Plant nutrient dynamics and stoichiometric homeostasis of invasive species Spartina alterniflora and native Cyperus malaccensis var. brevifolius in the Minjiang River estuarine wetlands

Aims Stoichiometric homeostasis is an important mechanism in maintaining ecosystem structure, function, and stability.The invasion of exotic species, Spartina alterniflora, has largely threatened the structure and function of native ecosystems in the Minjiang River estuarine wetland.However, how S. alterniflora invasion affect plant stoichiometric homeostasis is largely unknown.This could enhance our understanding on wetland ecosystem stability and expand the applications of ecological stoichiometry theory.Methods Nitrogen (N) and phosphorus (P) contents of plant organs and soils in the S. alterniflora, Cyperus malaccensis var.brevifolius, and S. alterniflora-C.malaccensis var.brevifolius mixture were measured, and the homeostatic index (H) was calculated according to the stoichiometric homeostasis theory.Important findings Our results showed that the invasion of S. alterniflora significantly increased soil N:P ratio (p < 0.05), but did not affect soil N or P contents.The N and P contents of leaf and stem were the highest for S. alterniflora, and those of the stem were the highest for C. malaccensis var.brevifolius.At the ecosystem level, the average of homeostatic index (H) of N (H N , 25.31) was larger than those of P (H P , 10.33) and N:P (H N:P , 2.50).At the organ level, root H N was significantly larger than stem H N (p < 0.05) and sheath H N:P was greater than root H N:P ©植物生态学报 Chinese Journal of Plant Ecology蒋利玲等: 闽江河口入侵种互花米草和本地种短叶茳芏的养分动态及植物化学计量内稳性特征 451 doi: 10