Responses of clonal architecture to experimental defoliation: a comparative study between ten grassland species |
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Authors: | Marie-Lise Benot Cendrine Mony Sara Puijalon Majid Mohammad-Esmaeili Jacques J M van Alphen Jan-Bernard Bouzillé and Anne Bonis |
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Institution: | (1) UMR CNRS 6553, ECOBIO, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France;(2) UMR CNRS 5023, Ecology of Fluvial Hydrosystems, Université Lyon 1, 69622 Villeurbanne Cedex, France;(3) Faculty of Rangeland and Watershed, Gorgan University of Agricultural Sciences and Natural Resources, Shahid Beheshti Street, Gorgan, Iran |
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Abstract: | Clonal architecture may enable plants to effectively respond to environmental constraints but its role in plant tolerance
to defoliation remains poorly documented. In several non-clonal species, modifications of plant architecture have been reported
as a mechanism of plant tolerance to defoliation, yet this has been little studied in clonal plants. In a glasshouse experiment,
five rhizomatous and five stoloniferous species of grazed pastures were subjected to three frequencies of defoliation in order
to test two hypotheses. (1) We expected plant clonal response to defoliation to be either a more compact architecture (low
clonal propagation, but high branching), or a more dispersed one (long-distance propagation and low branching). Such plastic
adjustments of clonal architecture were assumed to be involved in tolerance to defoliation i.e. to promote genet performance
in terms of biomass and number of ramets. (2) The response of clonal architecture to defoliation was expected to be dependent
on the species and to be more plastic in stoloniferous than in rhizomatous species. Most genets of each species were tolerant
to defoliation as they survived and developed in every treatment. Architectural modifications in response to defoliation did
not match our predictions. Clonal growth was either maintained or reduced under defoliation. Relative growth rate (RGR) decreased
in eight species, whereas defoliated genets of seven species produced as many ramets as control genets. Biomass allocation
to ramet shoots remained stable for all but one species. In defoliated genets, the number and mean length of connections,
and mean inter-ramet distance were equal to or lower than those in control genets. Four groups of species were distinguished
according to their architectural response to defoliation and did not depend on the type of connections. We hypothesised that
dense clonal architectures with low plasticity may be the most advantageous response in defoliated conditions such as in grazed
pastures.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Between-class PCA Glasshouse experiment Response groups Short-term defoliation Tolerance |
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