Disturbance,species loss and compensation: Wildfire and grazing effects on the avian community and its food supply in the Serengeti Ecosystem,Tanzania

An important question in biodiversity studies is whether disturbances in ecosystems will cause a net loss of species or whether such losses can be compensated by replacement of other species. We use two natural disturbances, fire and grazing, to examine the response of bird and arthropod communities in grasslands of Serengeti, Tanzania. Both burning and grazing by migrant ungulates take place at the end of the rains in June–July. We documented the communities before disturbance, then 1, 4 and 20 weeks after disturbance on three replicate plots and compared them with three undisturbed plots. Birds were recorded by observation, arthropods from pitfall, tray trap and sweepnet samples. We expected that as the grass biomass was reduced by either disturbance, bird communities would change with concomitant change in arthropod food abundance. Alternatively, bird communities would change not with the absolute amount of food but with the greater accessibility of food as the grass structure changed from long to short grass. Results showed first that both bird species richness and abundance increased after both types of disturbance, but burnt sites showed a greater increase than that for grazed sites. Second, there was a change in bird species composition with disturbance. The functionally equivalent athi short‐toed lark (Calandrella athensis) was replaced by the red‐capped lark (Calandrella cinerea). Third, the abundance of most groups of arthropods was lower on disturbed sites than those on undisturbed sites, and the reduction of arthropod numbers was greatest on burnt sites. These results imply that bird abundance did not occur through an increase in arthropod abundance but rather through a change in the grass structure making food more accessible; and the higher predation could have caused the lower arthropod abundance. In addition, some bird species replaced others thus functionally compensating for their loss.     

Diversity cascades in alfalfa fields: from plant quality to agroecosystem diversity

To examine top-down and bottom-up influences on managed terrestrial communities, we manipulated plant resources and arthropod abundance in alfalfa (Medicago sativa L.) fields. We modified arthropod communities using three nonfactorial manipulations: pitfall traps to remove selected arthropods, wooden crates to create habitat heterogeneity, and an arthropod removal treatment using a reversible leaf blower. These manipulations were crossed with fertilizer additions, which were applied to half of the plots. We found strong effects of fertilizer on plant quality and biomass, and these effects cascaded up to increase herbivore abundance and diversity. The predator community also exhibited a consistent positive effect on the maintenance of herbivore species richness and abundance. These top-down changes in arthropods did not cascade down to affect plant biomass; however, plant quality (saponin content) increased with higher herbivore densities. These results corroborate previous studies in alfalfa that show complex indirect effects, such as trophic cascades, can operate in agricultural systems, but the specifics of the interactions depend on the assemblages of arthropods involved.     

An invasive plant-fungal mutualism reduces arthropod diversity

Ecological theory holds that competition and predation are the most important biotic forces affecting the composition of communities. Here, we expand this framework by demonstrating that mutualism can fundamentally alter community and food web structure. In large, replicated field plots, we manipulated the mutualism between a dominant plant ( Lolium arundinaceum ) and symbiotic fungal endophyte ( Neotyphodium coenophialum ). The presence of the mutualism reduced arthropod abundance up to 70%, reduced arthropod diversity nearly 20%, shifted arthropod species composition relative to endophyte-free plots and suppressed the biomass and richness of other plant species in the community. Herbivorous arthropods were more strongly affected than carnivores, and for both herbivores and carnivores, effects of the mutualism appeared to propagate indirectly via organisms occurring more basally in the food web. The influence of the mutualism was as great or greater than previously documented effects of competition and predation on arthropod communities. Our work demonstrates that a keystone mutualism can significantly reduce arthropod biodiversity at a broad community scale.     

胜山阔叶红松林蚂蚁巢穴对其他地表节肢动物多样性的影响

为了阐明蚂蚁巢穴对其他地表节肢动物群落组成和多样性的影响,于2019年在胜山自然保护区的原始阔叶红松林内开展实验,并采用陷阱法收集地表节肢动物.共捕获地表节肢动物92266只,分别为蜈蚣目、盲蛛目、马陆目、蜘蛛目,大头蚁属和步甲科、隐翅虫科、葬甲科这8个类群;蚂蚁巢穴存在及到蚂蚁巢穴的不同距离对其他地表节肢动物个体数量...     

放牧干扰下的蝗虫－植物相互作用关系

本文研究了内蒙古典型草原植物和蝗虫群落在不同放牧强度影响下的多样性、均匀性和丰盛度变化。比较了蝗虫群落与植物群落在放牧梯度上的相互作用关系。研究发现,放牧干扰活动会明显地影响植物和蝗虫群落结构,但蝗虫群落结构的变化趋势并非与植物完全同步。蝗虫与植物间的联系更多地表现在植物起着蝗虫栖息地条件的作用,而并不完全是食料植物的作用。文中对放牧实践与多样性保护的关系进行了讨论。     

Impact of reindeer grazing on ground-dwelling Carabidae and Curculionidae assemblages in Lapland

Reindeer Rangifer tarandus L. grazing shapes forest vegetation, microclimate, and soil respiration in Lapland, especially due to grazing on lichens (Cladina). We studied how these changes and their magnitude affect ground‐dwelling species of beetle families Carabidae (predators) and Curculionidae (herbivores), by using pitfall traps to collect invertebrates from pairs of grazed and ungrazed study plots over a wide range of site types. Changes in abundance, composition, richness and diversity of beetle assemblage were tested in relation to magnitude of the impacts on vegetation. The species compositions of Carabidae and Curculionidae differed between grazed and ungrazed plots in all sites. The relative difference between grazed and ungrazed plots in the number of individuals increased linearly with the impact of reindeer on vegetation cover. Carabid beetles, as a family, were more common in grazed plots in all sites. Curculionid beetles were more common in ungrazed plots in the birch dominated sites. This difference was mainly due to the species that feeds on deciduous leaves. In the pine dominated sites with high Cladina cover and more changes in ground vegetation, the number of curculionids feeding on conifers was higher in grazed plots. Species richness and diversity (H’) of both families were higher in grazed plots. Of the total 27 species, 11 were found only in grazed plots, while not a single species was found only in ungrazed plots. The relative difference between plots in diversity and evennes (H’/H'max) had humped response to the difference in Cladina cover. The diversity values were greater in grazed plots at the intermediate levels of grazing impact, and only in sites with very low or extremely high Cladina cover difference was the diversity higher in ungrazed plots. The response of beetle diversity resembled the hypotheses suggested for the relationship between grazing and vegetation diversity: greatest positive effect at intermediate grazing intensity and negative effects at unproductive sites.     

Arctic arthropod assemblages in habitats of differing shrub dominance

Recent climate warming in the Arctic has caused advancement in the timing of snowmelt and expansion of shrubs into open tundra. Such an altered climate may directly and indirectly (via effects on vegetation) affect arctic arthropod abundance, diversity and assemblage taxonomic composition. To allow better predictions about how climate changes may affect these organisms, we compared arthropod assemblages between open and shrub‐dominated tundra at three field sites in northern Alaska that encompass a range of shrub communities. Over ten weeks of sampling in 2011, pitfall traps captured significantly more arthropods in shrub plots than open tundra plots at two of the three sites. Furthermore, taxonomic richness and diversity were significantly greater in shrub plots than open tundra plots, although this pattern was site‐specific as well. Patterns of abundance within the five most abundant arthropod orders differed, with spiders (Order: Araneae) more abundant in open tundra habitats and true bugs (Order: Hemiptera), flies (Order: Diptera), and wasps and bees (Order: Hymenoptera) more abundant in shrub‐dominated habitats. Few strong relationships were found between vegetation and environmental variables and arthropod abundance; however, lichen cover seemed to be important for the overall abundance of arthropods. Some arthropod orders showed significant relationships with other vegetation variables, including maximum shrub height (Coleoptera) and foliar canopy cover (Diptera). As climate warming continues over the coming decades, and with further shrub expansion likely to occur, changes in arthropod abundance, richness, and diversity associated with shrub‐dominated habitat may have important ecological effects on arctic food webs since arthropods play important ecological roles in the tundra, including in decomposition and trophic interactions.     

Experimental Manipulation of Grassland Plant Diversity Induces Complex Shifts in Aboveground Arthropod Diversity

Changes in producer diversity cause multiple changes in consumer communities through various mechanisms. However, past analyses investigating the relationship between plant diversity and arthropod consumers focused only on few aspects of arthropod diversity, e.g. species richness and abundance. Yet, shifts in understudied facets of arthropod diversity like relative abundances or species dominance may have strong effects on arthropod-mediated ecosystem functions. Here we analyze the relationship between plant species richness and arthropod diversity using four complementary diversity indices, namely: abundance, species richness, evenness (equitability of the abundance distribution) and dominance (relative abundance of the dominant species). Along an experimental gradient of plant species richness (1, 2, 4, 8, 16 and 60 plant species), we sampled herbivorous and carnivorous arthropods using pitfall traps and suction sampling during a whole vegetation period. We tested whether plant species richness affects consumer diversity directly (i), or indirectly through increased productivity (ii). Further, we tested the impact of plant community composition on arthropod diversity by testing for the effects of plant functional groups (iii). Abundance and species richness of both herbivores and carnivores increased with increasing plant species richness, but the underlying mechanisms differed between the two trophic groups. While higher species richness in herbivores was caused by an increase in resource diversity, carnivore richness was driven by plant productivity. Evenness of herbivore communities did not change along the gradient in plant species richness, whereas evenness of carnivores declined. The abundance of dominant herbivore species showed no response to changes in plant species richness, but the dominant carnivores were more abundant in species-rich plant communities. The functional composition of plant communities had small impacts on herbivore communities, whereas carnivore communities were affected by forbs of small stature, grasses and legumes. Contrasting patterns in the abundance of dominant species imply different levels of resource specialization for dominant herbivores (narrow food spectrum) and carnivores (broad food spectrum). That in turn could heavily affect ecosystem functions mediated by herbivorous and carnivorous arthropods, such as herbivory or biological pest control.     

The effects of sheep-grazing on the subterranean termite fauna (Isoptera) of the Western Australian wheatbelt

Abstract The majority of existing remnants of wandoo Eucalyptus capillosa woodland in the Western Australian wheatbelt have been grazed by sheep for several decades and are often visibly degraded. A pilot survey was conducted into the effects of sheep on vegetation and soil variables, and the abundance, diversity and species frequency of occurrence of subterranean termite communities. Ten 1/4 ha study plots were used for paired grazed/ungrazed comparisons. Ungrazed plots had more litter mass (dry weight), leaf and woody litter, canopy cover (%) and soil moisture (moisture content <1.2% across study plots); grazed plots had a higher percentage of bare ground. Termites were as abundant, and as diverse, in grazed as in ungrazed plots, and were equally often sampled in the soil and surface wood. Termite species eating sound wood, decayed wood/debris and grass were sampled equally often, and were of equal diversity in sheep-grazed as in ungrazed plots. The mounds of Drepanotermes tamminensis were more abundant in grazed plots. These findings indicate that prolonged sheep grazing in remnants of wandoo woodland of the Western Australian wheatbelt has had no detrimental or beneficial effect on its subterranean termites.     

Managing open habitats by wild ungulate browsing and grazing: A case‐study in North‐Eastern Germany

Question: Can wild ungulates efficiently maintain and restore open habitats? Location: Brandenburg, NE Germany. Methods: The effect of wild ungulate grazing and browsing was studied in three successional stages: (1) Corynephorus canescens‐dominated grassland; (2) ruderal tall forb vegetation dominated by Tanacetum vulgare; and (3) Pinus sylvestris‐pioneer forest. The study was conducted over 3 yr. In each successional stage, six paired 4 m²‐monitoring plots of permanently grazed versus ungrazed plots were arranged in three random blocks. Removal of grazing was introduced de novo for the study. In each plot, percentage cover of each plant and lichen species and total cover of woody plants was recorded. Results: Wild ungulates considerably affected successional pathways and species composition in open habitats but this influence became evident in alteration of abundances of only a few species. Grazing effects differed considerably between successional stages: species richness was higher in grazed versus ungrazed ruderal and pioneer forest plots, but not in the Corynephorus sites. Herbivory affected woody plant cover only in the Pioneer forest sites. Although the study period was too short to observe drastic changes in species richness and woody plant cover, notable changes in species composition were still detected in all successional stages. Conclusion: Wild ungulate browsing is a useful tool to inhibit encroachment of woody vegetation and to conserve a species‐rich, open landscape.     

放牧干扰下的蝗虫－植物相互作用关系

本文研究了内蒙古典型草原植物和蝗虫群落在不同放牧强度影响下的多样性、均匀性和丰盛度变化。比较了蝗虫群落与植物群落在放牧梯度上的相互作用关系。研究发现,放牧干扰活动会明显地影响植物和蝗虫群落结构,但蝗虫群落结构的变化趋势并非与植物完全同步。蝗早与植物间的联系列多地表现在植物起着蝗虫栖息地条件的作用,而并不完全是食料植物作用。文中对放牧实践与多样性保护的关系进行了讨论。     

Effects of landscape complexity and stand factors on arthropod communities in poplar forests

The arthropod communities are influenced by both local conditions and features of the surrounding landscape. Landscape complexity and stand factors may both influence arthropod communities in poplar forests, but the multiscale effects of these factors on poplar defoliators and natural enemies are still poorly understood. We collected poplar arthropods at 30 sampling sites within five forest landscapes in Xinjiang, China, and assessed whether landscape complexity and stand factors influence species abundance and diversity of poplar arthropods. Landscape complexity was quantified by several independent metrics of landscape composition, configuration, and connectivity at three spatial scales. We also determined the most powerful explanatory variables and the scale effect of each arthropod. Results found that landscape complexity and stand factors had different effects on different poplar arthropod communities. Landscape complexity promoted natural enemies at different spatial scales, but it inhibited the population of poplar defoliators at the scale of 200 m. Specifically, the abundance and diversity of all defoliators decreased with increasing proportion of nonhost plants. Landscape diversity only had a negative effect on defoliator abundance. The shape complexity of habitat patches increased the abundance of carabid beetles but reduced the abundance of green leafhoppers and migratory locusts. The abundance and diversity of predators increased with increasing structural connectivity of forest landscape. Additionally, both the abundance and diversity of all defoliators were positively correlated with the average height of herbaceous plants. Diversity of all defoliators increased with increasing size of host trees. The distance from sampling site to the nearest village positively influenced the abundance and diversity of all predators. Arthropod abundance and diversity in poplar forests were driven by stand factors and landscape complexity. Therefore, maintaining complex shape and structural connectivity of habitat patches and keeping poplar stands away from the village are crucial for management of forest landscape to enhance natural enemies. And in order to reduce the abundance of defoliators in poplar forest, the diversity of surrounding habitat types should be promoted within 200 m radii.     

Effects of fire on ground‐dwelling arthropods in a shrub‐dominated grassland

Arthropods are abundant and diverse animals in many terrestrial food webs. In western Oklahoma, some shrublands are interspersed with discrete, dense thickets of tall, woody vegetation, known as mottes. Some of these shrublands are managed with prescribed burning. The goal of this study was to examine whether prescribed burning interacted with habitat type (i.e., shrubland versus mottes) to affect ground‐dwelling arthropod communities. Arthropods were collected in pitfall traps at four sampling locations in relation to mottes; in the center of mottes, and three plot location in shrublands; 1 m, 15 m, and 50 m away from the edge of the motte. There were three treatment levels for burning: one year postburn (burned in dormant months of 2017), two years postburn (burned in dormant months of 2016), and unburned (burned in dormant season of 2014 and prior). There were no significant interactions between prescribed burning and habitat type. Mottes had a different community of arthropods compared with the surrounding shrubland. Mottes also had lower overall abundance, but a higher diversity of arthropods. In terms of fires, arthropod communities one year after burning were different from those two or more years after burning. There was no effect of burning on overall arthropod abundance, but plots that were one year since burning had significantly lower diversity compared with plots that were two or more years postburn. The results of this study suggest that both fire and mottes can independently facilitate heterogeneity in arthropod communities, but they do not appear to interact with one another.     

An experimental test of the effect of plant functional group diversity on arthropod diversity

Characteristics used to categorize plant species into functional groups for their effects on ecosystem functioning may also be relevant to higher trophic levels. In addition, plant and consumer diversity should be positively related because more diverse plant communities offer a greater variety of resources for the consumers. Thus, the functional group composition and richness of a plant community may affect the composition and diversity of the herbivores and even higher trophic levels associated with that community. We tested this hypothesis by sampling arthropods with a vacuum sampler (34 531 individuals of 494 species) from an experiment in which we manipulated plant functional group richness and composition. Plant manipulations included all combinations of three functional groups (forbs, C₃ graminoids, and C₄ graminoids) removed zero, one, or two at a time from grassland plots at Cedar Creek Natural History Area, MN. Although total arthropod species richness was unrelated to plant functional group richness or composition, the species richness of some arthropod orders was affected by plant functional group composition. Two plant characteristics explained most of the effects of plant functional groups on arthropod species richness. Nutritional quality, a characteristic related to ecosystem functioning, and taxonomic diversity, a characteristic not used to designate plant functional groups, seemed to affect arthropod species richness both directly and indirectly. Thus, plant functional groups designated for their effects on ecosystem processes will only be partially relevant to consumer diversity and abundance.     

Tree diversity drives diversity of arthropod herbivores,but successional stage mediates detritivores

The high tree diversity of subtropical forests is linked to the biodiversity of other trophic levels. Disentangling the effects of tree species richness and composition, forest age, and stand structure on higher trophic levels in a forest landscape is important for understanding the factors that promote biodiversity and ecosystem functioning. Using a plot network spanning gradients of tree diversity and secondary succession in subtropical forest, we tested the effects of tree community characteristics (species richness and composition) and forest succession (stand age) on arthropod community characteristics (morphotype diversity, abundance and composition) of four arthropod functional groups. We posit that these gradients differentially affect the arthropod functional groups, which mediates the diversity, composition, and abundance of arthropods in subtropical forests. We found that herbivore richness was positively related to tree species richness. Furthermore, the composition of herbivore communities was associated with tree species composition. In contrast, detritivore richness and composition was associated with stand age instead of tree diversity. Predator and pollinator richness and abundance were not strongly related to either gradient, although positive trends with tree species richness were found for predators. The weaker effect of tree diversity on predators suggests a cascading diversity effect from trees to herbivores to predators. Our results suggest that arthropod diversity in a subtropical forest reflects the net outcome of complex interactions among variables associated with tree diversity and stand age. Despite this complexity, there are clear linkages between the overall richness and composition of tree and arthropod communities, in particular herbivores, demonstrating that these trophic levels directly impact each other.     

森林放牧对东北虎豹国家公园东部有蹄类动物灌草层食物资源的影响

森林放牧是中国东北虎豹国家公园内影响最广泛且强度最大的人类干扰之一。研究放牧对有蹄类动物食物资源的影响,是估算当前状态下东北虎和东北豹主要猎物承载力的关键,可以为国家公园的管理提供有效的科学依据。本研究于2016年在中国东北虎豹国家公园东部的牧场和非牧场区域分层抽取50个林下样地设置围栏对照实验,于2017年生长季进行灌草层植被调查 (每个样地的围栏与对照各随机调查3个1m×1m的样方,共调查300个植物样方) ,并应用红外相机技术获取对照样地内有蹄类动物丰富度和活动情况,研究放牧对研究区灌草层植物及动物的影响。研究结果显示：在生长季内,森林放牧显著降低林下灌草层植物生物量 (减少约24%),牧场样地的嫩枝叶显著降低。除禾草外,牧场样地中其他类别植物的氮含量均显著高于非牧场样地 (平均超出非牧场样地25 %)。非牧场样地梅花鹿的相 对丰富度指数 (RAI) 显著高于牧场样地,而狍与野猪的相对丰富度指数 (RAI) 在这两类样地之间没有显著差别。研究结果表明,东北虎豹国家公园东部森林放牧,减少了有蹄类动物灌草层食物资源,降低了有蹄类动物的多度。建议停止森林放牧,恢复有蹄类动物栖息地。     

Nonnative plant invasion increases urban vegetation structure and influences arthropod communities

Aim

Ecological theory and empirical evidence indicate that greater structural complexity and diversity in plant communities increases arthropod abundance and diversity. Nonnative plants are typically associated with low arthropod abundance and diversity due to lack of evolutionary history. However, nonnative plants increase the structural complexity of forests, as is common in urban forests. Therefore, urban forests are ideal ecosystems to determine whether structural complexity associated with nonnative plants will increase abundance and diversity of arthropods, as predicted by complexity literature, or whether structural complexity associated with nonnative plants will be depauperate of arthropods, as predicted by nonnative plant literature.

Location

We sampled 24 urban temperate deciduous and mixed forests in two cites, Raleigh, North Carolina and Newark, Delaware, in the eastern United States.

Methods

We quantified ground cover vegetation and shrub layer vegetation in each forest and created structural complexity metrics to represent total, nonnative and native understory vegetation structural complexity. We vacuum sampled arthropods from vegetation and quantified the abundance, biomass, richness and diversity of spiders and non-spider arthropods.

Results

Nonnative plants increase understory vegetation complexity in urban forests. In Raleigh and Newark, we found support for the hypotheses that dense vegetation will increase arthropod abundance and biomass, and against the hypothesis that nonnative vegetation will decrease arthropods. Urban forest arthropod abundance and biomass, but not diversity, increased with greater nonnative and native structural complexity.

Main Conclusions

Invaded urban forests may provide adequate food in the form of arthropod biomass to transfer energy to the next trophic level, but likely fail to provide ecological services and functions offered by diverse species, like forest specialists. Urban land managers should survey urban forests for nonnative and native plant communities and prioritize replacing dense nonnative plants with native species when allocating vegetation maintenance resources.     

Plant Diversity Impacts Decomposition and Herbivory via Changes in Aboveground Arthropods

Loss of plant diversity influences essential ecosystem processes as aboveground productivity, and can have cascading effects on the arthropod communities in adjacent trophic levels. However, few studies have examined how those changes in arthropod communities can have additional impacts on ecosystem processes caused by them (e.g. pollination, bioturbation, predation, decomposition, herbivory). Therefore, including arthropod effects in predictions of the impact of plant diversity loss on such ecosystem processes is an important but little studied piece of information. In a grassland biodiversity experiment, we addressed this gap by assessing aboveground decomposer and herbivore communities and linking their abundance and diversity to rates of decomposition and herbivory. Path analyses showed that increasing plant diversity led to higher abundance and diversity of decomposing arthropods through higher plant biomass. Higher species richness of decomposers, in turn, enhanced decomposition. Similarly, species-rich plant communities hosted a higher abundance and diversity of herbivores through elevated plant biomass and C:N ratio, leading to higher herbivory rates. Integrating trophic interactions into the study of biodiversity effects is required to understand the multiple pathways by which biodiversity affects ecosystem functioning.     

Grazing‐induced changes in plant–soil feedback alter plant biomass allocation

Large vertebrate herbivores, as well as plant–soil feedback interactions are important drivers of plant performance, plant community composition and vegetation dynamics in terrestrial ecosystems. However, it is poorly understood whether and how large vertebrate herbivores and plant–soil feedback effects interact. Here, we study the response of grassland plant species to grazing‐induced legacy effects in the soil and we explore whether these plant responses can help us to understand long‐term vegetation dynamics in the field. In a greenhouse experiment we tested the response of four grassland plant species, Agrostis capillaris, Festuca rubra, Holcus lanatus and Rumex acetosa, to field‐conditioned soils from grazed and ungrazed grassland. We relate these responses to long‐term vegetation data from a grassland exclosure experiment in the field. In the greenhouse experiment, we found that total biomass production and biomass allocation to roots was higher in soils from grazed than from ungrazed plots. There were only few relationships between plant production in the greenhouse and the abundance of conspecifics in the field. Spatiotemporal patterns in plant community composition were more stable in grazed than ungrazed grassland plots, but were not related to plant–soil feedbacks effects and biomass allocation patterns. We conclude that grazing‐induced soil legacy effects mainly influenced plant biomass allocation patterns, but could not explain altered vegetation dynamics in grazed grasslands. Consequently, the direct effects of grazing on plant community composition (e.g. through modifying light competition or differences in grazing tolerance) appear to overrule indirect effects through changes in plant–soil feedback.     

热带次生林、旱稻种植地和火烧迹地土壤节肢动物群落结构特征及季节变化

通过模拟刀耕火种过程 ,对刀耕火种前后的次生林、旱稻地 (第 2年 )和火烧迹地 (火烧后直接撂荒地第 2年 )土壤节肢动物群落结构特征及季节变化进行了调查研究。结果显示 :3块样地土壤节肢动物群落的优势类群组成相同 ,均为蜱螨目、膜翅目和弹尾目 ,但不同生境样地中各优势类群所占群落总数的比例不同 ,并且 3样地常见和稀有类群的组成差异较大 ;土壤节肢动物类群数、个体数和 DG多样性指数表现为次生林高于其它 2块样地 ,而旱稻地和火烧迹地则无较大差异 ,但一些类群在旱稻地、火烧迹地的数量分布与次生林具有差异 ,且在土壤层的表现较为突出 ;3块样地土壤节肢动物群落具有较好相似性 ,其中旱稻地与火烧迹地达到极相似水平 (D、DS>0 .9)。3种不同类型生境土壤节肢动物群落在类群数、个体数和多样性指数的季节变化总体呈现出雨量少的干季或雨季初末期高于雨量最大的雨季中期 ,与当地降雨量和气温变化有密切关系 ,同时各样地土壤节肢动物群落因生境条件不同及人为活动干扰强弱而形成各自的季节消长特点。研究表明刀耕火种后的旱稻种植对土壤节肢动物群落的恢复和发展在一定限制条件 (面积、周围次生林和坡度 )下无破坏性影响 ,但植被改变、农事活动等对直接撂荒地和旱稻地土壤节肢动物群落的季节消长产生