To compete or not to compete an experimental stud

Authors: Marina Semchenko Kristjan Zobel Michael J Hutchings

Publish Date: 2010/07/04

Volume: 24, Issue: 6, Pages: 1433-1445

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Abstract

Gametheoretic models predict that plants with root systems that avoid belowground competition will be displaced by plants that overproduce roots in substrate shared with competitors Despite this both types of root response to neighbours have been documented We used two cooccurring clonal species Glechoma hederacea and Fragaria vesca with contrasting root responses to neighbours avoidance of competition and contesting of resources respectively to examine whether functional variation in other traits affected the success of each rooting strategy leading to a different outcome from that predicted on the basis of root behaviour alone Vegetative propagation rates morphology and biomass allocation patterns were examined when each species was challenged with competition from physically separate ramets with either the same rooting strategy intraclonal competition or the contrasting rooting strategy interspecific competition Contrary to the predictions of gametheoretic models the species that exhibits avoidance of root competition Glechoma was not competitively inferior to the species that does not Fragaria Glechoma achieved greater total mass in the interspecific treatment than in the intraclonal treatment However Fragaria did not experience more intense competition from Glechoma than it did in the intraclonal treatment Strong interference between the two species appeared to be avoided because Glechoma invested preferentially in rapid exploitation of unoccupied space whereas Fragaria invested in increasing the competitive ability and local persistence of established ramets Our results suggest that interspecific tradeoffs between traits related to competitive ability and resource exploitation can allow coexistence of species with contrasting rooting behaviours Full assessment of the adaptive value of different root responses to neighbours therefore requires concurrent consideration of the combined effects of a wide array of functional traitsWe gratefully acknowledge technical assistance from John Davison We thank Hans de Kroon Radka Wildová and two anonymous reviewers for insightful discussion and helpful comments on an earlier draft of this paper This study was supported by the University of Sussex University of Tartu 0119 grant 7576 from the Estonian Science Foundation and FP6 project Ecochange

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