THE RECOVERY OF AN ENDANGERED PLANT .1. CREATING A NEW POPULATION OF AMSINCKIA-GRANDIFLORA

The recovery of endangered plants often requires the creation of new p opulations in order to decrease the risk of extinction Despite numerou s attempts, no plant species have been fully recovered by creating new populations. Here we report on initial efforts to recover Amsinckia g randiflora Kleeb. ex Gray (Boraginaceae) by re-establishing the specie s in appropriate habitat within its historic range, with consideration given to genetic and demographic characteristics of the founding popu lation. 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 bad different g ermination and genetic characteristics. Nutlets directly descended fro m a wild Population bad 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 allozy me electrophoresis at 18 loci, were low overall, but much more so in t he cultivated population These data were used to maximize genetic vari ability among founding nutlets and to predict the frequency of alterna tive allele carriers in the new population. After sowing and plot trea tment at the Lougher Ridge re-establishment site, the 3460 founding nu tlets produced a large number of germinules (1774) during the 1989-199 0 growing season, and many (1101) survived to reproduce- From these pl ants, and estimated 35,800 nutlets were produced, indicating that the population bad a high potential for growth during subsequent years. In troduced grasses baa significant negative effects on survivorship to r eproduction, plant size, and nutlet production in the new Amsinckia po pulation Grass cover was effectively reduced by using fire or a grass- specific herbcide. Burning significantly decreased Amsinckia mortality rates early in the growing season and significantly increased survivo rship to reproduction and maximum plant size- Herbicide treatment bad no effect on mortality rates or survivorship to reproduction, but it s ignificantly increased plant size and, therefore, nutlet output per pl ant and per plot. The new population should be able to maintain itself within the existing grassland community, but growth and short-term vi ability would be assured by management practices that increased the av ailability of low-competition habitat patches for Amsinckia occupation