亚热带不同树种组成森林中土壤甲螨群落结构特征: 以江西新岗山为例

在全球环境变化的大背景下, 生物多样性丧失日益加剧。土壤动物作为生物多样性重要组成之一, 受到广泛的关注。位于我国江西省新岗山的亚热带森林生物多样性与生态系统功能实验样地(BEF-China)是全世界25个森林生物多样性控制实验样地之一。本研究自2019年9月至2022年4月在BEF-China两个不同树种组成的样地(A样地和B样地)内采样, 共获得甲螨23,704头, 隶属于34科50属61种。本文分析和对比了两个样地内甲螨群落结构的差异, 及其多度、物种丰富度、Shannon多样性指数的季节性差异; 通过Pearson检验探讨了甲螨多度与环境因子的关系。结果表明: 在A、B两个不同树种组成的森林生态系统内, 土壤甲螨群落结构及其季节动态具有显著差异。具体表现在: A样地奥甲螨科、罗甲螨科、若甲螨科和尖棱甲螨科的相对多度高于B样地; B样地菌甲螨科、盖头甲螨科和礼服甲螨科的相对多度高于A样地。A样地中夏季和秋季甲螨多度、物种丰富度和Shannon多样性指数显著低于春季和冬季; 而B样地中秋季甲螨多度和物种丰富度与春季差异不显著。Pearson检验结果显示, 凋落物木质素含量与单翼甲螨科和菌甲螨科多度呈负相关关系, 而与奥甲螨科多度呈正相关关系。菌甲螨科多度与土壤和凋落物同一理化因子的相关性基本相同(碳氮比除外), 但与凋落物碳氮比呈正相关关系而与土壤碳氮比呈负相关关系。     

小麦-玉米轮作农田土壤螨多样性空间分布格局

以农田土壤动物长期监测样地为平台, 阐明土壤动物物种和功能多样性空间分布格局, 是揭示农田土壤动物多样性维持机制、提高农田土壤质量的重要基础。本试验于2020年10月, 对河南商丘农田土壤动物大型固定样地(9 ha)的210个采样点进行土壤样品野外采集和室内分离, 将土壤螨样品鉴定到种并测量其体长体宽数据, 以说明小麦-玉米轮作农田土壤螨多样性及其体长体宽的空间分布格局。结果表明: (1)共捕获成螨个体17,256头, 其中甲螨亚目为优势类群, 其个体数占总捕获量的94.67%; MGP分析表明样地甲螨群落属于P型, 说明受人为因素影响强烈; 生态位宽度和重叠度分析表明, 进化程度越高甲螨的生态位宽度越宽, 进化程度越相近甲螨之间的竞争越激烈。(2) Moran’s I分析显示, 在20-100 m的空间尺度上, 土壤螨群落、优势种的个体数和体长体宽多为显著正相关; 在220-300 m的空间尺度上, 部分为显著负的空间自相关。半方差函数结果表明, 甲螨群落物种数、个体数和体长体宽的空间变异主要受确定性过程影响, 中气门螨群落的空间变异由确定性和随机性过程共同影响。(3)土壤螨个体数与体长体宽存在显著弱的负相关关系, 这种关系普遍存在于土壤螨各群落与优势种中。本研究建议同时开展物种多样性和以体长体宽为代表的功能多样性空间格局研究, 对揭示土壤螨群落维持机制、保护土壤螨多样性具有重要意义。     

Headwater biodiversity among different levels of stream habitat hierarchy

With the current loss of biodiversity and threats to freshwater ecosystems, it is crucial to identify hot-spots of biodiversity and on which spatial scale they can be resolved. Conservation and management of these important ecosystems needs insight into whether most of the regional biodiversity (i.e. γ-diversity) can be found locally (i.e. high α-diversity) or whether it is distributed across the region (i.e. high β-diversity). Biodiversity patterns of benthic macroinvertebrates and diatoms were studied in 30 headwater streams in five Swedish catchments by comparing the relative contribution of α- and β-diversity to γ-diversity between two levels of stream habitat hierarchy (catchment and region level). The relationship between species community structure and local environmental factors was also assessed. Our results show that both α- and β-diversity made a significant contribution to γ-diversity. β-diversity remained relatively constant between the two levels of habitat hierarchy even though local environmental control of the biota decreased from the catchment to the region level. To capture most of headwater γ-diversity, management should therefore target sites that are locally diverse, but at the same time select sites so that β-diversity is maximized. As environmental control of the biota peaked at the catchment level, the conservation of headwater stream diversity is likely to be most effective when management targets environmental conditions across multiple local sites within relatively small catchments.     

北方常见农业土地利用方式对土壤螨群落结构的影响

土壤螨群落与土壤健康状况密切相关,农业土地利用方式会影响土壤螨的生存环境,进而影响螨的群落分布。在北方传统农业区研究了小麦玉米常规轮作农田,1年温室蔬菜大棚、4年温室蔬菜大棚和4年露天菜地下土壤主要理化指标和螨群落结构。研究结果表明露天菜地和温室大棚的利用方式均会提高土壤碱解氮和有机质含量,同时温室大棚的长期利用会增加土壤有效磷含量。螨群落分析显示常规农田中甲螨亚目为优势类群;常规农田转变为温室大棚后,由于施肥造成土壤营养物质含量增加,以及人类对土壤扰动程度的提高,无气门亚目取代甲螨亚目成为温室内螨优势类群。但随着温室年限的延长,螨多样性和粉螨科丰度都要有所下降,这可能是磷累积和强扰动效应的共同后果。常规农田转变为露天菜地后,加强的人类扰动也会降低甲螨亚目丰度,但与温室螨群落相比,4个亚目分布要相对均匀。温室在3种土地利用类型中对土壤螨的负面影响最为明显,从土壤功能的自我维持和修复方面来讲是十分不利的,温室内土壤生物多样性的保护尤其值得人们关注和重视。     

Awesome or ordinary? Global diversity patterns of oribatid mites

Diversity of most above-ground organisms increases with decreasing latitude, but the biogeographical and macroecological diversity patterns of below-ground animals have been poorly studied. We investigated the latitudinal diversity gradient in a primarily below-ground living soil taxon, oribatid mites. Furthermore, oribatid mite species richness from islands and mainlainds was tested for correlation with the size of the respective area (island or mainland) to evaluate if their species–area relationships are similar to those of above-ground taxa. The results suggest that for oribatid mites 1) diversity increases from the boreal to the warm temperate region but not further to the tropics, and 2) species–area relationships for islands and mainlands are similar to those of above-ground taxa, but this is mainly caused by very small islands, such as Cocos islands, and very large islands, such as Madagascar. When these islands are excluded the species–area relationship strongly differs from those of typical islands. The results support the view that below-ground animal taxa are generalists that inhabit wide niches. Most small islands have relatively rich oribatid mite faunas, supporting the observation that a large number of species can coexist in a small area (high α-diversity).     

Soil biota diversity and plant diversity both contributed to ecosystem stability in grasslands

Understanding the effects of diversity on ecosystem stability in the context of global change has become an important goal of recent ecological research. However, the effects of diversity at multiple scales and trophic levels on ecosystem stability across environmental gradients remain unclear. Here, we conducted a field survey of α-, β-, and γ-diversity of plants and soil biota (bacteria, fungi, and nematodes) and estimated the temporal ecosystem stability of normalized difference vegetation index (NDVI) in 132 plots on the Mongolian Plateau. After climate and soil environmental variables were controlled for, both the α- and β-diversity of plants and soil biota (mainly via nematodes) together with precipitation explained most variation in ecosystem stability. These findings evidence that the diversity of both soil biota and plants contributes to ecosystem stability. Model predictions of the future effects of global changes on terrestrial ecosystem stability will require field observations of diversity of both plants and soil biota.     

Combining α - and β -diversity models to fill gaps in our knowledge of biodiversity

For many taxonomic groups, sparse information on the spatial distribution of biodiversity limits our capacity to answer a variety of theoretical and applied ecological questions. Modelling community-level attributes (α- and β-diversity) over space can help overcome this shortfall in our knowledge, yet individually, predictions of α- or β-diversity have their limitations. In this study, we present a novel approach to combining models of α- and β-diversity, with sparse survey data, to predict the community composition for all sites in a region. We applied our new approach to predict land snail community composition across New Zealand. As we demonstrate, these predictions of metacommunity composition have diverse potential applications, including predicting γ-diversity for any set of sites, identifying target areas for conservation reserves, locating priority areas for future ecological surveys, generating realistic compositional data for metacommunity models and simultaneously predicting the distribution of all species in a taxon consistent with known community diversity patterns.     

Patterns of diversity in the strata of boreal montane forest in British Columbia

Abstract. Patterns of diversity were analyzed in a boreal coniferous forest and its strata (tree, shrub, herb and bryophyte layers): number of species per community — α-diversity, total species richness — γ-diversity, mean similarity — β-diversity, and mosaic diversity, a measure of complexity. These four measures of diversity consistently decreased from lower to upper vegetation layers. To study the effect of juveniles of larger life forms on diversity of lower layers, they were removed from the data and the measures of diversity reanalyzed. Number of species per community and mosaic diversity decreased substantially, but β-diversity did not change. So, the effect of juveniles on γ-diversity is due to the greater number of species per community. Multiple regression models revealed that the relationships between α-diversity and the environmental variables were the same for the whole forest and for the herb layer. Elevation and soil pH were the major variables explaining α-diversity in the whole community. Climate was the only environmental gradient related to species richness in all individual strata. Tree and herb richness values were negatively related to soil drainage and acidity, respectively. Species richness of the plant community was affected by environmental variability mostly through the herb layer. Various explanations of the observed diversity patterns included: environmental constraints, resource competition, generation time, and colonization processes.     

Enhancing the structural diversity between forest patches—A concept and real-world experiment to study biodiversity,multifunctionality and forest resilience across spatial scales

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity–ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and services at the local (α-diversity) scale, but we largely lack empirical evidence on how the loss of between-patch β-diversity affects biodiversity and multifunctionality at the landscape scale (γ-diversity). Here, we present a novel concept and experimental framework for elucidating BEF patterns at α-, β-, and γ-scales in real landscapes at a forest management-relevant scale. We examine this framework using 22 temperate broadleaf production forests, dominated by Fagus sylvatica. In 11 of these forests, we manipulated the structure between forest patches by increasing variation in canopy cover and deadwood. We hypothesized that an increase in landscape heterogeneity would enhance the β-diversity of different trophic levels, as well as the β-functionality of various ecosystem functions. We will develop a new statistical framework for BEF studies extending across scales and incorporating biodiversity measures from taxonomic to functional to phylogenetic diversity using Hill numbers. We will further expand the Hill number concept to multifunctionality allowing the decomposition of γ-multifunctionality into α- and β-components. Combining this analytic framework with our experimental data will allow us to test how an increase in between patch heterogeneity affects biodiversity and multifunctionality across spatial scales and trophic levels to help inform and improve forest resilience under climate change. Such an integrative concept for biodiversity and functionality, including spatial scales and multiple aspects of diversity and multifunctionality as well as physical and environmental structure in forests, will go far beyond the current widely applied approach in forestry to increase resilience of future forests through the manipulation of tree species composition.     

Tree hollows harbour a specialised oribatid mite fauna

Tree hollows are known to harbour a species-rich and specialized beetle fauna, while other invertebrates, such as for instance mites, have been much less studied. The importance of hollows in oak trees (Quercus robur) for local oribatid mite diversity was studied at three sites in south eastern Sweden. The qualitative and quantitative composition of the oribatid mite fauna was studied in hollows of fifteen 240–420 years old oak trees and compared to that in the surrounding soil. A total of 5,530 specimen of adult oribatid mites were determined belonging to 63 taxa. Taxonomic composition and community structure of the tree hollow communities differed markedly from the soil communities. The most dominant and frequent component of the tree hollow communities comprised a Carabodes species new to Sweden that accounted on average for 44 % of all Oribatida. This species, that closely resembles both Carabodes oenipontanus and Carabodes granulatus, was specific to the tree hollows. Dominance patterns in the soil communities were more even, with the most common taxa also occurring in the tree hollows but exhibiting a significant preference for the soil. Overall, there was little taxonomic overlap between the communities, suggesting that tree hollows harbour an independent mite community from the soil and therefore significantly contribute to the overall mite diversity on the landscape level. The present study therefore strongly supports the use of hollow trees as biodiversity indicators and also their conservation, which will preserve specialised invertebrate communities, including mites.     

Secondary succession, soil formation and development of a diverse community of oribatids and saprophagous soil macro-invertebrates

Investigations into different stages of secondary succession (from a wheat field to a beechwood on Threstone; Northern Germany) demonstrated the formation of a carbon rich top soil in later successional stages. Parallel to changes in plant species and soil formation, there were also changes in species composition and diversity of saprophagous macro-invertebrates (Lumbricidae, Diplopoda, Isopoda) and oribatid mites (Acari: Oribatida). Diversity of diplopod and isopod species increased after cessation of cultivation, but in a late successional stage (ca 50 y-old fallow, ash-dominated wood) species number of diplopods and isopods declined strongly. In comparison with the other soil invertebrate groups, species composition of earthworms among the sites was more similar. Accumulation of soil C was assumed to be related to wood formation and occurrence of woody debris and recalcitrant leaf litter of beech trees. Incorporation of recalcitrant litter materials by earthworm species living in the upper mineral soil presumably contributed significantly to accumulation of soil C. Accumulation of soil C was accompanied by the development of an oribatid mite community rich in species. In early successional stages oribatids predominantly colonized the litter layer, while most oribatid mites of the beechwood inhabited the upper mineral soil. Maximum diversity of oribatid mites in the beechwood is assumed to be related to instability of the mineral soil caused by earthworm activity. Changes in species composition and diversity are discussed considering succession theory. Even soil invertebrates of similar trophic groups appear to respond very differently to successional changes. It is concluded that conservation strategies to maintain high diversity of soil invertebrates are most likely to be successful if a wide range of habitats of different successional stages is included.     

Decomposing logs increase oribatid mite assemblage diversity in mixedwood boreal forest

The removal of timber during harvesting substantially reduces important invertebrate habitat, most noticeably microhabitats associated with fallen trees. Oribatid mite diversity in downed woody material (DWM) using species-level data has not been well studied. We investigated the influence of decaying logs on the spatial distribution of oribatid mites on the forest floor at the sylviculture et aménagement forestiers écosystémique (SAFE) research station in the Abitibi region in NW Québec. In June 2006, six aspen logs were selected for study, and samples were taken at three distances for each log: directly on top of the log (ON), directly beside the log (ADJ) and at least one metre away from the log and any other fallen wood (AWAY). Samples ON logs consisted of a litter layer sample, an upper wood sample and an inner wood sample. Samples at the ADJ and AWAY distances consisted of litter samples and soil cores. The highest species richness was collected ON logs, and logs harboured a distinct oribatid species composition compared to nearby forest floor. There were species-specific changes in abundance with increasing distance away from DWM, which indicates an influence of DWM in structuring oribatid assemblages on the forest floor. Additionally, each layer (litter, wood and soil) exhibited a unique species composition and hosted a different diversity of oribatid mites. This study further highlights the importance of DWM to forest biodiversity by creating habitat for unique assemblages of oribatid mites.     

The ecological distribution of reproductive mode in oribatid mites, as related to biological complexity

The high incidence of asexuality in oribatid mites presents an unusual opportunity for examining hypotheses for the maintenance of sex. There is a presumed range in age of asexual species: many oribatid species are phylogenetically clustered, occurring in speciose early-derivative families or genera without sexual species, while others are phylogenetically isolated from other asexual species, occurring in later derivative taxa with sexual congeners. We examined the distribution of oribatid mite reproductive mode in soil of corn fields, grassy and shrub fields, and forests in central New York State (three replicate plots of each type, with 25 samples per plot), to test three ecological predictions from current theory. (1) If overall biotic uncertainty, as generated by competitors and predators, mediates the ecological distribution of oribatid mites, then the proportion of asexual oribatid mites should be negatively correlated with biological diversity; we examine this prediction using literature data as well. (2) If Muller’s Ratchet (the stochastic loss of best genotypes, which is independent of environment), mediates the success of asexuality, then no ecological pattern should exist. (3) If general purpose genotypes are characteristic of asexual oribatid mites, their habitat distribution should be broader than that of sexual species. For each plot the level of asexuality was compared to indices of overall biotic diversity, as calculated from the pooled oribatid mite (competitors) and mesostigmatid mite (predator) communities. We found no negative correlation in this relationship in our own data or in the literature analysis of 290 faunal surveys from 50 literature sources, so we reject biotic uncertainty as an important determinant of reproductive mode distribution. When only data on phylogenetically clustered asexuals are considered, there is instead a positive correlation between asexuality and diversity that is not explained. Because of the latter pattern we tentatively reject Muller’s Ratchet as the primary factor maintaining reproductive mode in these mites, but cannot reject it for isolated asexual species. Niche breadth in sexual and asexual oribatid mites provides no support for widespread general purpose genotypes but broad patterns in the literature suggest that the idea needs further investigation. Possible complicating or unknown factors that are discussed include historical disturbance in the study area, the relationship between parasitism and general biotic diversity, and the level and source of genetic diversity in asexual oribatid mites.     

Soil animal responses to moisture availability are largely scale,not ecosystem dependent: insight from a cross‐site study

Climate change will result in reduced soil water availability in much of the world either due to changes in precipitation or increased temperature and evapotranspiration. How communities of mites and nematodes may respond to changes in moisture availability is not well known, yet these organisms play important roles in decomposition and nutrient cycling processes. We determined how communities of these organisms respond to changes in moisture availability and whether common patterns occur along fine‐scale gradients of soil moisture within four individual ecosystem types (mesic, xeric and arid grasslands and a polar desert) located in the western United States and Antarctica, as well as across a cross‐ecosystem moisture gradient (CEMG) of all four ecosystems considered together. An elevation transect of three sampling plots was monitored within each ecosystem and soil samples were collected from these plots and from existing experimental precipitation manipulations within each ecosystem once in fall of 2009 and three times each in 2010 and 2011. Mites and nematodes were sorted to trophic groups and analyzed to determine community responses to changes in soil moisture availability. We found that while both mites and nematodes increased with available soil moisture across the CEMG, within individual ecosystems, increases in soil moisture resulted in decreases to nematode communities at all but the arid grassland ecosystem; mites showed no responses at any ecosystem. In addition, we found changes in proportional abundances of mite and nematode trophic groups as soil moisture increased within individual ecosystems, which may result in shifts within soil food webs with important consequences for ecosystem functioning. We suggest that communities of soil animals at local scales may respond predictably to changes in moisture availability regardless of ecosystem type but that additional factors, such as climate variability, vegetation composition, and soil properties may influence this relationship over larger scales.     

Regional factors rather than forest type drive the community structure of soil living oribatid mites (Acari, Oribatida)

Most European forests are managed by humans. However, the manner and intensity of management vary. While the effect of forest management on above-ground communities has been investigated in detail, effects on the below-ground fauna remain poorly understood. Oribatid mites are abundant microarthropods in forest soil and important decomposers in terrestrial ecosystems. Here, we investigated the effect of four forest types (i.e., managed coniferous forests; 30 and 70 years old managed beech forests; natural beech forests) on the density, diversity and community structure of oribatid mites (Acari). The study was replicated at three regions in Germany: the Swabian Alb, the Hainich and the Schorfheide. To relate changes in oribatid mite community structure to environmental factors, litter mass, pH, C and N content of litter, fine roots and C content of soil were measured. Density of oribatid mites was highest in the coniferous forests and decreased in the order 30 years old, 70 years old, and natural beech forests. Mass of the litter layer and density of oribatid mites were strongly correlated indicating that the litter layer is an important factor regulating oribatid mite densities. Diversity of oribatid mites was little affected by forest type indicating that they harbor similar numbers of niches. Species composition differed between the forest types, suggesting different types of niches. The community structure of oribatid mites differed more strongly between the three regions than between the forest types indicating that regional factors are more important than effects associated with forest type.     

Community structure,trophic position and reproductive mode of soil and bark-living oribatid mites in an alpine grassland ecosystem

The community structure, stable isotope ratios (¹⁵N/¹⁴N, ¹³C/¹²C) and reproductive mode of oribatid mites (Acari, Oribatida) were investigated in four habitats (upper tree bark, lower tree bark, dry grassland soil, forest soil) at two sites in the Central Alps (Tyrol, Austria). We hypothesized that community structure and trophic position of oribatid mites of dry grassland soils and bark of trees are similar since these habitats have similar abiotic characteristics (open, dry) compared with forest soil. Further, we hypothesized that derived taxa of oribatid mites reproducing sexually dominate on the bark of trees since species in this habitat consume living resources such as lichens. In contrast to our hypothesis, the community structure of oribatid mites differed among grassland, forest and bark indicating the existence of niche differentiation in the respective oribatid mite species. In agreement with our hypothesis, sexually reproducing taxa of oribatid mites dominated on the bark of trees whereas parthenogenetic species were more frequent in soil. Several species of bark-living oribatid mites had stable isotope signatures that were similar to lichens indicating that they feed on lichens. However, nine species that frequently occurred on tree bark did not feed on lichens according to their stable isotope signatures. No oribatid mite species could be ascribed to moss feeding. We conclude that sexual reproduction served as preadaptation for oribatid mites allowing them to exploit new habitats and new resources on the bark of trees. Abiotic factors likely are of limited importance for bark-living oribatid mites since harsh abiotic conditions are assumed to favor parthenogenesis.     

Changes in plant species diversity along a chronosequence of vegetation restoration in the humid evergreen broad-leaved forest in the Rainy Zone of West China

Plant species diversity has been recognized as one of the vital attributes for assessing vegetation restoration. Changes in the diversity may be related to different stages of succession. In this study, 54 sites of humid, evergreen, broad-leaved forest were selected in the Rainy Zone of West China. A chronosequence of the sites was used to study the successive patterns of the diversity in the forest that had undergone natural regeneration for 5 to 350 years and to test the hypothesis that the diversity is maximized in mid-succession. Data were collected simultaneously at different stages of succession, and four α-diversity indices (species richness, Margalef index, Shannon-Wiener index, Pielou Evenness index) and two β-diversity indices (Whittaker index, Sørensen’s index) were calculated for each stratum in each plot. A total of 394 vascular plant species were recorded. From the β-diversity indices, the forest succession may be divided into the early-successional stage (before 50 years), mid-successional stage (from 50 to 300 years), and late-successional stage (after 300 years). In this community, the species diversity and richness were found to be the greatest at the mid-successional stage, followed by the late- and early-successional stages. The results of regression analysis indicated that the richness and Margalef index peaked around the 175th and 165th year, respectively. Shannon-Wiener index values also appeared to follow an approximately humped pattern of succession and were maximal around the 100th year. However, the species evenness did not show any significant relationship with successional age. Our results demonstrate (1) forest restoration is a long-term process and the formation of climax forest requires at least 300 years and (2) the forest has a strong capacity for restoration. Our results also suggest Lindera limprichitii and Machilus pingii as ideal tree species for afforestation because of their wide niche.     

Consumption rate of phytonematodes by <Emphasis Type="Italic">Pergalumna</Emphasis> sp. (Acari: Oribatida: Galumnidae) under laboratory conditions determined by a new method

Although several generalist species of Pergalumna are known to be nematode predators, the potential of oribatid mites as natural enemies of phytonematodes has been underestimated. The objective of this work was to estimate the consumption rate of a Pergalumna sp. when feeding on two major pest nematodes, Meloidogyne javanica and Pratylenchus coffeae, under laboratory conditions. A new method was used, in which live nematodes are offered to mites and subsequently consumption is quantified based on the sclerotized, well preserved structures in the mite's fecal pellets. The assay was evaluated during 5 days, at 25 degrees C and 96% relative humidity, with three replicates for each nematode species. Every replicate consisted of a group of four mites isolated in an arena, to which 400 nematodes were transferred daily. The daily produced fecal pellets were mounted in Hoyer's medium for examination under a microscope. The nematode buccal stylets and cephalic frameworks were counted to estimate the number of nematodes consumed. It was estimated that a single mite daily ingested 18.3 +/- 0.8 (mean +/- SE) M. javanica (J(2) juveniles) or 41.6 +/- 7.2 P. coffeae (juveniles + adults), the maximal daily consumption being 34 M. javanica and 73 P. coffeae. The method showed to be practical, precise and suitable for laboratory studies in which nematophagous mites classified as engulfers are included.     

强度石漠化区不同植被修复模式下土壤螨类群落差异

石漠化治理区不同植被修复模式下的土壤螨类群落差异反映了生态系统的恢复状况,可籍以反映石漠化治理的生态效果。2014年1月、4月、8月和10月,对贵州花江喀斯特峡谷区顶坛小流域强度石漠化区域的"花椒"、"金银花"、"花椒+金银花"3种植被修复生境的土壤螨类进行了调查,共捕获土壤螨类1372头,隶属3目55科89属。采用类群(属)数、个体数量、个体密度、多样性指数(H')、丰富度指数(SR)、均匀性指数(J)、相似性指数(CN)、捕食性螨类成熟度指数(MI)和甲螨MGP类群等参数对土壤螨类群落差异进行了表征。结果显示,花椒林拥有较丰富的螨类属,金银花林拥有较高的的个体数量和个体密度。不同模式下的科、属类群组成呈现差异;属数、个体数量存在一定的季节差异,花椒林的螨类属数、金银花林的螨类个体数量和个体密度呈现一定的表聚性;群落多样性大多存在季节差异;捕食性革螨以r选择型为主,甲螨主要为O型和M型。研究表明,强度石漠化在不同植被修复模式下,土壤螨类生物生态类群存在差异,土壤生态系统仍处于修复之中,其中螨类优势属、具有典型生物学与生态学特性差异的螨类类群对石漠化治理的生态效果具有重要的指示作用。     

Does the Existence of Bird's Nest Ferns Enhance the Diversity of Oribatid (Acari: Oribatida) Communities in a Subtropical Forest?

We examined the effects of the presence of bird's nest ferns on the species diversity of oribatid mites in the whole forest in terms of the three categories of species diversity (α-, β-, and γ-diversity) in a subtropical forest in south-western Japan. The species diversity (1 − D) of oribatid communities in the ferns was significantly lower than those in bark of trees and the forest-floor litter and soil, and was similar to that in the branches. The oribatid faunas in the litter in and the roots of the fern were more similar to those in both the forest-floor litter and soil than to the faunas in the other arboreal habitats. However, the ferns can be colonized by endemic oribatid species specialized to such environments. The number of oribatid species estimated for a hypothetical stand with no ferns was about 180 species from 80 samples; this value did not differ significantly from that in another hypothetical stand with ferns (ca. 190 species). Thus, the species richness of oribatid communities estimated for the whole forest (the γ-diversity) was not affected by the presence or absence of bird's nest ferns. The α- and β-diversities of oribatid communities on bird's nest ferns were lower than those in other habitats, and they might not dramatically raise the overall γ-diversity of invertebrate communities in the whole forest. The bird's nest ferns, however, can generate a unique habitat for specialized species, and this would help to maintain species diversities of invertebrates at the whole-forest scale in subtropical forests.