Sarah L. Cook 1999

The growth and phosphorus-use efficiency of invasive Lythrum salicaria and native Typha latifolia and the implications for the competition mechanism

This study examines the effects of variation in available phosphorus on the growth of a native wetland plant, Typha latifolia, and its primary competitor, the invasive species Lythrum salicaria. The study also examines possible morphological and physiological characteristics of the species that may explain the different observed growth responses. Seedling growth in a low phosphorus treatment demonstrated that L. salicaria has a greater growth rate than T. latifolia. Lythrum salicaria biomass production was not affected by variations in P levels, while T. latifolia had significantly greater biomass at the highest P treatment level than at the lower three levels. The different growth responses can be explained by patterns of biomass allocation and phosphorus-use efficiency. Lythrum salicaria allocates a larger proportion of biomass to roots to capture more phosphorus. Lythrum salicaria's superior performance at low P levels also appears to be due to its greater P-use efficiency. Results suggest, however, that T. latifolia can take advantage of increases in available phosphorus by increasing P-use efficiency and biomass production, but L. salicaria's performance does not improve with increasing phosphorus. The results of this study indicate that L. salicaria would be the superior competitor at low P levels, but this relationship may reverse at high P levels.

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