Monitoring time of conservation-driven and mitigation-driven plant translocations in Europe

Abstract

Species translocations are increasingly used to improve the conservation status of threatened species, restore communities, or in response to mitigation hierarchy. Post-translocation monitoring is an essential step in any translocation protocol, as only demographic data collected over a sufficiently long period can be used to estimate whether a translocated population is viable and thus determine whether translocation is successful. We gathered European monitoring data from 575 plant translocation units to document monitoring time and determine how it varies. We examined this variation by translocation motivation between conservation-driven translocations (undertaken outside the mitigation hierarchy) and mitigation-driven translocations. We also compared the monitoring time to the type of biological material translocated and the number of individuals.We show that mitigation-driven translocations were more monitored in the first few years after translocation but for a shorter time than conservation-driven translocations. The same was observed for translocations made with diaspores compared to translocations made with plants.Moreover, monitoring time increased with the number of translocated plants but not with the number of diaspores. Although conservation-driven and mitigation-driven translocation programs exhibited distinct temporal monitoring patterns, both motivations of translocations were associated with rapid discontinuation of the monitoring. Indeed, after four years monitoring continued in only 37.9% of nonextinct population units. After ten years, this percentage falls to 11.8%. We recommend that translocations be monitored more assiduously over longer periods, and that the monitoring data be readily available to improve future translocations.