Contrasting mechanisms of recovery from defoliation in two intermountain-native bunchgrasses

Ray-Mukherjee, Jayanti and Jones, Thomas A. and Adler, Peter B. and Monaco, Thomas A. (2015) Contrasting mechanisms of recovery from defoliation in two intermountain-native bunchgrasses. Rangeland Ecology & Management, 68 (6). pp. 485-493. ISSN 15507424

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Abstract

Grazing tolerance of dominant native species may determine the fate of rangeland ecosystems, and using native plant populations with good grazing tolerance in restoration seedings may improve ecosystem resilience, especially when domestic herbivores are present. We examined interspecific and intraspecific differences in shoot biomass and defoliation tolerance for two semiarid, perennial cool-season bunchgrasses native to the Intermountain West, USA, Pseudoroegneria spicata and Elymus wawawaiensis, on the basis of four functional traits (specific leaf area [SLA], plant basal area, tiller number, and tiller mass). We applied two treatments, control and boot-defoliation, where the latter included defoliation at the early-reproductive (“boot”) stage, the phenological stage most vulnerable to herbivory, while the control treatment did not. We tested two contrasting hypotheses (i.e., that boot-defoliation tolerance is increased through either increases in SLA or through more favorable tiller demography). For shoot biomass, both grasses were less productive under the boot-defoliation treatment than for the control, but E. wawawaiensis displayed higher boot-defoliation tolerance than P. spicata. Interpopulation variation occurred in all four functional traits for P. spicata, but there were no such variation for E. wawawaiensis. The tiller demography hypothesis better explained boot-defoliation tolerance in both species, and neither SLA nor plant basal area was correlated with shoot biomass for either treatment. Of the traits measured, high tiller number served as the primary mechanism for shoot biomass and boot-defoliation tolerance in P. spicata, while tiller number and tiller mass were both important predictors of both shoot biomass and boot-defoliation tolerance.

Item Type:	Article
Authors:	Ray-Mukherjee, Jayanti and Jones, Thomas A. and Adler, Peter B. and Monaco, Thomas A.
Document Language:	Language English
Subjects:	Natural Sciences > Life sciences; biology > Ecology Natural Sciences > Plants (Botany)
Divisions:	Azim Premji University - Bengaluru > School of Arts and Sciences
Full Text Status:	None
URI:	http://publications.azimpremjiuniversity.edu.in/id/eprint/7359
Publisher URL:	https://doi.org/10.1016/j.rama.2015.07.011

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