关键词： Moringa   Leucaena   Mulberry fodder trees   In vitro gas production   DM and NDF degradations   Rabbit performance  

摘要： Leaves of Mulberry (Morus albaLam.), Leucaena (Leucaena leucocephalaLam de wit.) and Moringa (Moringa oleiferaLam.) were evaluated as dry season protein supplements for grazing animals based on chemical composition, in vitro and in sacco nutrient digestibility and a Rabbit feeding trial. All tree fodder forages had similar dry matter (DM) content, but crude protein was higher in Moringa (28.6%) followed by Leucaena (24.5%), Mulberry (24.1%) and Lucerne (18.0%). Ash content was highest in Mulberry followed by Moringa and Lucerne with Leucaena having lowest amounts. Polyphenols ranged from 2.72 to 3.64%, with Leucaena having highest and Mulberry lowest amounts. Dietary fibre were highest in Mulberry and Moringa, but there were no significant differences (P < 0.05) between Leucaena and Lucerne. In vitro gas production and DM disappearances were higher in Moringa followed by Mulberry and Lucerne with Leucaena having lowest amounts. Except for Leucaena, DM disappearances were increased when rumen fluid from dairy cattle steers was used. In sacco DM disappearances were 33.7% for Leucaena, 78.2% for Lucerne, 50.2% for Moringa and 50.7% for Mulberry. In vitro and in sacco crude fibre and neutral detergent fibre disappearances were relatively lower, but reflected DM disappearances. The Rabbit feeding trial showed diets based on Moringa, Leucaena and combined fodder forages to have significantly better performance than Mulberry and grass hay alone. The conclusion was that tested tree fodder forages have potential of being used as dry season protein supplements for grazing animals on traditional smallholder farms.

关键词： 人类疾病动物模型   实验动物   手术麻醉   树鼩   伦理问题   生理特点   灵长类  

摘要： 树鼩被认为是最接近灵长类的动物。它具有体型小、数量多、价格便宜、伦理问题少等优点。近年来随着对树鼩生理特点的深人研究,它被广泛应用于建立人类疾病动物模型[1]。

关键词： Africa   daily activity   home range   migration   predation   population dispersion   ungulates  

摘要： Nearly 90% of the world's large herbivore diversity occurs in Africa, yet there is a striking dearth of information on the movement ecology of these organisms compared to herbivores living in higher latitude ecosystems. The environmental context for movements of large herbivores in African savanna ecosystems has several distinguishing features. African large herbivores move in landscapes with high spatiotemporal variability, low predictability, seasonal restrictions in surface water as well as food resources, and exposure to a diverse assemblage of competitors, predators, and pathogens. These features influence mobility, diel activity routines, home-range fidelity, and exposure to predation. We review the knowledge that has been gained about the movements of African herbivores from Global Positioning System (GPS) telemetry and identify important gaps in knowledge that exist. Topics addressed include seasonal movement patterns, daily activity schedules, space utilisation, water dependency, responses to risks of predation, pathogen transmission, social affiliations, and local population density determination. While the growing number of GPS telemetry studies has addressed a wide range of topics in Africa, they remain fragmentary in terms of places and species represented. Most research has been focussed on three species, and practices for data sharing and analysis should be improved. African landscapes are changing perhaps faster than any other region on Earth, with rapidly expanding human populations, massive infrastructure development projects, and changes in climatic regimes. There is a crucial need to establish relationships between herbivore movements and their changing environments, especially in Africa where most of the world's large herbivore diversity resides.

关键词： CITES   International trading   IUCN   Plant blindness   Trafficking   Vertebratism  

摘要： Legal and illegal wildlife trade is a multibillion dollar industry that is driving several species toward extinction. Even though wildlife trade permeates the Tree of Life, most analyses to date focused on the trade of a small selection of charismatic vertebrate species. Given that vertebrate taxa represent only 3% of described species, this is a significant bias that prevents the development of comprehensive conservation strategies. In this short contribution, we discuss the significance of global wildlife trade considering the full diversity of organisms for which data are available in the IUCN database. We emphasize the importance of being fast and effective in filling the knowledge gaps about non-vertebrate life forms, in order to achieve an in-depth understanding of global trading patterns across the full canopy of the Tree of Life, and not just its most appealing twig.

关键词： Green tree   Avian   Biodiversity   Populus tremuloides   Ecological forestry  

摘要： Contemporary forest management is increasingly focused on maintaining ecosystem function and services including biodiversity conservation. As a result, harvest guidelines related to retention of live trees and woody biomass (fine and coarse residue arising from harvesting) have been developed to provide benefits for wildlife, but there is much uncertainty on the effectiveness of these guidelines depending on stage of succession, retention levels, and focal taxa. We used an operational-scale, fully replicated factorial experiment to determine the effects of both tree retention (none, dispersed, aggregated) and woody residue harvesting (no removal, 20% retention, all removed) on breeding bird and small mammal communities in aspen forests 7-8 years after harvest. Bird community metric responses showed a clear and consistent positive response to tree retention;both tree retention configurations resulted in higher total abundance, increased diversity, and higher species richness compared to stands with no tree retention. There was no difference in community metrics between the retention configurations and no evidence that early successional species were negatively affected by tree retention. Total abundance of small mammals was lower in clear-cuts compared to tree retention treatments;moreover, clear-cut stands had lower species diversity compared to stands with the aggregated tree retention. There were limited effects of biomass harvest treatments on small mammal communities, likely because actual biomass removal was much lower than experimental targets. Overall, our results provide conclusive evidence on the continued benefits of tree retention on wildlife communities se0ven and eight years post-harvest in regenerating aspen forests.

关键词： Insect herbivores   network structure   network descriptors   plant-insect interactions   specialisation   trophic guilds  

摘要： 1. Herbivorous insects can be classified into several trophic guilds with different levels of specialisation on their host plants, which may influence the topological structure of their trophic networks. The present study tested the hypothesis that the structure of plant-herbivore networks differs between guilds of galling, sucking, and chewing insects. 2. Six areas of Neotropical savannas were studied in two localities in the North of the state of Minas Gerais, Brazil. In each area, interactions between plant and insect species were used to build networks for different guilds. 3. In total, 18 plant-herbivore networks were built, comprising 317 insect morphospecies, 50 plant species, and 489 distinct interactions. The networks were characterised using species richness and different network topological measures (connectance, modularity, nestedness, and specialisation). 4. The results obtained showed no difference in species richness, network size, and connectance between distinct insect herbivore guilds. However, it was found that modularity was higher for exophagous than galling insect networks and nestedness was higher for chewers than for other guilds. On the other hand, galling insect networks showed higher specialisation than exophagous insect networks, and sucking insect networks were more specialised than chewing insect networks. 5. The findings of the present study indicate that, although species richness did not differ between insect guilds of herbivores in Neotropical savannas, the topological structure of networks is sensitive to biological and ecological differences between these herbivore groups. The present study stands out as the first to systematically compare the network structure of different herbivore guilds in Neotropical savannas.

关键词： carbon isotope niches   large mammal herbivores   species' diets   habitat type   Africa   grassland biome   savanna   stable isotope analysis  

摘要： Stable isotope analyses provide insights into large herbivore diets. Carbon isotopes are particularly useful for analysing diet given their ability to reflect C-3 or C-4 photosynthetic pathways and, therefore, distinguish between browser and grazer diets. Although isotopes are useful for comparing diets across a range of spatial and temporal scales, most studies have focused on either interspecific differences within habitats or single species averages across their geographic range. In this study, we use both new and existing carbon isotopic data to compare large mammal herbivore diets across habitat types in southern and east Africa. We examined whether species in the grassland biome of central South Africa had the same carbon isotopic signatures as counterparts from savannas in southern and east Africa. Within the grassland biome, isotopic signatures from faecal samples were strongly correlated with signatures from bone and dentine collagen samples, supporting our approach of comparing faecal data from the grasslands with savanna data obtained mainly through analysis of skeletal materials. Regression analysis comparing grasslands and savannas confirmed that species' isotopic niches within communities were conserved across different geographic regions. However, herbivore delta C-13 values were generally lower in the grassland compared with the savanna biome, highlighted particularly by the lower delta C-13 values of several grazer species (but not browsers), indicating greater consumption of C-3 vegetation in grasslands. This finding is counter-intuitive and suggests that non-woody C-3 vegetation may be an important component of grazer diets in the grassland biome. We speculate on various environmental factors, related to food abundance that could underline the pattern.

关键词： Ailanthus altissima   Decomposition   Detritus   Lonicera maackii   Rhamnus davurica  

摘要： Approximately 90% of all annual net primary productivity in temperate deciduous forests ends up entering the detritus food web as leaf litter. Due to chemical and physical differences from native litter, inputs from invasive species may impact the litter-dwelling community and ecosystem processes. We compared leaf-litter nutritional quality and decomposition rates from two invasive shrubs, Lonicera maackii and Rhamnus davurica, and the invasive tree Ailanthus altissima to litter from native oak-hickory forest in the Shenandoah Valley of Virginia, USA. We sampled litter from both invaded and uninvaded habitats and conducted litter colonization experiments to test for effects on microflora and the litter-dwelling arthropod communities. Litter from all three invasive species decomposed more rapidly than native litter, with native habitats averaging two to nearly five times as much litter by June. Invasive litter had higher nitrogen concentration and lower C:N ratios than native litter. Invasive litter supported greater growth of bacteria and fungi. Higher numbers of arthropods colonized invasive litter than native litter, but litter arthropod numbers on the forest floor of invaded habitats dropped in the early summer as litter decomposed. Litter had no effect on arthropod richness. Over short time scales, our results indicate that these invasive species represent beneficial, novel resources for the litter-dwelling community. However, the short-lived nature of this resource resulted in a crash in the abundance of the litter-dwelling organisms once the litter decomposed. As a whole, native habitat seems to support a larger, more stable litter-dwelling community over the course of a growing season.

关键词： aboveground biomass   browsers   C-13 isotopes   grazers   herbivore exclosures   isotopic mixing models  

摘要： Although studies have shown that mammalian herbivores often limit aboveground carbon storage in savannas, their effects on belowground soil carbon storage remain unclear. Using three sets of long-term, large herbivore exclosures with paired controls, we asked how almost two decades of herbivore removal from a semiarid savanna in Laikipia, Kenya affected aboveground (woody and grass) and belowground soil carbon sequestration, and determined the major source (C-3 vs. C-4) of belowground carbon sequestered in soils with and without herbivores present. Large herbivore exclusion, which included a diverse community of grazers, browsers, and mixed-feeding ungulates, resulted in significant increases in grass cover (similar to 22%), woody basal area (similar to 8 m(2)/ha), and woody canopy cover (31%), translating to a similar to 8.5 t/ha increase in aboveground carbon over two decades. Herbivore exclusion also led to a 54% increase (20.5 t/ha) in total soil carbon to 30-cm depth, with similar to 71% of this derived from C-4 grasses (vs. similar to 76% with herbivores present) despite substantial increases in woody cover. We attribute this continued high contribution of C-4 grasses to soil C sequestration to the reduced offtake of grass biomass with herbivore exclusion together with the facilitative influence of open sparse woody canopies (e.g., Acacia spp.) on grass cover and productivity in this semiarid system.

关键词： Macropores   Ecosystem engineers   Shrub-encroachment   Ecosystem functioning   Soil fauna   Land degradation  

摘要： Macropores created by invertebrates improve ecosystem functions such as soil properties and hydrological processes. In semi-arid savannas, where water is the main limiting resource and precipitation is scarce macropores might increase infiltration, and thereby improve water availability for plants. Macropores may therefore represent a buffering mechanism counteracting degradation in the form of shrub-encroachment. We investigated the interacting effects of vegetation structures at small scales and vegetation cover at landscape scales, and seasonality on invertebrate macropores. First, macropore density and size distribution was measured at open soil, in direct proximity to perennial grass tussocks and shrubs, at grass dominated, intermediate and shrub dominated sites. Secondly, we recorded macropores on randomly chosen plots along a shrub cover gradient at three points in time within the rainy season. Individual shrubs and the amount of large scale grass cover increased macropore densities. Interestingly, macropore numbers were highest at the beginning of the rainy season. We argue that macropore densities reflect the activity and influence of soil macrofauna on ecosystem functioning, which is greatest at highly heterogeneous vegetation. Rangeland management should aim for high grass cover with scattered shrubs for sustainable soil health, by applying appropriate stocking rates, selectively removing shrubs or reseeding perennial grasses.