Differences in seedling growth behaviour among species] trait correlations across species\ and trait shifts along nutrient compared to rainfall gradients

0 Species!pairs from woody dicot lineages were chosen as phylogenetically inde! pendent contrasts "PICs# to represent evolutionary divergences along gradients of rainfall and nutrient stress\ and within particular habitat types\ in New South Wales\ Australia[ Seedlings were grown under controlled\ favourable conditions and measurements were made for various growth\ morphological and allocation traits[ 1 Trait correlations across all species were identi_ed\ particularly with respect to seedling relative growth rate "RGR# and speci_c leaf area "SLA#\ a fundamental measure of allocation strategy that re~ects the light!capture area deployed per unit of photosynthate invested in leaves[ 2 Across all species\ SLA\ speci_c root length "SRL# and seed reserve mass were the strongest predictors of seedling RGR[ That is\ a syndrome of leaf and root surface maximization and low seed mass was typical of high RGR plants[ This may be a high!risk strategy for individual seedlings\ but one presumably mitigated by a larger number of seedlings being produced\ increasing the chance that at least one will _nd itself in a favourable situation[ 3 Syndromes of repeated attribute divergence were identi_ed in the two sets of gradient PICs[ Species from lower resource habitats generally had lower SLA[ Thus\ in this important respect the two gradients appeared to be variants of a more general {stress| gradient[ 4 However\ trends in biomass allocation\ tissue density\ root morphology and seed reserve mass di}ered between gradients[ While SLA and RGR tended to shift together along gradients and in within!habitat PICs\ no single attribute emerged as the common\ primary factor driving RGR divergences within contrasts[ Within!habitat attribute shifts were of similar magnitude to those along gradients[