Ontogenetic shifts in plant interactions vary with environmental severity and affect population structure

le Roux, Peter C., Shaw, Justine D. and Chown, Steven L. (2013) Ontogenetic shifts in plant interactions vary with environmental severity and affect population structure. New Phytologist, 200 1: 241-250. doi:10.1111/nph.12349


Author le Roux, Peter C.
Shaw, Justine D.
Chown, Steven L.
Title Ontogenetic shifts in plant interactions vary with environmental severity and affect population structure
Journal name New Phytologist   Check publisher's open access policy
ISSN 1469-8137
0028-646X
Publication date 2013-10
Year available 2013
Sub-type Article (original research)
DOI 10.1111/nph.12349
Open Access Status DOI
Volume 200
Issue 1
Start page 241
End page 250
Total pages 10
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell
Collection year 2014
Language eng
Formatted abstract
Summary
Environmental conditions and plant size may both alter the outcome of inter-specific plant–plant interactions, with seedlings generally facilitated more strongly than larger individuals in stressful habitats. However, the combined impact of plant size and environmental severity on interactions is poorly understood.

Here, we tested explicitly for the first time the hypothesis that ontogenetic shifts in interactions are delayed under increasingly severe conditions by examining the interaction between a grass, Agrostis magellanica, and a cushion plant, Azorella selago, along two severity gradients.

The impact of A. selago on A. magellanica abundance, but not reproductive effort, was related to A. magellanica size, with a trend for delayed shifts towards more negative interactions under greater environmental severity. Intermediate-sized individuals were most strongly facilitated, leading to differences in the size-class distribution of A. magellanica on the soil and on A. selago. The A. magellanica size-class distribution was more strongly affected by A. selago than by environmental severity, demonstrating that the plant–plant interaction impacts A. magellanica population structure more strongly than habitat conditions.

As ontogenetic shifts in plant–plant interactions cannot be assumed to be constant across severity gradients and may impact species population structure, studies examining the outcome of interactions need to consider the potential for size- or age-related variation in competition and facilitation.
Keyword Competition
Environmental gradient
Facilitation
Ontogenetic shift
Ontogeny
Plant-plant interaction
Population structure
Size-class distribution
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Biological Sciences Publications
 
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