Diversity patterns of eucalypt canopy arthropods in eastern and western Australia

1. As part of a larger study on canopy arthropods and birds, a 1‐year chemical knockdown study was carried out in one Western Australian forest, where jarrah Eucalyptus marginata and marri E. (Corymbia) calophylla were sampled, and one eastern Australian (New South Wales) forest, where narrow‐leaved ironbark E. crebra and grey box E. moluccana were sampled. 2. Ten trees of each species were sampled during each of the four seasons and the arthropods were sorted to morphospecies level. This paper documents the foliage‐associated component of arboreal arthropod communities and compares arthropod species richness within orders and families, between tree species, and between the two forest types. 3. Hymenoptera, Coleoptera, Diptera, and Araneae were the richest in species. Nine hundred and seventy‐six species in 173 families were found in the eastern Australian forest, while 687 species in 176 families were found in the western Australian forest. Only 53% of families were common to both forests, but almost half the families recorded were represented by fewer than five species. Species overlap between tree species in each region was 40–53%. 4. Analysis using nonparametric bootstrapping procedures showed that sampling of foliage was comprehensive and that only 4–9% more species would be expected with more intensive sampling of the canopy. Absolute richness, as well as differences between tree species and regions, therefore appear to be real and not the result of sampling errors. As a consequence, arthropod species richness in Australian eucalypt forests is shown to be substantially greater than previous estimates.     

Seasonality of canopy invertebrate communities in eucalypt forests of eastern and western Australia

Abstract Chemical knockdown procedures were used to sample canopy arthropods at 3 month intervals over 1 year at two sites, one in eastern Australia and the other in western Australia. Samples were taken from narrow-leaved ironbark, Eucalyptus crebra, and grey box, Eucalyptus moluccana, in the east and from jarrah, Eucalyptus marginata, and marri, Eucalyptus calophylla, in the west. Arthropods were more abundant on trees in eastern Australia and exhibited different seasonal patterns from those in the west. Members of different functional groups exhibited different seasonal patterns, with some herbivorous groups responding to times of leaf production, decomposers and fungus feeders responding to high moisture availability, and predators/parasites responding to the abundance of food items. Seasonal variability was slightly higher in the west, possibly reflecting the greater seasonal amplitude in rainfall. In the eastern forest, proportionately more taxa peaked in spring or summer and declined to minimum numbers in winter. In the western forest several taxa attained peak numbers in autumn, winter or spring, while others declined to minimum values in winter or summer. The phenological patterns of canopy arthropods appear to be linked to the condition of the host plant and/or to climatic factors. Comparison of the western Australian data to those from a second year of sampling at a time when rainfall was greater and fell later into the season indicated that variability in arthropod numbers between years can be as great as that between seasons. Implications of the variability in seasonal and annual patterns of canopy invertebrate communities are discussed in relation to the need for long-term sampling and in relation to evaluating the impact of disturbance on forest communities.     

Arthropod communities in a Japanese cedar (Cryptomeria japonica D. Don) plantation: Abundance,biomass and some properties

Arboreal arthropod communities were censused by insecticidal knockdown in a plantation of Japanese cedar,Cryptomeria japonica, in central Japan from April 1983 to February 1985 at intervals of two months. All arthropods sampled were allocated to higher taxonomic groups or guilds and the composition of the communities was analyzed with respect to abundance, biomass and their seasonal trends. The total densities fluctuated seasonally from 200 to 3500 m⁻²; corresponding biomass values ranged from 7 to 600 mg fresh weight m⁻². Maximum density and biomass generally occurred in summer and were minimum in winter. The consistently dominant guild in terms of abundance were the detritivores, mostly comprising Collembola and oribatid mites, accounting for 36–93% of all arthropods; phytophages, predators and detritivores were major guilds in terms of biomass, showing average proportions of 27%, 23% and 20%, respectively. Biomass ratios of predators to prey were generally high in some canopy communities, suggesting the importance of predation pressure in regulating the population levels of arthropods in forests. Average individual size of predators was approximately proportional to that of prey, irrespective of tree locality. Soil arthropod communities maintained densities approximately 10²–10³ times as large as the corresponding canopy communities throughout the year. The seasonal variations in abundance were much greater in canopy than in soil communities.     

Use of arthropods for the evaluation of the olive-orchard management regimes

Abstract 1 The presence and abundance of arthropods were compared in three olive orchards under organic, integrated and conventional management regimes. In each olive orchard, trees were sampled in the canopy by beating branches and soil arthropods by placing pitfall traps. Contrary to expectations, the highest abundance of arthropods occurred in the integrated management orchard. The most abundant groups were Formicidae and the species Euphyllura olivinae (Homoptera: Psyllidae). 2 Canopies and the soil under the tree canopy (interior soil) were selected as the most informative sites for sampling. The months with the strongest differences were May, June and July, especially June. In the canopy, Araneae, Coleoptera, Diptera, Heteroptera, Hymenoptera, Homoptera, Lepidoptera, Neuroptera and Thysanoptera were the most abundant, and showed significant differences in abundance among orchards with different management regimes. Moreover, in the canopies, Coleoptera and Lepidoptera showed a seasonal pattern of abundance and consistent significant differences between the organic orchard vs. the integrated and conventional ones in both years of study. In the soil, 12 orders showed significant differences in abundance among management regimes at some point of the sampling season. 3 In a search for biological indicators that could help to distinguish between management regimes, a discriminant analysis applied to the data indicated that only the samples from the canopy were classified according to their management regime in a consistent way over time. The groups selected by the analysis to establish differences among management regimes were Coleoptera, Diptera, Heteroptera, Lepidoptera and Thysanoptera. The analysis applied to compare organic vs. non‐organic olive orchards, again identified Coleoptera and Lepidoptera as suitable groups. The results suggest that these two orders are potential bioindicators to distinguish, in a simple way, organic olive orchards from non‐organic ones.     

车八岭山地常绿阔叶林冰灾后土壤节肢动物群落的多样性

2008年初车八岭山地常绿阔叶林受到中国南方80年一遇的冰灾的重创。为了揭示灾后林冠开度的梯度对土壤节肢动物多样性与分布的影响, 在受冰灾影响的车八岭山地常绿阔叶林设置2 ha固定样地, 按照冠层受损程度选取17个20 m×20 m的样方, 用半球面影像技术获取林冠开度, 并分凋落物层、0–10 cm和10–20 cm的矿质土层采集凋落物及土壤样品, 分析土壤节肢动物多样性。利用双向聚类分析(two-way cluster analysis)对凋落物层的土壤节肢动物和样地进行聚类, 以典范对应分析(canonical correspondence analysis)研究冠层开度、土壤有机质、电导率以及自然含水量与0–10 cm表土层土壤节肢动物的关系。结果表明土壤节肢动物的多度、丰富度和多样性随土壤层的加深而下降, 具有明显的表聚性; 林冠开度与凋落物层的土壤节肢动物类群数量呈负相关; 甲螨亚目、中气门亚目和前气门亚目动物对光照的适应范围广; 膜翅目、鞘翅目幼虫、综合纲和伪蝎目动物具有明显的避光性; 土壤节肢动物类群的分布与林冠开度、土壤自然含水量、电导率和有机质关系密切。因此可以推论, 冰灾对车八岭山地常绿阔叶林冠层的破坏及土壤因子的变化会进一步影响土壤节肢动物群落的组成和分布。本项研究还表明, 土壤节肢动物群落能有效地表征它们所栖息的生态系统的特点, 可用于监测冰灾后森林恢复和演替动态。而双向聚类分析和典范对应分析对于揭示土壤节肢动物的空间异质性及其与环境因子的相互关系具有理想的效果。     

Toward an optimal sampling protocol for Hemiptera on understorey plants

There are no standardised sampling protocols for inventorying Hemiptera from understorey or canopy plants. This paper proposes an optimal protocol for the understorey, after evaluating the efficiency of seven methods to maximise the richness of Hemiptera collected from plants with minimal field and laboratory time. The methods evaluated were beating, chemical knockdown, sweeping, branch clipping, hand collecting, vacuum sampling and sticky trapping. These techniques were tested at two spatial scales: 1 ha sites and individual plants. In addition, because efficiency may differ with vegetation structure, sampling of sites was conducted in three disparate understorey habitats, and sampling of individual plants was conducted across 33 plant species. No single method sampled the majority of hemipteran species in the understorey. Chemical knockdown, vacuum sampling and beating yielded speciose samples (61, 61 and 30 species, respectively, representing 53, 53 and 26% of total species collected). The four remaining methods provided species-poor samples (<18 species or <16% of total species collected). These methods also had biases towards particular taxa (e.g., branch clipping and hand collecting targeted sessile Hemiptera, and sticky trapping were dominated by five species of Psyllidae). The most time-efficient methods were beating, sweeping and hand collecting (200 minutes of field and laboratory time yielded >7 species for each technique). By comparison, vacuum sampling, sticky trapping, branch clipping and chemical knockdown yielded <5 species for the same period. Chemical knockdown had further disadvantages; high financial cost and potential spray drift. The most effective methods for a standardised sampling protocol to inventory Hemiptera from the understorey are beating and vacuum sampling. If used in combination, these methods optimise the catch of understorey hemipteran species, as their samples have high complementarity.     

Insect diversity: facts,fiction and speculation*

Biologists are still trying to grasp the global dimensions of the phylum Arthropoda and its major class the Insecta, in spite of the fact that over a million species of arthropods have been described. The canopy of rain forest trees is believed by many to hold the key to the immense diversity of insects. In recent years the use of knock-down insecticides to sample insects from rain forest canopy has revealed information on the canopy's arthropod inhabitants and community structure. The sampling techniques involved are outlined and data reviewed on taxonomic and guild structure, species abundance, body size and biomass of insects, and the faunal similarity of trees. Calculations by Erwin (1982), based on knock-down insecticide studies of the beetle fauna of one species of Central American tree, suggest there may be 30 million species of tropical forest arthropods. Reanalysis of these calculations, using additional data, produces a range of possible estimates from about 10 to 80 million. The unknown range of plant host-specificities of tropical insects is the main weakness of this method of calculation. Assessment of the faunal importance of the canopy in relation to that of other rain forest biotopes requires comparative quantitative studies. The preliminary results of one such simple study suggest that over 42 million arthropods may be found in a hectare of Seram rain forest (at the time of study), and that 70% occur in the soil and leaf litter and 14% in the canopy. They also suggest that Collembola and Acarina are the dominant groups in this hectare, and that there are as many ants as all the other insects (excluding Collembola).     

Patterns of resource use in an assemblage of birds in the canopy of a temperate alluvial forest

In our study, we assessed patterns of resource use in an assemblage of birds by observing their foraging behaviour from a crane in the canopy of a temperate alluvial forest. We selected 12 bird species and addressed seasonal changes in feeding activity during a 2-month period in spring focussing on average staying time and utilisation of crown strata in two tree species, the common oak (Quercus robur) and the sycamore maple (Acer pseudoplatanus). We further examined ecological characteristics of the trees (i. e., crown density) that are likely to influence resource use in birds. The selected birds differed in their preference for the tree species. Most birds preferred common oaks. This preference was probably associated with higher food abundance related to substrate characteristics (i.e., roughness of bark) which offer more microhabitats for arthropods and thus permit higher densities of potential prey. Some bird species switched feeding preferences within the study period from sycamore maples to common oaks in association with tree phenology. We found two main foraging techniques. All birds searched for prey at short distance (≤50 cm) and gleaned food from substrate except the Pied Flycatcher that foraged by hovering and searched over longer distances (>50 cm). Overall, we demonstrate in our study that canopy access with mobile crane systems provides excellent opportunities to observe canopy birds and enables detailed analysis of their foraging behaviour. The main result of our study reveals fine-grained resource partitioning of birds within the canopy as an important factor structuring assemblages, with species-specific and in part also seasonal differences in stratification and substrate use.     

Impact of fire on leaf nutrients,arthropod fauna and herbivory of native and exotic eucalypts in Kings Park,Perth, Western Australia

The vegetation of Kings Park, near the centre of Perth, Western Australia, once had an overstorey of Eucalyptus marginata (jarrah) or Eucalyptus gomphocephala (tuart), and many trees still remain in the bushland parts of the Park. Avenues and roadsides have been planted with eastern Australian species, including Eucalyptus cladocalyx (sugar gum) and Eucalyptus botryoides (southern mahogany), both of which have become invasive. The present study examined the effect of a recent burn on the level of herbivory on these native and exotic eucalypts. Leaf damage, shoot extension and number of new leaves were measured on tagged shoots of saplings of each tree species in unburnt and burnt areas over an 8‐month period. Leaf macronutrient levels were quantified and the number of arthropods on saplings was measured at the end of the recording period by chemical knockdown. Leaf macronutrients were mostly higher in all four species in the burnt area, and this was associated with generally higher numbers of canopy arthropods and greater levels of leaf damage. It is suggested that the pulse of soil nutrients after the fire resulted in more nutrient‐rich foliage, which in turn was more palatable to arthropods. The resulting high levels of herbivory possibly led to reduced shoot extension of E. gomphocephala, E. botryoides and, to a lesser extent, E. cladocalyx. This acts as a negative feedback mechanism that lessens the tendency for lush, post‐fire regrowth to outcompete other species of plants. There was no consistent difference in the levels of the various types of leaf damage or of arthropods on the native and the exotic eucalypts, suggesting that freedom from herbivory is not contributing to the invasiveness of the two exotic species.     

Stratification and diel activity of arthropods in a lowland rainforest in Gabon

The abundance, activity and species richness of arthropods, particularly of insect herbivores, were investigated in the upper canopy and understorey of a lowland rainforest at La Makandé, Gabon. In total 14 161 arthropods were collected with beating, flight interception and sticky traps, from six canopy sites, during the day and at night, from mid-January to mid-March 1999. The effects of stratum were most important, representing between 40 and 70% of the explained variance in arthropod distribution. Site effects represented between 20 and 40% of the variance and emphasized the néed for replication of sampling among canopy sites. Time effects (diel activity) explained a much lower percentage of variance (6–9%). The density and abundance of many arthropod taxa and species were significantly higher in the upper canopy than in the understorey. Arthropod activity was also higher during the day than at night. In particular, insect herbivores were 2.5 times more abundant and twice as speciose in the upper canopy than in the understorey, a probable response to the greater and more diverse food resources in the former stratum. Faunal overlap between the upper canopy and understorey was low. The most dissimilar herbivore communities foraged in the understorey at night and the upper canopy during the day. Further, a taxonomic study of a species-rich genus of herbivore collected there (Agrilus , Coleoptera Buprestidae) confirmed that the fauna of the upper canopy was different, diverse and very poorly known in comparison to that of the understorey. Herbivore turnover between day and night was rather high in the upper canopy and no strong influx of insect herbivores from lower foliage to the upper canopy was detected at night. This suggests that insect herbivores of the upper canopy may be resident and well adapted to environmental conditions there.     

Multiple canopy opening effects on recruited saplings in a typhoon-disturbed tropical rainforest,Taiwan

To investigate the influence of multiple canopy openings on the composition and diversity of recruited saplings in a forest frequently disturbed by typhoons. We conducted tree-by-tree censuses (diameter at breast height ≥ 1 cm) and mapped gaps (canopy height < 5 m) in 1993, 2000, 2008, and 2013 in a tropical mountain zonal foothill evergreen broad-leaved forest in Nanjenshan Nature Reserve, Taiwan. We analyzed the composition and diversity of recruited saplings within a 2.1 ha plot (840 sampling quadrats (5 m × 5 m)) with variable numbers of canopy openings recorded during the study period. Composition of recruited saplings was dissimilar between quadrats that stayed opened and those that stayed closed throughout the study period (pairwise similarity estimates C₀₂ = 0.52, 95% CI = 0.38–0.66). The quadrats under closed canopy had high diversity when weighting rare species (species richness), whereas quadrats with one or two gap opening records during the past 20 years had high diversity when weighting the abundance of species. Although canopy openings provided establishment conditions for saplings of some shade-intolerant species, due to the nature of small gap size, such habitats do not favor the dominance of shade-intolerant species. Even in a frequently disturbed forest, species composition and richness of recruited saplings were mainly contributed by shade-tolerant species. Although multiple canopy openings facilitated the establishment of shade-intolerant species, species diversity in the study forests is possibly mainly mediated by coexistence mechanisms of those shade-tolerant species rather than light-gap-related species strategies.     

Surface and leaf-litter arthropods in the coastal forests of Tanzania

Surface and leaf litter arthropod assemblages of the seasonal lowland coastal forests of eastern Tanzania were investigated from eleven sites over a 3-year period (1991–93). Pit-fall trap data show that four groups comprise more than 10% of the total sample: ants (Hymenoptera: Formicidae, 31%), grasshoppers and crickets (Orthoptera, 22%), beetles (Coleoptera: 17.39%) and spiders (Araneae: 13.48%). Arthropod abundance varies considerably with season, with greater total numbers of arthropods in all groups found in wetter periods. Arthropod abundance also varies considerably according to habitat, with greatest numbers found in forests with the most intact canopy cover, and in valley-bottom forest as compared to ridge-top forest; the valleys are normally both wetter and with a more complete and taller canopy. Tullgren Funnel data show that over 50% of the leaf litter fauna comprises tiny arthropods of the groups Collembola and Acarina. Abundance of arthropods in the leaf litter of these forests varies from a maximum of ≈ 16,000 m^–2, to a minimum of 780 m^–2. Abundance is highest in wetter periods, in the forest areas with the most intact canopy cover, and in valley-bottom as opposed to ridge-top habitats.     

Pollination Processes in Idiospermum australiense (Calycanthaceae), an arborescent basal angiosperm of Australia’s Tropical Rain Forests

Idiospermum australiense (Diels) S.T. Blake, a rainforest canopy tree restricted to a few small populations in northeast Australia, is the only southern hemisphere representative of the Calycanthaceae. Pollination processes in Idiospermum were investigated. Flowers are protogynous, with some populations of the species being andromonoecious, whilst others are hermaphrodite. Over their 10 – 16 day floral lifespan, movements of floral organs enforced spatial and temporal separation of male and female floral function. Changes in colour and intensity of fragrance may also influence their attractiveness to potential pollinators. Pollen is present in large quantities, and appears to act as a reward for floral visitors. Insect trapping was carried out both within flowers, and immediately adjacent to inflorescences. A wide variety of arthropods was trapped, with thrips being the most abundant. Other arthropods were trapped, including fourteen species of beetle. For arthropods other than thrips, the mean numbers of adults trapped on flowers remained more or less constant throughout the floral lifetime. However, there was a significant interaction between floral age and the number of pre-adult arthropods present – as the flower aged, the mean number of larvae and eggs per flower increased. The flowers appear to act as sheltered mating and brooding sites for small insects.     

Comparative analysis of telomeric restriction fragment lengths in different tissues of <Emphasis Type="Italic">Ginkgo biloba</Emphasis> trees of different age

Ginkgo trees of four different ages were selected as experimental material. Telomeric restriction fragment (TRF) lengths, as an indicator of telomere length, were determined for different tissues by Southern hybridization analysis. Statistical analysis was performed to compare two aspects of TRF length. By determining TRF lengths for different tissues for each age, a latent tendency was found. TRF length varied from short to long in these tissues in the order microspore < embryonal callus < leaf < branchlet. TRF lengths for leaf tissue and branchlet tissue were dissimilar for female and male mature trees, although this difference between TRF lengths for the two sexes was not statistically significant. Evaluation of TRF lengths for each tissue for trees of all four ages revealed TRF lengths increased with age to some extent. Different rates of change were found for leaf tissue and for branchlet tissue, although tendencies to increase were not linear for either. Finally, a simple mathematical model was formulated to describe the relationship between telomere length and age for Ginkgo biloba L.     

Intercellular Transport and Subcellular Distribution of Photoassimilates in Chara corallina

The mechanism of polar transport of ¹⁴C-photoassimilates betweenChara corallina branchlets and internodes was investigated usingan intracellular perfusion procedure. When the apex remained,more ¹⁴C-photoassimilates were transported from branchlet tointernode than in the opposite direction. When the apex wasdetached, this polarity disappeared. To study the polar transportmechanism, we examined the subcellular distribution of ¹⁴C-photoassimilatesin the three main intracellular compartments, the cortical chloroplastlayer, streaming sol endoplasm and vacuole. When the internode or branchlet of an internode-branchiet complexwas exposed to ¹⁴C-bicarbonate for 10 min, 70 to 80% of thetotal fixed carbon was found in the sol endoplasm. In the subsequent3 h chase, the ¹⁴C-photoassimilates in the sol endoplasm ofthe source cell decreased greatly to 20 to 40% of the totallabelled substances. When the apex remained, the branchlet showed higher photosyntheticactivity than the internode, which resulted in a concentrationgradient of 13·5 mol m^–3 in the sol endoplasm frombranchlet to internode after photosynthesis for 10 mm. In the3 h chase period, this gradient decreased to about 1·0mol m^–3. In the other three cases, involving transportfrom branchlet to internode when the apex was detached, or transportfrom internode with or without apex to branchlet, the intercellulargradient of ¹⁴C after 10 mm photosynthesis was about 70 molm^–3 in the sol endoplasm. Thus, when the apex remains,the greater gradient of photoassimilates between the sol endoplasmof branchlet and internode seems to be one of the reasons forpolar intercellular transport. Key words: Chara corallina, polar transport, ¹⁴C photoassimilates     

Nondestructive, Stereological Estimation of Canopy Surface Area

Summary .  We describe a stereological procedure to estimate the total leaf surface area of a plant canopy in vivo, and address the problem of how to predict the variance of the corresponding estimator. The procedure involves three nested systematic uniform random sampling stages: (i) selection of plants from a canopy using the  smooth fractionator , (ii) sampling of leaves from the selected plants using the  fractionator , and (iii) area estimation of the sampled leaves using  point counting . We apply this procedure to estimate the total area of a chrysanthemum ( Chrysanthemum morifolium L. ) canopy and evaluate both the time required and the precision of the estimator. Furthermore, we compare the precision of point counting for three different grid intensities with that of several standard leaf area measurement techniques. Results showed that the precision of the plant leaf area estimator based on point counting is high. Using a grid intensity of 1.76 cm²/point we estimated plant and canopy surface areas with accuracies similar to or better than those obtained using image analysis and a commercial leaf area meter. For canopy surface areas of approximately 1 m² (10 plants), the fractionator leaf approach with sampling fraction equal to 1/9 followed by point counting using a 4.3 cm²/point grid produced a coefficient of error of less than 7%. The  smooth fractionator  can be used to ensure that the additional contribution to the estimator variance due to between-plant variability is small.     

The Position of Arthropods in the Animal Kingdom: A Search for a Reliable Outgroup for Internal Arthropod Phylogeny

Morphological evidence for the phylogeny of the animal kingdom has been discussed by numerous authors. DNA sequencing and phylogenetic methods for analyzing these data are alternative approaches to animal phylogeny, but the phenomenon of long branch attraction and poor taxonomic sampling have caused misinterpretations of metazoan relationships. Here we report a cladistic approach to metazoan evolution including 133 18S rDNA sequences of 31 animal phyla. Despite the difficulties associated with analyzing large data sets, our data suggest that the Bilateria and Protostomia are monophyletic. The internal phylogeny of the protostomes is divided into two main clades. One clade includes the classical protostome worms (annelids, sipunculans, echiurans, pogonophorans, and vestimentiferans), mollusks, nemerteans, “lophophorates,” platyhelminths, rotiferans, and acanthocephalans, although the internal resolution of the clade is very low. The second clade includes arthropods and other molting animals: tardigrades, onychophorans, nematodes, nematomorphans, kinorhynchs, and priapulans. The arthropods and related phyla lack a ciliated larvae, lack a multiciliate (locomotory) epithelium, and share many features, notably, a reduced coelomic cavity and the presence of a cuticle which molts. The use of these outgroups within the molting clade to root arthropod phylogenies is recommended instead of using annelids or other spiralians. The data are quite conclusive in those phyla with a good taxonomic sampling (i.e., platyhelminths and arthropods).     

Arthropod Distribution in a Tropical Rainforest: Tackling a Four Dimensional Puzzle

Quantifying the spatio-temporal distribution of arthropods in tropical rainforests represents a first step towards scrutinizing the global distribution of biodiversity on Earth. To date most studies have focused on narrow taxonomic groups or lack a design that allows partitioning of the components of diversity. Here, we consider an exceptionally large dataset (113,952 individuals representing 5,858 species), obtained from the San Lorenzo forest in Panama, where the phylogenetic breadth of arthropod taxa was surveyed using 14 protocols targeting the soil, litter, understory, lower and upper canopy habitats, replicated across seasons in 2003 and 2004. This dataset is used to explore the relative influence of horizontal, vertical and seasonal drivers of arthropod distribution in this forest. We considered arthropod abundance, observed and estimated species richness, additive decomposition of species richness, multiplicative partitioning of species diversity, variation in species composition, species turnover and guild structure as components of diversity. At the scale of our study (2km of distance, 40m in height and 400 days), the effects related to the vertical and seasonal dimensions were most important. Most adult arthropods were collected from the soil/litter or the upper canopy and species richness was highest in the canopy. We compared the distribution of arthropods and trees within our study system. Effects related to the seasonal dimension were stronger for arthropods than for trees. We conclude that: (1) models of beta diversity developed for tropical trees are unlikely to be applicable to tropical arthropods; (2) it is imperative that estimates of global biodiversity derived from mass collecting of arthropods in tropical rainforests embrace the strong vertical and seasonal partitioning observed here; and (3) given the high species turnover observed between seasons, global climate change may have severe consequences for rainforest arthropods.     

Fine-grain pattern in Southern Cape plateau forests

Abstract. Regeneration levels, size class distributions and a nearest neighbour technique were used to describe apreliminary dynamics frameworkfortheplateauforests. Taken over a large area, most of the canopy dominants have a negative exponential distribution of stems > 10 cm dbh per size class. In small (0.04 ha) plots, if present as more than one stem, most species are present as both canopy (> 25 cm dbh) and understorey (10–15 cm dbh) individuals. The canopy dominants maintain their rank in the bank of advance regeneration (> 5 cm height < 10 cm dbh). However, relative numbers of all regeneration of most canopy individuals are not strongly correlated with canopy closure or local abundance of conspecific adults. The mean area of nearest neighbour polygons of canopy individuals around saplings of the more common species are small. In conclusion, most species appearto be shade tolerant and locally persistent conferring a fine grain on this forest. We support recent questioning of universality of the gaps/non gaps paradigm.     

Herbivory patterns in mature sugar maple: variation with vertical canopy strata and tree ontogeny

1. Although leaf morphology and chemistry show profound changes as trees age, the consequences of such changes to herbivory have received little attention, particularly late in the ontogeny of canopy trees. 2. Using a mobile aerial lift for canopy access, patterns of leaf damage were evaluated in canopy‐dominant mature sugar maple (Acer saccharum Marsh) trees ranging from ～20 to 70 cm in diameter, corresponding to an age range of ～40–180 years. 3. Herbivore damage patterns varied in relation to both vertical canopy position (among upper‐, mid‐, and lower‐canopy positions) and with tree size. Damage types attributable to herbivores active on leaf surfaces, including leaf skeletonizers and leaf cutters (both principally Lepidoptera), and leaf stippling inducers (Hemiptera) showed decreases with tree size, and with increasing height in the canopy. In contrast, leaf damage from the most abundant gall‐forming arthropod in the system, the eriophyid mite Vasates aceriscrumena, increased markedly with tree size. 4. The results indicate that herbivory patterns vary with both canopy stratum and with tree size in sugar maple, and that the relative strength of vertical stratification and tree ontogeny effects are similar in magnitude. The predominant patterns are of a decrease in herbivory with increasing height in the canopy and with tree size, but certain galling arthropods exhibit the reverse trends.