Rarity and threat relationships in the conservation planning of Iberian flora

We analysed the threatened flora of Iberia (including the Balearic Islands) in order to define and explain factors related to levels of rarity and threat. Conservation measures were derived from the relationships observed. We used a random sample of 59 narrowly distributed plant species from the pool (588 species) of potentially endangered flora. Twelve variables were used to classify species into groups based on a multivariate technique: non-parametric principal component analysis. Our results do not indicate a single management model driven by a single mechanism of rarity. Four classes of rare plants were produced from the statistical algorithm: agamospermic species, plants associated with water, endemics, and range-margin (geographical-limit) plants. Some specific strategies for each of these groups are proposed, allowing further discussion and assessment. The overall pattern in conservation practice of threatened Iberian plants seems to be defined by three of the variables in use: ecological specificity, geographical rarity and rate of threat. None of the biological variables in the sample show particularly strong trends in the data.[PUBLICATION ABSTRACT]