Methods for the Identification of Important Areas of Plant Diversity in Ireland

Abstract

The loss of biodiversity is an on-going global issue that not only results in the extinction of species but also threatens the ecosystem services and goods on which humanity depends. The global community has responded with ambitious targets to halt and reverse the loss of biodiversity. The causes of biodiversity loss are well understood and conservation measures can be deployed to protect biodiversity. However, conservation resources are limited and to be effective must be targeted to the most important areas of biodiversity. Using vascular plant distribution records for Ireland this research examined the distribution of plant species of conservation concern to determine if additional conservation measures should be targeted to these species. In an attempt to aid the targeting of conservation measures to the most important areas of biodiversity this research also investigated methods for the identification of priority areas for plant conservation. In an initial study vascular plant distribution records were collated and mapped for the island of Ireland. The tetrad scale (2km x 2km) data provided incomplete coverage for Ireland. Records for plant species of conservation concern were extracted and mapped at the tetrad scale for Ireland. The coincidence of the locations of the species of conservation concern and the distribution of areas designated for the protection of biodiversity in Ireland was examined. Between 22 – 40% of the locations of these species were found to occur outside of designated areas and for some individual species all of the locations occurred outside designated areas. The results indicated the importance of both designated areas and the wider countryside for biodiversity conservation. In particular the presence of species of conservation concern in non-designated areas highlights the need for conservation measures outside of designated areas. Subsequent research investigated a method for the identification of the most important areas of plant diversity at the tetrad and hectad (10km x 10km) scales in Ireland. A criteria-based scoring method was developed to characterise the landscape in terms of conservation value and identify the important areas of plant diversity. The effect of each of the criteria on priority area identification and on the representation of species (that is the extent to which species occur within a set of sites) within the priority areas was examined. The outcomes of this research identified a combination of criteria that allowed the identification of priority areas of high conservation value that contained a high species representation level. A subsequent investigation examined an alternative method for the identification of priority areas for conservation. A complementarity-based method using linear programming was used to identify the minimum number of priority areas in which species representation was guaranteed. Additional linear programs were formulated to identify restricted numbers of priority areas in which species representation was maximised. This research also developed a means of incorporating the outputs of the scoring method into the linear programming method. A combination of the plant distribution data, spatial environmental data, and a logistic regression method was used to build models to predict the distribution of the plant species of conservation concern group (SCC). The associations between the environmental data and SCC occurrence were examined and the predictive performance of both models was investigated using plant records in County Waterford. To conclude, this research showed that the tetrad-scale plant distribution coverage is patchy for most of Ireland. However, even with incomplete data the research indicated that conservation measures could be targeted to sites outside of protected areas. The plant distribution data can be used to characterise the landscape in terms of conservation value and both the scoring method and linear programming method can be used to identify priority areas for conservation. The scoring method and linear programming method can be combined to efficiently identify priority areas of high conservation value and the research showed the potential use of species distribution modelling for conservation planning in Ireland.