Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2003
Publication Date: 6/1/2004
Citation: Comas, L.H., Eissenstat, D.M. 2004. Linking root traits to maximum potential growth rate in eleven mature temperate tree species. Functional Ecology. 18(3):388-397. Interpretive Summary: Ecologists have a long history of attempting to classify plants by their growth patterns. However, few studies to date have examined root traits of plants, especially under field conditions. We compared five fast- and six slow-growing trees to investigate patterns in root morphology, architecture and physiology related to plant growth rate. Across all pairs of species, fast-growing species had thinner roots with more branching and lower concentrations of root defense compounds than slow-growing species but there were no differences in root physiology between fast- and slow-growing species. We propose that root morphology, architecture, and construction are determined by genetic differences between species, whereas root physiology in mature trees may be more influenced by factors such as soil microsites, root age or interactions with mycorrhizal fungi.
Technical Abstract: There is limited understanding of patterns of variation that exist among root traits of different species, especially in field conditions. We contrasted eleven fast- and slow-growing species paired within five evolutionary lineages to investigate whether root traits associated with soil resource acquisition were related to species potential growth rate. Measurements were taken on fine, non-woody roots sampled from several forests in central Pennsylvania. Across all five contrasts, roots of fast-growing species generally had higher specific root length, smaller diameters, greater degree of branching, and lower phenolic concentrations than those of slow-growing species, suggesting differences in soil exploration and root defenses among species of different potential growth rate. There were no significant differences between fast- and slow-growing species in root tissue density, respiration, N concentration, or P uptake. Lack of differences in root physiology contrasted with previous research in seedlings grown under controlled chamber conditions. The results imply that roots of fast-growing species were constructed for more rapid soil exploration and shorter lifespan than those of slow-growing species. Root physiology, however, was either more closely tied to overall plant physiology, which was more similar among mature trees, or masked by variation in soil microsites, root age or interactions with mycorrhizal fungi.