Köchy, M., and F. Jeltsch (2004)
We have examined the effect of rainfall characteristics on performance of ten annual species from Mediterranean and arid regions in Israel using a spatially explicit, rule-based model. The model simulates germination and growth of individual plants on a 1-m2 area. Using the model, we tested which single rainfall characteristics (annual rain volume, annual rain volume of days with >10 mm rain, number of days with >5, 10, 15, or 20 mm rain, or number of days with >10, 15, or 20 mm rain during the early growing season) best predicted total aboveground biomass. For six species, the number of days with >15 mm rain, for the others, the number of days >20 mm rain were the best predictors in linearized regressions. This indicates that plant performance would be affected by changes to rainfall patterns in two ways: changes to annual rain volume and changes to volume per rainstorm. Examination of long-term precipitation records suggests that changes to the volume per rainstorm would have the strongest impact on biomass in regions with <600 mm annual precipitation.