Management and Restoration Ecology of the Federal Threatened Mead's Milkweed, Asclepias meadii (Asclepiadaceae)

Abstract

The federal threatened Asclepias meadii Torr.(Asclepiadaceae) is a perennial, self-inc ompatible prairie о impe riled by habitat destruction and population fragmentation.Many large E persist in prairie haymeadows in Kansas and Missouri despite removal of seed poc y by annual summer mowing.Only a few small populations remain in Illinois, lowa, and northern Missouri.Recovery these small populations and restoration of new populations are recovery objectives for this species.This study was ene ted to determine habitat differences among are о а how а = and fire management affect the structure of A. meadii populations, and to test the effects of differ management treatments on restoration of this species.Soils analysis showed a onse puedes with өөн ин он оп E nutrient--poor soils, and еи окы dne on calcareous, nutrient-rich soils.Milkweed rame densities were lower in fire-managed prairies than in haymeadows; but burned sites had 68% flowering ramets while haymeadows had oniy 19% flowering ramets.This suggests that burning has selected for greater resource allocation toward sexual reproduction, while annual hay mowing has selected for greater resource allocation toward clonal spread.The Morton Arboretum is conducting experimental restoration a Asclepias meadii in the eastern part of its range, an objective of Federal Recovery Planning.In greenhouse and garden 1... Wii tition from oats as antly reduced seedling growth, with greater growth in artificially s 52 seedlings.At seven restoration sites in Illinois and northern Indiana, significant variation in milkweed pun пайоп; survivor BR a growth was caused ds weather, differences оа sites, and site management.Seedlings were vulnerable to drought, with greater survivorship when rainfall was 200% of normal.Planted j jave 'nile milkweeds "reater survivorship than seedlings, and less sensitivity to d ен а oni growth and survivorship also occurred in al than in unburned plots at three sites, but not in all life-stages.Propagated Ap from Missouri seed sources were larger than Kansas plants in the garden, but not in the field.ыле work is needed to determine if restored populations can become viable, and if there are negative effects of crossing and 1. 'ating genotypes.Managing for viable populations of endangered history stages (Fenster & Dudash, 1994;Weller, species requires knowledge of their life-history and 1994;Pavlik, 1994Pavlik, , 1996;;Guerrant, 1996).This habitat requirements, reproductive biology, and the paper examines factors that affect the management demographic, genetic, and ecological traits that апа restoration ecology of Mead's milkweed (Asclemake them vulnerable to extinction processes (Gil-pias meadii Torr., Asclepiadaceae), a federal threatіп & Soulé, 1986; Lande, 1988; Menges, 1986, ened (Harrison, 1988) plant essentially restricted 1991, 1992).Similar information is roued to re-to the virgin tallgrass prairies of the midwestern cover and restore new populations of these species, ^ United States (Betz, 1989).To better understand especially how site-management and stochastic en-how to manage and restore this species, we comvironmental processes affect population growth pare habitat characteristics across its range, exbased on their genetic attributes, reproductive amine the effects of management on population characteristics, and survivorship at different life structure, and use experimental propagation and !We thank the Illinois Department 9r Conservation,