HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Runion, G. B. Articles by Gjerstad, D. H. Search for Related Content PubMed Articles by Runion, G. B. Articles by Gjerstad, D. H. Agricola Articles by Runion, G. B. Articles by Gjerstad, D. H.

Longleaf Pine Photosynthetic Response to Soil Resource Availability and Elevated Atmospheric Carbon Dioxide

International Paper, 719 Southlands Road, Bainbridge, GA 31717;

R. J. Mitchell

JW. Jones Ecological Research Center, Route 2, Box 2324, Newton, GA 31770;

T. H. Green

Dep. of Plant and Soil Science, P.O. Box 1208, Alabama A&M Univ., Normal, AL 35762;

S. A. Prior and H. H. Rogers

USDA-ARS, National Soil Dynamics Lab., 411 S. Donahue Drive, Auburn, AL 36832;

D. H. Gjerstad

School of Forestry, 108 M. White Smith Hall, Auburn Univ., AL 36849.

^* Corresponding author (brett.runion{at}ipaper.com).

ABSTRACT

Gas exchange responses during a drought cycle were studied in longleaf pine (Pinus palustris Mill.) seedlings after prolonged exposure to varying levels of atmospheric CO₂ (365 or 730 µmol CO₂ mol^–1), soil N (40 or 400 kg N ha^–1 yr^–1), and water ("adequate" and "stressed"). Elevated atmospheric CO₂ concentration increased photosynthesis, tended to decrease stomatal conductance, and increased water-use efficiency (WUE). Although soil resource availability influenced gas exchange measurements, it generally did not affect the magnitude or direction of the response to CO₂ concentration. However, significant interactions among treatment variables were observed for plant xylem pressure potential. In seedlings grown with high N, a positive growth response to elevated atmospheric CO₂ increased whole-plant water use resulting in more severe plant water stress, despite increased leaf-level WUE; however, under low N conditions the lack of a growth response to elevated CO₂ reduced whole-plant water use, decreased water stress severity, and increased WUE. Photosynthetic response to CO₂ was greatest in the high N treatment at the beginning of the drought cycle, but diminished as water stress increased; however, plants grown with low N showed greater photosynthetic responses to CO₂ later in the drought cycle. Therefore, plant gas exchange rates interact with growth response in determining the severity of water stress under drought and, thus, the ability of elevated atmospheric CO₂ to ameliorate the effects of drought and allow plants to maintain increased rates of photosynthesis may be influenced by the availability of other resources, such as N and water.

This article has been cited by other articles:

				G. B. Runion, M. A. Davis, S. G. Pritchard, S. A. Prior, R. J. Mitchell, H. A. Torbert, H. H. Rogers, and R. R. Dute Effects of elevated atmospheric carbon dioxide on biomass and carbon accumulation in a model regenerating longleaf pine community. J. Environ. Qual., July 1, 2006; 35(4): 1478 - 1486. [Abstract] [Full Text] [PDF]