87 research outputs found

    Species abundance distributions should underpin ordinal cover-abundance transformations

    Get PDF
    Questions: The cover and abundance of individual plant species have been recorded on ordinal scales for millions of plots world-wide. Ordinal cover data often need to be transformed to a quantitative form (0%-100%), especially when scrutinising summed cover of multiple species. Traditional approaches to transforming ordinal data often assume that data are symmetrically distributed. However, skewed abundance patterns are ubiquitous in plant community ecology. The questions this paper addresses are (a) how can we estimate transformation values for ordinal data that account for the underlying right-skewed distribution of plant cover; (b) do different plant groups require different transformations; and (c) how do our transformations compare to other commonly used transformations within the context of exploring the aggregate properties of vegetation? Location: Global. Methods: We assigned Braun-Blanquet cover-abundance ordinal values to continuous cover observations. We fitted a Bayesian hierarchical beta regression to estimate the predicted mean (PM) cover of each of six plant growth forms within six ordinal classes. We illustrate our method using a case study (2,809 plots containing 95,812 observations), compare the model-derived estimates to other commonly used transformations and validate our model using an independent dataset (2,227 plots containing 51,497 observations) accessed through the VegBank database. Results: Our model found that PM estimates differed by growth form and that previous methods overestimated cover, especially of smaller growth forms such as forbs and grasses. Our approach reduced the cumulative compounding of errors and was robust when validated against an independent dataset. Conclusions: By accounting for the right-skewed distribution of cover data, our alternate approach for estimating transformation values can be extended to other ordinal scales. A more robust approach to transforming floristic data and aggregating cover estimates can strengthen ecological analyses to support biodiversity conservation and management

    Reference state and benchmark concepts for better biodiversity conservation in contemporary ecosystems

    Get PDF
    Measuring the status and trends of biodiversity is critical for making informed decisions about the conservation, management or restoration of species, habitats and ecosystems. Defining the reference state against which status and change are measured is essential. Typically, reference states describe historical conditions, yet historical conditions are challenging to quantify, may be difficult to falsify, and may no longer be an attainable target in a contemporary ecosystem. We have constructed a conceptual framework to help inform thinking and discussion around the philosophical underpinnings of reference states and guide their application. We characterize currently recognized historical reference states and describe them as PreHuman, Indigenous Cultural, Pre-Intensification and Hybrid-Historical. We extend the conceptual framework to include contemporary reference states as an alternative theoretical perspective. The contemporary reference state framework is a major conceptual shift that focuses on current ecological patterns and identifies areas with higher biodiversity values relative to other locations within the same ecosystem, regardless of the disturbance history. We acknowledge that past processes play an essential role in driving contemporary patterns of diversity. The specific context for which we design the contemporary conceptual frame is underpinned by an overarching goal - to maximize biodiversity conservation and restoration outcomes in existing ecosystems. The contemporary reference state framework can account for the inherent differences in the diversity of biodiversity values (e.g. native species richness, habitat complexity) across spatial scales, communities and ecosystems. In contrast to historical reference states, contemporary references states are measurable and falsifiable. This 'road map of reference states' offers perspective needed to define and assess the status and trends in biodiversity and habitats. We demonstrate the contemporary reference state concept with an example from south-eastern Australia. Our framework provides a tractable way for policy-makers and practitioners to navigate biodiversity assessments to maximize conservation and restoration outcomes in contemporary ecosystems

    Modeling biodiversity benchmarks in variable environments

    Get PDF
    Effective environmental assessment and management requires quantifiable bio-diversity targets. Biodiversity benchmarks define these targets by focusing on specific biodiver-sity metrics, such as species richness. However, setting fixed targets can be challenging becausemany biodiversity metrics are highly variable, both spatially and temporally. We present a mul-tivariate, hierarchical Bayesian method to estimate biodiversity benchmarks based on the spe-cies richness and cover of native terrestrial vegetation growth forms. This approach usesexisting data to quantify the empirical distributions of species richness and cover withingrowth forms, and we use the upper quantiles of these distributions to estimate contemporary,“best-on-offer”biodiversity benchmarks. Importantly, we allow benchmarks to differ amongvegetation types, regions, and seasons, and with changes in recent rainfall. We apply ourmethod to data collected over 30 yr at~35,000 floristic plots in southeastern Australia. Ourestimated benchmarks were broadly consistent with existing expert-elicited benchmarks, avail-able for a small subset of vegetation types. However, in comparison with expert-elicited bench-marks, our data-driven approach is transparent, repeatable, and updatable; accommodatesimportant spatial and temporal variation; aligns modeled benchmarks directly with field dataand the concept of best-on-offer benchmarks; and, where many benchmarks are required, islikely to be more efficient. Our approach is general and could be used broadly to estimate bio-diversity targets from existing data in highly variable environments, which is especially relevantgiven rapid changes in global environmental conditions.This research was supported by the Australian Research Council Centre of Excellence for Environmental Decisions (CE11001000104) and the New South Wales Office of Environment and Heritag

    grazing and biodiversity conservation highlights on a natura 2000 network site

    Get PDF
    This paper provides a summarisation of information on the biodiversity of Natura 2000 sites of Basilicata and the impacts of grazing on protected habitats and species. Besides, using a case study of a site particularly rich in biodiversity as an example, we described the application of the Driving Force, Pressure, State, Impact and Response (DPSIR) framework to evaluate the impacts of grazing and to propose corrective measures for ensuring restoration and conservation of habitats

    Eaten out of house and home:impacts of grazing on ground-dwelling reptiles in Australian grasslands and grassy woodlands

    Get PDF
    Large mammalian grazers can alter the biotic and abiotic features of their environment through their impacts on vegetation. Grazing at moderate intensity has been recommended for biodiversity conservation. Few studies, however, have empirically tested the benefits of moderate grazing intensity in systems dominated by native grazers. Here we investigated the relationship between (1) density of native eastern grey kangaroos, Macropus giganteus, and grass structure, and (2) grass structure and reptiles (i.e. abundance, richness, diversity and occurrence) across 18 grassland and grassy Eucalyptus woodland properties in south-eastern Australia. There was a strong negative relationship between kangaroo density and grass structure after controlling for tree canopy cover. We therefore used grass structure as a surrogate for grazing intensity. Changes in grazing intensity (i.e. grass structure) significantly affected reptile abundance, reptile species richness, reptile species diversity, and the occurrence of several ground-dwelling reptiles. Reptile abundance, species richness and diversity were highest where grazing intensity was low. Importantly, no species of reptile was more likely to occur at high grazing intensities. Legless lizards (Delma impar, D. inornata) were more likely to be detected in areas subject to moderate grazing intensity, whereas one species (Hemiergis talbingoensis) was less likely to be detected in areas subject to intense grazing and three species (Menetia greyii, Morethia boulengeri, and Lampropholis delicata) did not appear to be affected by grazing intensity. Our data indicate that to maximize reptile abundance, species richness, species diversity, and occurrence of several individual species of reptile, managers will need to subject different areas of the landscape to moderate and low grazing intensities and limit the occurrence and extent of high grazing

    Temporal dynamics in biotic and functional recovery following mining David J. Eldridge

    Get PDF
    12 páginas.- 5 figuras.- referencias.- Additional supporting information may be found in the online version of the article at the publisher’s website.Human-induced disturbance has substantially influenced the structure and function of terrestrial ecosystems globally. However, the extent to which multiple ecosystem functions (multifunctionality) recover following anthropogenic disturbance (ecosystem recovery) remains poorly understood. We report on the first study examining the temporal dynamics in recovery of multifunctionality from 3 to 12 years after the commencement of rehabilitation following mining-induced disturbance, and relate this information to changes in biota. We examined changes in 57 biotic (plants, microbial) and functional (soil) attributes associated with biodiversity and ecosystem services at four open-cut coal mines in eastern Australia. Increasing time since commencement of rehabilitation was associated with increases in overall multifunctionality, soil microbial abundance, plant productivity, plant structure and soil stability, but not nutrient cycling, soil carbon sequestration nor soil nutrients. However, the temporal responses of individual ecosystem properties varied widely, from strongly positive (e.g. litter cover, fine and coarse frass, seed biomass, microbial and fungal biomass) to strongly negative (groundstorey foliage cover). We also show that sites with more developed biota tended to have greater ecosystem multifunctionality. Moreover, recovery of plant litter was closely associated with recovery of most microbial components, soil integrity and soil respiration. Overall, however, rehabilitated sites still differed from reference ecosystems a decade after commencement of rehabilitation. Synthesis and applications. The dominant role of plant and soil biota and litter cover in relation to functions associated with soil respiration, microbial function, soil integrity and C and N pools suggests that recovering biodiversity is a critically important priority in rehabilitation programs. Nonetheless, the slow recovery of most functions after a decade indicates that rehabilitation after open-cut mining is likely to protracted.This project was supported by funding from the New South Wales (NSW) Department of Planning and Environment (DPIE). T.P., T.R. and B.H. were supported by Umwelt (Australia) Pty. Ltd. and The Australian Umwelt Research Program (grant C27038), B.W. by the NSW Environment Trust (2017/RD/0095). M.D-B. is supported by a Ramón y Cajal grant (RYC2018-025483-I), a project from the Spanish Ministry of Science and Innovation (PID2020-115813RA-I00), and a project PAIDI 2020 from the Junta de Andalucía (P20_00879). We thank Carmen Castor (University of Newcastle) for field support, Laura Castaneda-Gomez, Giles Ross, Chaturika Daulagala (Western Sydney University), the Environmental Analytical Research and Carbon Laboratories (University of New England) and the DPIE Soil and Water Environmental Laboratory (Yanco) for laboratory support. Open access publishing facilitated by University of New South Wales, as part of the Wiley - University of New South Wales agreement via the Council of Australian University Librarians.Peer reviewe

    Perceptions of the appropriate response to norm violation in 57 societies

    Get PDF
    Norm enforcement may be important for resolving conflicts and promoting cooperation. However, little is known about how preferred responses to norm violations vary across cultures and across domains. In a preregistered study of 57 countries (using convenience samples of 22,863 students and non-students), we measured perceptions of the appropriateness of various responses to a violation of a cooperative norm and to atypical social behaviors. Our findings highlight both cultural universals and cultural variation. We find a universal negative relation between appropriateness ratings of norm violations and appropriateness ratings of responses in the form of confrontation, social ostracism and gossip. Moreover, we find the country variation in the appropriateness of sanctions to be consistent across different norm violations but not across different sanctions. Specifically, in those countries where use of physical confrontation and social ostracism is rated as less appropriate, gossip is rated as more appropriate.info:eu-repo/semantics/publishedVersio

    Change in dominance determines herbivore effects on plant biodiversity

    Get PDF
    Herbivores alter plant biodiversity (species richness) in many of the world’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis—that herbivore-induced changes in the competitive environment determine the response of plant biodiversity to herbivory irrespective of productivity. Under this hypothesis, when herbivores reduce the abundance (biomass, cover) of dominant species (for example, because the dominant plant is palatable), additional resources become available to support new species, thereby increasing biodiversity. By contrast, if herbivores promote high dominance by increasing the abundance of herbivory-resistant, unpalatable species, then resource availability for other species decreases reducing biodiversity. We show that herbivore-induced change in dominance, independent of site productivity or precipitation (a proxy for productivity), is the best predictor of herbivore effects on biodiversity in grassland and savannah sites. Given that most herbaceous ecosystems are dominated by one or a few species, altering the competitive environment via herbivores or by other means may be an effective strategy for conserving biodiversity in grasslands and savannahs globally
    corecore