Organization of an Assemblage of Early Successional Species on a Soil Moisture Gradient

摘要: To determine the roles of prior evolutionary divergence and competitive displacement species in successional community organization, aspects colonizing strategy, 6 co- occurring annuals were grown together alone on a soil moisture gradient. The had similar broad vegetative reproductive responses to Interspecific competition reduced niche breadth similarities species. Competitive gradient stresses generally ab- sorbed through plasticity, although Polygonum pensylvanicum Chenopodium album showed some mortality. Response centers Polygonum, Ambrosia artemisiifolia, Chenopodium, com- petitively subordinate species, shifted due interspecific competition. Amaranthus retroflexus Setaria faberii, leading competitors, already slightly offset from each other when alone, did not shift response centers. Competition delayed start flowering Setaria, Polvgonum Ambrosia. success correlate with or overlap. Abutilon behaved differently different environments, indicating existence refugia. Refugia may be shifted, reduced, maintained depending competitors present. Coexistence depend on: (1) differences dimensions previously investigated, (2) heterogeneous unpredictable distributions neighbors. Thus, refugia will unthreatened at times places. Key 'ords: strategy; organization; competition; experimental analysis; gradient: Illinois; niche; overlap; community.