Taxonomic and community composition of epigeal arthropods in monoculture and mixed tree species plantations in a deciduous forest of Ghana

Tropical forests provide several ecosystem services and functions and support approximately two-thirds of the world’s biodiversity but are seriously threatened by deforestation.Approaches to counteract this menace have revolved around aff orestation with several or a single tree species.We thus investigated how plantation forests with either a single or several tree species infl uenced arthropod taxonomic and community composition using pitfall traps to sample selected groups of epigeal arthropods(Araneae,Coleoptera,Orthoptera and Hymenoptera)and with environmental variables assessed simultaneously.Our results revealed 54 taxonomic groups with signifi cantly higher taxonomic richness,activity density,and diversity in the mixed stands than in the monoculture stands.The significant differences in community composition were mainly driven by families including Lycosidae,Formicidae,Staphylinidae,Scotylidae,Hydrophilidae,Gryllidae and Scarabaeidae and were explained by distinct habitat characteristics(canopy openness,litter depth,deadwood volume,and tree height).While the diverse tree communities and heterogeneous vegetation structure off ered food and habitat resources for diverse arthropod groups,the allelopathic nature coupled with homogenous stand characteristics of the Tectona grandis stands in the monoculture suppressed the growth of understorey vegetation that could otherwise serve as food and habitat resources for arthropods,which might have led to limited activities and diversity of arthropods in the monoculture plantation stands.The fi ndings thus highlight the need to promote mixed tree plantations in degraded tropical areas,especially when restoring biodiversity is the prime management focus.

Tree species diversity and stand structure along major community types in lowland primary and secondary moist deciduous forests in Tripura,Northeast India

Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura. Overall 10,957 individual trees belonging to 46 family, 103 genera and 144 species were counted at ≥30 cm DBH （diameter at breast height） using 28 permanent belt transects with a size of 1 ha （10 m × 1000 m）. Four different tree communities were identified. The primary forests was dominated by Shorea robusta （mean density 464.77 trees.ha^-1, 105 species） and Schima wallichii （336.25 trees.ha^-1, 82 species）, while the secondary forests was dominated by Tectona grandis （333.88 trees.ha^-1, 105 species） and Hevea brasiliensis （299.67 trees.ha^-1, 82 species）. Overall mean basal area in this study was 18.01m2.ha^-1; the maximum value was recorded in primary Shorea forest （26.21 m2.ha^-1）. Mean density and diversity indices were differed significantly within four different communities. No significant differences were observed in number of species, genera, family and tree basal cover area. Significant relationships were found between the species richness and different tree population groups across the communities. Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumu- lation of native oligarchic small tree species. Seventeen species were recorded with 〈2 individuals of which Saraca asoka （Roxb.） de Wilde and Entada phaseoloides （L.） Men＇. etc. extensively used in local ethnomedicinal formulations. The present S. robusta Gaertn dominated forest was recorded richer （105 species） than other reported studies. Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests. Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur. The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species in secondary T. grandis L. dominated community.

Estimation of Population of Ten Selected Forest Tree Species Used by Communities around Kalinzu Forest Reserve, South-Western Uganda

Local communities depend on Kalinzu Forest Reserve (KFR) for plant resources. This resource utilization affects the population of tree species in the forest. This study set out to estimate the population of ten tree species in the forest. Results of this study are hoped to provide a basis for studying future changes in population dynamics of the species. The ten species selected were: Newtonia buchananii, Cynometra alexandrei, Teclea nobilis, Prunus africana, Entandrophragma exelsum, Sapium ellipticum, Diospyros abyssinica, Zanthoxylum gilletii, Rytiginia kigeziensis and Spathodea nilotica. Their selection was based on the results of a study (Aine-Omucunguzi et al., 2010) about utilization of plant resources by the local people around KFR. Species with high demand from the local people were selected. Alternate nested quadrants along five line transects, were used to estimate the population. The plants were categorized into three classes as trees (>5 cm diameter at breast height), saplings (2 cm root collar diameter-5 cm diameter at breast height) and wildings (<2 cm root collar diameter). Population, population density, relative density, frequency, and relative frequency of each species were determined. Generally, the number of wildings, saplings and trees of each species increased away from the forest edge inwards. For all the species, wildings had the highest population density followed by saplings and then trees. Teclea nobilis had the highest number of individual per hectare, followed by Newtonia buchananii, while Rytiginia kigeziensis and Spathodea nilotica had the lowest number of individuals per hectare.

Some of the Mechanisms for Coexistence of Tree Species Diversity in Tropical Forests: A Review of Effects of Tree Density Dependence

Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence of many tree species is not without competition. Therefore, coexistence of tree species and size diversities occur sequentially or simultaneously in tropical natural forests. Understanding coexistence and competition mechanisms of tree species requires knowledge of interactions within and between species. However, many conservation efforts and strategies failed due to inability to identify and maintain functional coexistence mechanisms among tree species in the forest. Also, most trees died because of pressure on their habitats and not because of limiting growth resources. Hence, species identity, minimum distance and size of the neighbouring trees which are responsible for coexistence of competing trees in most tropical forests have not been explicitly reviewed. Therefore, this review evaluated some of the density dependent mechanisms for coexistence of tree species alpha diversity in tropical forests. Many interactive mechanisms are responsible for coexistence tree species in tropical forests. Inter- and intra-specific competitions are the most significant and both facilitate positive and negative density dependence. Therefore, switching from negative to positive density dependence may occur in some situations. Positive and negative density effects regulate species abundance and coexistence through conspecific and heterospecific structures. Aggregates of conspecific and heterospecific neighbours constitute forest spatial structure. Negative density interactions are mutually exclusive and basically ranged from effect of species identity of neighbours, distance to neighbours and tree size of the neighbours to reference trees in the community structures. Some mechanisms shorten distances for heterospecific than conspecific interactions. Conspecific structures improved survival and growth of rare tree species. Interactive mechanisms in tree community and population structures facilitate species diversity and size inequality, respectively.

基于刘完素“火热论”探析“热-风”病因树在治疗抽动障碍中的应用

抽动障碍是起病于儿童或青少年时期的一种神经精神障碍性疾病,以不自主、反复、突发、快速、重复、无节律性的一个或多个部位运动抽动和发声抽动为主要特征,亦可共患一种或多种心理行为障碍,但智力一般不受影响。研究以刘完素创立的河间流派“火热论”观点为纲领,以小儿抽动障碍的临床特征为基础,提出儿童在外感六淫、饮食调护、情志内伤、先天禀赋等因素作用下,阴阳失衡,五脏失调,肝木之气郁结,郁久而化热,热极则生风;脾土失健,难化水湿,聚而成痰,痰热胶结,引动肝风;血液受热煎熬,化为瘀血,瘀、热互结;热久伤阴,使得阳亢而风动。“热”为本病的发病始动因素,“风”为本病的发病续动因素,且与痰、火、瘀、虚等病理要素紧密相干,提出建立“热-风”病因树模型,热为“热-风”病因树之根蒂,痰、瘀、虚为“热-风”病因树之叶、枝、蔓,风则为“热-风”病因树之果。以此模型来探析抽动障碍的病因机制,确定疾病发展阶段,防治小儿抽动障碍。在确定治疗原则上以河间流派“火热论”为指导,治以伐根摘叶之清热化痰,削其结果之息风止痉,平其枝蔓之滋水涵木等,提供治疗此病的新思路,并可从其中探寻完善和高效的论治方法和临床研究方向,为患儿带来福祉。

Conversion of pure Chinese fir plantation to multi-layered mixed plantation enhances the soil aggregate stability by regulating microbial communities in subtropical China

Background:Soil aggregates are the basic units of soil structure,and their stability is a key indicator of soil quality and capacity to support ecosystem functions.The impacts of various environmental factors on soil aggregates have been widely studied.However,there remains elusive knowledge on the synergistic effects of changing forest stand structure on soil aggregate stability(SAS),particularly in subtropical China where soil erosion remains a critical issue.Methods:We investigated variations in the components of soil humus(HS),including humic acids(HAs),fulvic acids(FAs),and humins(HMs),under pure Chinese fir(Cunninghamia lanceolata)plantation(PP)and multilayered mixed plantation(MP)comprising C.lanceolata,Castanopsis hystrix,and Michelia hedyosperma.The state of soil aggregate stability,was determined by three separate methods,i.e.,dry-sieving,wet-sieving,and the Le Bissonnais.High-throughput sequencing was used to determine the diversity and composition of microbial communities under PP and MP.We then built partial least squares path models(PLS-PM)for assessing the responses of SAS to the variations in soil microorganisms and HS components.Results:The MP stands had significantly greater SAS(P<0.05),higher content of HAs and more rapid organic matter humification within aggregates,than the PP stands.High-throughput sequencing confirmed that the Pielou andα-diversity index values(Chao1 and Shannon)for fungi were all significantly higher under MP than under PP,while no marked difference was found in bacterialα-diversity between the two plantation types.Moreover,there were markedly greater abundance of three bacterial phyla(Verrucomicrobia,Chloroflexi,and Gemmatimonadetes)and three fungal phyla(Ascomycota,Kickxellomycota,and Glomeromycota),and significantly less abundance of two bacterial phyla(Planctomycetes and Firmicutes)and four fungal phyla(Basidiomycota,Mortierellomycota,Mucoromycota,and Rozellomycota)under MP than under PP.The Chloroflexi and Ascomycota phyla appeared to be the primary drivers of soil aggregate distribution.Our findings revealed that the promotion of SAS under MP was mainly driven by increased soil organic matter(SOM)content,which altered bacterial communities and enhanced fungal diversity,thereby increasing HAs content and the rate of organic matter humification.Conclusions:Considering the combined effects of enhanced soil quality,productivity,and relevant economic costs,introducing broadleaved tree species into Chinese fir plantations can be an effective strategy for stabilizing soil structure against erosion in subtropical China.Our study elucidated the controls on variations of SAS in Chinese fir-dominated plantations and demonstrated the benefit of converting pure Chinese fir plantation to multi-layered mixed plantations in increasing soil structural stability and improving site quality.

Delineation of an Urban Community Life Circle Based on a Machine-Learning Estimation of Spatiotemporal Behavioral Demand

Delineating life circles is an essential prerequisite for urban community life circle planning. Recent studies combined the environmental contexts with residents’ global positioning system(GPS) data to delineate the life circles. This method, however, is constrained by GPS data, and it can only be applied in the GPS surveyed communities. To address this limitation, this study developed a generalizable delineation method without the constraint of behavioral data. According to previous research, the community life circle consists of the walking-accessible range and internal structure. The core task to develop the generalizable method was to estimate the spatiotemporal behavioral demand for each plot of land to acquire the internal structure of the life circle, as the range can be delineated primarily based on environmental data. Therefore, behavioral demand estimation models were established through logistic regression and machine learning techniques, including decision trees and ensemble learning. The model with the lowest error rate was chosen as the final estimation model for each type of land. Finally, we used a community without GPS data as an example to demonstrate the effectiveness of the estimation models and delineation method. This article extends the existing literature by introducing spatiotemporal behavioral demand estimation models, which learn the relationships between environmental contexts, population composition and the existing delineated results based on GPS data to delineate the internal structure of the community life circle without employing behavioral data. Furthermore, the proposed method and delineation results also contributes to facilities adjustments and location selections in life circle planning, people-oriented transformation in urban planning, and activity space estimation of the population in evaluating and improving the urban policies.

STUDY ON COMMUNITY STRUCTURE AND SELF-SUSTAINING MECHANISM OF BROAD-LEAVED/KOREAN PINE FORESTS IN NORTHEAST CHINA

The regeneration, tree growth, and community structure and dynamics were studied in old-growth Korean pine (Pinus koraiensis) forest.The results showed that the formation of tree form and growth character have been obviously related with the gap-phase regeneration.The ecological effects of the gap suppress the tree growth in diameter,and control that young tree stem fork in early stage.The heterogeneity of tree growth in time and space is the results of high quality in tree height and diameter.The hardwood species mixth Korean pine have different ecological effect on regeneration and tree growth of Korean pine in the early stage of gap reconstructing. Community dynamics depends on tree gaps oceurs,in which a 'cyclic sucession'between Korean pine and hard wood species may occurs.The process would take about 200 yers.

Tree structure and diversity of lowland Atlantic forest fragments：comparison of disturbed and undisturbed remnants

This study describes the tree community structure of three moist lowland Atlantic Forest fragments in Rio de Janeiro State, southeastern Brazil. Two fragments were disturbed and an undisturbed one was used as reference. Our hypothesis was that disturbed fragments show distinct structural patterns in comparison with undisturbed stands due to past disturbance practices and forest fragmentation. Four 100 ×5 m sampling plots were demarcated in each fragment and all live and dead trees with DBH C 5 cm were located, measured and identified. The results supported our hypothesis, due to the high values found for standing dead trees, an increase of dominance of a few pioneer species, lower values of large trees and species richness in disturbed fragments in comparison with the undisturbed one. The advanced fragmentation process in the Southern Brazilian lowland areas and the high species richness in undisturbed areas highlight these forest fragments as priority areas for conservation and management.

Phylogenetic Structure of Low Altitude Forest Communities in Baotianman Mountain

[Objectives]The paper was to reveal the phylogenetic structure of low altitude forest communities in Baotianman Mountain.[Methods]Ten 20 m×20 m plots were set at an altitude of 249-796 m in Baotianman Nature Reserve,in which 62 plant species were found.A phylogenetic tree was established on Phylomatic website,and the community related phylogenetic indexes at low altitude were calculated and analyzed,including net relatedness index(NRI),nearest taxon index(NTI),phylogenetic diversity Faith's PD index,phylogeneticβdiversity PhyloSor index and Dnn index.[Results]The NTI and NRI values of low altitude forest communities were generally greater than 0,showing phylogenetically clustered communities,and habitat filtration was the dominant factor in community construction.Combined with the species abundance matrix of plots,it was found that PD index had a significantly positive correlation with species richness.Phylogeneticβdiversity PhyloSor index was larger in the lower altitude area,which was exactly opposite to Dnn index.In other words,the more similar the community,the closer the distance between species,and the communities were phylogenetically clustered.[Conclusions]The study can provide a scientific basis for forest community management and restoration.

Effect of Soil Properties on Tree Distribution across an Agricultural Landscape on a Tropical Mountain, Tanzania

Distribution of tree species can result in many factors including environmental variables, biotic interaction and management. Better understanding of these interacting factors is crucial in planning management interventions especially in managed landscapes: this study on the effect of soil properties on tree species distribution in Kilimanjaro, Tanzania will aid in this. Standard tree inventory procedures and soil sampling techniques were used to survey 48 plots from altitudinal level of 680 to 1690 m a.s.l. along 25 km long transect. All trees ≥ 5 cm at DBH were recorded, while soils were sampled from top and subsoils (0 - 20 and 21 - 50 cm depths). Tree species distribution index was assessed through abundance and frequency, while species interaction with environmental variables was assessed using Detrended Correspondence Analysis. Distribution index indicated that 77% of tree species were categorized as rare, while 10% and 13% were categorized as occasional and abundant respectively. Soil organic carbon and moisture content have shown high correlation with tree species (r > 0.8, p < 0.01), while ExMg, soil pH, P, ExCa, ExK, ExNa and bulky density indicated less correlation (r < 0.2, p < 0.001). The DCA-1 axis explained nearly 70% of the relationships between soil properties and tree species distribution: suitability of tree species were influenced by soil properties across the land use systems which exhibited different soil types. Different tree species communities correspond differently with soil properties between the land use systems. Fewer tree species spread in the lowland, which is known to have saline soils. Therefore, despite intensive human management of the landscape, tree species indicated distribution patterns in line with the soil properties.

发达地区村级集体经济组织费用支出研究——以东莞市A社区股份经济合作社为例

本文通过对东莞市D城区A社区股份经济合作社的案例研究,分析了其费用支出存在的问题,并进一步剖析了问题产生的原因:收入依赖出租,增长缓慢,旧的发展模式难以为继。提出相应的对策,如:加快经济多元化发展、加强对新经济形态费用的控制、促进偿还债务、推行村级预算制度等。

Isolated alpine habitats reveal disparate ecological drivers of taxonomic and functional beta-diversity of small mammal assemblages

The interpretation of patterns of biodiversity requires the disentanglement of geographical and environmental variables.Disjunct alpine communities are geographically isolated from one another but experience similar environmental impacts.Isolated homogenous habitats may promote speciation but constrain functional trait variation.In this study,we examined the hypothesis that dispersal limitation promotes taxonomic divergence,whereas habitat similarity in alpine mountains leads to functional convergence.We performed standardized field investigation to sample non-volant small mammals from 18 prominent alpine sites in the Three Parallel Rivers area.We estimated indices quantifying taxonomic and functional alpha-and beta-diversity,as well as beta-diversity components.We then assessed the respective importance of geographical and environmental predictors in explaining taxonomic and functional compositions.No evidence was found to show that species were more functionally similar than expected in local assemblages.However,the taxonomic turnover components were higher than functional ones(0.471±0.230 vs.0.243±0.215),with nestedness components showing the opposite pattern(0.063±0.054 vs.0.269±0.225).This indicated that differences in taxonomic compositions between sites occurred from replacement of functionally similar species.Geographical barriers were the key factor influencing both taxonomic total dissimilarity and turnover components,whereas functional betadiversity was primarily explained by climatic factors such as minimum temperature of the coldest month.Our findings provide empirical evidence that taxonomic and functional diversity patterns can be independently driven by different ecological processes.Our results point to the importance of clarifying different components of beta-diversity to understand the underlying mechanisms of community assembly.These results also shed light on the assembly rules and ecological processes of terrestrial mammal communities in extreme environments.

Latitudinal gradients of associations between beta and gamma diversity of trees in forest communities in the New World

Aims We analyze two continental data sets of forest communities from across the New World to examine the latitudinal gradients of beta diversity after accounting for gamma diversity and the latitudinal gradient of gamma diversity after accounting for beta diversity.Methods Correlation and regression analyses were used to relate beta and gamma diversity to latitude along two latitudinal gradients in the New World(one including 72 forest sites located south of the equator and the other including 79 forest sites located north of the equator).Important Findings Beta diversity and gamma diversity were negatively correlated with latitude.Beta diversity was strongly and positively correlated with gamma diversity(Pearson’s correlation coefficient:0.783 for New World North and 0.848 for New World South).When beta diversity was regressed on latitude and gamma diversity,69.8 and 85.7%of the variation in beta diversity were explained,respectively,for New World North and New World South.When gamma diversity was regressed on latitude and beta diversity,81.8 and 84.3%of the variation in gamma diversity were explained,respectively,for New World North and New World South.After statistically removing the relationship between beta and gamma diversity,latitude has weak or no relationships with beta and gamma diversity.However,strong positive correlations between beta and gamma diversity may not be considered as evidence of one driving the other along a latitudinal gradient.

Patterns of forest composition and their long term environmental drivers in the tropical dry forest transition zone of southern Africa

Background： Tropical dry forests cover less than 13 % of the world＇s tropical forests and their area and biodiversity are declining. In southern Africa, the major threat is increasing population pressure, while drought caused by climate change is a potential threat in the drier transition zones to shrub land. Monitoring climate change impacts in these transition zones is difficult as there is inadequate information on forest composition to allow disentanglement from other environmental drivers. Methods： This study combined historical and modern forest inventories covering an area of 21,000 km2 in a transition zone in Namibia and Angola to distinguish late succession tree communities, to understand their dependence on site factors, and to detect trends in the forest composition over the last 40 years. Results： The woodlands were dominated by six tree species that represented 84 % of the total basal area and can be referred to as Bdikioea - Pterocarpus woodlands. A boosted regression tree analysis revealed that late succession tree communities are primarily determined by climate and topography. The Schinziophyton rautanenfi and Baikiaea plurijuga communities are common on slightly inclined dune or valley slopes and had the highest basal area （5.5 - 6.2 m^2 ha＆-1）. The Burkea africana - Guibourtia coleosperma and Pterocarpus angolensis - Diafium englerianum communities are typical for the sandy plateaux and have a higher proportion of smaller stems caused by a higher fire frequency. A decrease in overall basal area or a trend of increasing domination by the more drought and cold resilient B. africana community was not confirmed by the historical data, but there were significant decreases in basal area for Ochna pulchra and the valuable fruit tree D. englerianum. Conclusions： The slope communities are more sheltered from fire, frost and drought but are more susceptible to human expansion. The community with the important timber tree P. angolensis can best withstand high fire frequency but shows signs of a higher vulnerability to climate change. Conservation and climate adaptation strategies should include protection of the slope communities through refuges. Follow-up studies are needed on short term dynamics, especially near the edges of the transition zone towards shrub land.

An updated megaphylogeny of plants,a tool for generating plant phylogenies and an analysis of phylogenetic community structure

Aims The aim of this article is 3-fold.First,we present an updated version of a published megaphylogeny of vascular plants that can be used in studies of plant ecology and biogeography.second,we develop a tool that can be used by botanists and plant ecologists to generate phylogenetic hypotheses in three scenarios.Third,we use a set of regional assemblages of angiosperm trees in North america as a model system to evaluate the effect of differences in phylogenies generated using the three scenarios on the quantification of phylogenetic properties and the relationship between measures of phylogenetic properties and environment.Methods The taxonomy and nomenclature of plant species in the megaphy-logeny were standardized according to The Plant list(version 1.1).a tool for generating phylogenies was created using the r language.The robustness of derived phylogenies was evaluated using correlation and regression analyses.Important Findingsan updated megaphylogeny of vascular plants(PhytoPhylo)and a tool for reconstructing phylogenies of seed plants(s.Phylomaker)were generated.our study shows that phylogenies generated by s.Phylomaker using the PhytoPhylo megaphylogeny as a backbone are nearly as good as phylogeny resolved at the species level when using derived phylogenies to quantify phylogenetic properties(e.g.phylogenetic diversity and phylogenetic relatedness)of biological assemblages,and that s.Phylomaker-generated phylogenies are robust for studies of community ecology and biogeography,par-ticularly those seeking for patterns of phylogenetic properties along environmental gradients.

The effect of microclimate on wood decay is indirectly altered by tree species diversity in a litterbag study

Aims We studied the influence of tree species diversity on the dynamics of coarse wood decomposition in developing forest communities in a natural,topographically heterogeneous landscape.Using the litter bag technique,we investigated how and to which extent canopy tree species richness or the exclusion of mesoinvertebrates and macroinvertebrates affected wood decomposition in the light of natural variations in the microclimate.We compared the relative importance of the two aspects(experimental treatment versus microclimate)on wood decay rates using Schima superba as a standard litter.Methods Coarse woody debris(CWD)was deposited in litter bags with two different mesh sizes in a total of 134 plots along a gradient of canopy tree species richness(0-24 species).Wood decomposition was assessed at two consecutive time points,one and three years after deposition in the field.Local climatic conditions were assessed throughout the duration of the experiment.Microclimatic conditions were assessed both,directly in the field as well as indirectly via correlations with local topography.We used analysis of variance based approaches to assess the relative importance of the treatments(community tree species richness and macro invertebrate exclusion)and microclimatic conditions on wood decay.Important Findings No direct influence of tree species richness on wood decay could be detected.However,the exclusion of macroinvertebrates significantly decreased wood decomposition rates.In addition,microclimatic conditions accounted for a substantial proportion of explained variance in the observed data.Here,wood decomposition was negatively affected by low mean temperatures and high variations in local humidity and temperature.However,tree species richness as well as the respective species composition affected the presence of termites within forest communities.These,in turn,significantly increased the decay of CWD.The strength of both,experimental treatment and microclimate increased with ongoing decomposition.We conclude that,while tree species richness per se has no direct influence on wood decomposition,its influence on the local arthropod decomposer community(especially the presence of termites)does have an effect.

How forest edge-center transitions in the herb layer interact with beech dominance versus tree diversity

Aims Forest fragmentation and the associated augmentation of forest edge zones are increasing worldwide.Forest edges are characterized by altered plant species richness and community composition.As the tree layer and its species composition has been shown to influence herb layer composition,changes in tree species composition or richness may weaken or strengthen edge effects in forest ecosystems.We studied effects of the edge-center transition,tree species composition and their potential interaction on the understory vegetation in the Hainich National Park,Germany’s largest connected deciduous forest,allowing to cover large edge-center transects.Methods We established 12 transects in an area of 75 km^(2) of continuous forest,6 beech-dominated and 6 in multispecies forest stands.Each transect reached from the forest edge up to 500 m into the forest interior.Vegetation relevés were conducted in regular,logarithmic distances along each transect.Important Findings Herb species richness was influenced by an interaction of edge effects and tree diversity level.With increasing distance from the forest edge,herb species richness remained constant in multispecies forest stands but rapidly decreased in beech-dominated forest stands.Further,herb richness was higher in the interior of multispecies forest stands.Percent forest specialists increased and percent generalists decreased with distance from the edge and this contrasting pattern was much more pronounced in beech-dominated transects.By using structural equation modeling,we identified litter depth mediated by tree species composition as the most important driver of herb layer plant species richness.

Bird community comparisons of four plantations and conservation concerns in South China

Plantations of non-native,fast-growing trees are increasing in the tropics and subtropics,perhaps with negative consequences for the native avifauna.We studied bird diversity in 4 types of plantations in South China to deter-mine which plantation types are especially detrimental,and compared our findings with studies in nearby natu-ral forests to assess the magnitude of the negative impact.A total of 57 species was recorded.The mean capture rate of understory birds was 1.7 individuals 100-net-h-1.Bird richness and capture rate were lower in plantations than in nearby natural forests.Babblers(Timaliidae),primarily forest-dependent species in South China,were particularly under-represented in plantations.Species richness,composition and bird density,particularly of un-derstory birds,differed between plantation types.Plantations of Schima,which is native to South China,had the highest species richness according to point count data.Plantations of Acacia(non-native)supported the highest understory species richness and produced the highest capture rate of understory birds,probably because of their complex structure and high arthropod abundance.If bird diversity is to be considered,we strongly recommend that future re-afforestation projects in South China should,as far as possible,use mixed native tree species,and especially Schima,ahead of the other species.

Biomass dynamics of Quercus aliena var.acutesrata Community on Mountain Xiaolong in Gansu Province,China

The dynamics of tree layer biomass was studied by combining 35 sample plots of field census with biomass model estimation in a natural Quercus aliena var.acutesrata community on Mountain Xiaolong in Gansu Province,China.The tree layer biomass of Quercus aliena var.acutesrata community was 183660 kg/ha,in which the slow growth group accounted for 64.89%of the total biomass.The fast-medium growth group accounted for 33.40%and the coniferous group accounted for 1.38%.The organs biomass was found to be in the following order:trunk>root>branch>leaf.The total biomass accumulated with the development of the community.The total biomass and the biomass of the organs were highest in the mature community and became stable as the community developed.The relative growth rate of organs was in the following order:trunk>branch>root>leaf.The biomass ratio of the slow growth group trees tended to increase and the fast-medium group trees tended to decrease as the community developed,which was reveresed in the decline development stage.The biomass of the coniferous group was very small throughout the development process.