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Jenny Edwards Dauer

Reasons for differential leaf calcium concentrations in forest trees

M.S. in Ecology, 2005

Variation in leaf-litter Ca concentration among fourteen tree species growing in a common garden in central Poland was linked to variation in soil pH, exchangeable Ca, soil base saturation, forest floor turnover rates, and earthworm abundance. Given the potential importance of tissue Ca to biogeochemical processes, in this study we investigated two potential controls on leaf Ca concentrations. We investigated whether species with high Ca concentrations in green leaves and leaf litter access soil Ca to a greater extent than low-Ca species by growing more roots in high-Ca soil horizons. We also determined whether differences in Ca concentration of leaves and litter were due to differences in nutritive demand for Ca for growth by measuring seedlings of six of the fourteen species grown under controlled conditions of varying Ca supply. Root distribution in the field was determined in all 14 tree species by profile wall mapping of excavated pits. There was no correlation between root count density (number of roots m-2) and exchangeable soil Ca. Across species we found a positive correlation of leaf litter Ca and density of roots 45-100 cm deep in the soil, suggesting that a deeper root distribution confers an advantage in Ca acquisition. Variation among species in leaf Ca concentration of seedlings in the greenhouse was positively correlated with leaf Ca concentrations of mature trees in the field, indicating that the same rank variation in leaf Ca among species existed under controlled Ca supply. Species also differed in growth response to Ca supply. Tilia, the species with the highest leaf Ca in the field, had only 10% as great biomass, height and Ca concentration at low as at high Ca supply. The other species exhibited no significant differences in biomass or height at different levels of Ca supply. Our data support the hypothesis that variation among species in leaf and litter Ca concentration of mature trees in the field is a trait associated with innate physiological differences. Additionally, our data support the hypothesis that species with high- as opposed to low- Ca in leaves and litter have access to greater pools of Ca in deep soils.

Publications:

  • Edwards, J.M. 2005. Reasons for differential leaf calcium concentrations in forest trees. M.S. thesis. The Pennsylvania State University, University Park, PA. 71pp.
  • Dauer (Edwards) J.M., Chorover J., Chadwick O.A., Oleksyn J., Tjoelker M.G., Hobbie S.E., Reich P.B., Eissenstat D.M. 2007. Controls over leaf and litter calcium concentrations among temperate trees. Biogeochemistry 86:175-187
  • Dauer, J.M., Withington, J.M., Chorover, J., Chadwick, O.A., Oleksyn, J., Reich, P.B. and Eissenstat, D.M. 2009. A scanner-based approach to soil profile-wall mapping of root distribution. Dendrobiology 62: 35-40