Response of aquatic plants to abiotic factors : a review
Résumé
This review aims to determine how environ- mental characteristics of aquatic habitats rule species occurrence, life-history traits and community dynamics among aquatic plants, and if these particular adaptations and responses fit in with general predictions relating to abiotic factors and plant communities. The way key abiotic factors in aquatic habitats affect (1) plant life (recruitment, growth, and reproduction) and dispersal, and (2) the dynamics of plant communities is discussed. Many factors related to plant nutrition are rather similar in both aquatic and terrestrial habitats (e.g. light, temperature, substrate nutrient content, CO2 availability) or differ markedly in intensity (e.g. light), variations (e.g. temperature) or in their effective importance for plant growth (e.g. nutrient content in substrate and water). Water movements (water- table fluctuations or flow velocity) have particularly drastic consequences on plants because of the density of water leading to strong mechanical strains on plant tissues, and because dewatering leads to catastrophic habitat modifi- cations for aquatic plants devoid of cuticle and support tissues. Several abiotic factors that affect aquatic plants, such as substrate anoxia, inorganic carbon availability or temperature, may be modified by global change. This in turn may amplify competitive processes, and lead ulti- mately to the dominance of phytoplankton and floating species. Conserving the diversity of aquatic plants will rely on their ability to adapt to new ecological conditions or escape through migration.