PARENT SESSION
Oral Session # 61: Biogeochemistry IV: Al, Ca, P, and DOC.
Presiding: R Fitzhugh
Wednesday, August 6. 1:30 PM to 5:00 PM, SITCC Meeting Room 205.
Causes for differential calcium accumulation among diverse forest trees: The role of root distribution.
Edwards, J*,1, Reich, P2, Oleksyn, J2, 3, Eissenstat, D1, 1 Penn State University, University Park, PA2 University of Minnesota, St. Paul, MN3 Polish Academy of Sciences, Poznan, PL, Poland
ABSTRACT- While carbon and nitrogen cycling have been the primary focus in studies of biogeochemical processes in ecosystems, recently there has been increased recognition of the importance of calcium as well. Trees vary widely in the concentration of calcium in their leaves. Differences among species in the acquisition of calcium and the cycling of calcium via leaf-litter may profoundly affect ecosystem processes. In a common garden of 14 hardwood and conifer trees planted on relatively homogeneous soil we found that in just 30 years pH ranges from about 4.0 under Larix deciduas,and Pinus sylvestris to about 6.0 under Fagus sylvatica and Tilia cordata. The concentration of Ca in leaf litter ranged from 0.39% to 2.37% and correlated positively with soil Ca, soil pH, soil organic matter and soil C:N. Root distribution to a depth of 1 meter was determined using a novel scanning approach. Analysis of preliminary data showed a correlation of Ca in leaf litter with density of roots, total number of roots and % of total roots in the C horizon (R=0.7). There were no correlations with the O, A or B horizons. Our data supports the hypothesis that trees that accumulate more Ca in their leaves deploy more roots in the C horizon than non Ca-accumulating trees, contributing to greater Ca acquisition.
Key words: calcium, root distribution, nutrient cycling