This week EEB welcomes Dr. Amanda Tracey from the Department of Biology, Queens University:
Plant body size: when does it matter?
Identifying functional traits important for fitness is central to the interpretation of the structure and assembly of natural vegetation, and to management goals associated with biodiversity conservation and habitat restoration. Traditional plant competition theory is based on a ’size-advantage’ (SA) hypothesis — i.e. natural selection resulting from strongly contested resources within crowded vegetation generally favours capacity for a relatively large plant body size. In other words, gene transmission into future generations should increase as body size increases. However, smaller species (and smaller resident plants) typically dominate numerically at virtually all scales within vegetation. These patterns have been recently interpreted in terms of a ‘reproductive economy advantage’ (REA); i.e. when resident plants are severely suppressed in size because of intense resource competition, species with a smaller maximum potential body size (MAX) are generally more likely to produce at least some offspring because they tend also to have a smaller minimum reproductive threshold size (MIN). My PhD research has involved empirical investigations of the SA and REA hypotheses within old-field meadows at QUBS. Do bigger species have a greater abundance of seeds in the seed bank? Are they more abundant as resident plants? Are introduced species, under severely crowded conditions, more likely to establish and reproduce if they have a larger body size? Do bigger species contribute more to neighbourhood standing biomass? To explore these and other questions, I have used a combination of multi-season field experiments, greenhouse trials and natural vegetation surveys.
The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm. Light refreshments are served starting at 12:15.