Achieving similar ends by different means: leaf investment versus rate of return in three native and three invasive woody species.
Knapp, Liza*,1, 2, Fownes, James1, Harrington, Robin1, 1 University of Massachusetts, Amherst, MA2 firstname.lastname@example.org, Amherst, MA
ABSTRACT- Rapid growth may confer a competitive advantage in open or disturbed habitats, and several studies have suggested that the success of non-native invaders may be due to high photosynthetic capacity and resultant high growth rates relative to native species. We compared morphological and physiological components of growth rate among native and invasive forest species planted in replicated field plots. One invasive tree species (cer platanoides) and two invasive shrubs (Rhamnus frangula and Elaeagnus umbellata) were each paired with a native species of similar life form and shade tolerance. Leaf-level photosynthetic capacity and plant-level net wood assimilation rates were closely correlated among species. Within each pair, invasive and native species did not differ in relative diameter or stem mass growth rates; however,compared to their native partners, the two invasive shrub species achieved comparable growth rates with lower investment in leaf area or leaf biomass. Lower allocation to leaves may permit greater allocation to reproductive output; invasive shrubs in our study reached sexual maturity earlier than natives. The high photosynthetic capacities and net assimilation rates of invaders did not result in more rapid above-ground growth in canopy openings; rather, higher rates of return allowed invaders to maintain competitive growth rates with a smaller leaf investment.
Key words: invasive species, growth analysis
All materials copyright The Ecological Society of America (ESA), and may not be used without written permission.