The production of a comprehensive national vegetation classification is a key action in the current National Biodiversity Plan (action 3.2). This classification system is a fundamental requirement for improved management and ecological research in Ireland. It will:
- underpin a proposed national habitat map (action 3.3)
- aid in definition and identification of EU Habitats Directive (92/43/EEC) Annex I habitats
- inform the planning process, for example through Environmental Impact Assessments
- facilitate the monitoring of vegetation change as a result of management or climate change
- provide a detailed framework for academic research
- enable greater interaction with European initiatives
In achieving the overall objective the IVC will be guided by the following six principles:
- It will be statistically-based and validated. A classification will be produced using a range of appropriate contemporary statistical methods and quantitative vegetation data from Ireland. Validation methods will be used to ensure that proposed categories are statistically robust. It will not seek to statistically reproduce categories of existing classification systems.
- It will be a vegetation classification. A classification of vegetation communities will be produced not a habitat classification, thus the fundamental categories will be produced on the basis of floristic data analysis only. Environmental data (e.g. soil depth, altitude, inundation frequency) and management information (e.g. mowing regime, peat extraction) will be used post hoc where available to interpret categories and provide ecological meaning.
- It will recognise the vegetation continuum. Plant species respond individually to changes along environmental gradients, thus vegetation varies continuously across space and time. For practical purposes, a vegetation classification (which is an inherently artificial framework) seeks to identify the most frequently repeating combinations of plant species as communities. However, it should preferably also recognise that a proportion of vegetation will always be transitional between these communities.
- It will be user-friendly. A classification will be produced which can be readily and consistently applied by the range of potential users. These will include field surveyors, scientific officers, environmental managers and planners, policy makers and academics.
- It will be hierarchical. A classification will be produced with categories organised in a hierarchy. Categories at lower levels will be combined at high levels to produce categories of increasingly broader scope. A hierarchy will facilitate application of the classification at different scales and for a variety of purposes.
- It will be expandable and updatable. A classification is only as good as the data on which it is based. To remain relevant, the classification should be updated and expanded as new data become available. This is particularly relevant when a phased approach to the development of the classification is likely. Web-basing of the classification will facilitate making and logging such changes and their immediate dissemination.
The National Vegetation Database (NVD) maintained by the NBDC now holds data from over 30,000 relevés and provides a vital core resource for the development of the classification system. A review of the coverage of the NVD and its role in this regard has been conducted.
In parallel to this, recent habitat surveys commissioned by National Parks & Wildlife Service (NPWS) have produced several separate, statistically-defined, relevé-based national scale classifications for habitats. These data can be accessed through the NPWS maps and data webpages:
A recent project funded by the Environmental Protection Agency (EPA) has also produced a similar scheme for saltmarshes:
In addition, there is a wealth of information in the many Ph.D. theses which have been written over the last few decades focussing on the phytosociology of the various habitats. The IVC seeks to integrate these data and ideas into a single framework.