KNOWLTON, MARCUS R., JEAN M. CHAPPELL*, JEANMARIE HARTMAN, AND STEVEN N. HANDEL. Ecology and Evolution, Rutgers, The State University of NJ, Foran Hall, 59 Dudley Road, New Brunswick, NJ 08901. - Factors influencing population dynamics of the rare Sickle-leaved Golden Aster, Chrysopsis falcata.
Chrysopsis falcata (Asteraceae) is a perennial forb listed by
the New Jersey Natural Heritage Program as a state and globally
threatened species (S2, G3/G4). C. falcata typically colonizes
disturbed open patches of xeric, sandy soil and reproduces by
rhizomatous growth and wind dispersed seed. For three years we tested
the feasibility of initiating a population of C. falcata at
Clayton Sand Mine, Jackson NJ, located in the New Jersey Pinelands.
We studied the effects of canopy cover, nutrient and water
requirements, transplant techniques and seedling propagation on plant
survival, growth and flowering. C. falcata transplants had
much higher survival, growth and flowering in open habitats than in
partial or high shade. Nutrient additions provided no benefits within
the first year, and was detrimental to survival, growth and flowering
in the second year. This was likely due to decreased light
availability caused by increased aboveground biomass of grass and
forbs within the community. Increasing water availability during the
exceptionally dry summer of 1995 provided no benefit to survival,
growth and flowering. Greenhouse experiments showed that seedlings
have very specific, temporally varying, water requirements. We found
that naturally occurring seeds germinate and establish during the
fall. These seedlings had significantly higher germination and
establishment on soils dominated by a cryptogamic crust community, a
substrate that is thought to have allelopathic properties. Unknown
factors caused yearly variations in survival rates of C.
falcata; we noted a fourfold increase in mortally (40%, up from
10%) across all patches during the growing season of 1997. New
populations of this early colonizing species may be started in
narrowly defined microsuccessional sites.
Key words: Asteraceae, Chrysopsis falcata, pinelands, population dynamics, restoration, threatened species