Towards a method for attributing preliminary threat categories to Macromycetes of Flanders (Belgium)
1998
Kesel, A. de (Nationale Plantentuin van Belgie. Domein van Bouchout, Meise (Belgium))
In the light of the urging need to estimate the extent of the decline of our mycoflora, a method is proposed for attributing preliminary threat categories to macromycetes. The attribution of the threat category is based on the combination of a rarity and a trend criterion. This method is widely accepted and is proposed here for treating mycological data obtained from insufficiently investigated countries or regions. The rarity of a taxon is derived from its known area of occupancy and/or its estimated area of occupancy. The choice of the reference year is not based on the number of records, but depends on the grids that were visited before and after it. The trend is calculated, in accordance to one or more reference years, using an independence- or G-test (model I or II). Trend categorisation is based on the significance of the trend, i.e. the strength of the in- or decrease. It is stated that the reliability of the trend calculation is enhanced by using data from as much identical grids as possible. The method implicates that historically well-known grids should be rescreened regularly. Rarity assessment, however, necessitates the rescreening of all the grid squares, beginning from the last reference year. For smaller databases the estimation procedure can be used. Threat categories are given for three boletes, i.e. Boletus badius, Boletus erythropus and Boletus luridus.
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