The Recovery of an Endangered Plant. I. Creating a New Population of Amsinckia grandiflora

Abstract

The recovery of endangered plants often requires the creation of new populations in order to decrease the risk of extinction. Despite numerous attempts, no plant species have been fully recovered by creating new populations. Here we report on initial efforts to recover Amsinckia grandiflora Kleeb. ex Gray (Boraginaceae) by re‐establishing the species in appropriate habitat within its historic range, with consideration given to genetic and demographic characteristics of the founding population. An experimental framework with demographic monitoring was used to follow the fates of nutlets (propagules) from two sources (one wild, one cultivated) and to evaluate the effects of habitat manipulations (fire, herbicide application, clipping) for reducing competition from introduced grasses. Founding nutlets from two sources had different germination and genetic characteristics. Nutlets directly descended from a wild population had half the germination potential of nutlets from a cultivated population because of their greater age (about 25 years in cold storage). Levels of genetic variability, as measured by allozyme electrophoresis at 18 loci, were low overall, but much more so in the cultivated population. These data were used to maximize genetic variability among founding nutlets and to predict the frequency of alternative allele carriers in the new population. After sowing and plot treatment at the Lougher Ridge re‐establishment site, the 3460 founding nutlets produced a large number of germinules (1774) during the 1989–1990 growing season, and many (1101) survived to reproduce. From these plants, and estimated 35,800 nutlets were produced, indicating that the population had a high potential for growth during subsequent years. Introduced grasses had significant negative effects on survivorship to reproduction, plant size, and nutlet production in the new Amsinckia population. Grass cover was effectively reduced by using fire or a grass‐specific herbicide. Burning significantly decreased Amsinckia mortality rates early in the growing season and significantly increased survivorship to reproduction and maximum plant size. Herbicide treatment had no effect on mortality rates or survivorship to reproduction, but it significantly increased plant size and, therefore, nutlet output per plant and per plot. The new population should be able to maintain itself within the existing grassland community, but growth and short‐term viability would be assured by management practices that increased the availability of low‐competition habitat patches for Amsinckia occupation.

Centaurea corymbosa, a cliff-dwelling species tottering on the brink of extinction: A demographic and genetic study

“…For example, Levin and Clay (71) demonstrated that Phlox drummondii can successfully grow and reproduce at the species margin. Other authors have emphasized the importance of appropriate management practices that insure the viability of newly created populations of Amsinckia grandiflora (72), Erysimum capitatum, and Oenothera deltoides (73). Finally, Primack and Miao (74) concluded from their experimental study on four annual plant species that both site suitability and dispersal ability were limiting local distribution.…”

Commercial trade of federally listed threatened and endangered plants in the United States

“…However, declining populations, especially due to climate change, may eventually necessitate unconventional, directed efforts such as commercial propagation (Winter & Botha 1994;Affolter 1997) and assisted colonization of propagated plants (Vitt et al 2010) in coordination with other means to perpetuate species (Kostyack et al 2011;Maschinski et al 2011;Goodman et al 2012). If listed species need to be propagated to be reintroduced or moved to mitigate for climate change, examples of previous introductions highlight the need for collaborative, monitored studies coordinated by government agencies such as the FWS that (1) consider genetic diversity, (2) take an experimental approach to address ecological questions, such as using common garden experiments in multiple locations, and (3) minimize potential adverse impacts by conducting risk assessment and screening plants for pests and pathogens (Pavlik et al 1993;Gordon 1994;Reinartz 1995;Falk et al 1996;Gordon 1996;Pavlik 1997;Guerrant & Kaye 2007;Wendelberger et al 2008;Weeks et al 2011;. Some major impediments to cooperation include laws that do not require consultation with scientists and agencies for citizen-initiated projects (McDonald 1996), and the fact that long-term commitment is required, especially when efforts begin at a grassroots level (Falk et al 1996).…”

“…For example, one of the recommended standards is to maintain provenance (geographic locality) records of plant origin by geo-referencing original plant sources and indexing this information (Falk et al 1996;Guerrant et al 2004;Vitt et al 2010;. Provenance records are critical when species are rare in the wild, because species purity is important to preserve in cultivation, and genotypic diversity could act as biological insurance against environmental fluctuations (Pavlik et al 1993;Gordon 1994;Bischoff et al 2010). This controlled propagation approach is especially important if reintroduction is deemed necessary to Box 3: Collaboration contributing to conservation.…”

Fire and dynamics of granivory on a California grassland forb

“…ex Greene, a federally-listed endangered borage native to California grasslands (Carlsen et al 2000). This reduction in fecundity has been found in other native species, both annual and perennial (Guerrant 1992;Gordon and Rice 1993;Pavlik et al 1993). In California, fire has been used to control exotic annual grasses and remove thatch to stimulate native forb populations and to also re-establish native perennial bunch grasses (George et al 1992;Menke 1992;Meyer and Schiffman 1999).…”