Poplar Root System Responses to Defoliation by Gypsy Moths

Kosola, K.R., D. I. Dickmann, E.A. Paul, D. Parry, C.Easley, and E. Duncan

Presented at the All Scientist Meeting (1998-07-21 to 1998-07-22 )

Defoliation is predicted to lead to a strong increase in carbon allocation to leaf regrowth, at the expense of carbon allocation to root growth, root carbon stores, and perhaps nutrient acquisition. We tested this hypothesis in four replicate stands of hybrid poplars (Populus x euramericana cv Eugenii) on the Kellogg Biological Station LTER site, with a control and defoliated treatment in each block. We moved gypsy moth egg masses and insects off the control treatments and into the defoliated treatments, and achieved large differences between levels of defoliation in the two treatments in 1997. Early summer root production (May to July) and total nonstructural carbohydrates (TNC) in fine roots sampled at peak leaf regrowth were strongly reduced in the defoliated treatment compared to the control treatment. These changes in root growth and root carbon stores are consistent with a shift in carbon allocation away from roots and towards leaf regrowth following defoliation.Return to Contents

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