Phenotypic Responses To Resource Supply In Clonal Plants With Contrasting Growth Forms On The Tibetan Plateau

Clonal plants, especially those tussock grasses (such as Stipa purpurea Griseb and S. capillacea Keng) and rhizomatous sedges (such as Carex moorcroftii Falc. ex Boott and C. montis-everestii Kük.), may appear as constructive or dominant species in the alpine grassland ecosystems on the Tibetan Plateau.There was extensive phenotypic plasticity in Carex montis-everestii and Stipa capillacea, both from the typical alpine grasslands and the alpine scrublands, respectively, in response to light intensities and nutrient supplies. The growth form affected light-induced plasticity in the number of ramets, specific leaf area and length of leaf sheath; the habitat origin modified light-induced plasticity in the number of ramets, total plant biomass and total rhizome length. Plasticity in response to nutrient supply was not altered by the growth form or habitat origin. Guerilla clonal species seem to be more adaptive to the scrublands characterized by high heterogeneity, and phalanx species seem to be less affected by the habitat origin.High phenotypic plasticity was detected in Carex moorcroftii and Stipa purpurea in response to nutrient supplies. Populations affected only a few traits. Except rhizome allocation and photosynthetic characters, many other traits significantly differed between genotypes. Relatively fewer genotypic variations in phenotypic plasticity were detected except for biomass allocation to rhizomes. There were extensive phenotypic integration and plasticity integration among phenotypic traits. The integration patterns were different between species and changed with the amount of nutrient supply. Based on the analyses of reaction norms, the clonal plants in the alpine habitats may have evolved the potential to exploit highly heterogeneous nutrient conditions and to maintain growth under the limited nutrient availability, which is also a vital strategy for them to adapt to diverse nutrient environments.Phenoytpic plasticity in Carex moorcroftii and Stipa purpurea was mainly affected by the amount of nutrient supply. Given the equal total amount of...