Among-provence variability of gas exchange and growth in response to long-term elevated CO₂ exposure

Abstract

Genetic variability can have profound effects on the interpretation of results from elevated CO₂ studies, and future forest management decisions. Information on which varieties are best suited to future atmospheric conditions is needed to develop future forest management practices. A large-scale screening study of the effects of elevated CO₂ on 15 half-sibling sources of genetically superior ponderosa pine (Pinus ponderosa Dougl ex P. Laws.) is presented. These sources represent multiple elevations and latitudes throughout California. Among-provenance variability in the effects of elevated CO₂ on gas exchange and growth, and their correlation with geographic origin were investigated in ponderosa pine seedlings subjected to ambient or elevated CO₂ concentrations (525 umol^-1 CO₂ and 700 umol mol^-1 CO₂) for more than two years in open-top chambers. Substantial among-provenance variability in growth response to elevated CO₂ was evident, with 8 sources demonstrating no significant growth response to elevated CO₂ while 7 sources responded positively. For all sources, elevated CO₂ increased photosynthesis (ranging from 19% increase at 525 umol mol^-1 CO₂ to 49% increase at 700 umol mol^-1 CO₂). A modest correlation existed between geographic origin and above ground growth response to elevated CO₂.

Citation

Houpis, James L.J.; Anderson, Paul D.; Pushnik, James C.; Anschel, David J. 1999. Among-provence variability of gas exchange and growth in response to long-term elevated CO₂ exposure. Water, Air, and Soil Pollution. 116: 403-412. (1999)