首页期刊导航|Acta oecologica
期刊信息/Journal information
Acta oecologica
Gauthier-Villars
Acta oecologica

Gauthier-Villars

1146-609X

Acta oecologica/Journal Acta oecologica
正式出版
收录年代

    Network analysis highlights increased generalisation and evenness of plant-pollinator interactions after conservation measures

    Fisogni, AlessandroMassol, Francoisde Manincor, NatashaQuaranta, Marino...
    10页
    查看更多>>摘要：The decline of pollinators may alter the complex system of interactions that they establish with flowering plants, with potential negative consequences on both partners. Within this context, network analysis may be a useful tool to study ecological properties of plant-pollinator interactions and to evaluate the outcomes of conservation actions. Three conservation measures were implemented within the European LIFE + PP-ICON project to support the local pollinator community of a population of the rare plant Dictamnus albus in a protected area near Bologna, Italy. Artificial nesting sites were installed to support solitary bees, populations of native plants were reinforced to increase foraging resources for pollinators, and colonies of bumblebees reared from wild queens were released in the study area. In this work we evaluate the effects of these conservation actions on plant-pollinator networks over a period of four years, comparing a pre- (2011-2012) and a post-conservation (2013-2014) action period. The overall network generalisation increased after the implementation of conservation measures and interactions were more evenly distributed. Module composition significantly changed between the two periods, showing a marked rewiring of interactions. D. albus was a module hub both before and after conservation actions, thus emerging as an important node within its own module. In addition, some plant and pollinator species directly targeted by conservation measures became module connectors, highlighting their increased importance in linking different modules. Finally, the reinforcement of plant and pollinator populations led to increased flower visitation. These results indicate that conservation actions affected species both directly and indirectly and that the network of interactions has potentially increased its robustness and resilience towards possible species loss. This study highlights ways in which network analysis can be used to measure changes in plant-pollinator interactions in response to conservation actions.
      原文链接:
    • NSTL
    • Elsevier

    Taxonomic and morphological diversity of the ground-dwelling ant fauna in Eastern Amazonian grasslands

    Siqueira, Emely L. S.Silva, Rogerio R.
    9页
    查看更多>>摘要：Amazonian grassland ecosystems are poorly understood, highly threatened, and under-protected. This study combined taxonomic and trait-based diversity approaches to provide the first description of the diversity of the ground-dwelling ant fauna of grasslands in Eastern Amazonia. We surveyed two types of open vegetation habitats: campinarana (unique to Amazonia; five sites) and savanna (two sites). Of the 89 ground-dwelling ant species we collected from pitfall traps, a few species were characteristic of open vegetation habitats. We found significant differences among these sites in terms of their species richness, which was positively associated with vegetation complexity. Morphological diversity, via species richness, was positively related to flooding and negatively related to soil cover. In conclusion, we observed some characteristic ant species of open vegetation habitats in Amazonian grasslands, and morphologically rich, ground-dwelling ant fauna. Further, a trait-based approach improved our understanding of community organization in the Amazon, which is the most bio-diverse tropical biome on Earth.
      原文链接:
    • NSTL
    • Elsevier

    Greenhouse gas emissions from termite mounds in a transition area between the Cerrado Savanna and the Atlantic Forest in Brazil

    Quevedo, Helio DaniloBrandani, Carolina BragaBento, Camila BolfariniPitombo, Leonardo Machado...
    9页
    查看更多>>摘要：The contribution of termites to the global balance of greenhouse gases, which is aggravated by large seasonal variations in their emissions, remains unclear. The objectives of this study were to evaluate the influence of termite mounds on CH4, CO2 and N2O emissions and to analyze their diurnal variations over a 9-month (249-day) period in a transition area of the Cerrado Savanna and Atlantic Forest biomes in Brazil where the current land use was a non-managed pasture. We used transects to estimate greenhouse gas emissions across the study area. The results revealed that soils settled by termites emitted more CH4 than they consumed, exhibiting 113% higher CH4 emissions than soils without termites, which emitted an estimated 10.09 g of CH4 ha (-1) day(-1) on average. The wood-feeding Cornitermes sp., the most abundant species in the mounds area analyzed in the experiment, accounted for 83.12% and 83.09% of the CH4 and CO2 fluxes. Extrapolating our results to non-managed Brazilian pastures, CH4 emissions arising termite mounds could reach up to 6.25 Tg ha(-1) yr(-1). The results of this study reveal that tropical pastures in transition areas between Cerrado and Atlantic Forest biomes infested by termite mounds can greatly contribute to increased CH4 emissions and should be considered in the inventory of greenhouse gas emissions.
      原文链接:
    • NSTL
    • Elsevier

    A review of seed ecology of poisonous plants in the world's grasslands

    Li, XiaoteMa, WenjunXing, Fu
    10页
    查看更多>>摘要：In degraded grasslands, luxuriant growth and rapid expansion of poisonous plants threaten livestock safety and reduce forage quality. Most of the poisonous plants propagate through seeds, but previous studies have paid insufficient attention to seed ecology, leading to a lack of sufficient support for ecological research regarding the formulation and implementation of relevant prevention and control methods. Based on a review of 172 references (1933-2020), we have summarized the research on soil seed banks, seed germination and dormancy, and seed dispersal of poisonous plants in the world's grasslands. The plants involved are Euphorbia esula, Eupatorium adenophorum, Lantana camara, Stellera chamaejasme, Achnatherum inebrians, genera of Senecio, Delphinium, Cicuta, Aconitum, Lupinus, Halogeton, and locoweed, which refers specifically to a kind of poisonous plants of Astragalus and Oxytropis genus containing swainsonine. There are some commonalities in the seed ecology of different poisonous plants in grasslands, including the persistence and surface aggregation of soil seed banks, as well as primary, long-distance dispersal by wind and animals. However, there are many differences between poisonous plants in terms of soil seed density, preference conditions of seed germination, seed dispersal media, and distance. For controlling the spread of poisonous plant seeds must reduce the disturbance to the surface soil and prohibit grazing during the active stage of seed rain. We recommend future studies investigate the influence of grazing on seed germination and propagation, the formation and fall of seed rain, and the impact of global change on poisonous plants. This review will be helpful for grassland researchers and managers in the study of seed ecology and the control strategy of poisonous plants.
      原文链接:
    • NSTL
    • Elsevier

    Ecological relevance of high and low nucleic acid content bacteria in a monsoon influenced tropical estuary: Implications on the beta-Glucosidase activity

    Eswaran, RanjithKhandeparker, Lidita
    10页
    查看更多>>摘要：Heterotrophic bacteria that differ in their nucleic acid content are frequently observed in aquatic environments. However, their relevance and roles in organic matter utilization in monsoon-influenced tropical estuaries have not been addressed. Transparent exopolymer particles (TEP) are one of the carbohydrate rich organic matter forms in aquatic environments, and their breakdown is mostly mediated by a heterotrophic bacterial ectoenzyme, i.e., beta - glucosidase (BGase). The present study evaluated the influence of shifts in high nucleic acid content- (HNA) and low nucleic acid content - (LNA) bacteria on the degradation of TEP with emphasis on BGase activity. For this, monthly observations were carried out along the Zuari estuary, India, on the abundance of HNA, LNA bacteria, bacterial production (BP), and BGase activity. The results showed that the contribution of HNA bacteria to total bacterial count was high and positively influenced the BP and BGase activity during the non-monsoon seasons, which represents a well-mixed water column. During this time, HNA also influenced the active utilization of TEP. Whereas, LNA bacteria dominated during the monsoon, wherein the water column is strongly stratified, and showed decoupling with BGase activity, irrespective of the depth. Redundancy and response curve analyses revealed that the interactive effect of monsoon (rainfall) and stratification significantly altered the bacterial activity in this estuary. Besides, the variability in side scatter (SSC), and fluorescence intensity (FL 1) of HNA and LNA bacteria suggest that these two groups play distinct ecological roles in the tropical estuarine systems. Unravelling the links between the different nucleic acid content bacteria and their phylogenetic composition can provide insights into their functional roles in monsoonal estuaries.
      原文链接:
    • NSTL
    • Elsevier

    Effects of livestock on nitrogen and carbon cycling in a savanna in Burkina Faso

    Ye, LambienouLata, Jean-ChristopheNacro, Hassan BismarckMasse, Dominique...
    7页
    查看更多>>摘要：The nitrogen and carbon cycles are fundamental ecosystem processes influenced by several factors including soil type and other abiotic factors, plant species, grazing and soil organisms. Herbivores profoundly influence the functioning of ecosystems and the recycling of nutrients in interaction with plants in natural ecosystems. This study focuses on the effects of livestock on carbon and nitrogen cycling in a grazed savanna in Burkina Faso. Dominant grass species (aerial and root parts) and soil samples were collected under grasses and bare soil patches in 48 plots (24 protected and 24 unprotected plots), 18 months after setting up herbivores exclosures. Soil and grass C-13 and N-15 were used as integrative indicators of carbon and nitrogen cycles. The results revealed no significant effect of livestock on soil total carbon and nitrogen and on soil delta C-13 and delta N-15 values. Moreover, grazing had no significant effect on grass carbon and delta C-13, while it significantly increased grass total nitrogen and delta N-15. Therefore, our hypothesis that grazing would increase soil C-13 and N-15 values and plant biomass was only verified for grass N-15. Grass delta N-15 results suggest that grazing improves the immediate availability of nitrogen but could also increase nitrogen losses.
      原文链接:
    • NSTL
    • Elsevier

    Vulture numbers and densities in a large protected savannah in West Africa

    Salewski, Volker
    6页
    查看更多>>摘要：A number of vulture species were ubiquitous in undisturbed West African savannahs. However, in recent decades most species have declined rapidly and some are now at the brink of extinction. For some species, large protected areas are their last strongholds, but even there pronounced declines have become obvious in recent years. However, we lack even basic knowledge about current distribution, densities, movement patterns and threats. Comoe National Park (CNP) in northeast Cote d'Ivoire is one of the largest protected savannahs in West Africa and still hosts breeding populations of three critically endangered species (Hooded Vulture Necrosyrtes monachus, White-backed Vulture Gyps africanus, White-headed Vulture Trigonoceps occipitalis). In total, 590 km of searches for vultures and their nests were conducted on foot in southwest CNP in the dry seasons of 2018 and 2019. Thirty-seven active vulture nests (Hooded Vulture - 2, White-backed Vulture - 32, White-headed Vulture - 3) were discovered. CNP may be one of the last refuges for these species in Cote d'Ivoire and important for their conservation in West Africa. There are, however, hints that vultures have declined in CNP since the 1990s and are now rarer especially at the Park's fringe. Together with observations of increasing poaching activities, this underlines that large reserves with strict law-enforcement are needed to save West Africa's vultures from extinction.
      原文链接:
    • NSTL
    • Elsevier

    How steady is the nested pattern in saline grassland true bug communities? Effects of sampling effort and data completeness on nestedness

    Seat, JelenaNadazdin, BojanaMilic, NikolaCuk, Mirjana...
    8页
    查看更多>>摘要：Nestedness is currently one of the most explored structural patterns of biological communities, especially since its major application in studies on ecological networks. Research on the nested pattern, as a spatial structural descriptor of communities, was mostly focused on theoretical background in the conservation of habitat islands. Here, we explore, to what extent nested true bug communities are present in saline grassland fragments of the Pannonian ecoregion and what are the reasons for their nestedness. In 2015 and 2017, we sampled true bugs from 17 saline pastures in northern Serbia. We applied three different sampling procedures (i.e. gradient in sampling effort) for collecting true bugs: along 20 m long transect, 3 x 30 m long parallel transects and total inventory. Analyses showed significant nestedness of the true bug communities and consistency of the pattern regardless of the data type (binary vs. weighted data) and applied metrics (NODF vs. spectral radius, WNODF vs. spectral radius). However, with the decrease of sampling effort and/or the exclusion of grass feeders, all metrics gradually detect less frequently significant nestedness. The only constant factor which was found to induce nestedness in true bug communities was true bug species richness. Plant cover features showed a weak influence on the nested pattern and landscape features did not take part at all. We believe nestedness of true bugs was the result of differences in habitat complexity among sampling sites, but detailed studies are needed to reveal which abiotic and/or biotic factors are responsible for it. For further studies, priority should be given to investigating the influence of management of saline grasslands on the nestedness in true bug communities.
      原文链接:
    • NSTL
    • Elsevier

    Epigeic fauna (with emphasis on ant community) response to land-use change for sugarcane expansion in Brazil

    Vanolli, Beatriz S.Canisares, Lucas P.Franco, Andre L. C.Delabie, Jacques H. C....
    9页
    查看更多>>摘要：The epigeic fauna, ground surface-dwelling invertebrates that inhabit leaf-litter, acts on multiple soil processes and key ecosystem services and is threatened by global land-use change (LUC). In Brazil, LUC for sugarcane expansion over extensive pasture has been taking place for promoting bioenergy production; however, conventional sugarcane cultivation includes monoculture, periodic soil tillage and agrochemicals may alter the quantity and quality of crop residue inputs, soil habitats and communities of soil fauna. Thus, a field study at three sites in central southern Brazil was conducted to evaluate if the expansion of sugarcane cultivation affects soil epigeic fauna. In each site, we sampled epigeic fauna in areas under LUC from native vegetation to extensive pasture, and from that to sugarcane. The epigeic fauna was collected using pitfall traps and then quantified and classified in taxonomic groups (Order, Class, Family). In addition, as a focal organism group, ants were classified at the species level. Overall, 13 taxonomic groups were identified, in which the Formicidae family was the most abundant group (i.e., 67% of individuals), followed by Diptera (13%), Araneae (5%) and Coleoptera (4%). Land transition from native vegetation to pasture increased fauna abundance by 27% but reduced the diversity of epigeic fauna community by 43%. In contrast, sugarcane expansion over extensive pasture reduced fauna abundance (22%), did not alter the diversity of the invertebrate community at a broad taxonomic level, but decreased species richness of the dominant taxa (ants) by 55%. Ant individuals were classified into 37 species, allowing to verify that sugarcane cultivation over pastures decreased both the abundance and richness of ants and altered community composition. Ant species Ectatomma brunneum were more sensitive to LUC and, therefore, could be characterized as potential indicators of disturbed environments. We demonstrate that sugarcane expansion over pasturelands reduces the total abundance of the soil epigeic fauna, and that effects on fauna diversity vary from broad to fine taxonomic resolutions. Further studies are needed to evaluate if the declines in fauna abundance and ant species richness impair specific soil functions and soil-related ecosystem services.
      原文链接:
    • NSTL
    • Elsevier

    Comparing germination metrics of Opuntia ficus-indica and O. robusta between two sets of bird species (Pied Crows and two smaller species)

    Mokotjomela, Thabiso MichaelThabethe, VuyisileDowns, Colleen
    5页
    查看更多>>摘要：The fleshy fruits of exotic Opuntia ficus-indica (L.) Mill and Opuntia robusta (Haw.) Haw (Cactaceae family) are consumed and dispersed by many vertebrates, which likely influences their invasion success. We tested whether seed ingestion by Pied Crows (Corvus albus) and other smaller birds (African Pied Starling Lamprotornis bicolor and the Red-eyed Bulbul Pycnonotus nigricans) improve the germination and speed in O. ficus-indica and O. robusta. Controlled germination trials for two Opuntia species were set up using the seeds extracted from faecal material, depulped seeds, and intact fruits. Overall, results show that seed germination for O. robusta was significantly higher than for O. ficus-indica. There were significant differences in seed germination between treatments of two Opuntia species, with the total mean germination of seeds defecated by the Pied Crows being equivalent to that of seeds defecated by the other smaller birds but significantly greater than the other treatments (i.e., depulped seeds and intact fruit). We noted that removal of the fruit pulp from seeds significantly improved germination in both Opuntia species compared to intact fruits. The O. robusta seeds defecated by the smaller birds had significantly greatest and most accelerated germination of all other treatments followed by the seeds defecated by the Pied Crows. Seeds of O. ficus-indica defecated by the Pied Crows had significantly greater germination than the seeds ingested by smaller birds. We conclude that seed germination success in fleshy fruits including those of alien species, varies with seed treatment by different vertebrate dispersal agents, and their net effect on seeds, may have consequences on species invasion success.
      原文链接:
    • NSTL
    • Elsevier