OOS 31-9 - Patterns of fine root turnover in temperate trees

Wednesday, August 10, 2011: 4:20 PM
15, Austin Convention Center
M. Luke McCormack, Department of Plant Biology, University of Minnesota, St. Paul, MN, Thomas S. Adams, Department of Ecosystem Science and Management, The Pennsylvania State University, State College, PA and David Eissenstat, Horticulture, The Pennsylvania State University, State College, PA

Fine root turnover is a key process regulating carbon flux from plants into soils and total root biomass available for nutrient and water uptake.  This tight coupling of carbon, water, and nutrient cycles makes fine root turnover an important area of study in plant and ecosystem ecology as well as for ecological modeling.  Unfortunately, difficulty in obtaining robust, accurate quantifications of fine root turnover has made any hardy descriptions or fine root turnover beyond a single site difficult and contentious.  Here, we investigate whether consistent patterns of fine root turnover exist across a range of temperate tree species based on shoot traits and fine root traits.  We hypothesized that turnover rates would be positively related to specific root length (SRL), root nitrogen content, fine root respiration and plant potential growth rate and negatively related to root and stem tissue densities.  Turnover rates were measured separately for 12 temperate tree species at the Rock Springs Common Garden in central Pennsylvania.  The site includes three con-generic contrasts (Acer, Pinus, Quercus) and covers a wide range of root traits and life history traits. 


In general, we observed a wide range of root traits, plant growth rates, and fine root turnover rates.  While observed patterns among most root traits and fine root turnover were equivocal there was a consistent pattern of faster fine root turnover rates with faster plant growth rates.  Within a genus faster-growing species exhibited faster root turnover than slower-growing species.  Furthermore, across 12 species of different families and genera, growth rate was positively correlated with root turnover (p<0.05).  However, the relationship was relatively weak (R2=0.17) indicating a large amount of variability was left unexplained.  However, we found little increase in the explanatory power of our model by incorporating different root traits with plant growth rate.

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