Movement patterns of selected insect groups between natural forest,open land and rubber plantation in a tropical landscape (southern Yunnan,SW China)

In many regions of tropical Asia, the expansion of rubber monoculture plantations is conducted by replacement of natural forest areas and strongly affects biodiversity and movement patterns of wild species, including insects. Against this background, we conducted a study on selected insect groups (longhorn beetles, bark beetles, wild bees and hoverflies) along transects between rainforest patches, open uncultivated land and rubber plantation habitats in a region of Xishuangbanna (southern Yunnan, China), with the objectives to identify (a) movement directions and patterns of selected insect groups based on their abundances in modified Malaise traps in the different habitats, and (b) the role of remaining natural rainforest patches and rubber plantations, respectively, for insect diversity maintenance and conservation. The highest total numbers of species and individuals of bark beetles, longhorn beetles and wild bees were recorded from the natural forest edge compared to open land and rubber plantation edge. This result clearly indicates that the natural forest plays an important role in maintenance of these three insect groups. However, the highest number of hoverfly species and individuals was recorded from the open land sites, indicating the most relevant habitat type for this group of species. Overall, the lowest species and individual numbers were recorded from the rubber plantation edge, indicating the unsuitability of this habitat type for all insect groups considered. The distribution of species and individuals in the opposite trap sides along the transect indicates that longhorn beetles, bark beetles and wild bees show not only movements from the forest to the surrounding habitats, but also return back after encountering the unsuitable rubber plantation habitat. Bark beetle composition showed the relatively highest similarity between all trap sites and opposite trap sides among the insect groups considered, indicating a higher movement activity than the other groups. The four insect groups considered in this study show different movement modes between the forest, open land and rubber plantation, which are not the same for all taxa. Except for hoverflies, the natural forest was found to be the most important habitat for the maintenance of species diversity in the different land use types of the study area.     

Non-native plantation forests as alternative habitat for native forest beetles in a heavily modified landscape

The once extensive native forests of New Zealand’s central North Island are heavily fragmented, and the scattered remnants are now surrounded by a matrix of exotic pastoral grasslands and Pinus radiata plantation forests. The importance of these exotic habitats for native biodiversity is poorly understood. This study examines the utilisation of exotic plantation forests by native beetles in a heavily modified landscape. The diversity of selected beetle taxa was compared at multiple distances across edge gradients between each of the six possible combinations of adjacent pastoral, plantation, clearfell and native forest land-use types. Estimated species richness (Michaelis–Menten) was greater in production habitats than native forest; however this was largely due to the absence of exotic species in native forest. Beetle relative abundance was highest in clearfell-harvested areas, mainly due to colonisation by open-habitat, disturbance-adapted species. More importantly, though, of all the non-native habitats sampled, beetle species composition in mature P. radiata was most similar to native forest. Understanding the influence of key environmental factors and stand level management is important for enhancing biodiversity values within the landscape. Native habitat proximity was the most significant environmental correlate of beetle community composition, highlighting the importance of retaining native remnants within plantation landscapes. The proportion of exotic beetles was consistently low in mature plantation stands, however it increased in pasture sites at increasing distances from native forest. These results suggest that exotic plantation forests may provide important alternative habitat for native forest beetles in landscapes with a low proportion of native forest cover.     

Restore it,and they will come: trap-nesting bee and wasp communities (Hymenoptera: Aculeata) are recovered by restoration of riparian forests

Riparian forests have been greatly affected by anthropogenic actions with formerly continuous riparian forests being slowly converted into small and isolated patches. Riparian forests are extremely important habitats for many groups of insects, including bees and wasps, because they are sources of shelter and food for them and their offspring. There is a growing body of evidence of success in the restoration of riparian forest plant communities; however, little research has been done on the associated invertebrate communities. We test whether restoring plant communities is sufficient for restoring the taxonomic composition of trap-nesting bees and wasps and which functional traits are favored in different sites. We predict that species richness, abundance, and community composition of trap-nesting bees and wasps of riparian sites undergoing restoration will converge on the “target” of a reference site with increasing time, since restoration increases habitat complexity. We also predict that the width of restored patches will also influence the species richness, abundance and community composition of trap-nesting bees and wasps. Bee richness and abundance, and wasp richness, were strongly related to fragment width, but not to age since restoration. Our results indicate that although restored sites are relatively small and scattered in a fragmented landscape, they provide suitable habitat for re-colonization by community assemblages of trap-nesting bees and wasps and the traits selected captured the responses to the habitat restoration. Hence, restored riparian areas can be considered important habitats for invertebrates, thus contributing to an increase in local biodiversity and, possibly, the restoration of some of the ecosystem services they originally provided.     

同域分布大熊猫和水鹿生境利用分异特征

野生动物的生境利用特征研究是动物生态学核心问题之一,同域分布动物对生境的利用特征及共存机制是其重要组成部分,也是实现珍稀濒危物种保护与栖息地恢复的基础。基于空间利用和生境因子选择差异研究了卧龙自然保护区同域分布大熊猫(Ailuropoda melanoleuca)和水鹿(Rusa unicolor)的生境利用关系,探讨了同域分布野生动物在生境因子选择和空间利用的分异特征。结果表明:(1)空间利用上,大熊猫和水鹿的空间重叠系数为58.35%,其中,在原始林和次生林生境中的空间重叠系数分别为66.58%和36.64%,二者在原始林中的空间重叠较高;(2)生境因子选择上,大熊猫和水鹿对物理因子的选择有坡位、离小路距离和离水源距离3个变量有显著性差异,对生物因子的选择有乔木密度、灌木盖度、灌木密度、竹林盖度、幼竹密度、幼竹基径、幼竹高度、成竹高度和死竹密度9种变量有显著性差异;(3)大熊猫和水鹿都表现为更偏好原始林生境,但大熊猫对原始林的依赖性更强。分析同域分布动物的生境利用关系有利于深入了解不同动物对资源的空间利用特征及共存机制,可以为保护区制定珍稀野生动物保护和栖息地恢复政策提供科学依据。     

Mimicking natural disturbances of boreal forests: the effects of controlled burning and creating dead wood on beetle diversity

The young successional stages of boreal forests are an important habitat for many saproxylic species. These habitats are formed by disturbances such as forest fires and they are characterized by large volumes of dead wood and sun-exposed conditions. Today, young successional stages of natural origin are very rare in Fennoscandia and there is need for restoration. We constructed a large-scale field experiment in which we studied the effects of two restoration practices on beetle diversity: controlled burning and partial harvesting with creating different volumes of dead wood. We sampled beetles with flight-intercept traps recording a total of 56,031 individuals and 755 species. The species richness and abundance of both saproxylic and non-saproxylic beetles were increased by burning and harvesting but the volume of dead wood created on harvested sites had no short-term effect on species richness or abundance. Rare species, especially saproxylic ones, preferred burned sites and a similar trend was observed among red-listed and pyrophilous species. Burning and harvesting also resulted in different species assemblages and there were some additional differences according to the volume of dead wood. We conclude that fire can be successfully used in restoration of managed boreal forests to increase species diversity and to facilitate the recovery of declined species. However, long-term monitoring is needed to clarify the effects of the restoration practices, in particular those of creating dead wood without using fire.     

Dung beetle assemblages in primary forest and disturbed habitats in a tropical dry forest landscape in western Mexico

Dung beetles (Scarabaeinae) are conspicuous components in most terrestrial ecosystems, performing important ecological functions and services. Being sensitive to several types of disturbance, they have been successfully used as indicators of habitat change. Dung beetle communities in tropical rainforests have been well studied, but considerably less information is available for tropical dry forests. In this study I sampled dung beetles in two undisturbed habitats, deciduous forest and semideciduous forest, and two disturbed habitats, secondary forest and open area habitat, in the Chamela-Cuixmala region of western Mexico. Dung beetle species with high indicator value for each habitat were identified. Beetle abundance, observed species richness and estimated species richness were similar in the three forest habitats, but significantly lower in the open area habitat. A more detailed analysis of species-specific abundances in the three forest habitats revealed some differences. Transects of one of the undisturbed habitats, the deciduous forest, were more similar to the non-adjacent transects of disturbed secondary forest, than to the adjacent undisturbed semideciduous forest transects. Unlike studies in other tropical sites that have found a decrease in equitability in Scarabaeinae assemblages between undisturbed forest and disturbed habitat (particularly open habitats), in the Chamela-Cuixmala region all four habitats showed similar low equitability in community structure, with two or three very dominant species.     

Capture Rates of Male Euglossine Bees across a Human Intervention Gradient, Chocó Region, Colombia1

Euglossine bees are important pollinators of lowland Neotropical forests. Compared to disturbed habitats, undisturbed ones have been previously characterized by higher abundance and diversity of euglossine bees. Most past studies have relied on chemically baiting male bees at single sites within habitats. Over a two‐year period, we employed a repeated‐measures design in which we sampled bees at multiple sites within three different habitat types, reflecting a mosaic of human disturbance (farm, secondary forest, and old logged forest). After 22 monthly samples, a total of 2008 male bees were captured, representing 31 species in five genera: 1156 at the farm (57.6%, 21 spp.), 505 in the secondary forest (25.1%, 27 spp.), and 347 in the old logged forest (17.2%, 21 spp.). Eighty‐one percent of the bees captured belonged to the five most abundant species: Eulaema cingulata, El. chocoana, Euglossa hansoni, Eg. ignita, and Eg. imperialis. These species differed significantly in capture frequencies among habitats. Eulaema cingulata, El. chocoana, and Eg. ignita were captured most frequently at the farm, while Eg. imperialis was most abundant in the secondary forest. In contrast, Eg. hansoni, the sole short‐tongued species among the five, was equally abundant in the two forest habitats but occurred rarely on the farm. Additionally, habitats differed in bee composition. The high capture rates for long‐proboscis species at the farm may have been due to their ability to extract nectar from flowers with long floral tubes, which probably occurred at a greater density on the farmed land than in the adjacent forests.     

The effects of forestry on carabid beetles (Coleoptera: Carabidae) in boreal forests

As compared to natural forests, managed boreal forests are younger, more homogeneous in terms of tree age and species composition, and consist of smaller fragments. Here we examine the effects of such characteristics caused by forestry on carabid beetles (Coleoptera, Carabidae) in the boreal region. The main results are the following. (1) Fragmentation of forests and the size of a fragment appear not to be crucial for the survival of the majority of forest carabids, as they tend to be distributed over various successional stages, but species requiring old-growth habitats suffer. (2) For carabids there appear to be no or very few edge specialist species, and forest-open land edges appear to be effective barriers for species associated with forest or open habitat. However, generalist species easily cross the edge, and edges of forest fragments may be invaded by species from the surrounding open habitat. (3) Habitat change following clear-cutting dramatically changes the composition of carabid assemblages: species restricted to mature forests disappear and open-habitat species invade, while habitat generalists survive at least in the short term. Carabid diversity can probably best be maintained if forest management mimics natural processes, maintains natural structures and includes the natural composition of vegetation and other structural elements (such as dead wood) within the stands, provided that these forest features can be maintained and recreated through forest management practices. At a larger scale, the whole spectrum of forest types and ages (especially old-growth forests), and different successional processes (especially fire) should be maintained. These require the development and use of innovative logging methods, and the planning, implementation, and assessment of landscape-scale ecological management strategies.     

Asymmetric carabid beetle spillover between calcareous grasslands and coniferous forests

Central European calcareous grasslands are considered biodiversity hotspots, but are severely threatened by the change in land-use and by habitat fragmentation. Coniferous forests are typical adjacent habitats to calcareous grasslands, as abandoned calcareous grasslands are often afforested or develop into coniferous forests by succession. To investigate spillover between calcareous grasslands and coniferous forests, a total of 144 pitfall traps for carabid beetles were placed at three different distances (1, 5, 20 m) from the edge in both habitats at eight locations from April to late August. We found that both habitats had a distinct species assemblage and a decrease in spillover with increasing distance from the habitat edge into the adjacent habitat. Calcareous grasslands were more affected by spillover from the adjacent coniferous forests than vice versa because more forest specialists penetrated into calcareous grasslands than grassland specialists penetrated into coniferous forests. We conclude that spillover into small and isolated habitats can severely change species assemblages, which has to be considered in conservation measures. The protection of large sites with small edge-interior ratios can reduce negative effects on species assemblages in endangered calcareous grasslands.     

Landscape context of plantation forests in the conservation of tropical mammals

Plantation forests have been expanding in many tropical and subtropical environments. Howerver, even when they replace less wildlife friendly land uses such as pastures and annual crops, the biodiversity levels of pristine natural habitats often have not been recovered. Here we addressed how the landscape context of plantation forests located in South-eastern Brazil affects species richness and community resilience of medium and large size mammals. The area covered by native habitat fragments surrounding plantation forests is positively related to functional richness, including the presence of species more vulnerable to extinction in fragmented landscapes. In addition, the degree of aggregation of plantation forest stands is negatively related to more vulnerable species. No primates were recorded in our seven plantation forest sites (ranging from 272 to 24,921 ha), even when they were seen in native habitat fragments adjacent to commercial tree stands. Two invasive species (Sus scrofa and Lepus capensis) were recorded in four plantation forest sites. The impoverishment of fauna in plantation forests is due to two factors. First, plantation forests generally are structurally simplified habitats when compared to highly diverse tropical forests. Secondly, the isolation from habitat fragments which act as source of individuals in the landscape precludes the establishment of individual in plantation forest. We also highlighted the management practices to improve the complexity of vegetation in commercial tree stands should be taken cautiously, insofar as reduced productivity per area entails a greater demand for land. Thus, an alternative would be intensify the management of the commercial tree stands for wood production together with the restoration of adjacent areas set aside to conservation and native habitat fragments protection.     

The specific assemblage structure of longhorn beetles (Coleoptera,Cerambycidae) in floodplain forests of the western part of Saratov oblast

The biodiversity structure and habitat requirements of longhorn beetles (Cerambycidae) in floodplain forests of the western part of Saratov oblast were studied from 2011 to 2014. A total of 51 species of longhorn beetles has been identified. The largest subfamilies are Cerambycinae (19 species), Lepturinae (17 species), and Lamiinae (13 species). The specific communities include 34, 14, 11, 9, 7, 7, 6, and 3 species for oak, aspen, elm, willow, linden, maple, alder, and ash tree, respectively. The largest number of longhorn beetle species was found in oak forests.     

Effects of intensive human management on the taxonomic and functional diversity of ground beetles in a planted forest landscape

The rapid expansion of planted forests harms native biodiversity. Few studies report the effects of replacing wetlands with planted forests on ground beetles. We analyze how the taxonomic and functional diversity of ground beetles are affected by intensive management of a planted forest landscape in the Lower Delta of the Parana River. We defined six habitat types (n?=?3, N?=?18): young and mature willow (YW, MW), young and mature poplar without cattle (YP, MP), young and mature silvopastoral poplar (YS, MS). Using pitfall traps (N?=?1728), we recorded 35 species (1896 individuals). YW and MS reached the highest taxonomic diversity and richness. YW with more vertical heterogeneity showed higher species richness than MW. Hydrophilic species were more abundant in YW. Zoophagous species were more abundant in MS. YS, MS, and YW reached the highest functional evenness, which implies that a large part of the functional niches was used. Cattle dung and freshwater canals for livestock offer more resources for ground beetles. The planted tree species, stand age, and presence of cattle affects taxonomic and functional diversity of ground beetles. Willow and silvopastoral planted forests are the most suitable habitats for hosting wetland species. So, we recommend using willow species rather than poplar species when planted forests replace fluvial wetlands, increasing irrigation of poplar planted forests through ditches and canals, conserving or restoring different strata of understory to increase vertical heterogeneity, and maintaining the landscape heterogeneity. These management measures are essential to prevent the loss of wetland species and conserve ground beetle’s diversity.

     

Connectivity with primary forest determines the value of secondary tropical forests for bird conservation

Species extinctions caused by the destruction and degradation of tropical primary forest may be at least partially mitigated by the expansion of regenerating secondary forest. However, the conservation value of secondary forest remains controversial, and potentially underestimated, since most previous studies have focused on young, single‐aged, or isolated stands. Here, we use point‐count surveys to compare tropical forest bird communities in 20–120‐year‐old secondary forest with primary forest stands in central Panama, with varying connectivity between secondary forest sites and extensive primary forest. We found that species richness and other metrics of ecological diversity, as well as the combined population density of all birds, reached a peak in younger (20‐year‐old) secondary forests and appeared to decline in older secondary forest stands. This counter‐intuitive result can be explained by the greater connectivity between younger secondary forests and extensive primary forests at our study site, compared with older secondary forests that are either (a) more isolated or (b) connected to primary forests that are themselves small and isolated. Our results suggest that connectivity with extensive primary forest is a more important determinant of avian species richness and community structure than forest age, and highlight the vital contribution secondary forests can make in conserving tropical bird diversity, so long as extensive primary habitats are adjacent and spatially connected.Abstract in Spanish is available with online material.     

Plant-pollinator interactions in tropical monsoon forests in Southeast Asia

Forests with different flora and vegetation types harbor different assemblages of flower visitors, and plant-pollinator interactions vary among forests. In monsoon-dominated East and Southeast Asia, there is a characteristic gradient in climate along latitude, creating a broad spectrum of forest types with potentially diverse pollinator communities. To detect a geographical pattern of plant-pollinator interactions, we investigated flowering phenology and pollinator assemblages in the least-studied forest type, i.e., tropical monsoon forest, in the Vientiane plain in Laos. Throughout the 5-year study, we observed 171 plant species blooming and detected flower visitors on 145 species. Flowering occurred throughout the year, although the number of flowering plant species peaked at the end of dry season. The dominant canopy trees, including Dipterocarpaceae, bloomed annually, in contrast to the supra-annual general flowering that occurs in Southeast Asian tropical rain forests. Among the 134 native plant species, 68 were pollinated by hymenopterans and others by lepidopterans, beetles, flies, or diverse insects. Among the observed bees, Xylocopa, megachilids, and honeybees mainly contributed to the pollination of canopy trees, whereas long-tongued Amegilla bees pollinated diverse perennials with long corolla tubes. This is the first community-level study of plant-pollinator interactions in an Asian tropical monsoon forest ecosystem.     

Butterfly communities respond to structural changes in forest restorations and regeneration in lowland Atlantic Forest,Paraná, Brazil

The Atlantic forest is one of the most diverse biomes on Earth but human activities are transforming this ecosystem into one of the most endangered. Most remnant old-growth rainforest is embedded within a mosaic of regenerating forest, tree plantations, pastures, and agricultural production. This has left a large percentage of the region’s endemic species threatened with extinction. Butterflies are considered as sensitive indicators of ecological conditions, especially in the Atlantic forest. This community can provide a window into animal response to restoration and how recovering habitats are used by native animal communities. The primary goal of this paper was to determine if butterfly communities respond to measures of structural recovery in naturally regenerating and re-forested pastures, and if this response increases the similarity of recovering butterfly communities relative to those of intact forests. Butterfly communities were sampled using two sampling methodologies, passive bait trapping and timed meander counts. These data sets were combined and correlated to assessment of habitat structure. We found that butterfly communities respond rapidly to structural changes in habitats as forest structure recovers on abandoned and restored pastures. While many species of mature forest inhabiting butterflies use regenerating forests as habitat, our young forests also retained an almost intact community of ruderal pasture inhabiting butterflies as well, indicating that these habitats retain many features of highly disturbed pastures. We suggest that measures of beta-diversity, which can be used to assess convergence in community structure, are far superior to the alpha-diversity measures that are typically used for assessing restoration recovery.     

Primate and Dung Beetle Communities in Secondary Growth Rain Forests: Implications for Conservation of Seed Dispersal Systems

Conservation efforts are often aimed at one or a few species. However, habitat sustainability relies on ecological interactions among species, such as seed dispersal. Thus, a community-scale conservation strategy may be more valuable in some settings. We describe communities of primary (primates) and secondary (dung beetles) seed dispersers from 5 sites in the Brazilian Amazon. We estimate community biomass of these taxa and, using multivariate ordination, examine the potential for natural reforestation at each site, given the communities of seed dispersers present. Since disturbed habitat is increasingly common and increasingly the focus of conservation efforts, we also examine differences among seed disperser communities between primary forest and secondary growth at each site. Analyses of faunal biomass in different localities and habitats indicate that secondary growth receives nearly as much use by primates as primary forest; given the dominant groups of dung beetles in secondary growth, disturbed habitat should show a pattern of seed burial that is clumped and deep. Areas with high biomass of Alouatta spp. and the large nocturnal dung beetle species may have the greatest potential for natural reforestation of secondary growth particularly for large seeded species. The data suggest that knowledge of the biomass of primary and secondary dispersing fauna facilitates predictions for the likelihood of disturbed habitat to regenerate and comparisons of sites in broader geographical areas e.g., Neotropical vs. Paleotropical forests.     

Mean latitudinal range sizes of bird assemblages in six Neotropical forest chronosequences

Aim The geographical range size frequency distributions of animal and plant assemblages are among the most important factors affecting large‐scale patterns of diversity. Nonetheless, the relationship between habitat type and the range size distributions of species forming assemblages remains poorly understood. We examined how the mean latitudinal range sizes of species in Neotropical bird species assemblages shift during forest clearance and subsequent regeneration. We tested the hypothesis that bird species assemblages in early successional habitats tend to have larger latitudinal ranges than those in more mature forests. Location We considered breeding bird chronosequence data from six Neotropical forests. Results Breeding bird assemblages were found to have the species with the largest average latitudinal range sizes in cleared areas, intermediate in young secondary forests and smallest in old secondary and mature forests. Similar differences were also found when we compared congeners differing in their successional preferences. Sizes of regional ranges (within the Neotropics) did not, however, differ consistently among successional stages. The larger latitudinal (but not regional) ranges of early successional species was as a result in part of the tendency of early successional species to have ranges that extend beyond the Neotropical forest biome. Conclusions Our analysis of chronosequences suggests that as early successional habitats mature, a consistent shift from large‐ranged species towards more small ranged species occurs. Even relatively old secondary forests have bird species with larger average ranges than mature forests. As a consequence, conservation of secondary forests alone will miss many of the species most at risk of extinction and most unlikely to be conserved in other locations or biomes.     

Direct costs of forest reproduction,bee-cycling and the efficiency of pollination modes

The bee guild represents direct primary costs of angiosperm reproduction. Tropical flower visitors take an amount comparable to herbivores, exceeding 3% of net primary production energy. Therefore herbivory and aboveground net primary production have been underestimated. Comparing pollinators to other herbivores, harvest in mature forest by tropical bees is greater than leafcutter ants, game animals, frugivores, vertebrate folivores, insect defoliators excluding ants, flower-feeding birds and bats, but not soil organisms. The ratio of total aboveground net primary production to investment in pollen, nectar and resin used by pollinators suggests wind pollination is several times more efficient in temperate forests than is animal pollination in neotropical moist forest. Animal pollination may be favoured by habitat mosaics and an unpredictable or sparse dispersion of conspecifics — consequences of fluctuating abiotic and biotic environments. Natural selection evidently favours diminished direct reproductive costs in forests, for example by wind pollination, regardless of latitude and disturbance regime. An example is “wind pollination by proxy” of dominant trees in seasonal southeast Asian forests. They flower only occasionally and their pollen is dispersed by tiny winged insects that are primarily carried by the wind — rather than the nectar-hungry bees, bats, birds and moths used by most tropical flora. Increasing evapotranspiration is associated with greater net primary production; I show its correlation with species richness of social tropical bees across the isthmus of Panama, which may indicate increasing forest reproductive effort devoted to flowering, and its monopolization by unspecialized flower visitors in wetter and less seasonal lowland forests.     

Tree colonization by the Asian longhorn beetle,Anoplophora glabripennis (Coleoptera: Cerambycidae): effect of habitat and tree suitability

Tree colonization and feeding activity of the invasive wood‐borer Asian longhorn beetle (Anoplophora glabripennis), an Asian pest introduced into North America and Europe, was studied in a newly invaded area in Italy. The hypothesis being tested was that the reproductive success of the insect depend on habitat type and tree suitability. Adult beetles were caged on branches of host and nonhost species, in both urban and forest habitats. Two months later, number and size of feeding patches on plant tissues, eggs laid, and surviving larvae were assessed. Bark concentration of C and N was also measured from the same trees. Results indicated that the mean area of plant tissues consumed by adult feeding was significantly larger on trees growing in forest than in urban habitat, although within the same habitat there were no differences between susceptible and nonsusceptible trees. ALB tree colonization, in terms of number of eggs laid and young larvae survival, was not affected by habitat while it was higher on susceptible trees. Although trees growing in forests had a lower nitrogen concentration, they allowed colonization rates similar to those of trees growing in the urban habitat. Hence, the amount of carbon and nitrogen did not fully explain tree suitability or habitat selection. We suggest compensatory feeding as a potential mechanism that might explain this peculiar situation, as supported by a more intensive feeding activity recorded on trees in the forest. Suitability of different trees may be due to other factors, such as secondary chemical compounds.     

小兴安岭森林地表鞘翅目成虫对不同干扰梯度的响应

为探讨小兴安岭凉水自然保护区森林生态系统中地表鞘翅目成虫群落对不同人为干扰梯度的响应,于2015年7月、8月和10月分别对轻度干扰[原始阔叶红松林(KY)和谷地云冷杉林(YL)]、中度干扰[阔叶红松择伐林(ZF)和次生白桦林(BH)]及重度干扰[落叶松人工林(RL)和红松人工林(RHS)]的6个林型进行取样调查。结果表明:(1)整个采样周期共捕获地表鞘翅目成虫879只,隶属9科44物种;其中轻度干扰生境共捕获6科29种251只(KY捕获5科21种150只,YL捕获4科20种101只),中度干扰生境捕获6科27种276只(ZF捕获3科20种144只,BH捕获6科23种132只),重度干扰生境捕获6科29种352只(RL捕获4科22种232只,RHS捕获5科17种120只)。(2)7月和8月步甲科和葬甲科占据数量优势,10月步甲科和葬甲科成虫数量明显减少而隐翅虫科数量占优势;不同林型及不同干扰梯度地表鞘翅目成虫物种总数和总个体数于7、8、10月均表现为下降趋势,且群落多样性也呈不同程度下降。(3)林型和月份对地表鞘翅目成虫群落结构具有显著影响,干扰梯度对群落结构无显著影响;6个林型之间地表鞘翅目成虫个体数量具有显著差异,但在物种组成上无显著差异;不同干扰梯度间地表鞘翅目成虫个体数、物种数无显著差异,且随干扰梯度变化没有明显的梯度性规律;相似性系数和聚类分析表明,属于同一干扰梯度的两个林型没有表现出高度的相似性。本研究表明干扰梯度不是决定各林型间地表鞘翅目成虫群落多样性存在差异的主要原因,凉水森林生态系统地表鞘翅目成虫对不同干扰梯度的响应不符合中度干扰假说,林型和时间则是影响地表鞘翅目成虫群落组成的显著因素,本实验为地表生物多样性保护和森林生态系统管理提供数据支撑。