The small-scale spatiotemporal pattern of a seed bank in the Negev Desert, Israel

Abstract

Seed banks are generally considered clumped, but few studies document the small-scale horizontal spatial pattern of seeds. We measured the horizontal spatial pattern of a seed bank for an annual plant community (ca 20 species) in the Negev desert, Israel, using geostatistics to test whether the seed bank changes over time or along a natural stress gradient. We also tested for differences between large and small seeds. Seed was collected at three different times and at two locations (high and low stress) on a semi-stabilized sand dune using contiguous 3-cm cores. Using semivariograms to measure the degree of aggregation, we detected a clump size of 85 cm2 that was consistent across time, stress level, and seed size. This consistency could be extremely important if small-scale clumping of seed banks generates specific associations between species of seeds and the emergent plants. Further work with seed bank-based communities would strongly benefit from measures of spatial pattern and species associations of seeds.