关键词： HAZARDOUS substances -- Physiological effect   SILVER nanoparticles   METALS -- Toxicology   DECISION trees   CELL-mediated cytotoxicity   CELL lines  

关键词： Acacia mortality   Introduced species   Nature conservation   Seed viability   Ungulate herbivores   Wildlife reservation  

摘要： Acacia trees are keystone species of drylands. The recruitment of Acacia seedlings is regulated by large herbivores. The study objective was to investigate the effect of several large herbivore species on Acacia germination and recruitment. These species include the addax (Addax nasomaculatus), Arabian oryx (Oryx leucoryx), Asiatic wild ass (Equus hemionus), African wild ass (Equus africanus), and dorcas gazelle (Gazella dorcas). Feces of these herbivore species were collected in a safari reservation in the hyper-arid Arava Valley, where Acacia raddiana and Acacia tortilis trees are widespread. The study was implemented in a net house, where the feces were laid in small piles on the ground and irrigated. Two batches of the feces were studied: one in the winter and one in the spring of 2012. The winter batch encompassed only the feces of the addax, oryx, and Asiatic ass, and it was found that the addax feces generated a significantly greater number of seedlings than the feces of other species. Of this batch, only 13 % of seedlings were alive similar to 250 days later. The spring batch encompassed all five species and revealed a germination rate in the feces according to the following order: addax > oryx > Asiatic ass > gazelle > African ass. Of this batch, 46 % of seedlings were alive similar to 200 days later. This study provides new knowledge regarding the effect of each of the ungulate species on recruitment capacity of new trees to the Acacia population. The results propose that the two most significant factors affecting recruitment are rumination and size of herbivores.

关键词： Research Article  

摘要： With grasslands and savannas covering 20% of the world's land surface, accounting for 30-35% of worldwide Net Primary Productivity and supporting hundreds of millions of people, predicting changes in tree/grass systems is priority. Inappropriate land management and rising atmospheric CO2 levels result in increased woody cover in savannas. Although woody encroachment occurs world-wide, Africa's tourism and livestock grazing industries may be particularly vulnerable. Forecasts of responses of African wildlife and available grazing biomass to increases in woody cover are thus urgently needed. These predictions are hard to make due to non-linear responses and poorly understood feedback mechanisms between woody cover and other ecological responders, problems further amplified by the lack of long-term and large-scale datasets. We propose that a space-for-time analysis along an existing woody cover gradient overcomes some of these forecasting problems. Here we show, using an existing woody cover gradient (0-65%) across the Kruger National Park, South Africa, that increased woody cover is associated with (i) changed herbivore assemblage composition, (ii) reduced grass biomass, and (iii) reduced fire frequency. Furthermore, although increased woody cover is associated with reduced livestock production, we found indigenous herbivore biomass (excluding elephants) remains unchanged between 20-65% woody cover. This is due to a significant reorganization in the herbivore assemblage composition, mostly as a result of meso-grazers being substituted by browsers at increasing woody cover. Our results suggest that woody encroachment will have cascading consequences for Africa's grazing systems, fire regimes and iconic wildlife. These effects will pose challenges and require adaptation of livelihoods and industries dependent on conditions currently prevailing.

关键词： Research Article  

摘要： Biological invasions are a major threat to biodiversity;however, the degree of impact can vary depending on the ecosystem and taxa. Here, we test whether a top invader at a global scale, the tree Robinia pseudoacacia (black locust or false acacia), which is known to profoundly change site conditions, significantly affects urban animal diversity. As a first multitaxon study of this kind, we analyzed the effects of Robinia dominance on 18 arthropod taxa by pairwise comparisons of woodlands in Berlin, Germany, that were dominated by R. pseudoacacia or the native pioneer tree Betula pendula. As a negative effect, abundances of five arthropod taxa decreased (Chilopoda, Formicidae, Diptera, Heteroptera, Hymenoptera);13 others were not affected. Woodland type affected species composition of carabids and functional groups in spiders, but surprisingly did not decrease alpha and beta diversity of carabid and spider assemblages or the number of endangered species. Tree invasion thus did not induce biotic homogenization at the habitat scale. We detected no positive effects of alien dominance. Our results illustrate that invasions by a major tree invader can induce species turnover in ground-dwelling arthropods, but do not necessarily reduce arthropod species abundances or diversity and might thus contribute to the conservation of epigeal invertebrates in urban settings. Considering the context of invasion impacts thus helps to set priorities in managing biological invasions and can illustrate the potential of novel ecosystems to maintain urban biodiversity.

关键词： 树鼩   动物模型   综述  

摘要： 树鼩属于低等灵长类动物,其形态、生理机能和生化代谢等与人类相似,实验研究的结果容易推广到人,广泛应用于医学生物学研究。研究人员利用树鼩已经建立许多模拟人类疾病的树鼩动物模型,如肝炎病毒性疾病、糖尿病、肿瘤和老年痴呆模型等。对树鼩在动物模型中的应用研究进行概述。

关键词： climate extremes   ecosystem processes   extreme climate events   flowering   frugivores   fruiting   nectarivores   tree reproductive phenology   vertebrate species  

摘要： Forest vertebrate fauna provide critical services, such as pollination and seed dispersal, which underpin functional and resilient ecosystems. In turn, many of these fauna are dependent on the flowering phenology of the plant species of such ecosystems. The impact of changes in climate, including climate extremes, on the interaction between these fauna and flora has not been identified or elucidated, yet influences on flowering phenology are already evident. These changes are well documented in the mid to high latitudes. However, there is emerging evidence that the flowering phenology, nectar/pollen production, and fruit production of long-lived trees in tropical and subtropical forests are also being impacted by changes in the frequency and severity of climate extremes. Here, we examine the implications of these changes for vertebrate fauna dependent on these resources. We review the literature to establish evidence for links between climate extremes and flowering phenology, elucidating the nature of relationships between different vertebrate taxa and flowering regimes. We combine this information with climate change projections to postulate about the likely impacts on nectar, pollen and fruit resource availability and the consequences for dependent vertebrate fauna. The most recent climate projections show that the frequency and intensity of climate extremes will increase during the 21st century. These changes are likely to significantly alter mass flowering and fruiting events in the tropics and subtropics, which are frequently cued by climate extremes, such as intensive rainfall events or rapid temperature shifts. We find that in these systems the abundance and duration of resource availability for vertebrate fauna is likely to fluctuate, and the time intervals between episodes of high resource availability to increase. The combined impact of these changes has the potential to result in cascading effects on ecosystems through changes in pollinator and seed dispe

关键词： genotypic diversity   herbivores   predators   species diversity   species richness  

摘要： Despite potential interactive effects of plant species and genotypic diversity (SD and GD, respectively) on consumers, studies have usually examined these effects separately. We evaluated the individual and combined effects of tree SD and mahogany (Swietenia macrophylla) GD on the arthropod community associated with mahogany. We conducted this study within the context of a tree diversity experiment consisting of 74 plots with 64 saplings/plot. We sampled 24 of these plots, classified as monocultures of mahogany or polycultures of four species (including mahogany). Within each plot type, mahogany was represented by either one or four maternal families. We surveyed arthropods on mahogany and estimated total arthropod abundance and species richness, as well as abundance and richness separately for herbivorous and predatory arthropods. Overall tree SD and mahogany GD had positive effects on total arthropod species richness and abundance on mahogany, and also exerted interactive effects on total species richness (but not abundance). Analyses conducted by trophic level group showed contrasting patterns;SD positively influenced herbivore species richness but not abundance, and did not affect either predator richness or abundance. GD influenced predator species richness but not abundance, and did not influence herbivore abundance or richness. There were interactive effects of GD and SD only for predator species richness. These results provide evidence that intra- and inter-specific plant diversity exert interactive controls on associated consumer communities, and that the relative importance of SD and GD may vary among higher trophic levels, presumably due to differences in the underlying mechanisms or consumer traits. Resumen A pesar del potencial de efectos de interaccion entre la diversidad de especies y la diversidad genotipica (DS y DG respectivamente) sobre los consumidores, en general dichos efectos han sido evaluados de manera aislada. Evaluamos los efectos individu

关键词： Wildlife crime   Enforcement   Mobile app   Conservation technology   Customs  

摘要： Accurate field identification of illegally traded wildlife and wildlife products is critically important in the detection and suppression of wildlife crimes. Yet many law enforcement officers and concerned citizens lack access to resources for identifying species and products;this is particularly true for those with no formal expertise in biology, zoology or wildlife training. Emerging digital technologies such as mobile applications may provide important easy-to-use decision-tree style tools for in situ identification. With local government and civil society partners, we are piloting such tools in China and Vietnam to identify whole animals and ivory products;and in the United States developing tools that will be used at U.S. military bases in Afghanistan to identify species from wildlife products. We are coordinating these efforts to minimize redundancy and overhead;we benefit from shared backend support for a photo database and species ID keys that can be translated easily to ensure enough flexibility for targeting needs of the specific country and audience. Planned inclusion of 'ask the expert' and geolocation functions will increase accuracy in identification and aid monitoring and research of supply chains. For these emerging technologies to be successful, deployment must be accompanied with on-the-ground trainings to recruit and retain enforcement personnel. The establishment of a supporting network of experts and a user community will be critical for long-term implementation and evaluation of success. Preliminary response from users of a pilot app in China demonstrates high potential for employing these technologies as routine tools to help fight wildlife crimes. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Birds   Deadwood   Exotic Species   Forest Management   LIFE Project   Saproxylic Organisms  

摘要： The cavities that develop in veteran trees represent a key microhabitat for forest biodiversity and especially for secondary cavity nesters that rely on this resource for shelter. Since the availability of deadwood, veteran and hollow trees is threatened by forest management, we explored the possibility of increasing the presence of these scarce resources. To increase the abundance of dead wood-microhabitats, 113 trees of the hybrid planes (Platanus x acerifolia) were converted into new living structures, the Habitat Trees (HT). To investigate the potential of this resource on the native avian fauna, six types of cavities were designed according to the size requirements of the target bird species. The temporal evolution of the cavities and their use by birds were then studied for eight years. The artificial cavities generally did not compromise growth and stability of the trees, and the majority remained alive. These hollows offered better thermal insulation compared to traditional nest-boxes and natural cavities. Their use increased during the first three years, reaching the 80%. In the following years, the use declined (probably because of the increase of rot and displacement of the lids). This highlights the need of management to maintain their suitability through time. Our results suggest a possible cost-effective alternative use of alien tree species, which should be included in management actions to compensate the shortage of hollow trees in managed forests.

关键词： Akaike's information criterion   Biodiversity conservation   Ecosystem engineer   Evenness   Richness   Southeastern coastal plain  

摘要： Keystone species are important drivers of diversity patterns in many ecosystems. Their effects on ecological processes are fundamental to understanding community dynamics, making them attractive conservation targets for ecosystem management. However, many studies assume keystone effects are constant. By developing functional relationships of species' effects and assessing how they vary with context, we can design more efficient conservation strategies to maintain keystone impacts. The threatened gopher tortoise (Gopherus polyphemus) is presumed to be a keystone species promoting biodiversity in endangered longleaf pine ecosystems of the Southeastern Coastal Plain, USA. Although many commensals use tortoise burrows, their putative keystone influence on emergent diversity patterns lacks critical evaluation. We quantified the functional relationship between tortoise burrow density and non-volant vertebrate diversity in a longleaf pine savanna, located in central Florida. Tortoise burrow density had a positive effect on vertebrate diversity and evenness but did not affect species richness. This relationship was robust across fire disturbance regimes and was the primary factor explaining diversity at the local scale. Our results demonstrate keystone effects of the gopher tortoise through an ecosystem engineering mechanism. Continued gopher tortoise population declines will have large, negative impacts on vertebrate diversity in this biodiversity hotspot. Therefore, maintaining gopher tortoise populations is critical to effectively conserve dependent species and the function of endangered longleaf pine ecosystems. We show that developing a functional understanding of keystone relationships (not a binomial categorization) can lead to important insights into community processes.