Microdistribution of Viable Weed Seed in Two Tropical Soils

Localized horizontal and vertical buried viable weed seed distribu- tions were examined in the soils of a pasture and a corn field in Belize, Central America. Seeds in the corn field were contagiously distributed and concentrated at the soil surface. Those in the pasture were of higher density, more diverse, more evenly distributed, and concentrated in deeper soil layers. The larger seed reservoir in the pasture soil, despite inferred low inputs, is attributed to low seed depletion rates at the untilled site. Much of the observed horizontal and vertical patterning can be explained if the probability of a viable seed being lost from the reservoir is assumed to be constant through time, but to vary inversely with soil depth.