A comparison of phenotypic plasticity between two species occupying different positions in a successional sequence

We compared the phenotypic plasticity of two greenhouse-grown species (Corispermum macrocarpum and Salsola collina) occupying different positions in a successional sequence in Horqin Sandy Land, by treating with different population density and the availability of soil nutrients and water. The same species can exhibit different patterns of plasticity in response to different environmental factors. In the soil nutrient treatments, the plasticity pattern of S. collina could be described as “master-of-some”. However, in the soil-water and population-density treatments, it showed no significant difference from C. macrocarpum in the reaction norm for plasticity. It was similar to a “jack-of-all-trades” plasticity pattern. Contrary to the previous conclusion that late successional species had higher reproductive allocation than early successional species, in this successional sequence, the late species had lower reproductive allocation in all treatments. Reproductive allocation of both species increased with the increase in water availability and also increased with a decrease in nutrient levels. However, density had no effect on reproductive allocation. Although the root:shoot ratio increased with decreasing water availability, there were no differences in the plasticity pattern for this trait in both species. Root:shoot ratio was, however, not significantly affected by nutrient availability and density. In a word, the plasticity patterns of invaders are adapted to the analyses of succession.