CWR In Situ Strategy Helpdesk

National CWR flora methodology

Step 2: Prioritizing CWR taxa/diversity

Applying a broad definition of a CWR will result in the national CWR inventory containing a relatively large number of taxa, even for a country like the UK that is regarded internationally as relatively floristically depauperate. If all the taxa in the same genus as the crop are included, the number is therefore likely to be too large a conservation target for the available resources. There will inevitably be a need to apply a strategy to prioritize the CWR that require most immediate conservation action to determine how best to utilize the available conservation resources. Opinions vary as to how this prioritization should be undertaken and it is inevitable that prioritization will vary according to needs within a region as a whole, or an individual country or specific organization within a country. Biodiversity conservationists may have opposing views to plant breeders, and the views of a forester will differ from those of a horticulturist.

Maxted et al. (1997) reviewed the various factors that can be used to ascribe ‘value’ and prioritize taxa for conservation. These included current conservation status, socio-economic use, threat of genetic erosion, genetic distinctiveness, ecogeographic distribution, biological importance, cultural importance, cost, feasibility and sustainability, legislation, ethical and aesthetic considerations, and the priorities of the conservation agency. However, there is some consensus for an initial, simple prioritization on the basis of economic value and relative threat alone (Barazani et al., 2008; Ford-Lloyd et al., 2008a; Magos Brehm et al., 2008b). To undertake this analysis the data must be available for the taxa in the National CWR Inventory, which will often at least be the case for broad economic value as these kinds of data are recorded within national agricultural statistics. However, some proxy for threat may be necessary if the taxa have not already been assessed using the IUCN Red List criteria (IUCN, 2001). For example, a simple assessment of geographic distribution may be used, with endemic and narrowly distributed taxa being given higher priority than more widely distributed taxa; the assumption being that they are more likely to be threatened. However prioritization is achieved and whatever criteria are used, the total number of target CWR species must be reduced to a number that can be actively conserved using the available resources.

For the UK, a combination of relative economic value and threat was used to prioritize the CWR taxa. For economic value, UK national statistics on the economic value of UK crops were used to prioritize CWR at genus level based on UK production (in £ ‘000) for 2002 (Anonymous, 2004), Basic Horticultural Statistics (Defra, 2004a) averaged over 1993–2003 and the estimated value of production of forages was calculated using seed supply data (Defra, 2004b). The most economically important UK crop is wheat; however, it has no naturalized CWR in the UK. Therefore, the genus containing CWR taxa of highest economic importance in the UK is Brassica, which has three CWR species in the UK, two of which are native. Threat was assessed for all UK taxa using the IUCN (2001) Red List Criteria by Cheffings et al. (2005), and all those CWR they assessed as being Critically Endangered (CR), Endangered (EN) or Vulnerable (VU) were given priority. Combining relative economic value and threat generated a priority list of 250 UK CWR taxa.

Step 3: Ecogeographic and genetic diversity analysis of priority CWR

Helpdesk references