Effects of resource heterogeneity and environmental disturbance on the growth performance and interspecific competition of wetland clonal plants

Resource heterogeneity significantly influences the growth, reproduction, and vegetation composition of wetland plants. However, the effect of the interaction of resource heterogeneity and environmental disturbance on growth performance and interspecific relationships among emergent plants is far from clear. In this study, we used a mesocosm experiment to examine the plasticity in clonal growth responses of Acorus calamus and Schoenoplectus tabernaemontani to different levels of flooding disturbance and soil sediment heterogeneity types. Soil nutrient heterogeneity treatments did not always have a positive effect on the growth of A. calamus and S. tabernaemontani because species-specific characteristics and environmental disturbance can influence the positive effect of environmental heterogeneity on clonal plants. A. calamus exhibited longer root length, behavior advantageous for heterogeneous distributions of nutrients. To adapt to deep water habitats, A. calamus and S. tabernaemontani transform clonal growth in the horizontal direction into the vertical direction. Soil nutrient heterogeneity can cause interspecific competition between A. calamus and S. tabernaemontani. However, with increasing water level, the effects of interspecific competition on S. tabernaemontani and A. calamus decreased gradually. The two wetland species compete for heterogeneously distributed soil nutrients under low water levels. However, an increase in water level results in limited illumination, so vertical growth is employed to compete for light resources. Our results show that S. tabernaemontani and A. calamus used both plasticity strategies to cope with resource heterogeneity and environmental disturbance. These spatial and temporal variations may modify growth and vegetation stability in disturbed environments. (C) 2020 The Authors. Published by Elsevier B.V.