An experimental study was designed to investigate the demographic mechanisms by which annual plants inhabiting desert sand dunes respond to local gradients in the stability of the sand. The results indicated that individual plants emerging at different topographic positions along the dune experience different probabilities of survival and reproduction. The general trend observed was a decrease in seedling survival, plant biomass, fecundity, reproductive allocation, and fruit weight from the relatively stable, interdune corridor towards the unstable crest of the dune. However, all of these demographic responses were highly species-specific, indicating that coexisting annual species respond differentially to underlying patterns of spatial heterogeneity in the stability of the sand. These results suggest that local-scale spatial heterogeneity in sand stability may be important in promoting coexistence of desert sand dune annuals.
Bibliographical noteFunding Information:
I thank H. Leschner for her assistance with the fieldwork. The study was funded by the Arid Ecosystem Research Center, The Hebrew University of Jerusalem, and by the Israel Science Foundation administered by The Israel Academy of Sciences and Humanities.