Document: KUR-3-99-138

Flower and fruit production of eastern leatherwood (Dirca palustris) understory shrub of northern conifer-hardwood forests.

ZASADA, J. ², K.SCHULZ ¹, K.KAHL ¹, E.NAUERTZ ³ and W.MATTSON ³

Southern Illinois University Edwardsville, Edwardsville, IL 62026 USA ¹
USDA Forest Service, Grand Rapids, MN 55744 USA ²
USDA Forest Service, Rhinelander, WI 54501 USA ³

Abstract:
Eastern leatherwood is a slow-growing, medium-sized (< 2.5 m tall) understory shrub of Acer-Tsuga-Betula hardwood forests in the western Great Lakes Region. Within this forest type, population sizes and characteristics vary greatly from stand to stand. Leatherwood populations within stands tend to be aggregated, suggesting that population recruitment or expansion depends on canopy gap formation. Widespread dispersal of the seeds (or drupes) within stands is limited by the absence of vectors capable of transporting intact seeds. We suspect that varying stand histories, dating back as much as 100 years, determine current leatherwood distribution within stands. In the absence of effective dispersal, absolute rates of fruit and seed production likely determine the capacity for future population growth and spread within stands. The flowering and fruiting rates of ca. 50 mature individuals distributed across five stands was monitored over five years. As a rule, annual flower production varied moderately (= 25%), but rates of fruit set fluctuated by a factor of five, imparting an apparent pattern of alternating good and poor fruiting years. Nearby stands under different management systems showed significant differences in fruit production per capita. In one stand, branch damage by late season wet, freezing snow entirely eliminated fruiting in 1997. Within populations, individuals of similar size consistently differed in fruit production by ca. 50%. Canopy openness had surprisingly little effect on fruit production.

Keywords: Leatherwood

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