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

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. 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 6months 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. 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. Because of seasonal fluctuations in the variables considered, at least 4months 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. 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. © 2012 John Wiley & Sons, Ltd

Estimating influence of environmental quality and management of channels on survival of a threatened endemic quillwort

Iso\uebtes malinverniana Ces. et De Not. is a narrow endemic quillwort occurring within channels used for rice fields water supply, in the lowland area of North Italy. The range of I. malinverniana is highly fragmented and in the last 10 years the whole population decreased by more than 80%. This strong decline is assumed to be mainly related to the intensification of agricultural practices, which led to decreasing water quality, alteration of flow regimes and mechanized management. In order to highlight which of these factors may affect population performance and fate (persistence vs. extinction) of the species, plant cover, density and leaf length were measured, and a range of water and sediment parameters were analyzed at the plot scale, within the extant populations and in eight historical sites where I. malinvarniana recently disappeared. At least 4 out of 11 populations, characterized by cover values never exceeding 15% and density hardly approaching 20 plants m 122, revealed scarce chance for survival, under current conditions. On the basis of discriminant analysis, nutrient enrichment did not result the main predictor of Iso\uebtes decline, as generally noticed for isoetids, since higher water nitrates, P, K and organic C content in the sediments were found in the sites where I. malinverniana showed the highest performance compared to sites of less viable populations. On the other hand, the high water depth, the strong increase of water flow during the rice growing season and the intensive mechanized management of channels, e.g. cutting of aquatic vegetation and dredging using excavators, were among the most important parameters explaining the disappearance of the species. Our findings may have useful implications for the conservation or restoration of I. malinverniana and other rare aquatic species occurring in running waters of lowland agricultural areas. Hydrological alterations and mechanized maintenance of channels should be restricted where the species still occurs, to improve population performance and seedling survival