Shade Tolerance of Temperate Asian Bamboos: a Harbinger of their Naturalization in Pacific Northwest Coniferous Forests?

Authors: Smith, Melissa; MACK, RICHARD - Washington State University

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2013
Publication Date: 3/2/2013
Publication URL: http://link.springer.com/article/10.1007%2Fs10530-013-0434-y/fulltext.html
Citation: Smith, M., Mack, R.N. 2013. Shade Tolerance of Temperate Asian Bamboos: a Harbinger of their Naturalization in Pacific Northwest Coniferous Forests?. Biological Invasions. http://link.springer.com/article/10.1007%2Fs10530-013-0434-y/fulltext.html.

Interpretive Summary: Plant invasions are costly economically and environmentally, but could be prevented if anticipated and tested before dispersal. Many of the worst plant invasions are able to take hold in new regions because of ecological similarities between the species’ native range and the introduced range. Our primary goal is to test the ability of physiologically-based response tests to predict a species’ potential to naturalize. To do so, we chose a group of organisms that is increasing in importation frequency and horticulture popularity: temperate Asian bamboos. We tested the responses of bamboos to light, a limiting force within the understory of forests in North America, particularly forest in the Pacific Northwest. We found that with the exception of two species, all of the temperate Asian bamboos we tested are acclimated and could persist in forests with low light. This preadaptation to low light conditions could make forest understories more vulnerable and allow whole functional groups, including rhizomatous temperate grasses, to invade. Future naturalization assessments should include a component of field testing when literature searches do not immediately yield outcomes.

Technical Abstract: Bamboos native to temperate East Asian forests may be pre-adapted to floristically related coniferous forests in western North America that conspicuously lack large, rhizomatous grasses. Given the increasing opportunity for Asian bamboos to enter North America through horticulture, such pre-adaptation could allow frost tolerant bamboos to become established, for example, in forest understories in the Northern Rocky Mountains. Seven temperate Asian bamboos and one North American bamboo (Arundinaria gigantea) were grown under three light levels (50, 30, 10% of PAR) that occur routinely within North American coniferous forests. Species’ responses under these light levels were measured by their light response curves to photosynthesis, resource allocation to light or carbon harvesting centers inferred by CO2 response curves, and shifts in leaf Chlorophyll. Bashania fargesii shows lower chlorophyll content and photosynthetic output under high shade. B. fargesii, Sasa kurilensis, and A. gigantea, also show lower photosynthetic output under 90% shade and lower electron transport capacity under 70% and 90% shade. Pleioblastus chino, Pleioblastus distichus, Pseudosasa japonica, Sasa palmata and Sasaella ramosa display strong pre-adaptation to low light. Our results reveal these five Asian bamboos (and others yet to be introduced) could skirt a major environmental barrier to new species establishment in these North American forests. Constructing a species’ light response curve offers a reliable, rapid means to assess an immigrant species’ potential to tolerate forests’ varied light regimes.