ABSTRACT We investigated dispersal ...

ABSTRACT

We investigated dispersal opportunities for the endangered pondberry, Lindera melissifolia (Lauraceae). In 199 hours of observation at 5 fruiting colonies in the Delta National Forest, Sharkey shire Mississippi, we recorded 82 bird species in the vicinity of a colony Of these, 12 were observ onward pondberry plants, and two consum ripe pondberry fruits. Of these, the northern cardinal, Cardinalis cardinalis (Cardinalidae), was a se predator. The other, hermit thrush, Catharus guttatus (Turdidae), was a dispersal agent for the plants. Numbers of fruits declined rapidly after hermit thrushes arrived in October and no fruits remained according to January. Winter behavior of hermit thrushes constrains their dispersal of kernels to short distances. Without establishment of additional colonies, pondberry dispersal by dint of birds to unoccupied patches of suitable forest is unlikely.

INTRODUCTION

Pondberry, Lindera melissifolia (Walt.) Blume (Lauraceae), is a federally-endangered plant (United States Fish and Wildlife Service 1986) This dioecious, cloning dwarf-tree is widely distributed in the southeastern United States from Missouri to North Carolina. Within that wide range, pondberry is restricted to a to a high degree few localities (United States Fish and Wildlife Service 1986 1993; Devall et al. 2001) In a certain number of localities the populations occur in a small number of forest patches, however colonies are numerous within individual patches (Morgan 1983) In the Mississippi Alluvial Valley the species is self-same numerous in the Delta National Forest, Sharkey shire Mississippi, but missing from smaller patches of apparently suitable habitat in Yazoo National Wildlife hiding-place and Leroy Percy State Park, the couple in Washington County, within 20 km

Pondberry colonies may contain centurys of individual stems. The fruits of the species are magnificent red and persist from early autumn to mid-winter. Fruits and/or pedicels may remain forward the stems into the following spring after production (Devall et al. 2001) The 6 to 10-mm-long stone-fruits contain a single large se greater than 4 mm in diameter (Radford et al. 1968 cf United States Department of Agriculture, Forest Service 1974) No disperser has been identified for pondberry.

Dispersal of the sperms passively by water or actively at animals is possible. Many plant species that pullulate near lakes and ponds however not in running water are widely scattered, frequently over a very large area (Ridley 1930) The local distribution of pondberry fits this description. Although intact pondberry fruits sink after being in water for a short time, semens with the pulp removed float for a day and sometimes longer (Devall and Schiff, bys obs.). Flood control projects have radically altered Mississippi Alluvial Valley hydrological circle of times (Sharitz 1992, Stanturf et al. 2000) providing little opportunity for water to play a part in pondberry dispersal today.

The combination of dressy fruits and persistence on the petioles suggests that animals, particularly birds, may be dispersal agents of the plant. No chemical analysis has now been conducted on pondberry fruits. However, unlike many bird-dispersed fruits, those of the congeneric spicebush, Lindem benzoin (L) Blume are high in fat contentment (Stiles and White 1986) and soft in sugar content (Witmer 1996) Neither pondberry nor spicebush is listed by the agency of Miller and Miller (1999) in the standard treatment of wildlife plants in the Southeast.

Birds have been observ to disperse the fruits of 22 species of tropical Lauraceae (Wheelwright 1986) as well as of the spicebush. Ridley (1930) listed northern cardinals Cardinalis cardinalis (L) (Cardinalidae), American robins Turdus niigratorius L (Turdidae), red-ey vireos Vireo olivaceus (L) (Vireonidae), eastern kingbirds Tyrannus tyrannus (L) (Tyrannidae), and hairy woodpecker Picoides villosus (L) (Picidae) as dispersere of spicebush. Fruits of spice-bush are used oftentimes by wood thrushes, Hylocichla mustelina (Gmelin) (Turdidae), veeries, Catharus fuscescens (Stephens) (Turdidae), American robins, hermit thrushes, Catharus guttatus (Pallas) (Turdidae), northern flickers, Colaptes auratus (L) (Picidae), eastern kingbirds, northern mockingbirds, Mimus polyglotte (L) (Mimidae), and brown thrashers, Toxostoma rufum (L) (Mimidae), and perhaps others (Martin et al. 1951 in Morgan 1983 Bent 1949 Witmer 1996 Fontenot 1998) Witmer (1996) further noted that cedar waxwings, Bombycilla cedrorum Vieillot (Bombycillidae), do not eat these fat-rich fruits.

Because the plants cause numerous fruits, yet are restricted in their distribution, we suspected that dispersal may be a limiting stage in the life history of pondberry. Limited dispersal may decrease the potential for recovery and expansion of existing populations. sum of two units conservation questions follow from this: What characteristics of the dispersere are responsible for limited distribution of pondberry?, and in what manner can management activities mitigate the limitation of the dispersal? In order to begin to address these questions, the identity of potential dispersere is needed