The Canopy Starts at 0.5 m: Predatory Mites (Acari: Mesostigmata) Differ between Rain Forest Floor Soil and Suspended Soil at any Height

Suspended soils in forest canopies are thought to harbor a substantial fraction of canopy biomass and many arboreal specialists, but do forest floor generalist predators with high vagility also use this habitat? We tested the hypothesis of no difference between forest floor and suspended-soil predatory mite faunas (Acari: Mesostigmata) in an Australian rain forest. Our results show that instead of being habitat generalists, many predatory mites partition soil into two main strata: soil suspended aboveground irrespective of height (0.5–20 m) and soil on the ground. Of 53 species of Mesostigmata in suspended soil, 53 percent (28 species) were absent from or rarely found on the ground. This increased to 60 percent (15/25 species) if only common species are considered. Among these 15 ‘suspended-soil specialists’, all but the three least abundant were found throughout the arboreal strata. Moreover, ten species also occurred in litter accumulated on the surface of decaying logs or boulders close to the forest floor. Thus, although the arboreal predatory mite fauna is distinct from that on the forest floor, it is not restricted to the high canopy: even slightly elevated substrate appears acceptable as habitat for these suspended-soil specialists. Our data suggest that a substantial portion of a rain forest's soil and litter fauna is held above the forest floor.     

Mixed leaf litter effects on decomposition rates and soil microarthropod communities in an oak–pine stand in Japan

Rates of decomposition, and soil faunal abundance and diversity associated with single-species and mixed-species litters were studied in a litter bag experiment in an oak–pine forest. We used two canopy species of leaf litter, pine and oak, and one shrub species, Sasa, and compared decomposition rates, and soil microarthropod abundance and community structure of oribatid mites in the litter bags. Mass loss of single species decreased in the order: oak > pine > Sasa. While the total mass loss rates of mixed litter were intermediate between those of the constituent species, enhancement of mass loss from the three-species mixture and from mixed slow-decomposing litters (pine and Sasa) was observed. Faunal abundance in litter bags was higher in mixed-species litter than in those with single-species litter, and species richness of oribatid mites was also higher in the three-species mixed litter. Faunal abundance in single-species litter bags was not correlated with mass loss, although enhancement of mass loss in mixed litter bags corresponded with higher microarthropod abundance. Habitat heterogeneity in mixed litter bags seemed to be responsible for the more abundant soil microarthropod community.     

Mites in the mist: How unique is a rainforest canopy-knockdown fauna?

Abstract We intensively sampled the parasitiform mite faunas of three subtropical rainforest canopy habitats (leaves, bark, hanging humus) and three forest floor habitats (leaf litter, fungal sporocarps, arthropod associates) in the Green Mountains section of Lamington National Park, Queensland, and compared them to 423 specimens collected from the canopy by pyrethrin knockdown (PKD). In total, 165 species (80% new to science) were identified, including 58 from PKD. Few species occurred in more than one habitat, and complementarity averaged 96 ± 1%. About half of the species from PKD were found in canopy habitats, but less than 10% occurred in forest floor habitats. Thus, the canopy fauna is composed primarily of canopy specialists, not of forest floor mites, and habitat specificity is a major component of acarine diversity. An Incidence-based Coverage estimator (generated by the EstimateS program) proved useful in predicting asymptotes for collector's curves. Conservative extrapolations from this study suggest that more than 2000 species of mites live in subtropical rainforest in the Green Mountains.     

An altitudinal comparison of caterpillar (Lepidoptera) assemblages on Ficus trees in Papua New Guinea

Aim This analysis of caterpillar (Lepidoptera) beta‐diversity between tropical lowlands and highlands attempts to separate the effects of between‐site (1) turnover of herbivore species on particular host plants, (2) changes in host use by herbivores, and (3) turnover of plant species on changes in herbivore assemblages. Location Two rain forest areas 130 km and 1700 altitudinal metres apart were studied in Papua New Guinea: one in the lowlands (100 m a.s.l.) on the northern coast of the island and one in the central New Guinean cordillera at 1800 m a.s.l. Methods The analysis is based on caterpillar feeding records obtained by quantitative sampling and rearing of caterpillars from four Ficus species studied in the mountains and 21 Ficus species and 62 plant species from other genera and families studied in the lowlands, including three Ficus species studied in both areas. Results Only 17% of species feeding on Ficus in the highlands also occurred in the lowlands. These species represented 1–46% of individuals in caterpillar assemblages on particular Ficus hosts. Widespread species included both Ficus specialists and generalists feeding on numerous plant families. Some of the Ficus specialists changed their preferred host species with altitude. High species turnover was not explained by changes in the species composition of host plants with altitude as lowland and montane assemblages feeding on the same Ficus species showed high turnover. Despite the rarity of widespread caterpillars, the lowland and montane Ficus assemblages were remarkably similar in their dominance structure, species richness, host specificity, generic composition and familial composition. Main conclusions Ficus‐feeding Lepidoptera assemblages between tropical lowlands and highlands are characterized by substantial species turnover not explained by altitudinal changes in the composition of the vegetation. Further, species‐rich plant genera can support caterpillar assemblages with relatively low beta‐diversity compared with species‐poor genera as caterpillars can switch their host preferences from one congeneric host species to another along an altitudinal gradient. Closely related plant species can thus represent a broad, continuously distributed resource along such gradients.     

Chemical defenses shift with the seasonal vertical migration of a Panamanian poison frog

Dendrobatid poison frogs sequester lipophilic alkaloids from their arthropod prey to use as a form of chemical defense. Some dendrobatid frogs seasonally migrate between the leaf litter of the forest floor in the dry season to the canopy in the wet season, which may yield differences in prey (arthropods) and therefore alkaloid availability over space and time. Here, we document a seasonal vertical migration of Andinobates fulguritus (the yellow‐bellied poison frog) from ground to canopy between dry and wet seasons. We observed turnover in alkaloid composition between seasons and found that dry season frogs contained a lower relative quantity of alkaloids; however, there was no change in alkaloid richness between seasons. The 77 alkaloids of 13 structural classes identified in this population appear to be derived mostly from mites and ants, though the two most common alkaloids were mite derived. Our observed shifts in defensive profiles are consistent with well‐documented turnover in mite and ant communities between seasons and vertical strata. As climate change is expected to lengthen and strengthen dry seasons in many tropical regions, our results suggest that arboreal poison frogs forced to the ground for longer periods of time may see a shift in the abundance of alkaloids, possibly decreasing their defensive potential. This study provides further predictions for the wide‐reaching effects of climate change, even as nuanced as charismatic poison frogs losing their poisons. Abstract in Spanish is available with online material.     

Leaf domatia and foliar mite abundance in broadleaf deciduous forest of north Asia

Plant morphology may be shaped, in part, by the third trophic level. Leaf domatia, minute enclosures usually in vein axils on the leaf underside, may provide the basis for protective mutualism between plants and mites. Domatia are particularly frequent among species of trees, shrubs, and vines in the temperate broadleaf deciduous forests in north Asia where they may be important in determining the distribution and abundance of mites in the forest canopy. In lowland and montane broadleaf deciduous forests at Kwangn;akung and Chumbongsan in Korea, we found that approximately half of all woody species in all forest strata, including many dominant trees, have leaf domatia. Pooling across 24 plant species at the two sites, mites occupied a mode of 60% (range 20-100%) of domatia and used them for shelter, egg-laying, and development. On average, 70% of all active mites and 85% of mite eggs on leaves were found in domatia; over three-quarters of these were potentially beneficial to their hosts. Further, mite abundance and reproduction (expressed as the proportion of mites at the egg stage) were significantly greater on leaves of species with domatia than those without domatia in both forests. Effects of domatia on mite abundance were significant only for predaceous and fungivorous mite taxa; herbivore numbers did not differ significantly between leaves of species with and without domatia. Comparable patterns in broadleaf deciduous forest in North America and other biogeographic regions suggest that the effect of leaf domatia on foliar mite abundance is general. These results are consistent with several predictions of mutualism between plants and mites, and indicate that protective mutualisms may be frequent in the temperate zone.     

Does microhabitat structure affect foliar mite assemblages?

1. Habitat structure is an important factor influencing population dynamics and trophic organisation of terrestrial invertebrates. The phylloplane zone on vascular plant leaves is topographically complex, containing a multitude of microhabitats such as leaf hairs, lesions, and structural refugia such as domatia, which may modify interactions between resident invertebrate communities, colonisers, and subsequent trophic relationships. Leaf domatia are small indentations on the underside of leaves and are often inhabited by potentially beneficial mites and other arthropods. 2. This study investigated the relationship between domatia availability and foliar mite assemblages in contrasting habitats (native forest, plantation forest, and pasture) using a standard test plant (the endemic New Zealand shrub Coprosma lucida, J.R. & G. Forst.). 3. Diverse woody native vegetation types supported higher numbers of mite species than either plantation forest or pastoral grasses. The highest number of mite species occurred in the native forest (63%), plantation forest (38%), and pastoral grasses (25%). In the native vegetation type, experimental C. lucida leaves with domatia supported higher mite densities, greater colonisation success, and more diverse mite assemblages than those without domatia. Mite assemblages within the pastoral site were significantly different from the other two vegetation types. Only one fungivorous mite species, Orthotydeus californicus, occurred compared to five mite species in native and plantation forests. 4. This study indicated that foliar mite assemblages in native vegetation on experimental C. lucida shrubs are influenced by domatia availability, resident foliar mites, and local mite assemblages.     

A gall-inducing arthropod drives declines in canopy tree photosynthesis

Mature forest canopies sustain an enormous diversity of herbivorous arthropods; however, with the exception of species that exhibit large-scale outbreaks, canopy arthropods are thought to have relatively little influence on overall forest productivity. Diminutive gall-inducing mites (Acari; Eriophyoidae) are ubiquitous in forest canopies and are almost always highly host specific, but despite their pervasive occurrence, the impacts of these obligate parasites on canopy physiology have not been examined. We have documented large declines in photosynthetic capacity (approx. 60%) and stomatal conductance (approx. 50%) in canopy leaves of mature sugar maple (Acer saccharum) trees frequently galled by the maple spindle gall mite Vasates aceriscrumena. Remarkably, such large impacts occurred at very low levels of galling, with the presence of only a few galls (occupying approx. 1% of leaf area) compromising gas-exchange across the entire leaf. In contrast to these extreme impacts on the leaves of adult trees, galls had no detectible effect on the gas-exchange of maple saplings, implying large ontogenetic differences in host tolerance to mite galling. We also found a significant negative correlation between canopy tree radial increment growth and levels of mite galling. Increased galling levels and higher physiological susceptibility in older canopy trees thus suggest that gall-inducing mites may be major drivers of “age-dependent” reductions in the physiological performance and growth of older trees.     

Riparian land use and the relationship between the benthos and litter decomposition in tropical montane streams

1. Although stream–catchment interactions have been analysed in some detail in temperate environments, little is known about the effects of land‐use changes in the tropics. Here, we analyse differences in benthic communities (macroinvertebrates and fungi) under two contrasting land uses (mature secondary forest and pasture) in montane streams in north‐western Ecuador and their influence on the rates of litter processing. 2. Between 2005 and 2006, we used a combination of coarse and fine mesh bags to study the relative contribution of macroinvertebrates and fungi to processing of two types of litter, Alnus acuminata and Inga spectabilis, in three‐first‐order streams running through mature secondary montane forests and adjacent downstream reaches running through pastures. At the same time, we characterised the assemblages of shreddering macroinvertebrates and fungi communities and the litter processing rates in stream reaches under both vegetation types. 3. Litter processing rates attributable to invertebrate feeding (coarse mesh bags) were significantly slower in streams running through pastures. Nevertheless, shredder diversity and richness were similar between pasture and forest sections, while shredder abundance was significantly higher in forest streams (mainly Phylloicus sp. :Trichoptera). Fungal reproductive activity and litter processing rates were low (fine mesh bags) and did not differ significantly between pasture and forest stream reaches. 4. Phylloicus sp. abundance was the best predictor of the percentage of litter remaining in coarse mesh bags across pasture and forest sites. Neither shredder diversity nor their species richness was a significant predictor of mass loss, as most of the decomposition was performed by a single keystone species. Although litter decomposition by microbial decomposers was low, fungal biomass (but not diversity) was the best variable explaining the percentage of litter remaining in fine mesh bags. 5. Our data suggest that, in these Neotropical montane streams, land use can have a significant impact on the rates of critical ecosystem processes, such as litter decomposition. In this study, this effect was not mediated by a major shift in the structure of the benthos, but by a decrease in the abundance and relative representation of a single species whose life history makes it critical to litter processing. 6. This study highlights the significant role that macroinvertebrate fauna can have in the processing of litter in Neotropical streams and the predominant role that single species can have in terms of controlling stream ecosystem‐level processes. Understanding the extent to which these patterns affect the long‐term and large‐scale functioning of stream ecosystems still needs further research and will become increasingly important in terms of managing lotic ecosystems in the context of rapid land‐use change.     

Scale dependent diversity patterns in arboreal and terrestrial oribatid mite (Acari: Oribatida) communities

In naturally fragmented, isolated, or patchily distributed habitats that contain non‐vagile organisms, we expect dispersal to be limited, and patterns of diversity to differ from similar, yet continuous habitats. We explored the alpha‐beta‐gamma relationship and community composition of oribatid mites (Acari: Oribatida) inhabiting spatially discrete canopy suspended soils, and compared the patterns of diversity with the continuous forest floor soils over two years. We explored dispersal limitation for oribatid mites in the canopy by using additive partitioning of species richness at multiple spatial scales. ANOSIM was used to demonstrate differences in oribatid mite community composition between the canopy and forest floor habitats over different sampling periods. Community composition of oribatid mites differed significantly between canopy and forest floor habitats, by season and yearly sampling period. Oribatid mite richness and abundance were positively correlated with substrate moisture content, particularly in the canopy. Richness and abundance of ground oribatid mites was greater in September than in June, a trend that is reversed in the canopy, suggesting canopy oribatid mite species may have altered life histories to take advantage of earlier moisture conditions. Alpha diversity of oribatid mites in the canopy was lower than the ground at all sampling levels, and not significantly different from a random distribution in either habitat. Beta diversity was greater than expected from a random distribution at the patch‐ and tree‐level in the canopy suggesting dispersal limitation associated with physical tree‐to‐tree dispersal barriers, and limited dispersal among patches within a tree. Beta diversity at the tree‐level was the largest contribution to overall species richness in both canopy and ground habitats, and was also greater than expected on the ground. These results suggest that factors other than physical dispersal barriers, such as aggregation, habitat availability, and environmental factors (moisture), may limit the distribution of species in both habitats.     

Conversion of Andean montane forests into plantations: Effects on soil characteristics,microorganisms, and microarthropods

Tropical montane forests in the Andes are subjected to deforestation and subsequent transformation into pastures. Abandoned pastures are frequently reforested by planting monoculture timber plantations, resulting in reduced aboveground diversity and changes in soil characteristics compared to primary forests. In this study, we evaluated differences in soil properties (litter layer thickness, pH, water content, and C-to-N ratio) between degraded primary montane forest and monoculture pine (Pinus patula) and alder (Alnus acuminata) plantations and their effects on density, diversity, and community structure of litter and soil-living mesofauna, with focus on oribatid mites (Acariformes). The study was performed in a montane region in the southern Ecuadorian Andes (2,000–2,600 m a.s.l.). C-to-N ratios in the litter and upper 5 cm soil layer were higher in pine plantations, while other soil characteristics were similar between vegetation types. Surprisingly, microbial biomass and density of soil mesofauna in the litter layer did not differ between vegetation types, while density and species richness of oribatid mites were higher in pine plantations. Community structure of oribatid mites differed between vegetation types with only a few species overlapping. The results indicate that quality and diversity of litter were not the major factors regulating the mesofauna community. Instead, soil animals benefited from increased habitat structure in thicker litter layers and potentially increased availability of root-derived resources. Overall, the results suggest that from a soil animal perspective, monoculture plantations are less detrimental than commonly assumed and enrichment of abandoned plantations with native tree species may help to restore tropical montane forests.     

Contribution of oribatid and mesostigmatid soil mites in ecologically based estimates of global species richness

Erwin’s method for estimating total global species richness assumes some host‐specificity among the canopy arthropods. This study examined possible host habitat specialization in two major groups of soil arthropods, the oribatid and mesostigmatid mites, by sampling beneath three tree species: Eucalyptus pilularis Smith, Eucalyptus propinqua Deane and Maiden and Allocasuarina torulosa (Aiton) L. Johnson. The sample sites were in the Lansdowne State Forest, New South Wales, Australia and the three tree species were selected on the basis of their known differential effects on soil. Sampling was conducted over three seasons, and 79 oribatid and 34 mesostigmatid species were identified from 25 196 and 3634 individuals, respectively. Tree species had little effect on mite species composition with only three oribatid species and no mesostigmatid species identified as host‐habitat specialists using a niche breadth measure. Of mite species found under E. pilularis, E. propinqua and A. torulosa trees, 2%, 1% and 0% were defined as host‐habitat specialists, respectively. In contrast, tree species had significant and consistent effects on mite community structure, which differed in relative abundance of the oribatid species, their size class distributions and species rankings. In the mesostigmatid communities, there was a difference in the ranking of the mite species among tree species. Although it was demonstrated that tree species have an impact on the soil environment, the differences between tree species were insufficient to change species composition. The low degree of host‐habitat specialization suggested that other factors were more important for determining mite species composition at a site, and soil mite host‐habitat specialization may not make a large contribution to estimates of total global species richness using methods such as those proposed by Erwin (1982) .     

Oribatid mite communities in the canopy of montane Abies amabilis and Tsuga heterophylla trees on Vancouver Island, British Columbia

To study the oribatid mite community inhabiting microhabitats in the canopy of montane Abies amabilis [(Douglas ex D. Don) Lindl.] and Tsuga heterophylla [(Raf.) Sarg] tree species across five elevational sites, we collected 180 branch tips and 180 foliose/crustose lichen samples over three time periods. Thirty-three species of oribatid mites were identified from the study area. Mite species richness and abundance was significantly affected by microhabitat, and this association was independent of sampling time. At the microhabitat scale, distinct species assemblages were associated with lichen and branch tip habitats, and to a lesser degree, tree species. Conifer specificity was most apparent in the closely related species of Jugatala, where Jugatala tuberosa Ewing was only found on branch tips from A. amabilis and Jugatala sp. was primarily found on branch tips from T. heterophylla. Microhabitat specificity was most pronounced in Dendrozetes sp. where most individuals were found on branch tips and Anachiperia geminus Lindo et al. that occurred primarily on lichens. Principal components analysis of oribatid mite community composition further showed a high degree of association with microhabitat and tree species. Habitat profiles are difficult to discern for many species because tree, microhabitat, and elevation preferences confound distribution patterns. Given the significant tree-microhabitat associations in species composition in this montane canopy study, we suggest that sampling multiple microhabitats across elevations to look for patterns in community structure offers opportunities to explicitly test organizing principles in community ecology.     

Are tree trunks habitats or highways? A comparison of oribatid mite assemblages from hoop-pine bark and litter

Abstract Oribatid mites (Acari: Oribatida) are among the most diverse and abundant inhabitants of forest soil and litter, but also have species-rich assemblages on bark and in the canopies of trees. It is unclear whether the trunk of a tree acts simply as a 'highway' for movement of mites into and out of the canopy, or whether the trunk has a distinctive acarofauna. We compare oribatid assemblages from the trunk bark of hoop pine ( Araucaria cunninghamii ) with those from litter collected beneath the same trees. A 1.0 by 0.5 m area of bark was sampled from three trees at each of five sites using a knockdown insecticide. A 1-L sample of leaf litter was collected as close as possible to the base of each sampled tree. Mites were extracted using Tullgren funnels, identified to genus and morphospecies, and counted. Assemblages were almost 100% distinct, with only one oribatid morphospecies ( Pseudotocepheus sp.) collected from both litter and bark. Litter had a higher taxon richness than bark in total and per sample, but oribatids made up a greater percentage of the acarofauna in the bark samples. We had expected that the more consistent physical substrate of bark would be reflected in greater similarity of oribatid faunas on trunks than in litter; however, the opposite proved to be the case. We conclude that hoop-pine trunks are habitats rather than highways for oribatid mites. Based on the observed higher turnover among bark faunas, tree trunks may represent habitat islands whose colonisation by particular oribatid species is more stochastic than that of the more continuous 'sea' of litter.     

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

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

Nested patterns of community assembly in the colonisation of artificial canopy habitats by oribatid mites

An observed species–area relationship (SAR) in assemblages of oribatid mites inhabiting natural canopy habitats (suspended soils) led to an experimental investigation of how patch size, height in canopy and moisture influence the species richness, abundance and community composition of arboreal oribatid mites. Colonisation by oribatid mites on 90 artificial canopy habitats (ACHs) of three sizes placed at each of three heights on the trunks of ten western redcedar trees was recorded over a 1‐year period. Fifty‐nine oribatid mite species colonised the ACHs, and richness increased with the moisture content and size of the habitat patch. Oribatid mite species richness and abundance, and ACH moisture content decreased with increasing ACH height in the canopy. Patterns in the species richness and community composition of ACHs were non‐random and demonstrated a significant nested pattern. Correlations of patch size, canopy height and moisture content with community nestedness suggest that species‐specific environmental tolerances combined with the differential dispersal abilities of species contributed to the non‐random patterns of composition in these habitats. In line with the prediction that niche‐selection filters out species from the regional pool that cannot tolerate environmental harshness, moisture‐stressed ACHs in the high canopy had lower community variability than ACHs in the lower canopy. Colonising source pools to ACHs were almost exclusively naturally‐occurring canopy sources, but low levels of colonisation from the forest floor were apparent at low heights within the ACH system. We conclude that stochastic dispersal dynamics within the canopy are crucial to understanding oribatid mite community structure in suspended soils, but that the relative importance of stochastic dispersal assembly may be dependent on a strong deterministic element to the environmental tolerances of individual species which drives non‐random patterns of community assembly.     

Species shift drives decomposition rates following invasion by hemlock woolly adelgid

Insect and disease outbreak is an important cause of selective species removal and accompanying functional change in North American forests. Outbreak of hemlock woolly adelgid, Adelgies tsugae– HWA, is causing selective removal of eastern hemlock Tsuga canadensis at a regional scale. Impacts of outbreak‐caused canopy mortality and shifts in dominant species on litter decay were compared across sites that range in HWA‐caused canopy damage and subsequent canopy dominance by black birch Betula lenta. Senescent litter from eastern hemlock, black birch, and equal litter mixes were decomposed in the field for 36 months within nine sites in Connecticut and Massachusetts USA. Mass loss and % N accumulation of black birch was 65% and 52% greater compared to eastern hemlock. In contrast, outbreak related canopy damage increased litter mass loss by 11.5% in high mortality stands relative to uninfested stands but canopy damage had no impact on % N dynamics. Non‐additive effects of litter mixing influenced chemical dynamics of decaying litter; black birch accumulated less N and eastern hemlock accumulated more N compared to each species decaying alone. However, these changes offset and mixed litter bags overall showed no differences in N dynamics compared to values from each species decaying alone. In eastern hemlock stands invaded by hemlock woolly adelgid, canopy damage influences the rates and dynamics of decay but species differences between hemlock and black birch leaf litter are the dominant mechanisms of decomposition changes and a long‐lasting driver of increased N cycling rates. Species shifts may be the dominant driver of altered ecosystem processes for other insect outbreaks, particularly when replacement species have very different characteristics regulating decomposition and N cycling.     

Do plant mites commonly prefer the underside of leaves?

The adaxial (upper) and abaxial (lower) surfaces of a plant leaf provide heterogeneous habitats for small arthropods with different environmental conditions, such as light, humidity, and surface morphology. As for plant mites, some agricultural pest species and their natural enemies have been observed to favor the abaxial leaf surface, which is considered an adaptation to avoid rain or solar ultraviolet radiation. However, whether such a preference for the leaf underside is a common behavioral trait in mites on wild vegetation remains unknown. The authors conducted a 2-year survey on the foliar mite assemblage found on Viburnum erosum var. punctatum, a deciduous shrub on which several mite taxa occur throughout the seasons, and 14 sympatric tree or shrub species in secondary broadleaf-forest sites in Kyoto, west–central Japan. We compared adaxial–abaxial surface distributions of mites among mite taxa, seasons, and morphology of host leaves (presence/absence of hairs and domatia). On V. erosum var. punctatum, seven of 11 distinguished mite taxa were significantly distributed in favor of abaxial leaf surfaces and the trend was seasonally stable, except for Eriophyoidea. Mite assemblages on 15 plant species were significantly biased towards the abaxial leaf surfaces, regardless of surface morphology. Our data suggest that many mite taxa commonly prefer to stay on abaxial leaf surfaces in wild vegetation. Oribatida displayed a relatively neutral distribution, and in Tenuipalpidae, the ratio of eggs collected from the adaxial versus the abaxial side was significantly higher than the ratio of the motile individuals, implying that some mite taxa exploit adaxial leaf surfaces as habitat.     

Community structure and the habitat templet: ants in the tropical forest canopy and litter

The tropical forest canopy and litter differ in physical structure, resource availability, and abiotic conditions. We used standardized bait experiments in the canopy and litter of four neotropical tree species to explore how these differences shape the behavior, morphology, and diversity of ant assemblages. Ant activity (biomass at a bait after 32 min) was higher in the canopy, and higher on protein baits than carbohydrate baits. Aggressive bait defense occurred more frequently in the canopy (60%) than in the litter (32%), but was not associated with tree species or bait type in either habitat. The median size of workers of species in the canopy and litter was nearly identical, but body size distribution was unimodal in the canopy and bimodal in the litter. The colony size of the most aggressive species was an order of magnitude larger in the canopy. Species richness at a bait was relatively uniform across tree species and habitats. Litter and canopy shared no species, but overlap among tree species was three times higher in the litter assemblages. Litter assemblages showed less activity, less interference, less differentiation across the landscape, and different size distributions than canopy assemblages. The canopy and litter templets subsume a number of environmental gradients that combine to shape ant community structure.     

Vertical stratification of the termite assemblage in a neotropical rainforest

The importance of termites as decomposers in tropical forests has long been recognized. Studies on the richness and diversity of termite species and their ecological function have flourished in more recent times, but these have been mostly conducted in a thin stratum within a standing man’s reach. Our aims were to evaluate the specific richness and composition of the termite assemblage in the canopy of a tropical rainforest and to determine its originality with respect to the sympatric ground-level fauna. We conducted systematic searches for canopy termites, together with conventional sampling of the sympatric ground-level fauna, in the San Lorenzo forest, Panama. We hypothesized that (1) the canopy accommodates two categories of wood-feeding termites (long-distance foragers and small-colony “one-piece” species) and possibly soil-feeders in suspended soil-like habitats; (2) due to the abundance of soil-feeders, the overall diversity of the ground fauna is higher than that of the canopy; (3) differences in microclimate and resource accessibility favour vertical stratification among wood-feeders. Sixty-three canopy samples yielded ten species of termites, all wood-feeders. Five of these were not found at ground level, although a total of 243 ground samples were collected, representing 29 species. In addition to long-distance foragers (Microcerotermes and Nasutitermes spp.) and small-colony termites (mostly Kalotermitidae), the canopy fauna included Termes hispaniolae, a wood-feeding Termitidae from an allegedly soil-feeding genus, living in large dead branches. Soil-feeders were absent from the canopy, probably because large epiphytes were scarce. As predicted, the ground fauna was much richer than that of the canopy, but the species richness of both habitats was similar when only wood-feeders were considered. Vertical stratification was strongly marked among wood-feeders, as all common species, apart from the arboreal-nesting Microcerotermes arboreus, could unequivocally be assigned to either a ground or a canopy group. The canopy, therefore, contributes significantly to the total species richness of the termite assemblage, and the diversity, abundance and ecological importance of canopy termites in tropical rainforests may be higher than previously recognized.Electronic Supplementary Material Supplementary material is available to authorized users in the online version of this article at .