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Abstract Detail


Ecophysiology

Pratt, R. B. [1], Jacobsen, A. L. [2].

The ecophysiology of resprouting fynbos shrubs with different life history types.

Different life history types of fynbos species were analyzed for physiological differences between co-occurring unburned and burned plants. Facultatively sprouting (FS) species are those that, following crown fire, resprout from the base and recruit seedlings from a dormant fire-cued seed bank. Obligate sprouters (OS) have seeds that are sensitive to fire and only regenerate after fire by vegetative sprouting. Because of these life history type differences, it was hypothesized that OS species would be under greater demographic pressure to successfully resprout on account of their inability to recruit seedlings post-fire, and accordingly would have traits that facilitated a vigorous resprout response. Carbon assimilation and water stress resistance for FS and OS species were analyzed between adjacent unburned and recently burned plants. Carbon assimilation rates were greater for OS species than FS species at both the leaf and canopy levels. Water stress resistance measured as resistance of stem xylem to cavitation was greater for FS species than OS species. Unburned and burned plants did not differ in cavitation resistance. The data suggest that fynbos FS and OS life history types are divergent physiologically and that OS species are vigorous resprouters fueled by rapid assimilation of carbon. The greater rate of carbon assimilation came at a cost of reduced water stress resistance.

Broader Impacts:
This work demonstrates a link between photosynthetic and hydraulic physiology and life history type in the biodiverse South African fynbos shrubland. This information provides insight into the divergent evolutionary pathways between different post-fire sprouting types in the biodiverse Mediterranean-type ecosystems across the globe.


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1 - California State University, Bakersfield, Biology, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
2 -

Keywords:
seasonal carbon gain
cavitation
fire
hydraulic conductivity
life history
Photosynthesis
xylem.

Presentation Type: Oral Paper:Papers for Topics
Session: 30
Location: 551B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 9:30 AM
Number: 30005
Abstract ID:379


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