Location: Rangeland Resources ResearchTitle: Invasive forb benefits from water savings by native plants and carbon fertilization under elevated CO2 and warming) Author
Submitted to: New Phytologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/3/2013
Publication Date: 8/22/2013
Publication URL: http://handle.nal.usda.gov/10113/58182
Citation: Blumenthal, D.M., Resco, V., Morgan, J.A., Williams, D.G., Lecain, D.R., Hardy, E.M., Pendall, E., Bladyka, E. 2013. Invasive forb benefits from water savings by native plants and carbon fertilization under elevated CO2 and warming. New Phytologist. 200(4):1156-1165. Interpretive Summary: Although global change may favor invasive plants, limited mechanistic understanding make it difficult to predict invasions in future environments. Here we show that elevated carbon dioxide can strongly promote invasion of semi-arid mixed-grass prairie by increasing availability of two resources, carbon and water. Four years of carbon dioxide enrichment dramatically increased growth and reproduction of the problematic invader, Dalmatian toadflax, both with and without warming. Measurements of water use efficiency and photosynthesis suggested that rapid growth and less conservative water use allowed this invasive species to take advantage of both carbon-fertilization and water saved by native species under elevated carbon dioxide. More generally, these results suggest that water-limited ecosystems may be particularly vulnerable to invasion under future climates.
Technical Abstract: As global changes reshuffle plant communities, invasive plants may benefit. Unfortunately, potential interactions among global changes and limited mechanistic understanding make it difficult to predict invasions in future environments. Here we show that elevated CO2 can strongly promote invasion by increasing availability of two resources, carbon (C) and water, both with and without warming. Four years after transplanting the invasive forb Linaria dalmatica into mixed-grass prairie, Free Air CO2 Enrichment (FACE) had increased L. dalmatica biomass 13-fold, seed production 32-fold, and clonal expansion 7-fold. Warming had no net effect on L. dalmatica biomass, reducing survival, but also increasing growth. Elevated CO2 decreased stomatal conductance in the dominant native grass, Pascopyrum smithii, contributing to an increase in soil water, but increased stomatal conductance in L. dalmatica. Elevated CO2 also increased photosynthetic CO2 assimilation more in L. dalmatica (87%) than in P. smithii (23%), as a result of both increased soil water and increased CO2 when controlling for soil water. These results suggest that rapid growth and less conservative water use may allow invasive species to take advantage of both C-fertilization and water saved by native species under elevated CO2. Water-limited ecosystems may therefore be particularly vulnerable to invasion under future climates.