Frequency of cyanogenesis in tropical rainforests of far north Queensland, Australia

BACKGROUND AND AIMS: Plant cyanogenesis is the release of toxic cyanide from endogenous cyanide-containing compounds, typically cyanogenic glycosides. Despite a large body of phytochemical, taxonomic and ecological work on cyanogenic species, little is known of their frequency in natural plant communities. This study aimed to investigate the frequency of cyanogenesis in Australian tropical rainforests. Secondary aims were to quantify the cyanogenic glycoside content of tissues, to investigate intra-plant and intra-population variation in cyanogenic glycoside concentration and to appraise the potential chemotaxonomic significance of any findings in relation to the distribution of cyanogenesis in related taxa. METHODS: All species in six 200 m(2) plots at each of five sites across lowland, upland and highland tropical rainforest were screened for cyanogenesis using Feigl-Anger indicator papers. The concentrations of cyanogenic glycosides were accurately determined for all cyanogenic individuals. KEY RESULTS: Over 400 species from 87 plant families were screened. Overall, 18 species (4.5 %) were cyanogenic, accounting for 7.3 % of total stem basal area. Cyanogenesis has not previously been reported for 17 of the 18 species, 13 of which are endemic to Australia. Several species belong to plant families or orders in which cyanogenesis has been little reported, if at all (e.g. Elaeocarpaceae, Myrsinaceae, Araliaceae and Lamiaceae). A number of species contained concentrations of cyanogenic glycosides among the highest ever reported for mature leaves-up to 5.2 mg CN g(-1) d. wt, for example, in leaves of Elaeocarpus sericopetalus. There was significant variation in cyanogenic glycoside concentration within individuals; young leaves and reproductive tissues typically had higher cyanogen content. In addition, there was substantial variation in cyanogenic glycoside content within populations of single species. CONCLUSIONS: This study expands the limited knowledge of the frequency of cyanogenesis in natural plant communities, includes novel reports of cyanogenesis among a range of taxa and characterizes patterns in intra-plant and intra-population variation of cyanogensis.     

Mangrove zooplankton of North Queensland,Australia

Food consumption, growth, fish length distributions,population sizes and habitat use of the salmonids intwo lakes in the Høylandet area were studied in1986–89. The allopatric brown trout (Salmotrutta L.) in the tarn Røyrtjønna (27 ha) fed mainlyon organisms at the lake surface , crustaceanplankton, Trichoptera and Chironomidae. Only 5% ofthe trout reached an age of 6 years and a length of25 cm. Sexual maturation started at age 3 and a lengthof 14 cm. Through mark – recapture technique thenumber of trout >10 cm was estimated to 115 ha^-1.Growth, fish length frequencies and sexualmaturation of the sympatric brown trout and Arcticcharr (Salvelinus alpinus (L.)) in LakeStorgrønningen (530 ha) were not much different. TheStorgrønningen charr fed chiefly on zooplankton whichby volume represented 33% for the trout. The foodconsumption of Storgrønningen trout was at maximum inJuly with 2.06 mg food (d.w.) per g live fish and forcharr in September with 1.26 mg food. The maximumsize-independent growth rate of trout was 5.2%day^-1 in late June, and for charr 4.1%day^-1 in late July. Seventy percent of theirseasonal growth took place before 15 August. The charrstayed mainly deeper than 3-4 m, at water temperatures<15 °C. Brown trout stayed mainly the littoralzone and in near surface water of the pelagic. Thenumber of pelagic charr was estimated hydroacusticallyto 50 ind. ha^-1. The charr spawn in thelake. Mean numbers of juvenile trout in the twolargest tributaries were 26 and 48 per 100 m².Their annual length increment was 2.8–3.4 cm. Noindication of acidification or other human inducedimpacts were found. The lakes and their tributariesrepresent complex aquatic systems, representative forpristine oligotrophic Norwegian lowland lakes.John W. Jensen died shortly after easter in 1996     

Vertical and seasonal distribution of flying beetles in a suburban temperate deciduous forest collected by water pan trap

Vertical and seasonal distributions of flying beetles were investigated in asuburban temperate deciduous forest in Kanazawa, Japan using water pan traps to determine the abundance and composition among vertical strata, change in the abundance and composition through seasons and determinant factors in generating the distributions. Traps were placed at three levels (0.5 m, 10 m, and 20 m above ground) on a tower. Samplings were carried out seasonally from May to November in 1999 and 2000. Variations in the abundance of flying beetles were observed from different layers. The results showed that the abundance and composition of flying beetles varied among strata and seasons. In both 1999 and 2000,Elateridae was consistently most abundant in the bottom layer, while Attelabidae and Cantharidae were most abundant in the upper layer. In 1999, Eucnemidae and overall scavengers were most abundance in the bottom layer, but results were not consistent with those in 2000. In general, the abundance of herbivores reaches a peak in the early season(May/June) and decreases in the following months. Peaks of abundance in predators vary vertically. In the bottom layer a peak was observed in the early season (May/June), while in the upper layer this was observed in July. Scavengers had two peaks, in May/June and September. These patterns indicated that vertical distributions in the abundance of differentfeeding guilds varied through seasons.     

Establishment of exotic dung beetles in Queensland: the role of habitat specificity

Between 1968 and 1983, 22 species of dung beetles from southern Africa were released into pastoral regions of Queensland in northern Australia. Seven species have become widespread and abundant and the others either occur in isolated patches, are rare or have failed to establish self perpetuating populations. These species all occur in the Hluhluwe district in southern Africa which has a climate similar to that of coastal central and southern Queensland. The numberical abundance and habitat associations of the 22 speices were examined at Hluhluwe to seek an explanation for their performance in Australia. It was concluded that habitat specificity and the adequacy with which habitat was matched in Australia were critical factors. Species which established in Australia were relatively common in cattle dung in Africa where they showed a preference for grassland on clay-loam soils.      

Seasonality of a Diverse Beetle Assemblage Inhabiting Lowland Tropical Rain Forest in Australia

One of the least understood aspects of insect diversity in tropical rain forests is the temporal structuring, or seasonality, of communities. We collected 29,986 beetles of 1473 species over a 4-yr period (45 monthly samples), with the aim to document the temporal dynamics of a trophically diverse beetle assemblage from lowland tropical rain forest at Cape Tribulation, Australia. Malaise and flight interception traps were used to sample adult beetles at five locations at both ground and canopy levels. Beetles were caught throughout the year, but individual species were patchy in their temporal distribution, with the 124 more abundant species on average being present only 56 percent of the time. Climatic variables (precipitation, temperature, and solar radiation) were poorly correlated with adult beetle abundance, possibly because: (1) seasonality of total beetle abundance was slight; (2) the peak activity period (September–November) did not correspond to any climatic maxima or minima; or (3) responses were nonlinear owing to the existence of thresholds or developmental time-lags. Our results do not concur with the majority of tropical insect seasonality studies suggesting a wet season peak of insect activity, perhaps because there is no uniform pattern of insect seasonally for the humid tropics. Herbivores showed low seasonality and individual species' peaks were less temporally aggregated compared to nonherbivores. Canopy-caught and larger beetles (> 5 mm) showed greater seasonality and peaked later in the year compared to smaller or ground-caught beetles. Thus seasonality of adult beetles varied according to the traits of feeding ecology, body size, and habitat strata.     

High abundance of an exotic amphipod indicates disturbance in tropical rainforests

Previous studies have proposed terrestrial amphipods as potential bioindicators of forest condition. In order to investigate the response of the exotic terrestrial amphipod Talitroides topitotum (Crustacea: Amphipoda: Talitridae) to anthropogenic disturbances and its potential as a bioindicator, we compared its abundance among three forest reserves in southeastern Brazil, under different types and intensities of disturbance. We observed significantly higher abundances in disturbed sites compared to undisturbed sites in two of the reserves sampled, corroborating previous studies. In the third reserve, in which both forest disturbance and the abundance of amphipods were much lower than in the other two reserves, there was no significant difference between the sampling sites. We also speculate about the potential use of terrestrial amphipods as global indicators of forest disturbance.     

Vertical stratification of feeding guilds and body size in beetle assemblages from an Australian tropical rainforest

Abstract The vertical stratification of insect species assemblages inhabiting tropical rainforests is well established but few have examined whether these patterns are reflected in vertical stratification of body size or feeding guilds. We used Malaise and Flight Interception Traps to sample beetle assemblages from five locations, at both canopy and ground zones of a tropical lowland rainforest site near Cape Tribulation, Australia. Beetles from 4 years of sampling were sorted to Family and morphospecies, and allocated to one of five feeding guilds. Within feeding guilds the number of species and individuals, from canopy‐ and ground‐caught traps were compared. The body lengths of species were measure and compared within feeding guilds and families. Herbivores was the dominant guild but was not the majority of all species or individuals. Most beetle species (69%) were less than 5 mm in length and the mean size of canopy‐caught species was greater than that for ground‐caught species. This was probably due to slightly more species of plant feeders (herbivores and xylophages) present in the canopy, which were significantly larger than saprophages, fungivores and predators. Among feeding guilds, there were few overall canopy–ground differences. These results contrast with species composition results presented elsewhere where strong differences between the canopy and the ground were evident. We suggest that our guild groupings may have been too coarse to detect fine‐scale differences and that resource partitioning may have also masked faunal stratification. We propose that fine‐scale differences in resources between the canopy and the ground, together with strong microclimate gradients, are likely to be important in structuring the vertical stratification of insect assemblages at the level of species, but not with respect to functional groups.     

Vertical stratification of ichneumonid wasp communities: the effects of forest structure and life‐history traits

Parasitoid wasp communities of the canopy of temperate forests are still largely unexplored. Very little is known about the community composition of parasitoids between canopy and understory and how much of this difference is related to forest structure or parasitoid biological strategies. In this study we investigated upon the difference in the community composition of the parasitic wasps Ichneumonidae between canopy and understory in a lowland temperate forest in northern Italy. We used general linear models to test whether parasitic strategy modifies species vertical stratification and the effect of forest structure. We also tested differences in β‐diversity between canopy and understory traps and over time within single forest layers. We found that stand basal area was positively related to species richness, suggesting that the presence of mature trees can influence local wasp diversity, providing a higher number of microhabitats and hosts. The ichneumonid community of the canopy was different from that of the understory, and the β‐diversity analysis showed higher values for the canopy, due to a higher degree of species turnover between traps. In our analyses, the vertical stratification was different between groups of ichneumonids sharing different parasitic strategies. Idiobiont parasitoids of weakly or deeply concealed hosts were more diverse in the understory than in the canopy while parasitoids of spiders were equally distributed between the two layers. Even though the ichneumonid community was not particularly species‐rich in the canopy of the temperate forests, the extension of sampling to that habitat significantly increased the number of species recorded.     

Efficacy of bird-baited traps placed at different heights for collecting ornithophilic mosquitoes in eastern Queensland, Australia

To compare the efficacy of bird-baited traps with standard CO₂-baited Centers for Disease Control (CDC) light traps for collecting ornithophilic mosquito species, seven Latin square trials were conducted at six urban sites in Cairns and Brisbane, Australia. Traps were placed 1 m above ground level and 5–10 m according to tree canopy height. CO₂-baited CDC traps consistently collected more mosquitoes of all species than the bird-baited traps at all locations. In Brisbane, CO₂-baited CDC traps placed at ground level collected significantly more Culex annulirostris Skuse than those at canopy height during two trials, and more Aedes vigilax (Skuse) and Ae. procax (Skuse) during one trial each. Conversely, in Cairns, CO₂-baited CDC traps placed in the tree canopy collected significantly more Cx. squamosus (Taylor) during two trials, and significantly more Aedeomyia catasticta Knab and Cx. cubiculi Marks during one trial each. Consistently low yields of ornithophilic species including Cx. australicus Dobrotworsky & Drummond and Cx. quinquefasciatus Say in all traps tested suggests the need to employ alternative trapping measures to target these species in urban areas.     

龙脑香热带雨林附生苔藓沿宿主垂直梯度的微生境偏好及其指示作用

该研究首次借助林冠塔吊调查了西双版纳国家级自然保护区龙脑香热带雨林样地内69棵树13个垂直高度上的附生苔藓植物,结果表明:目标样树上共记录到隶属于25科60属的90种附生苔藓,其中细鳞苔科物种数最多,占比达25.6%。13个垂直高度上共划分出三种生态类型:喜阳苔藓(散生巨树上45 m的区域),喜阴苔藓(乔木树干上15 m的区域),广布苔藓(广泛分布于宿主各个垂直高度上,生态位宽),并筛选出对微生境有特殊偏好的17种苔藓指示种(IndVal≥0.7,P0.05)。随宿主垂直高度的升高,扇型和交织型的苔藓占比降低,悬垂型苔藓占比先升高后降低,细平铺型和粗平铺型的苔藓占比升高。大气湿度、水汽压、胸径以及树皮粗糙度对附生苔藓生活型的分布偏好具有显著影响。总之,沿宿主垂直高度上的附生苔藓对微环境变化在生活型和形态结构上有着不同的响应方式,而同一种生态型的苔藓群落有相似的适应机制。因此,在森林林冠生境变化的监测和管理中,对微生境具有明显偏好的附生苔藓物种可作为有效的指示材料。     

A comparison of trapping methods for Tabanidae (Diptera) in North Queensland, Australia

The ability to monitor the abundance and diversity of tabanid flies over wide areas requires effective and low-cost surveillance methods. Such monitoring activities help to quantify the risk of transmission of pathogens by tabanids. Here we examine the effectiveness and practicality of two types of trap (canopy traps and Nzi traps) and two types of attractant (octenol and carbon dioxide) for monitoring tabanid flies in tropical Australia. The Nzi trap consistently caught more tabanids and more species of tabanids than the canopy trap. It was also more robust and therefore required less maintenance in remote locations. The use of attractants substantially increased capture rates, both of individuals and species, and traps using both attractants were consistently the most effective. However, in remote locations, where it is not possible to check traps frequently, the use of attractants may not be feasible. When attractants were not used, the canopy trap caught very few tabanids, but the Nzi trap remained effective enough to be useful as a monitoring device. In addition, the number of tabanid species caught by the Nzi traps remained high, and included those that were most abundant. We therefore conclude that, in this region, Nzi traps are preferable for tabanid monitoring and that attractants greatly improve their effectiveness. However, for longterm monitoring, especially in remote locations, Nzi traps without attractants are a satisfactory option.     

Species diversity in spatial and temporal dimensions of fruit-feeding butterflies from two Ecuadorian rainforests

To test the hypotheses that butterflies in an intact lowland rainforest are randomly distributed in space and time, a guild of nymphalid butterflies was sampled at monthly intervals for one year by trapping 883 individuals of 91 species in the canopy and understory of four contiguous, intact forest plots and one naturally occurring lake edge. The overall species abundance distribution was well described by a log-normal distribution. Total species diversity (γ-diversity) was partitioned into additive components within and among community subdivisions (α-diversity and β-diversity) in vertical, horizontal and temporal dimensions. Although community subdivisions showed high similarity (l-β-diversity/γ-diversity), significant β-diversity existed in each dimension. Individual abundance and observed species richness were lower in the canopy man in the understory, but rarefaction analysis suggested that the underlying species richness was similar in both canopy and understory. Observed species richness varied among four contiguous forest plots, and was lowest in the lake edge plot. Rarefaction and species accumulation curves showed that one forest plot and the lake edge had significantly lower species richness than other forest plots. Within any given month, only a small fraction of total sample species richness was represented by a single plot and height (canopy or understory). Comparison of this study to a similar one done in disturbed forest showed diat butterfly diversity at a naturally occurring lake edge differed strongly from a pasture-forest edge. Further comparison showed that species abundance distributions from intact and disturbed forest areas had variances that differed significandy, suggesting mat in addition to extrapolation, rarefaction and species accumulation techniques, the shapes of species abundance distributions are fundamental to assessing diversity among sites. This study shows the necessity for long-term sampling of diverse communities in space and time to assess tropical insect diversity among different areas, and the need of such studies is discussed in relation to tropical ecology and quick surveys in conservation biology.     

The sterol and fatty acid compositions of seven tropical seagrasses from North Queensland,Australia

The sterol and fatty acid compositions of fresh leaves of the seagrasses Cymodocea serrulata, Enhalus acoroides, Halodule uninervis, Halophila ovalis, H. ovata, H. spinulosa and Thalassia hemprichii are reported. The major fatty acids were palmitic acid, linoleic acid and linolenic acid as expected. H. ovalis and H. ovata were characterized by the relatively high abundance (ca 5%) of the acid hexadeca-7,10,13-trienoic acid (16:3<7 > ). The sterol compositions were typical of higher plants, with sitosterol and stigmasterol accounting for 60–90% of the observed sterols. 28-Isofucosterol was a major sterol (20–30%) only in the Halophila spp. Cluster analysis of the sterol composition data clearly separated the Halophila spp. from the other seagrasses and enabled the distinction of Enhalus sp. from Cymodocea, Halodule and Thalassia spp. The seagrass species were clearly separated into five chemical groups using the combined fatty acid and sterol composition data and the need for a reappraisal of the taxonomic position of Halophila was indicated.     

四川南充市郊瓢虫物种多样性的初步研究

20 0 3年3月～2 0 0 4年5月,分别在南充市郊的人工林、农田、河漫滩草丛、灌木丛4种生境进行瓢虫种群结构及多样性的抽样调查研究,共采集瓢虫标本1 2 1 6只,经鉴定隶属7亚科,2 2属,3 6种。个体数量以瓢虫亚科最多,食植瓢虫亚科次之。物种数以瓢虫亚科最多,食植亚科次之,小艳瓢虫亚科最少。各生境的多样性指数和物种丰富度排序为灌木丛>河漫滩草丛>人工林>农田。     

Biodiversity hanging by a thread: the importance of fungal litter-trapping systems in tropical rainforests

The exceptionally high species richness of arthropods in tropical rainforests hinges on the complexity of the forest itself: that is, on features such as the high plant diversity, the layered nature of the canopy and the abundance and the diversity of epiphytes and litter. We here report on one important, but almost completely neglected, piece of this complex jigsaw-the intricate network of rhizomorph-forming fungi that ramify through the vegetation of the lower canopy and intercept falling leaf litter. We show that this litter-trapping network is abundant and intercepts substantial amounts of litter (257.3 kg ha(-1)): this exceeds the amount of material recorded in any other rainforest litter-trapping system. Experimental removal of this fungal network resulted in a dramatic reduction in both the abundance (decreased by 70.2 ± 4.1%) and morphospecies richness (decreased by 57.4 ± 5.1%) of arthropods. Since the lower canopy levels can contain the highest densities of arthropods, the proportion of the rainforest fauna dependent on the fungal networks is likely to be substantial. Fungal litter-trapping systems are therefore a crucial component of habitat complexity, providing a vital resource that contributes significantly to rainforest biodiversity.     

The relative importance of trees versus lianas as hosts for phytophagous beetles (Coleoptera) in tropical forests

Aim Insect assemblages associated with lianas in tropical forests are poorly studied compared with those associated with trees. The importance of lianas for the maintenance of local species richness of insect herbivores in tropical forests is therefore poorly understood. With this in mind, a comparative study of the relative importance of trees and lianas as hosts for phytophagous beetles was carried out. Location The study area was located in the canopy of a dry tropical forest in Parque Natural Metropolitano, Panama province, Republic of Panama. Methods A crane system was utilized to access the canopy. The number of species and host specialization of adult phytophagous beetles associated with twenty‐six liana species of ten different families, and twenty‐four tree species of twelve different families were compared. Results A total of 2561 host associations of 697 species of beetles were determined (1339 for trees and 1222 for lianas). On average 55.8 ± 6.8 beetle species were found to be associated with each tree species while the comparable number for lianas was 47.0 ± 6.1. The pooled numbers of phytophagous beetle species associated with trees and lianas, respectively, were not significantly different. However, there were significantly more species feeding on green plant parts on lianas than on trees, and there were significantly more wood eaters on trees than on lianas. Phytophagous beetles associated with lianas were significantly more specialized than the tree associates due to a higher degree of specialization among the species feeding on green plant parts of lianas. Wood eaters and flower visitors showed no differences in host specialization on different growth forms. Main conclusion The present study shows that lianas are at least as important as trees for the maintenance of local species diversity of phytophagous beetles at this site. The mechanisms that drive the patterns can only be hypothesized. Plant architecture, size, and length of growing season are probably involved. Further studies, should include measurements of plant traits to elucidate experimentally what mechanisms that drive the patterns. Additional insight would come from similar studies in other forest types, and also studies of other major taxonomic groups of arthropod herbivores.     

Diversity of pselaphine beetles (Coleoptera: Staphylinidae: Pselaphinae) in eastern Thailand

Pselaphine beetles (Coleoptera: Staphylinidae: Pselaphinae) are cosmopolitan, species‐rich, and yet poorly studied, particularly in the tropics. We sampled beetles in three types of primary forest and two types of disturbed forest habitats in eastern Thailand to assess the utility of pselaphine beetles as bioindicators of forest disturbance. We simultaneously measured leaf litter mass, soil moisture, soil acidity and canopy cover at each site to infer which environmental factors affect pselaphine beetle diversity and abundance. At each site, pselaphine beetles were extracted from ten 1 m² samples of leaf litter and soil with Tullgren funnels. We sampled 1867 adult beetles representing six supertribes, 51 genera and 114 morphospecies; 7% of the genera and 92% of the species were undescribed. Forest types differed significantly in species richness, abundance, diversity and evenness. Primary forest had greater numbers of species and individuals, and higher diversity indices (H′). Teak plantation and secondary forest had substantially fewer individuals and species of pselaphine beetles. Species composition differed between primary and degraded forests. Canopy cover, soil moisture, and leaf litter mass positively correlated with beetle species richness and abundance. Leaf litter mass and soil moisture were the two most important factors affecting the diversity of pselaphine beetle assemblages. Among the 114 morphospecies collected, 43 morphospecies were specific to two or three habitats and 64 morphospecies were found only in a single habitat. Thus pselaphine beetles appear to have rather narrow habitat requirements and their presence/absence was correlated with environmental differences. These traits make pselaphine beetles a suitable bioindicator taxon for assessing forest litter diversity and monitoring habitat change.     

Before Cattle: A Comparative Floristic Study of Eucalyptus Savanna Grazed by Macropods and Cattle in North Queensland,Australia1

Floristic differences between cattle-grazed and macropod-grazed sites (protected from domestic stock by enclosure within a Holocene lava flow) were examined in Eucalyptus savanna in north Queensland, Australia. While macropod-grazed sites have had a lower incidence of fire than the cattle-grazed sites, it seems probable that grazing impacts per se are the major differences between these treatments. One dominant (Capillipedium parviflorum) and another common (Sehima nervosa) native perennial grass in the macropod-grazed treatment were not recorded within the cattle-grazed treatment. There was generally a lower species richness and Shannon-Weaver diversity of perennial forbs in the cattle-grazed treatment compared to the macropod-grazed treatment. There was higher richness, diversity, and abundance of annual grasses in the cattle-grazed treatment compared to the macropod-grazed treatment. The relative richness of native and exotic species was not significantly affected by cattle grazing.     

Diversity of fungi on rainforest litter in North Queensland, Australia

Ten leaves from each of 13 different tree types from two differentrainforest sites in North Queensland, Australia were examined in order toestablish the fungal diversity developing on these leaves. A total of 57microfungi were identified, most of which were mitosporic fungi. Speciesdiversity in terms of richness and evenness were compared and the Mt Lewis sitewas found to be richer as compared to the Butchers Creek site. Statisticalmeasurements of diversity indices, however, showed that the two forest siteswere of similar diversity. Thirty-six of the fungi identified occurred only onone leaf type, indicating possible host specificities or recurrences. The samplesize, however, is deemed to be insufficient, as a larger sample size may haveresulted in less of the fungi appearing to be host specific. It is recommendedthat future studies should include more leaf samples and less tree types. It isparticularly important that the same leaf species are collected within the samesite and at different sites in order to establish the effects of host on fungalcomposition.