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Jennifer M. Withington

Fine root production and lifespan in eleven temperate tree species growing in a common garden in Poland.

PhD in Ecology, 2005

Leaf lifespan and structure have been linked to plant competition and nutrient cycling. Analyses of leaf structure and leaf lifespan on global data sets provide strong evidence for long leaf lifespan coupled with low specific leaf area and low mass-based N concentrations. Because fine roots share many characteristics with leaves (e.g. resource acquisition, ephemeral nature), we hypothesized that fine root and leaf lifespan should be correlated, and fine roots lifespan should couple with root traits.

Our common garden in central Poland consisted of replicated, monospecific plots of five hardwood and six conifer species. We used minirhizotrons to observe root production and lifespan over four years.

Minirhizotrons are used to nondestructively observe roots. We tested the important assumption that tube material does not influence root behavior using butyrate and acrylic tubes in plots of three hardwoods and three conifers. Root survivorship near acrylic tubes was shorter for the conifers and longer for the hardwoods, indicating that multi-species lifespan data can be influenced by tube material. Compared to butyrate, acrylic tube standing crop data were more similar to standing crop estimates from soil cores, suggesting acrylic tubes provide the more accurate data in our study systems.

Our species had one peak of root production in summer, while the site experienced no summer drought. Maximum peak production shifted similarly for all species from year to year indicating a strong influence of external factors.

Though the eleven tree species exhibited a wide range in leaf and fine root lifespans, leaf lifespan was not correlated with fine root lifespan. Root nitrogen:carbon ratio was inversely correlated with root lifespan. Other root traits, such as diameter and specific root length, were not correlated with root lifespan. Our studies show that tissue structure and patterns of longevity aboveground can contrast markedly with patterns belowground. To better understand larger-scale nutrient cycling in ecosystems as well as patterns associated with belowground growth strategies, we need to understand similarities of roots across species. We can do this by observing root production and lifespan patterns in multi-year, multi-species studies.

Publications:

  • Withington, J.M., P.B. Reich, J. Oleksyn, and D.M Eissenstat. 2006. Comparisons of structure and life span in roots and leaves among temperate trees. Ecological Monographs 76:381-397
  • Withington J.M., A.D. Elkin, B. Bulaj, J. Olesinski, K.N. Tracy, T.J. Bouma, J. Oleksyn, L.J. Anderson, J. Modrzynski, P.B. Reich and D.M. Eissenstat. 2003. The impact of material for minirhizotron tubes for root research. New Phytologist 160: 1-12
  • Withington J.M. 2005. Fine root production and lifespan in eleven temperate tree species growing in a common garden in Poland. Ph.D. thesis. The Pennsylvania State University, University Park, PA.120pp.