Araucaria hunsteinii from New Guinea, A. laubenfelsii from New Caledonia, and Agathis australis from New Zealand) are used to test the validity of the temporal stand replacement model proposed by Ogden (1985) and Ogden & Stewart (1995) to explain the structural and compositional properties of New Zealand rain forests containing the conifer Agathis australis. Here we propose the model as a general one which explains the stand dynamics of rain forests with Araucariaceae across a range of sites and species in the western Pacific. Forest stands representing putative stages in the model were examined for changes through time in species recruitment, growth and survivorship, and stand richness, density and basal area. Support for the model was found on the basis of: 1. Evidence for a phase of massive conifer recruitment following landscape-scale disturbances (e.g. by fire at the Huapai site, New Zealand for Agathis australis); 2. Increasing species richness of angiosperm trees in the pole stage of forest stand development (i.e. as the initial cohort of conifers reach tree size; >10 cm DBH); 3. A high turnover rate for angiosperms (<100 yr), and low turnover for conifers (≥ 100 yr) in the pole stage, but similar turnover rates for both components (50–100 yr) as forests enter the mature to senescent phase for the initial conifer cohort; 4. Very low rates of recruitment for conifers within mature stands, and projected forest compositions which show increasing dominance by angiosperm tree species; 5. A low probability of conifer recruitment in large canopy gaps created by conifer tree falls during the initial cohort senescent phase, which could produce a second generation low density stand in the absence of landscape scale disturbance; 6. Evidence that each of the three species examined required open canopy conditions (canopy openness > 10 %) for successful recruitment. The evidence presented here supports the temporal stand replacement model, but more long-term supporting data are needed, especially for the phase immediately following landscape level disturbance.