SEED SIZE AND SHAPE PREDICT PERSISTENCE IN SOIL

1. An understanding of seed persistence in the soil is important to ve getation management and weed control, but experimental collection of s eed bank data is tedious and expensive. We report a rapid, simple meth od for predicting seed persistence in the soil. The method is tested o n a range of British, mostly herbaceous, species. 2. Diaspore (seed or fruit) weight is plotted against variance of the three linear dimensi ons of the diaspore. All diaspores within an area of the graph defined by a maximum weight and variance are persistent in the soil. The crit ical weight is the same for fruits and seeds, but the critical varianc e of diaspore dimensions appears slightly higher for fruits. The great majority of diaspores outside this region are short lived, and the re latively few ambiguous cases can be resolved by reference to habitat. 3. The generality of the suspected underlying mechanism suggests that the method can also be applied to floras outside north-west Europe.