Maintained nutrient accumulation in invasive Solidago canadensis in response to competition

Successful invasions into native plant communities may depend on critical functional traits of invaders, such as inherent high growth rate and associated massive nutrient absorption and utilization, which are affected by species-dependent soil properties. To test these hypotheses, we grew the invasive plant Solidago canadensis and its co-occurring native species Imperata cylindrica alone or in interspecific competition in soils collected from the stands of either S. canadensis or I. cylindrica. The soil from the S. canadensis stands had much higher available nitrogen, phosphorus and potassium concentrations than that from the I. cylindrica stands, and enhanced the growth of both species to a similar magnitude. Interspecific competition decreased the growth of both species, but S. canadensis was much more tolerant to interspecific competition than I. cylindrica. Soil origin had no effect on the magnitude of the competition tolerance of either species. Nutrient accumulation in shoots was less negatively affected by interspecific competition in S. canadensis than in I. cylindrica and was even maintained in S. canadensis when growing in the soil from the S. canadensis stands. The maintenance of nutrient accumulation in S. canadensis under interspecific competition was mostly achieved through increased or unchanged shoot nutrient concentration. These findings suggest that the successful invasion of S. canadensis into native plant communities is associated with its inherent high capacity of nutrient accumulation, while plant-dependent soil properties seem to play less important roles.