Reichman and Smith measured the response of Tragopogon dubius to different intensities of root and leaf removal. Data indicated that pocket gopher (Geomys bursarius) root herbivory was successfully simulated by the root clipping treatments used in this study. Plants with 25% of their leaf tissue removed did not differ significantly from controls in total biomass. Those with any root tissue trimmed produced significantly less biomass while the 75% leaf removal treatment was intermediate. Plants that had one or more flowers removed by herbivores grew significantly larger and produced significantly more flowers than plants that lost no flowers, regardless of the treatment. Few consistent patterns emerge from an analysis of nitrogen allocation patterns in response to treatments. In general, the greatest effects were seen shortly after manipulation, and values tended to converge over time. There was a weak trend for root-trimmed treatments to have the lowest values for nitrogen by the end of sampling. Seeds had approximately twice the nitrogen concentration of leaves and roots. The authors suggest that the response of T. dubius to herbivory is determined by the type and intensity of herbivory applied and may also be determined by environmental variables which require further research.
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