Valverde, Oscar , Blackwood, Christopher .
Functional traits in fine roots: integrating below and above ground traits in Angiosperms.
The study of the relationships among chemical and morphological traits has been broadly used in plant ecology to understand the physiological and anatomical constraints that shaped plant adaptations to their environment. Fine roots (the most distal portions of the root system) have rarely been studied in this context. More importantly, few studies have linked functional traits at the entire plant level, limiting our ability to predict whether plant organ evolution is coordinated in plants. It has been hypothesized that functional traits in leaves reflect an integrated life history strategy. One hypothesis is that similar trade-offs will be found in root traits. Alternatively it is possible that root traits could be highly conserved phylogenetically due to complex fungal symbiotic relationships,decoupling root traits from above ground organs. In this study we test the hypothesis of coordinated traits by analyzing morphological and chemical traits for 34 woody species representing three main Angiosperm clades (Asterid,Magnolid and Rosid); all of them associated with arbuscular mycorrhizal fungi (AMF). Root, leaf, twig and branch samples were obtained from four individuals of each species located in two different common gardens. Entire root systems were dissected into three separate root orders. Fifteen morphological and chemical traits were determined for each plant organ, including specific tissue area, N content, polar extractives, and acid hydrolyzable compounds. Our results did not support the hypothesis of a single axis of variation explaining trait variation across plant organs. In fact, we found low correlation not only between above and below ground tissues, but also between leaves and branches as well. Only N concentration was consistently correlated across all plant organs. We found the typical positive relationship between N concentration and leaf morphology, but not between N and root morphology. In support of the phylogenetic hypothesis, we found a more phylogenetically conserved trait distribution among below ground than above ground tissues. Magnolid root morphology was consistently different from other angiosperms, whereas Rosid root chemical composition was substantially different from the other two clades. We conclude that different selective forces act upon the evolution of functional traits in different plant tissues. For roots, evolutionary trends are probably better explained as alternative acquisition pathways, possibly strongly influenced by their mycorrhizal dependence and constrained by plant phylogeny.Further studies should focus on the role of root morphology and chemistry on the assemblage of mycorrhizal communities.
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1 - 621 Franklin Av, Kent, OH, 44240, USA
2 - Kent State University, Biological Sciences, 125 Cunningham Hall, Kent, OH, 44240, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 1:30 PM