关键词： Alligator rivers region   Radionuclide transfer   Tropical radioecology   Wildlife  

摘要： Preliminary values of whole organism concentration ratio (CRwo-soil) were derived for terrestrial vertebrates of an Australian tropical savanna environment. Wildlife groups included bird, bat, ground-dwelling mammal and reptile. Sample data for some of the wildlife groups (bird and bat in particular) were limited. The bird and bat CRwo-soil values were generally lower than the ground-dwelling mammal and reptile CRwo-soil values based on the available data. Arithmetic mean CRwo-soil values for two species of native marsupial and two species of non-native placental were not significantly different (p < 0.05) when tested using a one-way analysis of variance. The results hinted at possible sampling efficiencies for terrestrial vertebrates. However, verification with additional data was recommended. Used cautiously, the CRwo-soil values may assist in environmental assessments of Australian uranium mining sites. They also enhance the available data on radionuclide transfer to wildlife for use internationally.

关键词： Carbon footprint   Liveweight   Methane emissions   Orinoco basin   Reproductive performance   Soil emissions  

摘要： The savannas of eastern Colombia located in the Orinoco river basin represent 18% of the Latin American neotropical savannas, and those areas that are tillable and closer to markets are subject to considerable anthropic pressure in the quest for intensification. Historically, and even today, beef cattle production constitutes the main land use, and much of it is subjected to extensive management. This paper describes for the first time, the use of cattle grazing experiments to assess methane (CH4) emissions from neotropical savanna-based beef breeding systems, and with the support of published research conducted next to them, estimates of the carbon (C) footprint in carbon dioxide equivalents (CO2-eq) for the whole system. Over 5 years and covering complete reproductive cycles, a conventional weaning (CW) herd system was compared to an early weaning (EW) herd system, that represented a modest degree of more intensive savanna management. Differences were found between the two management practices in total CH4 emissions, emission intensities [kg CH4 kg(-1) calf born and kg CH4 kg(-1) liveweight gain (LWG)] and emission efficiencies (kg CO2-eq kg(-1) calf born and kg CH4 kg(-1) LWG), that mostly associated with the different lactation lengths. When both herd systems were carried over until calves, later yearlings, reached to 25 months of age, the differences in favor of EW breeding herd system were diminished. The calculated C footprint in (CO2-eq) of both management practices was near neutral subjected to a number of assumptions and the use of limited published information on savanna C stocks and CH4 and nitrous oxide (N2O) emissions from soil, and it is posited that both herd systems were nearly in equilibrium. The available data and results show the need for further information on the neotropical savanna C stocks and C sequestration potential of soils of the Orinoco river basin. More reliable datasets regarding below-ground C inputs and CH4 and N2O emissions from so

关键词： browse trap   bush encroachment   coppice   Crematogaster   recruitment limitation   sapling   storage effect   tree-grass co-existence  

摘要： Savanna tree cover is dynamic due to disturbances such as fire and herbivory. Frequent fires can limit a key demographic transition from sapling to adult height classes in savanna trees. Saplings may be caught in a fire trap', wherein individuals repeatedly resprout following fire top-kill events. Saplings only rarely escape the cycle by attaining a fire-resistant height (e.g. taller than the minimum scorch height) during fire-free intervals. Large mammalian herbivores also may trap trees in shorter size classes. Browsing herbivores directly limit sapling height, while grazing herbivores such as cattle facilitate sapling growth indirectly via grass removal. Experimental studies investigating how meso-wildlife, megaherbivores and domestic livestock affect height of resprouts following fire are rare, but necessary for fully understanding how herbivory may reinforce (or counteract) the fire trap. In our study system, interactive fire-herbivore effects on transitions from sapling (<1m) to adult tree (>1m) height classes may be further influenced by plant defences, such as symbiotic ants. We used the Kenya Long-term Exclosure Experiment (KLEE) to investigate how post-fire resprout size of a widespread monodominant East African tree, Acacia drepanolobium was influenced by (a) herbivory by different combinations of cattle, meso-wildlife (15-1,000kg) and megaherbivores (>1,000kg) and (b) the presence of acacia-ant mutualists that confer tree defences. We sampled height, stem length and ant occupancy of resprouts exposed to different herbivore combinations before and after controlled burns. Resprout height of saplings that were short prior to fire (<1m) was reduced primarily by meso-wildlife. Negative effects of elephants on post-fire resprout height increased with pre-fire tree size, suggesting that resprouts of the tallest trees (with the greatest potential to escape the fire trap cycle) were preferentially browsed and reduced in height by elephants. There were no signific

关键词： cavity-dependent wildlife   ephemeral rivers   Hollow-bearing trees   river red gum   semi-arid woodland  

摘要： Up to 37 species of the birds and microbats inhabiting inland Australia are dependent on tree cavities for breeding or roosting. The river red gum (Eucalyptus camaldulensis), a well-known hollow-bearing tree species, occurs in linear semi-arid woodland along thousands of kilometres of ephemeral river channels and is the only tree species that provides widespread, aggregated hollow resources across a landscape otherwise dominated by shrublands. Here we assess the type and quantity of hollows available along ephemeral rivers of the MacDonnell Ranges bioregion in central Australia and determine which characteristics of river red gums best predict the abundance and characteristics of different tree hollows, as first steps towards assessing the current availability of hollows in the region. Approximately a third of all river red gums sampled were hollow-bearing, but individual trees with abundant hollows were rare. Further, 36% of hollows had an entrance <= 5 cm, and 37% had entrances which were 6-10 cm in diameter, whereas only 13% of hollows had an entrance diameter > 20 cm suitable for larger hollow-using species. Large and high hollows only occurred on trees that did not display post-disturbance resprouting. Trees with multiple and diverse hollows were rare and tended to be in advanced stages of senescence and had larger stems (82.3 +/- 3.33 cm) and were taller (14.4 +/- 0.53 m) compared to non-hollow-bearing trees (23.44 +/- 1.68 cm, 8.0 +/- 0.34 m). Further research is required to establish whether the current abundance of hollows and diversity of hollow types are limiting to cavity-dependent wildlife, and to identify any threats to availability of hollows.

关键词： Coarse woody debris   Ecological restoration   Fire   Grazing   Herbivore   Refugia  

摘要： Long-term faunal responses to restoration efforts can be very different from those in the short term, but are often not quantified systematically to identify ways that maximise restoration outcomes. We report on a 9-year landscape-scale ecological experiment that tests the long-term responses of reptile populations to coarse woody debris (CWD) addition, reduced native macropod grazing, and prescribed fire. We found that reptile species richness was increased 9years after CWD addition, as was the abundance of several common reptile species. Further, the more CWD was added to the system, the more benefits were afforded to reptiles. The positive effect of CWD depended on the surrounding vegetation structure and was greater in sites with low tree and shrub cover. Further, lower levels of macropod grazing appeared to lessen the effects of CWD addition in the long term. Our results show that restoration projects in open woodlands and scattered tree ecosystems should consider the addition of CWD as a fundamental element of their management actions. To maximise benefits of CWD addition for reptiles, we recommend a strategy of placing CWD in areas with low tree and shrub cover rather than areas with high tree and shrub cover. The addition of CWD in such areas would provide crucial shelter and foraging substrates for reptiles in a comparatively hostile portion of the landscape. Our study helps to establish guidelines for achieving long-lasting effects of ecosystem restoration for vertebrates and demonstrates the benefits of monitoring vertebrates over the long term.

关键词： Spontaneous retinal venous pulsations   Intracranial pressure   Intraocular pressure   Translaminar pressure gradient   Tree shrews  

摘要： Spontaneous retinal venous pulsations (SRVPs), pulsations of branches of the central retinal vein, are affected by intraocular pressure (IOP) and intracranial pressure (ICP) and thus convey potentially-useful information about ICP. However, the exact relationship between SRVPs, IOP, and ICP is unknown. It is not easily feasible to study this relationship in humans, necessitating the use of an animal model. We here propose tree shrews as a suitable animal model to study the complex relationship between SRVPs, IOP, and ICP. Tree shrew SRVP incidence was determined in a population of animals. Following validation of a modified IOP control system to accurately and quickly control IOP, IOP and/or ICP were manipulated in two tree shrews with SRVPs and the effects on SRVP properties were quantified. SRVPs were present in 75% of tree shrews at physiologic IOP and ICP. Altering IOP or ICP produced changes in tree shrew SRVP properties;specifically, increasing IOP caused SRVP amplitude to increase, while increasing ICP caused SRVP amplitude to decrease. In addition, a higher IOP was necessary to generate SRVPs at a higher ICP than at a lower ICP. SRVPs occur with a similar incidence in tree shrews as in humans, and tree shrew SRVPs are affected by changes in IOP and ICP in a manner qualitatively similar to that reported in humans. In view of anatomic similarities, tree shrews are a promising animal model system to further study the complex relationship between SRVPs, IOP, and ICP.

关键词： grass   occupancy modeling   rodent   shrub encroachment  

摘要： Disturbance by large herbivores, fires, and humans shapes the structure of savannas, altering the amount of woody vegetation and grass. Due to change in the intensity and frequency of these disturbances, savannas are shifting toward grass-dominated or shrub-dominated systems, likely altering animal communities. Small mammals are critical components of savannas, and their distributions likely are affected by these ecosystem-wide changes in vegetative cover. We assessed the responses of small mammals to a gradient of woody cover in low-lying savannas of southeastern Africa. In Kruger National Park (South Africa) and in three nearby reserves (Eswatini), we livetrapped for over 2 years to build multispecies occupancy models that assessed the responses of the small mammal community to grass and woody cover. Overall, whole-community occupancy increased with grass biomass. More species responded positively to woody cover than to grass biomass, but woody cover was associated with reduced occurrence of one species (Mastomys natalensis). Our results suggest that an increase in grass biomass enhances whole-community occupancy of small mammals, but regional diversity is likely to be higher in areas that contain patches of high grass biomass as well as patches of woody cover.

关键词： Animals   Arthropoda   Biology and life sciences   Community ecology   Computer and information sciences   Data management   Ecological metrics   Ecology   Ecology and environmental sciences   Ecosystems   Eukaryota   Forests   Herbivory   Insects   Invertebrates   Organisms   Plant ecology   Plant science   Plant taxonomy   Plant-animal interactions   Plant-herbivore interactions   Plant-insect interactions   Plants   Research Article   Species diversity   Taxonomy   Terrestrial environments   Trophic interactions  

摘要： Oceanic islands have been providing important insights on the structuring of ecological communities and, under the context of the present biodiversity crisis, they are paramount to assess the effects of biological invasions on community assembly. In this study we compare the taxonomic and functional diversity of insect herbivore assemblages associated with the dominant tree species of Azorean native forests and investigate the ecological processes that may have originated current patterns of plant-herbivore associations. Five dominant trees-Erica azorica, Ilex perado subsp. azorica, Juniperus brevifolia, Laurus azorica and Vaccinium cylindraceum-were sampled in the remnants of the native forest of Terceira Island (Azores) using a standardised methodology. The taxonomic and functional diversity of insect herbivore assemblages was assessed using complementary metrics and beta diversity partitioning analysis (species replacement and richness differences) aiming to evaluate the variation in insect herbivore assemblages within and between the study plant species. Sixty two insect species, mostly bugs (Hemiptera) and caterpillars (Lepidoptera), were found in the five study plants with indigenous (endemic and native non-endemic) insects occurring with higher species richness and abundance than introduced ones. Species replacement was the most important component of insect herbivore taxonomic beta diversity while differences in trait richness played a major role on functional beta diversity. The endemic E. azorica stands out from the other study plants by having associated a very distinct insect herbivore assemblage with a particular set of functional attributes, mainly composed by large bodied and long shaped species that feed by chewing. Despite the progressive biotic homogenization witnessed in the Azores during the last few decades, several strong associations between the endemic trees and their indigenous insect herbivores remain.

关键词： community size structure   detritivores   diversity   functional group   invertebrate community   pioneer plants   predators   trophic pyramids  

摘要： Ecosystem engineers structure species richness and the composition of biological communities. Although several studies have uncovered the importance of engineering environments, few studies have evaluated the effect of pioneering plants as ecosystem engineers, especially in tropical environments. When dead, Cecropia leaves become architecturally complex, acquiring a tridimensional shape due to desiccation, and may facilitate other organisms. Here, we evaluate the role of these dead leaves in structuring species richness, abundance, biomass, and composition of macroinvertebrate communities on leaf litter in six protected areas of Brazilian Atlantic Rainforest. Predators were larger, more abundant, and presented higher standing stock in the presence of dead Cecropia leaves compared to soil debris (i.e., common leaf litter);however, detritivores had the opposite patterns. This resulted in shifts in body size structure of the assemblage, thus causing inversion of biomass pyramids to top-heavy in advanced stages of Cecropia leaves desiccation. Dead Cecropia leaves did not influence species richness and abundance of species, but they influenced the biomass of detritivores and predators in the communities. Our results demonstrated that pioneer trees can act as ecosystem engineers, by facilitating communities of invertebrate predators. In addition, our results suggest that the presence of Cecropia leaves can mediate trophic interactions and shape food web structure on the forest floor. in Portuguese is available with online material.

关键词： exclosure experiment   hunting defaunation   plant-animal interactions   seed predation trampling   Southeast Asia Malaysia   tree and liana regeneration   tropical forest   wild boar Sus scrofa  

摘要： Hunting and land use change modify native herbivore abundances and cause cascading effects in natural ecosystems. The outcomes for vegetation depend on changes to specific plant-animal interactions, such as seed dispersal or predation, or physical disturbances. We experimentally manipulated terrestrial wildlife populations in a primary lowland forest in Malaysia over an 18-year period (1996-2014) to understand how artificially high or low animal densities affect tree and liana regeneration. Our study site retains a diverse wildlife community and artificially high densities of native wild pigs (Sus scrofa) that are sustained by crop raiding in distant oil palm plantations. We used fencing that excluded terrestrial animals >1 kg to experimentally simulate conditions similar to those in defaunated forests. These two treatments - abnormally high pig abundances and megafauna loss from hunting - represent common outcomes in disturbed Southeast Asian forests and are characteristic of many forests globally. We focused on trees and lianas because they are the two dominant woody life-forms in tropical forests and crucial determinants of forest structure and function. We found that liana sapling abundances (30-100 cm height) increased by 86% in unfenced control plots with wildlife but were stable in exclosures. In contrast, tree abundances did not change in unfenced control plots but increased by 83% in exclosures without wildlife. Evidence of scaring on surviving stems suggested that these inverted outcomes were driven by selective use of tree saplings for wild pig nests. Lianas may also have greater tolerance to wildlife disturbances like nest building. By the end of the study, lianas comprised 38% of all saplings in unfenced controls but just 14% in exclosures. Synthesis and applications. We conclude that artificially abundant wildlife, such as crop-raiding wild pigs, may shift tropical forest understories towards lianas while defaunation may shift it towards trees. These r