关键词： camera traps   drylands   invasive   Prosopis   riparian   wildlife  

摘要： Ephemeral rivers and the vegetation they support have numerous ecological and economic values to the mammals and people who rely on these systems. Yet, these crucial environments are believed to be threatened by exotic plant invasion. In Africa, invasive trees of the genus Prosopis have detrimental effects on native vegetation, bird and dung beetle communities;however, to date, there is no evidence that Prosopis establishment has affected indigenous wild mammalian distribution and ecology in its introduced range. Using a combination of camera traps and vegetation surveys, we tested the hypothesis that Prosopis invasion has a negative impact on the mammals of the ephemeral Swakop River in Namibia by reducing mammal species richness and species occupancies. Prosopis was found to have no negative impact on species richness;however, evidence for species-specific responses to Prosopis abundance was found. This is the first study to confirm an impact of Prosopis on sub-Saharan African mammals, providing a foundation for future research and the development of appropriate management policy.

关键词： Acacia   Acacia   Animals   Antelopes   Canidae   Food Chain   Food Chain   Geographic Information Systems   Herbivory   Panthera   Predatory Behavior   Trees  

摘要： Understanding how predation risk and plant defenses interactively shape plant distributions is a core challenge in ecology. By combining global positioning system telemetry of an abundant antelope (impala) and its main predators (leopards and wild dogs) with a series of manipulative field experiments, we showed that herbivores' risk-avoidance behavior and plants' antiherbivore defenses interact to determine tree distributions in an African savanna. Well-defended thorny Acacia trees (A. etbaica) were abundant in low-risk areas where impala aggregated but rare in high-risk areas that impala avoided. In contrast, poorly defended trees (A. brevispica) were more abundant in high-than in low-risk areas. Our results suggest that plants can persist in landscapes characterized by intense herbivory, either by defending themselves or by thriving in risky areas where carnivores hunt.

关键词： Africa   Arthropod   Community   Diversity   Mistletoe   Savanna  

摘要： The below-canopy soil moisture content and litter-layer arthropod abundance and diversity of Acacia karroo trees parasitized by each of three mistletoe species (Erianthemum ngamicum, Plicosepalus kalachariensis, and Viscum verrucosum) and uninfected A. karroo trees were investigated in semi-arid savanna, southwest Zimbabwe. The soils below the canopies of mistletoe-infected trees were significantly low in moisture content compared to those beneath uninfected A. karroo trees. Nevertheless, arthropod species diversity was greater by up to 34 % below the canopies of mistletoe-infected trees than beneath uninfected A. karroo trees, with greater abundances beneath trees infected by E. ngamicum and P. kalachariensis. In addition, the majority of the arthropod species associated with mistletoe-infected trees had litter as their dominant foraging substrate. Our findings show that mistletoes increase the abundance and diversity of litter-dwelling and -foraging arthropods due to increase in the quality and quantity of litterfall beneath mistletoe-infected trees. By altering the below-canopy arthropod communities and soil moisture content, mistletoes have potential to modify ecosystem processes such as decomposition, soil process rates, and nutrient cycling. Therefore, we suggest that the resulting increase in resource heterogeneity plays an important role in determining the structure and functioning of semi-arid savanna ecosystems.

关键词： BEF-China   biodiversity effects   Formicidae   Gutianshan National Nature Reserve   soil properties   species diversity   trophic guilds   vegetation structure  

摘要： 1. Epigeic ants are functionally important arthropods in tropical and subtropical forests, particularly by acting as predators. High predation pressure has been hypothesised to be a mechanism facilitating high diversity across trophic levels. 2. In this study, standardised pitfall traps were used in a highly diverse subtropical forest to test if and how ant species richness is related to tree species richness and a comprehensive set of other environmental variables such as successional age, soil properties or elevation. 3. A total of 13 441 ant individuals belonging to 3839 species occurrences and 71 species were collected, of which 26 species were exclusive predators and 45 species were omnivores. 4. Occurrence and species richness of total and omnivore ants were positively related to soil pH. Predator ant occurrence was unrelated to all environmental variables tested. 5. The species richness of predator ants increased with tree species richness but decreased with leaf functional diversity and shrub cover. Elevation negatively influenced only total ant species richness. 6. The evenness of predators increased with tree species richness, while the evenness of all ants decreased with shrub cover. Omnivore ant evenness decreased with tree evenness, but increased with successional age. 7. The results highlight the value of diverse forests in maintaining species richness and community evenness of a functionally important predator group. Moreover, the results stress the importance of analysing trophic groups separately when investigating biodiversity effects.

关键词： SAVANNA ecology   HERBIVORES   ECOLOGY   LANDSCAPES  

摘要： Areas within regional landscapes that make a disproportionate contribution to supporting large herbivore populations have been interpreted as key resource areas, hotspots, buffers, stepping stones or serving other functional roles. We investigated the role that the restricted extent of habitat types exploited at different stages of the seasonal cycle might play in limiting the abundance of a blue wildebeest subpopulation in the Kruger National Park, South Africa. GPS collars enabled the space use patterns of the animals to be related to available habitat types, and faecal nutrient concentrations to be related to the habitats exploited at that time. Wildebeest herds occupied primarily grazing lawn grasslands associated with gabbro uplands or sodic lowlands through the wet season into the early dry season. During the late dry season, they switched to seep-zone grasslands in mid slope regions of granitic landscapes. Use of recently burned areas enhanced forage quality at the beginning of the wet season. The seasonal habitat shifts enabled wildebeest to obtain adequate nitrogen, phosphorus and sodium throughout the year. Lawn and seep-zone grasslands combined constituted 10% of the available area. Grazing lawns, which encompassed only 3% of the study area, appeared to be the primary limitation on the abundance of wildebeest. However, the greater security from predation provided by the open vegetation cover in the grazing lawns is not easily disentangled from the resource benefits that they yield. Nevertheless, findings indicate how local abundance can be restricted by the extent of portions of the landscape providing crucial benefits during particular phases of the seasonal cycle. Hence the key resources concept needs to be expanded to accommodate the functionally distinct contributions made by different habitats towards supporting local herbivore populations.

关键词： 树鼩   肝脏疾病   动物模型  

摘要： 肝病的危害,尤其是肝炎的流行以及肝癌的高死亡率已经成为国内外共同关注的重要卫生问题之一,由于缺乏理想的动物模型,某些肝炎及肝癌目前尚未清楚其发病的生理学机制,为了寻找有效的防治方法,建立合适的动物模型显得极其重要。树鼩在医学研究中的价值近年来受到越来越多的关注。国内外的研究发现,人们利用树鼩成功建立了多种肝脏疾病的动物模型,多数研究集中在人类病毒性肝炎及肝癌方面。本文主要介绍肝脏疾病树鼩动物模型的国内外新进展。

关键词： 实验动物   树鼩   疾病动物模型   灵长类动物   种属差异   药靶  

摘要： 创新药物的研发依赖优良的实验动物和疾病动物模型。中科院昆明动物所的科技人员最近研究发现,树鼩作为新型实验动物在特定药物研发中有着独特优势。目前药物研发中广泛使用啮齿类动物(大鼠,小鼠),由于与人种属差异较大,获得的研究结果经常与人相距甚远,造成药物研发在大量投入后的最终失败。树鼩是灵长类动物的近亲。

关键词： Arthropods   Biodiversity   Ecosystem function   Herbivore control   Identity effects   Spiders  

摘要： Stand diversification increasingly emerges as a promising means for improving the multi-functionality and sustainability of management in plantation forests. Increasing tree species richness might potentially also benefit natural enemies, which can substantially contribute to sustainable forest management via top-down control of forest pests. However, there is little empirical evidence on how tree species richness affects the diversity and abundance of predators, as the majority of analyses to date have rarely gone beyond comparisons of monocultures and two species mixtures. Here, we analyzed the performance of spiders as important generalist predators in a tree diversity experiment that uses four of the economically most important broadleaved and coniferous tree species in Europe. We tested the extent to which tree species richness and the identity of the planted tree species affect the abundance, biomass, species richness and functional diversity of spiders. Whereas tree species richness in general had no significant effect, tree species identity strongly affected spider biomass and abundance-with a particularly strong negative effect of the non-native Douglas fir (Pseudotsuga menziesii (Mirb.) Franco). Our results indicate that increasing tree species richness does not necessarily promote characteristics of natural enemy assemblages relevant for pest control in forests and thus not all functions that may be important in a multi-functional management context. Rather, tree species composition and identity will often be of crucial importance in determining forest ecosystem functions and services. The fact that the severe impact of Douglas fir persisted even in diversified tree species mixtures suggests that stand-level predator efficiency can be reduced for tree species growing adjacent to or in mixture with this species. This calls for a more thorough examination of the ecological consequences of the increasing use of this species in forestry across Europe, in part

关键词： functional heterogeneity   grazers   Kruger National Park   microclimates   plant-available nutrients   plant-soil (below-ground) interactions   resource limitation   spatial heterogeneity  

摘要： 1. Savannas are highly heterogeneous tree-grass mixtures, and the structural variation imposed by a discontinuous canopy cover results in spatial variation in soil properties such as plant-available nutrients, temperature and soil moisture. Many savannas are also dominated by large vertebrate herbivores, which impose a different suite of effects on soil properties related to consumption, excretion and physical disturbance. 2. In nutrient-poor, water-limited systems, variation in soil resource availability may play a fundamental role in structuring plant communities, but the relative and interactive effects of key drivers of heterogeneity have received little attention in savanna ecosystems. 3. We investigated the independent and interactive effects of herbivores and tree canopy cover on multiple soil properties up to a depth of 10 cm, including bulk density, soil C pools, total and plant-available nutrients, moisture dynamics and temperature at two contrasting sites in Kruger National Park, South Africa. We analysed samples from locations under and between adult tree canopies and inside and outside long-term herbivore exclosures using a nested design. 4. We found strong positive effects of tree canopies on total and labile pools of soil C and N and negative effects on plant-available P and soil temperature. Tree canopy effects on soil moisture availability were small but clearly detectable. During precipitation events, trees increased moisture inputs on granite soils but decreased moisture inputs on basalt soils compared to open sites. 5. Conversely, we found mixed evidence for herbivore effects on soil chemistry and temperature, but a clearer effect on soil moisture, with areas outside exclosures experiencing higher soil moisture retention, particularly immediately following precipitation events. Soil bulk density, a driver of both nutrient and soil moisture dynamics, was lower under trees and when herbivores were excluded. 6. Synthesis. Our results suggest that va

关键词： agricultural landscape   central place   home range   multinomial logit model   semi-arid  

摘要： Understanding factors that influence habitat selection in heterogeneous landscapes is fundamental for establishing realistic models on animal distribution to inform rangeland management. In this study, we tested whether seasonal variation in habitat selection within the home range of a large herbivore was influenced by constraints such as, distances from water and central place using semi-free range cattle (Bos taurus) as a case study. We also tested whether shifts in space use over time were dependent on spatial scale and on the overall abundance of resources. We predicted that distance from water significantly influenced dry season habitat selection while the influence of the central place on habitat selection was season-independent. We also predicted that shifts in space use over time were spatial scale-dependent, and that large herbivores would include more diverse habitats in their home ranges during the dry season, when water and food resources are less abundant. Multinomial logit models were used to construct habitat selection models with distances from water and central place as habitat-specific constraints. Results showed significant variations in habitat selection between the dry and wet season. As predicted, the effect of distance from central place was season-independent, while the effect of water was not included in the top dry season models contrary to expectation. A diverse range of habitats were also selected during the dry season including agricultural fields. Results also indicated that shifts in space use were spatial scale dependent, with core areas being more sensitive to changes than the home range. In addition, shifts in space use responded to temporal changes in habitat composition. Overall, our results suggest that semi-free range herbivores adopt different foraging strategies in response to spatial-temporal changes in habitat availability.