Incorporating clonal growth form clarifies the role of plant height in response to nitrogen addition

TitleIncorporating clonal growth form clarifies the role of plant height in response to nitrogen addition
Publication TypeJournal Article
Year of Publication2012
AuthorsGough, L, Gross, KL, Cleland, EE, Clark, CM, Collins, SL, Fargione, JE, Pennings, SC, Suding, KN
Pagination1053 -1062
Accession NumberKNZ001497
KeywordsClonal growth, Competition, grassland, Nitrogen addition, productivity

Nutrient addition to grasslands consistently causes species richness declines and productivity increases. Competition, particularly for light, is often assumed to produce this result. Using a long-term dataset from North American herbaceous plant communities, we tested whether height and clonal growth form together predict responses to fertilization because neither trait alone predicted species loss in a previous analysis. Species with a tall-runner growth form commonly increased in relative abundance in response to added nitrogen, while short species and those with a tall-clumped clonal growth form often decreased. The ability to increase in size via vegetative spread across space, while simultaneously occupying the canopy, conferred competitive advantage, although typically only the abundance of a single species within each height-clonal growth form significantly responded to fertilization in each experiment. Classifying species on the basis of two traits (height and clonal growth form) increases our ability to predict species responses to fertilization compared to either trait alone in predominantly herbaceous plant communities.