A cost-effective model for preliminary site evaluation for the reintroduction of a threatened quillwort

1. The choice of suitable sites for establishment of a new population of a species is the first step in a translocation programme. However, evaluation of a large number of sites can be demanding of time and money; practitioners need time- and cost-effective evaluation tools. 2. A predictive model for the preliminary evaluation of potential reintroduction sites was developed using the endangered quillwort Isoëtes malinverniana as a case study. The reliability of three water habitat variables (pH, conductivity, and clarity) as predictors of the presence/absence of I. malinverniana was tested. Three sets of logistic models were produced on the basis of the mean values of pH and conductivity measured over 3, 4 and 6 months to understand whether frequency of measurement affected the reliability of the models. Models of each set were ranked according to AIC and their reliability was then tested using data from the literature. 3. The conductivity of water and pH were the most effective predictors of the suitability of sites for the reintroduction of I. malinverniana. In particular there was a negative relationship between the presence of I. malinverniana and these variables. 4. Because of seasonal fluctuations in the variables considered, at least 4 months monitoring are required to obtain reliable results. Despite this, the method is still advantageous in terms of costs, compared with repeated measurements of a wide range of chemical characteristics at a large number of sites. 5. The main goal of this method is to limit expensive chemical analysis to a few sites chosen after the exclusion of unsuitable sites, through application of the model. Considering the similar ecophysiological features of quillworts from oligotrophic waters, the same model or conceptual framework could be applied to other quillworts and isoetid species growing in degraded areas and needing active conservation.