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The aim of this paper is to propose an integrated approach (including population and habitat monitoring and the study of reproductive biology and genetic diversity) for the comprehensive study of threatened plants, for which conservation measures are imperative. We applied this model to the plant species Arabis kennedyae which is classified as endangered according to the IUCN criteria. The current population of the species consists of three small subpopulations (AR1, AR2, and AR3) at three locations. Population size was characterized by considerable annual fluctuations. The distribution pattern of the plant followed habitat availability. Relative Reproductive Success remained stable but moderate. Germination of dormant seeds was promoted by light and was optimal at 15 and 20 °C. Genetic analysis showed low interpopulation variability and detected two groups: haplotype I (AR1 and AR3) and haplotype II (AR2), which may represent two altitudinal ecotypes. The direct threats identified were related to recreation activities, road construction and fire. The subpopulations of the plant are regulated by density and depend on fecundity and on the soil seedbank while their persistence depends mainly on habitat availability. Low genetic diversity combined with small population size and a possible reduction in fitness suggest increased susceptibility to loss of genetic variation. The overall results suggest that ex situ conservation in a seed bank, and in situ conservation in the form of population restoration, are suitable conservation measures and the study of the different aspects of the species' biology has provided the data required for their implementation. © 2011 Elsevier Masson SAS. |
