Reference # 6454635
TOPIC 8. Plant invasions
East Asian plants in Eastern US forests: are invaders pre-adapted for more efficient resource use?
Mason HEBERLING & Jason FRIDLEY
Syracuse University, Syracuse, New York, USA
The globalization of human activities has resulted in the widespread movement of plants around the world.
Paradoxically, many of these exotic species are out-competing native plants, despite the presumption that native
species have locally adapted to their environments. Further, global invasion patterns are frequently asymmetric,
with some regions more likely to produce invasive species and others more likely to be invaded. This phenomenon
is particularly prominent in eastern North American (ENA) forests, where an unexpected, substantial fraction of woody
invaders originated from East Asia (EAS). Although both regions lie primarily in the north temperate mesic forest biome
with comparable niches, EAS has much greater phylogenetic and species diversity than ENA. Historically, diversity
differences may have led to greater competition and intense selection for more efficient resource-use strategies in
the EAS flora. This bias could provide a mechanistic explanation for modern invasion patterns between the floristic
regions. We used a large database of leaf physiological traits (including photosynthetic rate, leaf lifespan,
leaf mass per area, and leaf nitrogen) and species native distribution data to test for large-scale functional
differences among biogeographic regions. With some exceptions, the EAS flora exhibited a generally more efficient
carbon economy than ENA plants. This general finding was supported in a common garden study that compared the leaf
physiologies of congeneric ENA native and EAS invasive shrubs and lianas. These included 31 species representing 6
plant families from 8 genera, including Lonicera, Euonymus, Berberis, Celastrus,
and Rhamnus. On average, introduced EAS species invasive in ENA forests had similar leaf metabolic costs,
but had greater photosynthetic returns than ENA natives. Efficiency differences were further magnified through
time when considering leaf lifespan. Overall, these findings suggest important region-level functional differences
between ENA and EAS floras and could have implications for understanding modern patterns of floristic interchange
and community re-assembly through plant invasions.
© 2012 Organizing Committee
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