The Power of Expert Opinion in Ecological Models Using Bayesian Methods: Impact of Grazing on Birds

One of our greatest challenges as researchers is predicting impacts of landuse on biota and predicting the impact of livestock grazing on birds is no exception. Insufficient data and poor survey design often yield results that are not statistically significant or difficult to interpret because researchers cannot disentangle the effects of grazing from other disturbances. This has resulted in few publications on the impact of grazing on birds alone. Ecologists with extensive experience in bird ecology in grazed landscapes could inform an analysis when time and monetary constraints limit the amount of data that can be collected. Using responses from twenty well-recognised ecologists throughout Australia we capture this expert knowledge and incorporate it into a statistical model using Bayesian methods. Although relatively new to ecology, Bayesian methods allow straightforward probability statements to be made about specific models or scenarios and they allow the integration of different types of information, including scientific judgement while formally accommodating and incorporating the uncertainty in the information provided. Data on bird density was collected across three broad levels of grazing (no/low, moderate and high) typical of sub-tropical Australia. This field data was used in conjunction with expert data to produce estimates of species persistence under grazing. The addition of expert data through priors in our model strengthened results under at least one grazing level for all but one bird species examined. When experts were in agreement credible intervals were tightened substantially, whereas when experts were in disagreement results were similar to those evaluated in the absence of expert information. In fields where there is extensive expert knowledge, yet little published data, the use of expert information as priors for ecological models is a cost effective way of making more confident predictions about the effect of management on biodiversity

Species richness estimation for benthic data

This thesis addresses species richness estimation for benthic data by describing the clustering of individuals within a species using a Neyman Type A distribution, and incorporating this into species richness estimates. A review of current species richness estimation methods is included. The maximum-likelihood approach to species richness estimation is extended to incorporate the Neyman Type A model, with a gamma mixing distribution on the mean abundance of individuals within a species. Species richness estimates of this model are compared to those of the simpler negative binomial and Poisson models. The use of a penalised-likelihood is applied to avoid spuriously large estimates of species richness that can be associated with the "boundary problem". The Bayesian approach to species richness is considered, using uninformative and informative priors. Informative priors are elicited using expert opinion obtained from a number of benthic ecologists at the Centre for Environment, Fisheries and Aquaculture Science. These are incorporated into species richness estimation in the form of priors, and also converted into penalties for use in the frequentist approach. Several benthic data sets are analysed throughout, along with a Lepidoptera data set, and a data set from a common bird census carried out in the USA. In addition, several simulation studies are undertaken to illustrate the performance of the estimators. The research culminates in the application of species richness estimators to estimate species mortality due to dredging carried out off the Norfolk coast. Several estimators can be considered to gain a picture of the effect of dredging, and I recommend that species richness estimators should reflect the underlying distribution of the data. I also recommend that a precautionary approach should be taken when using these estimators in practical applications

Structuring expert input for a knowledge-based approach to watershed condition assessment for the Northwest Forest Plan, USA

Assessments of watershed condition for aquatic and riparian species often have to rely on expert opinion because of the complexity of establishing statistical relationships among the many factors involved. Such expert-based assessments can be difficult to document and apply consistently over time and space. We describe and reflect on the process of developing a computer-based decision support application from expert judgments for assessing aquatic and riparian conditions over the 100,000 km2 managed by the US federal government under the Northwest Forest Plan. The decision support system helped structure and document the assessment process and provided consistency and transparency to the evaluation methodology. However, many decisions and trade-offs were required in the expert engagement and model-building processes. Knowledge elicitation in an interactive group had a number of benefits over nominal group or Delphi processes, but efficient knowledge capture required considerable planning and expertise in the subject matter and modeling process. Communicating model results for validation was problematic and only effectively accomplished via in-person workshops. The choice to use different expert groups for each biophysical province provided more opportunities for participation and promoted greater ownership in the assessment, but it also led to increased variation among the resulting model structures. We propose three possible approaches for better managing the consistency of assessment models when multiple expert groups are involved

Expert elicitation, professional judgement, and current exposure assessment practices in the field of occupational hygiene

Occupational hygienists work across a diverse range of industrial environments. In the course of their work, hygienists will need to assess and control worker exposure levels by deploying methods based on the science of risk management, exposure assessment and industrial safety. Hygienists will regularly make decisions relating to worker exposure based on professional judgement, usually in the absence of quantitative data and in the presence of high uncertainty. These factors have the potential to lead to heterogeneity between practitioners, bias, error, and practice variation in the form of departure from established guidelines or protocols. The primary aim of this PhD research project was to examine experience and current practices with respect to exposure assessment processes and judgement amongst occupational hygienists

Adaptive management of Ramsar wetlands

Abstract The Macquarie Marshes are one of Australia’s iconic wetlands, recognised for their international importance, providing habitat for some of the continent’s more important waterbird breeding sites as well as complex and extensive flood-dependent vegetation communities. Part of the area is recognised as a wetland of international importance, under the Ramsar Convention. River regulation has affected their resilience, which may increase with climate change. Counteracting these impacts, the increased amount of environmental flow provided to the wetland through the buy-back and increased wildlife allocation have redressed some of the impacts of river regulation. This project assists in the development of an adaptive management framework for this Ramsar-listed wetland. It brings together current management and available science to provide an informed hierarchy of objectives that incorporates climate change adaptation and assists transparent management. The project adopts a generic approach allowing the framework to be transferred to other wetlands, including Ramsar-listed wetlands, supplied by rivers ranging from highly regulated to free flowing. The integration of management with science allows key indicators to be monitored that will inform management and promote increasingly informed decisions. The project involved a multi-disciplinary team of scientists and managers working on one of the more difficult challenges for Australia, exacerbated by increasing impacts of climate change on flows and inundation patterns

Transforming Conservation

There are severe problems with the decision-making processes currently widely used, leading to ineffective use of evidence, faulty decisions, wasting of resources and the erosion of public and political support. In this book an international team of experts provide solutions. The transformation suggested includes rethinking how evidence is assessed, combined, communicated and used in decision-making; using effective methods when asking experts to make judgements (i.e. avoiding just asking an expert or a group of experts!); using a structured process for making decisions that incorporate the evidence and having effective processes for learning from actions. In each case, the specific problem with decision making is described with a range of practical solutions. Adopting this approach to decision-making requires societal change so detailed suggestions are made for transforming organisations, governments, businesses, funders and philanthropists. The practical suggestions include twelve downloadable checklists. The vision of the authors is to transform conservation so it is more effective, more cost-efficient, learns from practice and is more attractive to funders. However, the lessons of this important book go well beyond conservation to decision-makers in any field

A Computer Supported Method to Reveal and Assess Personal Professional Theories in Vocational Education

Please refer only to the article as published by Technology, Pedagogy & EducationThis article introduces a dedicated, computer supported method to construct and formatively assess concept maps of Personal Professional Theories: internalized bodies of knowledge (i.e. mental models) that professionals use as reference to interpret and acquire knowledge and to direct their behaviour and which vocational students are expected to develop. However, the development of essentially mental models is difficult to monitor and assess. Traditional elicitation and assessment methods such as semi-structured interviews and concept mapping, are either too labour intensive to be applied in education or do not reveal the quality of the student’s mental models. The article presents a new method which has been shown to be valid, reliable and easy usable in education, and which reveals the quality in a way comparable to and in many cases better than the traditional methods

Transforming Conservation

There are severe problems with the decision-making processes currently widely used, leading to ineffective use of evidence, faulty decisions, wasting of resources and the erosion of public and political support. In this book an international team of experts provide solutions. The transformation suggested includes rethinking how evidence is assessed, combined, communicated and used in decision-making; using effective methods when asking experts to make judgements (i.e. avoiding just asking an expert or a group of experts!); using a structured process for making decisions that incorporate the evidence and having effective processes for learning from actions. In each case, the specific problem with decision making is described with a range of practical solutions. Adopting this approach to decision-making requires societal change so detailed suggestions are made for transforming organisations, governments, businesses, funders and philanthropists. The practical suggestions include twelve downloadable checklists. The vision of the authors is to transform conservation so it is more effective, more cost-efficient, learns from practice and is more attractive to funders. However, the lessons of this important book go well beyond conservation to decision-makers in any field

Developing measures for valuing changes in biodiversity : final report

This document reports the findings from the DEFRA funded research project 'Developing measures for valuing changes in biodiversity'. The aim of the research was to develop an appropriate framework that will enable cost-effective and robust valuations of the total economic value of changes to biodiversity in the UK countryside. The research involved a review of ecological and economic literature on the valuation of biodiversity changes. The information gathered from this review, along with the findings from a series of public focus groups and an expert review of valuation methodologies, were used to develop a suite of valuation instruments that were used to measure the economic value of different aspects of biodiversity. Contingent valuation and choice experiment studies were administered to households in Cambridgeshire and Northumberland, while valuation workshops were conducted in Northumberland only. The data from these studies were also used to test for benefits transfer