Growth strategies of temperate grassland species adapted to grazing by large herbivores.
Comas, Louise*,1, 2, Skinner, Howard1, 1 USDA-ARS, University Park, PA, USA2 Penn State University, University Park, PA, USA
ABSTRACT- Despite considerable interest in defoliation effects on plant productivity and competitive interactions, few studies have investigated growth strategies across a broad array of species adapted to frequent defoliation. We explored 18 traits related to growth, morphology, and allocation among 21 temperate species adapted to grazing by large herbivores that had been subjected to defoliation 63 d following seedling emergence. Species that recovered quickly following defoliation had a combination of faster initial RGR, larger seed size, and faster RGR during re-growth. Species with fast growth rate, both before and after defoliation, had compact shoot architecture following defoliation, suggesting that compact shoot architecture is an important adaptation to defoliation. Principal Component Analysis (PCA) of 12 traits that accounted for unique variation among these plants identified several significant components of variation. Ordination of species by these PCA scores identified species most tolerant to frequent defoliation as those having fast RGR prior to defoliation, compact shoot architecture and maintenance of allocation to root growth relative to shoot growth following defoliation, and large SLA. Thus, our examination of plant allocation patterns among species adapted to defoliation identified the importance of belowground allocation and fast initial plant growth in addition to shoot morphological traits such as SLA, commonly associated with fast growth, as components of a competitive growth strategy under defoliation.
Key words: plant biodiversity, plant allocation, plant growth strategies, relative growth rate, RGR, belowground
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