Ecological Stoichiometry Characteristics and Nutrition Strategy of Trifolium repens at Different Invasion Degrees
The study of ecological stoichiometry characteristics of invasive plants can contribute to reveal the invasion mechanisms and nutrition strategies.In this research,soil properties,carbon,nitrogen,and phosphorus contents of plant organs(root,stem,and leaf),ecological stoichiometry,and their interac-tions were analyzed at different Trifolium repens invasion levels.The results demonstrated that:(1)Soil organic carbon,total nitrogen,total potassium,ammonium nitrogen,nitrate nitrogen,and available phos-phorus content increased with the rise of the invasion degree of T.repens,whereas soil total phosphorus and available potassium contents decreased.(2)The carbon content,carbon nitrogen ratio,carbon phos-phorus ratio,and nitrogen phosphorus ratio of plant organs of T.repens decreased with the rise of the inva-sion degree,while the nitrogen and phosphorus contents increased.Under the same invasion level,the car-bon,nitrogen,and phosphorus contents in T.repens leaves were higher than those in roots and stems.Car-bon nitrogen ratio and carbon phosphorus ratio in roots and stems were higher than those in leaves.Nitro-gen phosphorus ratio followed the trend of roots>leaves>stems.The growth rate of T.repens stems and leaves was accelerated when the invasion degree rose.(3)There was a significantly positive correlation between nitrogen and phosphorus in leaf and nitrogen and phosphorus in stem of T.repens,whereas carbon nitrogen ratio and carbon phosphorus ratio in root were positively correlated.(4)The effects of soil proper-ties on the carbon,nitrogen,phosphorus contents and ecological stoichiometry characteristics in T.repens organs were ranked following TK>AK>TN>SOC>AN>AP>NN>TP.In conclusion,the invasion of T.repens changed soil nutrients and created a favourable soil environment for its growth.In the process of invasion,strong absorption and utilization of nitrogen and phosphorus and high growth rate of stem and leaf brought competitive growth advantage to T.repens and contributed to successful invasion.
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