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- PublicationThe significance of biodiversity in agriculture: relevance, aims and progress of the Ag-Biota ProjectWe describe and review the scientific and policy background with respect to the impact of agriculture on biodiversity and outline the structure and objectives of the Ag-Biota Project. The latter is a large, multiinstitutional study funded by the ERTDI Programme (2000–2006) under the aegis of the National Development Plan. As such, Ag-Biota represents an ongoing commitment to the protection and conservation of biodiversity, and the integration of policy towards the achievement of these goals in all economic sectors. Ag-Biota is addressing directly the practical needs for agri-environmental policy development, such as the need to identify suitable biodiversity indicators for agriculture and begin the development of realistic and practical monitoring and assessment methods; is focussing on the development of ecological understanding concerning the more effective utilisation of beneficial biological populations and processes within the agro-ecosystem; and is asking more fundamental ecological questions concerning the functional role and significance of biological diversity in community structures. The Ag-Biota project represents a suitably policy-focussed response to, and a considerable investment in, the needs of Irish biodiversity research within the context of modern agriculture. As such, we feel that the project is a good model for future biodiversity research, addressing the need for information and an appropriate knowledge base to support practical environmental protection measures.
- PublicationRegional and farm system drivers of avian biodiversity within agriculture ecosystemsFarm-wide bird surveys were carried out on 119 grass-based farms located in three separate regions in Ireland during the winter and breeding seasons. Data relating to livestock production system (dairy or non-dairy) and participation in the Irish agrienvironment scheme (AES) at the time, the Rural Environmental Protection Scheme, were collected. GLMMs were used to establish the factors influencing bird populations during the winter and breeding season. Region and farming system had significant effects on avian biodiversity and there were frequently greater numbers on more intensively managed dairy farms, compared with less intensive non-dairy farms. AES participation had no significant effect on bird populations. Our findings demonstrate a clear influence of region and farm system on avian biodiversity, and suggest that the greater resource availability in more intensive farm systems may actually be beneficial for certain components of farmland biodiversity.
- PublicationSurvey evaluation for species richness of farmland birdsTo estimate biodiversity it may be important to establish whether increased data can be obtained from repeated surveys. Bird species richness was determined after repeated surveys in winter and in the breeding season. Data were collected over two breeding seasons and two winter seasons at nine sites, with three surveys in each winter and four surveys in each breeding season using a standard method. Poisson models were used to determine differences in total cumulative species richness recorded after each additional survey. There were significant increases in species richness in winter between survey one and survey two and between survey two and survey three across nine sites. There was a significant increase between survey one and survey two for resident breeding species richness. Based on pure species richness, three surveys recorded at least 95% of the total observed species richness recorded after four surveys in the breeding season within the agricultural survey area.
- PublicationDifferent bioindicators measured at different spatial scales vary in their response to agricultural intensityEcologically, potential bioindicator taxa operate at different scales within agricultural ecosystems, and thereby provide a means to investigate the influence of changing management practice on biological diversity at different scales within the agro-ecosystem. Surveys of grassland plant species at field level, parasitoid Hymenoptera at the field and farm scale, and bird populations and habitats at farm scale were carried out on 119 grass-based farms across three regions in the Republic of Ireland. In addition, habitat richness and aquatic macroinvertebrates were quantified at landscape scale. Agricultural intensity on the surveyed farms was quantified by mean farm stocking rate, calculated as livestock units per ha (LU/ha), and generalised linear mixed models used to evaluate relationships between stocking rate and the incidence of chosen bioindicator groups. Field scale bioindicators (plant species richness and parasitoid taxon richness and abundance) were negatively associated with mean farm stocking rate. Over much of its observed range, mean farm stocking rate was positively associated with total bird species richness and abundance, and the species richness and abundance of farmland bird indicator species recorded in the winter season. However, these relationships were quadratic, and above a relatively high upper limit of 2.5–3.5 LU/ha, further increase in farm stocking rate had a negative influence. Results demonstrate that different bioindicators measured at different spatial scales vary in their response to agricultural intensity. The lack of a consistent bioindicator response to farm stocking rate suggests that within predominantly farmed regions, maximising biodiversity requires a careful targeting and monitoring with bioindicator taxa that are informative of influences at relevant operational scales. The insights provided may then be much more informative for the design and implementation of agri-environment measures that maximise biodiversity within farmed landscapes.
968Scopus© Citations 22
- PublicationAn assessment of bird species within Irish agricultural landscapes using the Field Boundary Evaluation and Grading System.Capsule The Field Boundary Evaluation and Grading System (FBEGS) is a useful predictor of bird populations found in field boundaries located in southeast Ireland. Aims To assess the potential of FBEGS to evaluate the ecological quality of field boundaries in agricultural ecosystems and as a tool for the measurement of bird populations within field boundaries. Methods Surveys of bird populations were made in selected field boundaries on 50 farms in southeast Ireland in winter and during the breeding season. FBEGS surveys were also carried out on field boundaries to assess ecological quality. glms were fitted to assess the utility of the FBEGS Index as a predictor of bird populations. Results The FBEGS Index was an effective predictor of bird populations in the breeding season, but had limited use in predicting bird populations in winter. Within the overall FBEGS Index, the Associated Features score was a good predictor for populations in both the winter and breeding seasons. In addition, the Boundary Structural score of the field boundary was also an accurate predictor of birds in the breeding season. Conclusion The FBEGS Index has high potential for predicting the effect that changes in the farmed landscape will have on bird populations.
414Scopus© Citations 7
- PublicationA novel method for quantifying overdispersion in count data with application to farmland birdsThe statistical modelling of count data permeates the discipline of ecology. Such data often exhibit overdispersion compared with a standard Poisson distribution, so that the variance of the counts is greater than that of the mean. Whereas modelling to reveal the effects of explanatory variables on the mean is commonplace, overdispersion is generally regarded as a nuisance parameter to be accounted for and subsequently ignored. Instead, we propose a method that models the overdispersion as a biologically interesting property of a data set and show how novel inference is provided as a result. We adapted the double hierarchical generalized linear model approach to create an easily extendible model structure that quantifies the influence of explanatory variables on the overdispersion of count data, and apply it to farmland birds. These data were from a study within Irish agricultural ecosystems, in which total bird species abundance and the abundance of farmland indicator species were compared on dairy and non-dairy farms in the winter and breeding seasons. In general, overdispersion in bird counts was greater on dairy farms than on non-dairy farms, and for total bird numbers, overdispersion was greatest on dairy farms in winter. Our code is fitted using the Bayesian package Rstan, and we make all code and data available in a GitHub repository. Within a Bayesian framework, this approach facilitates a meaningful quantification of the effects of categorical explanatory variables on any response variable with a tendency to overdispersion that has a meaningful biological or ecological explanation.
203Scopus© Citations 2
- PublicationInteractions between livestock systems and biodiversity in South-East IrelandBotanical and arthropod surveys at field level, and bird counts within field boundaries were undertaken on the same random sample of 50 grass-based farms in SE Ireland. Additional data relating to farm system, farm-level nutrient inputs, stocking rates, and participation (or otherwise) in the Irish Rural Environment Protection Scheme (REPS) were collated. Generalized linear models (GLM) showed that farm system was a predominant influence explaining observed biological diversity. Both sward plant and arthropod diversity were greater on non-dairy (drystock) farms, but total arthropod abundance was greater on dairy farm swards. Both the breeding bird abundance and species richness were significantly greater in field boundaries on dairy, compared with non-dairy farms. These insights have relevance to the debate regarding the most effective use of public expenditure on agri-environment policy, and suggest that such incentive schemes need to become more clearly customised to realise the conservation potential of different farming systems.
1149Scopus© Citations 23