NUTRIENT RESPONSES OF CAREX SCHMIDTII TO CONSECUTIVE DROUGHT AND RE-FLOODING EPISODES IN SEMI-ARID WETLANDS: IMPLICATIONS FOR TUSSOCK RESTORATION

The regulation mechanism of wetland plants in response to consecutive drought (D) and reflooding (RT) events can be identified via nutrient responses.Nutrient responses of Carex schmidtii were tested using a simulation experiment with five treatments: D, wetting (W) and RT resulted in C. schmidtii being re-flooded after 30, 40 and 60 days of drought.D and RT treatments partly affected nutrient stoichiometry of C. schmidtii.Plant nutrient stoichiometry experienced a shift of adaption from drought to flooding and making part or full recoveries after RT with reference to D and W treatments. Plant P concentration had a negative relationship with N:K ratio.D and RT effects on plant trade-offs and scaling exponents of C. schmidtii were profound; the scaling exponent of P~N increased with initial re-flooding time, while that of K~N decreased.Although nutrient trade-offs in D gradually differed from W and RT over time, the nutrient trade-offs of RT recovered with reference to W. The D and RT were recorded to contribute to nutrient flexibility of C. schmidtii; however, strong internal stability of stoichiometric relationships effectively relieved changes in plant nutrient stoichiometry.The findings aid our understanding of nutrient responses of C. schmidtii to D and RT.