In 2000, it was urgent to translocate a newly discovered population of an inconspicuous autumnal plant (Narcissus cavanillesii) threatened by the construction of the Alqueva dam in Portugal (Rossello-Graell et al. 2004; Marques et al. 2009). The construction of this dam in the Guadiana River (Alentejo region) resulted in the flooding of 25,000 ha, and the traditional landscape of the Alentejo plains changed forever once the floodgates were closed in 2001 (Santos et al. 2008). Just 2 years before closing the floodgates, a project was initiated to study the flora of the affected territory. All of the species in the Habitats Directive (92/43/EEC) registered in the area were included in the project as well as several additional species of conservation interest.
Narcissus cavanillesii was one of the species (referred as N. humilis) listed in the Annexes II and IV of the Habitats Directive (92/43/EEC) found in this area, and one of the plant species most severely affected by the Alqueva dam. At the beginning of the project, only one location outside the area affected by this dam was known in Portugal, and at that time, we classified the species as Data Deficient (DD) (IUCN 2001) because no information was available for a proper assessment. However, during our field work, a second population was found very close to the river. Consequently, it would become extinct when the flooding started. There was no prior knowledge of the ecology, population dynamics, reproductive biology, or phenology of this plant and the scarce existing knowledge supported the classification of this species as Critically Endangered in Portugal (Rossello-Graell et al. 2003). Time constraints imposed by the relentless schedule of the construction work of the Alqueva dam and the lack of previous knowledge of the species forced us to design an intensive work program that had to be executed in less than 2 years.
Thirteen years after the translocation and annual monitoring, it was found that the translocated population has recovered the number of mature individuals available before the translocation. In the ninth year of monitoring (2010), census values even exceeded for the first time the percentage of breeding individuals measured before the translocation.
Minimizing habitat differences and mimicking original conditions were the key for this successful translocation. Even so, in the case of this particular species, the population still faces the typical problems of small and fragmented populations at the edge of a species’ range and therefore other future minimizing actions should be implemented.
Read the full article written by David Draper and colleagues for a special volume devoted to plant translocations being published by Plant Ecology: