关键词： feeding behavior   Hemideina thoracica   insect   lipids   nutrition   protein   selective foraging  

摘要： Insects are important but overlooked components of forest ecosystems in New Zealand. For many insect species, information on foraging patterns and trophic relationships is lacking. We examined diet composition and selectivity in a large-bodied insect, the Auckland tree wet Hemideina thoracica, in three habitat zones in a lowland New Zealand forest. We asked whether *** selectively forage from available plant food sources, and whether these choices were lipid-rich compared to nonpreferred available plants. We also identified the proportion of invertebrates in their frass as a proxy for omnivory. From reconnaissance plot sampling, together with fecal fragment analysis, we report that more than 93% of individual tree wet had eaten invertebrates before capture. Additionally, wet in the highest elevation hillslope habitat zone consumed significantly fewer species of plants on average than wet on the low-elevation terrace habitat. Upper hillslope wet also had the highest average number of invertebrate fragments in their frass, significantly more than wet in the low-elevation terrace habitat zone. Wet showed high variability in the consumption of fruit and seeds across all habitat zones. Generally, we did not observe diet differences between the sexes (although it appears that male wet in the mid-hillslope habitat ate fruits and seeds more voraciously than females), suggesting that the sexes have similar niche breadths and display similar degrees of omnivorous behavior. Extraction of leaf lipids demonstrated a range of lipid content values in available plants, and Ivlev's Electivity Index indicated that plant species which demonstrated high electivity tended to have higher concentrations of lipids in their leaves. Our findings indicate that *** forage omnivorously and selectively, and hence play multiple roles in native ecosystems and food webs.

摘要： Information on amphibian diversity in Neotropical savannas and in protected areas in the Caribbean is lacking. We evaluated amphibian diversity and species composition in the Aripo Savannas Scientific Reserve in Trinidad, in relation to the two major habitat types, savanna and marsh forest. Thirty 200-m-long transects were sampled visually and aurally in 4 periods (total 120 samples), with 10 transects in savanna, and 20 in marsh forest (10 along trails and 10 off trails), at night in the wet season from June to December 2015. We recorded 895 individuals representing 16 species, 11 genera, and 7 families, with greater counts and diversity of amphibians in marsh forest compared to savanna. The three species recorded in savanna (Leptodactylus fuscus, Scinax ruber, and Rhinella beebei) were also found in marsh forest, with no separate savanna amphibian community. Audio detection was more effective at sampling most species, and there were greater counts along trails compared to transects off trails.

关键词： Canopy trees   Functional traits   Leaf economics   Plant defense   Tropical forests  

摘要： Trade-offs among plant functional traits indicate diversity in plant strategies of growth and survival. The leaf economics spectrum (LES) reflects a trade-off between short-term carbon gain and long-term leaf persistence. A related trade-off, between foliar growth and anti-herbivore defense, occurs among plants growing in contrasting resource regimes, but it is unclear whether this trade-off is maintained within plant communities, where resource gradients are minimized. The LES and the growth-defense trade-off involve related traits, but the extent to which these trade-off dimensions are correlated is poorly understood. We assessed the relationship between leaf economic and anti-herbivore defense traits among sunlit foliage of 345 canopy trees in 83 species on Barro Colorado Island, Panama. We quantified ten traits related to resource allocation and defense, and identified patterns of trait co-variation using multivariate ordination. We tested whether traits and ordination axes were correlated with patterns of phylogenetic relatedness, juvenile demographic trade-offs, or topo-edaphic variation. Two independent axes described similar to 60% of the variation among canopy trees. Axis 1 revealed a trade-off between leaf nutritional and structural investment, consistent with the LES. Physical defense traits were largely oriented along this axis. Axis 2 revealed a trade-off between investments in phenolic defenses versus other foliar defenses, which we term the leaf defense spectrum. Phylogenetic relationships and topo-edaphic variation largely did not explain trait co-variation. Our results suggest that some trade-offs among the growth and defense traits of outer-canopy trees may be captured by the LES, while others may occur along additional resource allocation dimensions.

关键词： cattle grazing   herpetofauna   land sharing   off-reserve conservation   reptile community   sustainable grazing   wildlife conservation  

摘要： Rangelands are areas used primarily for grazing by domestic livestock;however, because they support native vegetation and fauna, their potential role in conservation should not be overlooked. Typically, "off-reserve" conservation in agricultural landscapes assumes a trade-off between maintaining the ecological processes that support biodiversity and successful food production and profitability. To evaluate this potential biodiversity trade-off in rangelands, we need to understand the effect of different livestock grazing strategies on biodiversity, in relation to their performance in terms of profitability and land condition. We monitored reptile community responses to four cattle-grazing strategies (heavy, moderate, and variable stocking rates and a rotational wet season spelling treatment) in a replicated, long-term grazing trial in north Queensland, Australia. Simultaneously, measures of profitability and land condition were collected for the different grazing strategies. Overall, reptile abundance was not negatively impacted by the more sustainably managed treatments (moderate, variable, and rotational) compared with heavy stocking, although the effect of grazing treatment alone was not significant. Profitability and land condition were also higher in these treatments compared with the heavy stocking rate treatment. As drought conditions worsened over the 3 yr, the negative impact of the heavy stocking treatment on both profitability and biodiversity became more pronounced. Heavy stocking negatively impacted reptiles and was also the least profitable grazing strategy over the long term, resulting in the worst land condition. This suggests that in this tropical savanna rangeland there was no trade-off between economic performance and reptile abundance and diversity. Grazing regimes with a moderate stocking rate or flexible management strategies were better able to buffer the effects of climate variability. The consequence was a more resilient reptile community an

关键词： arthropods   bats   birds   conservation planning   human-modified landscapes   large old trees  

摘要： Aim: The biodiversity value of scattered trees in modified landscapes is often overlooked in planning and conservation decisions. We conducted a multitaxa study to determine how wildlife abundance, species richness and community composition at individual trees are affected by (1) the landscape context in which trees are located;and (2) the size of trees. Location: Canberra, south-eastern Australia. Methods: Trunk arthropod, bat and bird surveys were undertaken over 3 years (2012-2014) at 72 trees of three sizes (small (20-50 cm DBH), medium (51-80 cm), large (>= 80 cm)) located in four landscape contexts (reserves, pasture, urban parklands, urban built-up areas). Results: Landscape context affected all taxa surveyed. Trunk arthropod communities differed between trees in urban built-up areas and reserves. Bat activity and richness were significantly reduced at trees in urban built-up areas suggesting that echolocating bats may be disturbed by high levels of urbanization. Bird abundance and richness were highest at trees located in modified landscapes, highlighting the value of scattered trees for birds. Bird communities also differed between non-urban and urban trees. Tree size had a significant effect on birds but did not affect trunk arthropods and bats. Large trees supported higher bird abundance, richness and more unique species compared to medium and small trees. Main conclusions: Scattered trees support a diversity of wildlife. However, landscape context and tree size affected wildlife in contrasting ways. Land management strategies are needed to collectively account for responses exhibited by multiple taxa at varying spatial scales. We recommend that the retention and perpetuation of scattered trees in modified landscapes should be prioritized, hereby providing crucial habitat benefits to a multitude of taxa.

关键词： BEF-China   biodiversity and ecosystem function   density-dependence   predator   trophic interaction  

摘要： Plant diversity is hypothesized to strengthen biological control by promoting top-down pressure of predators on herbivores. However, studies on the effects of plant diversity on actual predation rates are still scarce, particularly in forest ecosystems. We analyzed the effect of tree species richness, and the potential influence of neighbor tree density, on predation rates of arthropods and birds on artificial clay caterpillars in a large-scale forest biodiversity experiment in south-east China. Our study was focused on three broadleaved tree species that are frequently damaged by lepidopteran caterpillars. Predation rates were influenced by tree species richness on only one of the three tree species, on which arthropod predation increased and bird predation decreased with increasing tree species richness. Importantly, these relationships were mediated by neighbor tree density, being most pronounced when focal trees had fewer surrounding neighbor trees. Our findings indicate that low tree density reduced arthropod predator abundances and predation rates, but that negative effects of this reduction were compensated for in more diverse tree mixtures by a functionally more diverse predator community. In contrast, lower tree densities might have benefited insectivorous birds by making trees more accessible particularly in monocultures, which are often structurally more uniform and denser than tree mixtures. Overall, our results point to an important role of species-specific and density-dependent mechanisms in modifying the consequences of biodiversity loss on top-down effects in forest ecosystems. Future work should aim at separating the effects of different predator guilds and those of host diversity from host density.

关键词： Biomass production   ECOLINK-Salix   Genetic diversity effects   Herbivores   Predators   Salix  

摘要： Demand for bioenergy has rapidly developed in recent decades, resulting in expansion of bioenergy cropping systems such as willow short rotation coppice (SRC). Increasing the number of willow genotypes in SRC can potentially enhance species diversity in the associated arthropod community, which may promote ecosystem functions within plantations. However, the ecology of SRCs and their effects on biodiversity have only rarely been investigated. Therefore, to study the role of plant genetic diversity (GD) in SRC, we established a replicated common garden experiment comprising genetic monocultures and mixtures of two, three and four different Salix genotypes used in commercial SRC. We sampled arthropods and examined the effect of GD across trophic groups, to test if the use of genotype mixtures increases arthropod richness and abundance. Species richness of total arthropods and of herbivores increased significantly with increasing GD, regardless whether data were pooled per plot or analysed on tree level. However, effects varied among willow genotypes as positive correlations between GD and different trophic groups were genotype-specific. We show that establishing and managing commercial willow SRCs with a mixture of varying genotypes can help to increase arthropod diversity within a bioenergy system that is a promising renewable energy source.

关键词： ant communities   Cerrado   latitudinal diversity gradient   Neotropical arid diagonal   species diversity   tropical savanna  

摘要： Aim: To evaluate the extent to which ant species richness in Neotropical savannas varies with macrogeographic variables, and to identify the potential climatic drivers of such variation. Location: The Cerrado savanna biome of central Brazil, in a region spanning ca. 20 degrees of latitude and 18 degrees of longitude. Methods: Standardized sampling of the arboreal and ground-dwelling faunas was performed in 29 well-preserved savanna sites using pitfall traps. Species were classified according to their habitat affinities: open-savanna specialists, forest-associated species or habitat generalists. We used generalized linear models to evaluate the importance of geographic (latitude, longitude and elevation) and climatic (mean temperature and three metrics of rainfall) variables as predictors of species richness. Results: The total number of species recorded at each site varied more than twofold (from 59 to 144), and latitude was the best geographic correlate of overall species richness. However, contrary to the expected pattern, more species were found at higher than lower latitudes. This reversed latitudinal pattern of diversity occurred for both the arboreal and ground-dwelling faunas, and for the habitat generalists and forest specialists. The savanna specialists showed a mid-latitudinal peak in diversity. Overall, there was a significant positive association between rainfall and species richness, but the strength of this relationship varied with ant habitat affinity. Main conclusions: The Cerrado ant fauna shows a reverse latitudinal gradient in species diversity, and this can be explained by increasing rainfall during the warmest months of the year (and therefore in plant productivity) with increasing latitude. The sensitivity of Cerrado ant diversity to declining rainfall contrasts with the high resilience to aridity of the Australian savanna ant fauna, and this reflects the contrasting evolutionary histories of these faunas. Our findings highlight the importance

关键词： consumer-driven nutrient cycling   ecological stoichiometry   Hluhluwe-iMfolozi Park   megaherbivore   nitrogen   nutrient aggregation   phosphorus   white rhinoceros  

摘要： 1. Territorial or resting behaviour of large herbivores can cause strong local deposits of dung, in different places than where they graze. Additionally, dung beetles and other macrodetritivores can subsequently affect local nutrient budgets through post-depositional re-dispersion of dung and accompanying nutrients. Such horizontal displacement of nutrients by animals has strong implications for savanna ecosystem functioning, but remains poorly studied as it is notoriously difficult to accurately map these flows and incredibly time-consuming. 2. In an African savanna, with alternating patches of lawn, bunch grasses and trees/shrubs, we undertook such effort and studied nutrient aggregation and redistribution by different large herbivore functional groups and dung beetles for a full growing season. We used movable cages to quantify herbivore consumption rates and measured nutrient return through biweekly dung counts. Furthermore, we estimated the offtake of nitrogen (N) and phosphorus (P) by the dominant megagrazer (white rhinoceros) to middens (dung deposition hotspots). Last, we experimentally measured the removal amount and movement paths of telocoprid dung beetles to quantify their nutrient redistribution effects. 3. Our estimates suggest white rhinoceros to cause a large export of nutrients from grazing areas towards middens resulting in negative nutrient budgets for both lawn and bunch grassland types. Mesograzers (50-600kg) realized a net nitrogen input towards high forage quality lawn vegetation at the expense of lower quality bunch grasslands. Browsers caused a net flow from trees/shrubs towards grassland patches. 4. Interestingly, while the magnitude of our estimated flows of N consumption and return by large herbivores were rather similar, the P returns were about half of what has been consumed. This is in agreement with ecological stoichiometry theory that predicts that large herbivores should recycle more N than P, due to their relatively high P demand.

关键词： Apociemus agrarius   Apodemus peninsulae   downed tree   ground vegetation   habitat variable  

摘要： This study was conducted to investigate the influence of tree thinning on habitat variables and small rodents in a natural deciduous forest in South Korea. We focused on the populations of the small forest-dwelling rodents, striped field mouse Apodemus agrarius and Korean field mouse A. peninsulae. Populations were monitored for 2 years in a natural deciduous forest subject to tree thinning. The coverage of ground vegetation and number and volume of downed trees were significantly increased after thinning. However, the coverage of overstory and understory vegetation and number of standing trees were decreased in postthinning session. The abundance and survival probability of captured A. agrarius and the total small rodents were significantly influenced by tree thinning. We hypothesize that the major factors determining the greater abundance and survival of small rodents after thinning may be the increased coverage of ground vegetation and number of downed trees, and the decreased number of standing trees. This study suggests that tree thinning could be a tool to both encourage tree productivity and create suitable habitats for small rodents.