Conservation of a rare plant requires different methods in different habitats: demographic lessons from Actaea elata

Abstract

Understanding species decline and conserving endangered species requires demographic information, and variation in the environment may affect demography. Actaea elata is a globally rare, perennial herb found in a range of Pacific Northwest forest stand types that differ in canopy openness. Canopy openness increases reproductive output in this species and so was expected to have demographic impact. We performed a demographic analysis of A. elata in contrasting forest stands (broadleaved vs. coniferous) over two annual intervals, and predicted that population growth rate would be higher in the open-canopy broadleaved stand. Population growth was determined using stage-based matrix models, and the most influential transitions were identified using elasticity analyses. The finite rate of population increase (λ) was lower for the two transition periods at the broadleaved stand than at the coniferous stand (λ = 0.86 and 0.87 vs. 0.94 and 0.98), even though the former population was more fecund. The decline in the broadleaved stand reflects greater mortality and retrogression to previous stages, partly as a consequence of herbivory. In contrast, lower recruitment occurred in the coniferous stand, but there was also less mortality and retrogression. Our results suggest that management decisions for conservation of A. elata should be tailored to differing habitats, with a focus on preventing mortality in some populations and increasing recruitment in others.

Resource use in two contrasting habitat types raises different challenges for the conservation of the dryad butterfly Minois dryas

“…These habitat types are sometimes so distinctive in terms of their resources, vegetation and structure that the behavior and biology of a species may differ substantially depending upon the type (Boudjemadi et al 1999;Potts et al 2001;Allen and Thompson 2010). Species conservation, especially for endangered species using differing habitat types, is particularly challenging and requires a differentiated application of methods (Mayberry and Elle 2010). One such species is the dryad Minois dryas (Scopoli, 1763), a grassland butterfly of the family Nymphalidae.…”

Population structure of Laurus nobilis L. in Central Italian forests: evidence for its ongoing expansion

“…The high number of dynamic and stable populations of L. nobilis suggests that an increasing amount of individuals in the more aged life stages can be expected, in the future, to enter the structure of many forest communities in Central Italy, including local dominance in environmentally suitable stands. However, a multi-year demographic study including the mortality rate of individuals would be necessary to infer the potential growth rate of the species' populations (Mayberry and Elle 2010). This is especially true for longlived species as trees, where a reverse J-shaped age structure, similar to the dynamic population structure presented in this study, could be indicative for the structure of an oldgrowth forest (Wang et al 2004;Dang et al 2010;Chhetri and Cairns 2015).…”