关键词： BEF-China   biodiversity   canopy layers   community composition   ecosystem functioning   forest succession   plant-herbivore interactions   trophic groups  

摘要： The high tree diversity of subtropical forests is linked to the biodiversity of other trophic levels. Disentangling the effects of tree species richness and composition, forest age, and stand structure on higher trophic levels in a forest landscape is important for understanding the factors that promote biodiversity and ecosystem functioning. Using a plot network spanning gradients of tree diversity and secondary succession in subtropical forest, we tested the effects of tree community characteristics (species richness and composition) and forest succession (stand age) on arthropod community characteristics (morphotype diversity, abundance and composition) of four arthropod functional groups. We posit that these gradients differentially affect the arthropod functional groups, which mediates the diversity, composition, and abundance of arthropods in subtropical forests. We found that herbivore richness was positively related to tree species richness. Furthermore, the composition of herbivore communities was associated with tree species composition. In contrast, detritivore richness and composition was associated with stand age instead of tree diversity. Predator and pollinator richness and abundance were not strongly related to either gradient, although positive trends with tree species richness were found for predators. The weaker effect of tree diversity on predators suggests a cascading diversity effect from trees to herbivores to predators. Our results suggest that arthropod diversity in a subtropical forest reflects the net outcome of complex interactions among variables associated with tree diversity and stand age. Despite this complexity, there are clear linkages between the overall richness and composition of tree and arthropod communities, in particular herbivores, demonstrating that these trophic levels directly impact each other.

关键词： carbon dynamics   mesocosm   non-additive effects   old growth   Panama   pioneer   soil fauna  

摘要： Disturbance can alter tree species and functional diversity in tropical forests, which in turn could affect carbon and nutrient cycling via the decomposition of plant litter. However, the influence of tropical tree diversity on forest floor organisms and the processes they mediate are far from clear. We investigated the influence of different litter mixtures on arthropod communities and decomposition processes in a 60-year-old lowland tropical forest in Panama, Central America. We used litter mixtures representing pioneer and old growth tree species in experimental mesocosms to assess the links between litter types, decomposition rates, and litter arthropod communities. Overall, pioneer species litter decomposed most rapidly and old growth species litter decomposed the slowest but there were clear nonadditive effects of litter mixtures containing both functional groups. We observed distinct arthropod communities in different litter mixtures at 6 mo, with greater arthropod diversity and abundance in litter from old growth forest species. By comparing the decay of different litter mixtures in mesocosms and conventional litterbags, we demonstrated that our mesocosms represent an effective approach to link studies of litter decomposition and arthropod communities. Our results indicate that changes in the functional diversity of litter could have wider implications for arthropod communities and ecosystem functioning in tropical forests. Abstract in Spanish is available with online material.

关键词： Animal conservation   Wildlife monitoring   Object detection   Active learning   Crowd-sourcing data   Unmanned aerial vehicles   Very high resolution  

摘要： Unmanned aerial vehicles (UAVs) offer new opportunities for wildlife monitoring, with several advantages over traditional field-based methods. They have readily been used to count birds, marine mammals and large herbivores in different environments, tasks which are routinely performed through manual counting in large collections of images. In this paper, we propose a semi-automatic system able to detect large mammals in semi-arid Savanna. It relies on an animal -detection system based on machine learning, trained with crowd-sourced annotations provided by volunteers who manually interpreted sub-decimeter resolution color images. The system achieves a high recall rate and a human operator can then eliminate false detections with limited effort. Our system provides good perspectives for the development of data-driven management practices in wildlife conservation. It shows that the detection of large mammals in semi-arid Savanna can be approached by processing data provided by standard RGB cameras mounted on affordable fixed wings UAVs.

关键词： Burn   Coarse woody debris   Distance of vulnerability   Ground cover   Peromyscus   Reithrodontomys  

摘要： Following decades of fire suppression many oak-pine savanna ecosystems have shifted to close-canopied forests. Restoration of these ecosystems to their savanna condition is seen as a way to reduce woody species encroachment and dangerous fuel loads, and restore community species composition. The management practices to achieve these goals typically involve thinning and prescribed fire. We assessed how thinning to reduce basal area combined with frequent prescribed fire influenced small mammal communities and their habitat. We focused on six habitat variables that can influence small mammal abundance and species composition: stand basal area of live trees and snags, volume of coarse woody debris, percent ground cover, forest floor depth, and distance of vulnerability, a measure of understory vegetation structure and animal vulnerability to predators. Although savanna restoration reduced basal area by 80%, there was no change in snag density or coarse woody debris volume. Savanna restoration significantly increased the ground cover of graminoids, forbs, bare ground, and down woody debris and reduced forest floor depth and distance of vulnerability. These habitat changes likely contributed to the significant differences between small mammal communities in restored and non-restored stands. Restoration treatments caused a large increase in abundance of White-footed Mouse (Peromyscus leucopus) and important changes in community assemblages. Least Shrew (Cryptotis parva), Fulvous Harvest Mouse (Reithrodontomys fulvescens), Eastern Harvest Mouse (R. humulis), and Hispid Cotton Rat (Sigmodon hispidus) were caught only in restored stands, while House Mouse (Mus musculus), Plains Harvest Mouse (R. montanus), and Texas Mouse (P. attwateri) were caught only in non-restored stands. (C) 2017 Elsevier B.V. All rights reserved.

关键词： BEF-China   biodiversity and ecosystem functioning   climatic niche   functional traits   fungal pathogens   plant-herbivore interactions  

摘要： Herbivores and fungal pathogens are key drivers of plant community composition and functioning. The effects of herbivores and pathogens are mediated by the diversity and functional characteristics of their host plants. However, the combined effects of herbivory and pathogen damage, and their consequences for plant performance, have not yet been addressed in the context of biodiversity-ecosystem functioning research. We analyzed the relationships between herbivory, fungal pathogen damage and their effects on tree growth in a large-scale forest-biodiversity experiment. Moreover, we tested whether variation in leaf trait and climatic niche characteristics among tree species influenced these relationships. We found significant positive effects of herbivory on pathogen damage, and vice versa. These effects were attenuated by tree species richnessbecause herbivory increased and pathogen damage decreased with increasing richnessand were most pronounced for species with soft leaves and narrow climatic niches. However, herbivory and pathogens had contrasting, independent effects on tree growth, with pathogens decreasing and herbivory increasing growth. The positive herbivory effects indicate that trees might be able to (over-)compensate for local damage at the level of the whole tree. Nevertheless, we found a dependence of these effects on richness, leaf traits and climatic niche characteristics of the tree species. This could mean that the ability for compensation is influenced by both biodiversity loss and tree species identityincluding effects of larger-scale climatic adaptations that have been rarely considered in this context. Our results suggest that herbivory and pathogens have additive but contrasting effects on tree growth. Considering effects of both herbivory and pathogens may thus help to better understand the net effects of damage on tree performance in communities differing in diversity. Moreover, our study shows how species richness and species characteristics

关键词： plant architecture   structural defences   herbivory   cage architecture   spinescence   bite rate  

摘要： 1. Where large browsers are abundant, the survival of trees depends on their ability to deploy defences, either chemical or structural. Structural defences include the arrangement of dense and intricate architecture, termed ` cage' architecture. Previous studies showed that trees developing in herbivore-rich environments tend to have more cage architecture but its precise effect on mammalian herbivores remains unknown. 2. In this paper, we experimentally test how cage architecture affects the bite rate of goats, a generalist mammalian herbivore. 3. We selected 11 palatable tree species with contrasting architectures. We described their caginess using an index combining spinescence and woodiness of their stems. Finally, we evaluated how the caginess of trees slows down herbivores when feeding on the inner leaves in tree crowns. 4. We observed that the bite rate of goats on inner leaves of the cagiest trees was so severely reduced that they could not satisfy their daily nutritional requirements. We discuss how this could affect the preference of wild herbivores for less cagy trees, especially at the end of the dry season.

关键词： camera trap   Minas Gerais   occupancy analysis   secondary vegetation  

摘要： Debate about the conservation value of secondary habitats has tended to focus on tropical forests, increasingly recognizing the role of secondary forests for biodiversity conservation. However, there remains a lack of information about the conservation value of secondary savannas. Here, we conducted a camera trap survey to assess the effect of secondary vegetation on large mammals in a Brazilian Cerrado protected area, using a single-season occupancy framework to investigate the response of individual species (species-level models) and of all species combined (community-level models). In addition, we investigated the cost effectiveness of different sampling designs to monitor globally threatened species in the study area. At the community level, savanna that regenerated from eucalyptus plantation had similar occupancy estimate as old growth areas. At the species level, none of the ten species individually assessed seemed to respond to succession stage, with greater support for the effect of other covariates on occupancy, such as distance from water and vegetation physiognomy. These results demonstrate that secondary vegetation does not appear to negatively impact large mammals in the study area and suggest that, given a favorable context, Cerrado mammals can recolonize and use secondary savannas that regenerated from clearcut. However, our study area should be considered a best-case scenario, as it retained key ecological attributes of high-value secondary habitats. Our simulations showed that a sampling design with 60 camera trap sites surveyed during nine occasions is appropriate to monitor most globally threatened species in the study area, and could be a useful starting point for new monitoring initiatives in other Cerrado areas. RESUMO O debate sobre a importancia de habitats secundarios para a conservacAo tende a focar em florestas tropicais, existindo evidencia consideravel sobre o papel das florestas secundarias na manutencAo da biodiversidade. Entretanto, p

关键词： α-淀粉酶   节肢动物   系统进化树   序列分析  

摘要： 目的:构建节肢动物α-淀粉酶的系统进化树,探讨其进化关系,找出进化树中聚类在一起的α-淀粉酶的特异性序列。方法:在美国国立生物技术信息中心(National Center for Biotechnology Information,NCBI)数据库中选取了56个节肢动物的α-淀粉酶氨基酸序列,利用CLUSTALX2.0进行序列比对、MEGA6.0建立进化树,通过BOXSHADE找到聚类的α-淀粉酶特异性序列。结果:56个α-淀粉酶聚类成A、B、C、D四大簇,A簇特异性序列为"VD NHD NQ",B簇特异性序列为"ID NHD NX",C簇特异性序列为"ID NHD NQ",D簇特异性序列为"XGN NHD X"。A、B、C、D四簇都含有保守的NHD(天冬酰胺-组氨酸-天冬氨酸)序列,但序列两端氨基酸种类不同。结论:56个节肢动物α-淀粉酶分为4簇,每簇都有其特异性序列,但都含有保守序列NHD。

关键词： arthropod phylogenetics   common garden   community genetics   community phylogenetics   foundation species   hybridization  

摘要： Although hybridization in plants has been recognized as an important pathway in plant speciation, it may also affect the ecology and evolution of associated communities. Cottonwood species (Populus angustifolia and ***) and their naturally occurring hybrids are known to support different plant, animal, and microbial communities, but no studies have examined community structure within the context of phylogenetic history. Using a community composed of 199 arthropod species, we tested for differences in arthropod phylogenetic patterns within and among hybrid and parental tree types in a common garden. Three major patterns emerged. (1) Phylogenetic diversity (PD) was significantly different between arthropod communities on hybrids and Fremont cottonwood when pooled by tree type. (2) Mean phylogenetic distance (MPD) and net relatedness index (NRI) indicated that communities on hybrid trees were significantly more phylogenetically overdispersed than communities on either parental tree type. (3) Community distance (D-pw) indicated that communities on hybrids were significantly different than parental species. Our results show that arthropod communities on parental and hybrid cottonwoods exhibit significantly different patterns of phylogenetic structure. This suggests that arthropod community assembly is driven, in part, by plant-arthropod interactions at the level of cottonwood tree type. We discuss potential hypotheses to explain the effect of plant genetic dissimilarity on arthropod phylogenetic community structure, including the role of competition and environmental filtering. Our findings suggest that cottonwood species and their hybrids function as evolutionarily significant units (ESUs) that affect the assembly and composition of associated arthropod communities and deserve high priority for conservation.

关键词： metabolic theory of ecology   macroevolution   phylogenetic comparative methods   allometry  

摘要： Metabolism is the link between ecology and physiology-it dictates the flow of energy through individuals and across trophic levels. Much of the predictive power of metabolic theories of ecology derives from the scaling relationship between organismal size and metabolic rate. There is growing evidence that this scaling relationship is not universal, but we have little knowledge of how it has evolved over macroevolutionary time. Here we develop a novel phylogenetic comparative method to investigate how often and in which clades the macroevolutionary dynamics of the metabolic scaling have changed. We find strong evidence that the metabolic scaling relationship has shifted multiple times across the vertebrate phylogeny. However, shifts are rare and otherwise strongly constrained. Importantly, both the estimated slope and intercept values vary widely across regimes, with slopes that spanned across theoretically predicted values such as 2/3 or 3/4. We further tested whether traits such as ecto-/endothermy, genome size, and quadratic curvature with body mass (i.e., energetic constraints at extreme body sizes) could explain the observed pattern of shifts. Though these factors help explain some of the variation in scaling parameters, much of the remaining variation remains elusive. Our results lay the groundwork for further exploration of the evolutionary and ecological drivers of major transitions in metabolic strategy and for harnessing this information to improve macroecological predictions.