Transient changes in transpiration, and stem and soil CO2 efflux in longleaf pine (Pinus palustris Mill.) following fire-induced leaf area reduction

Abstract

In 20-year-old longleaf pine, we examined short-term effects of reduced live leaf area (A L) via canopy scorching on sap flow (Q; kg H2O h-1), transpiration per unit leaf area (E L; mm day-1), stem CO2 efflux (R stem; µmol m-2 s-1) and soil CO2 efflux (R soil; µmol m-2 s-1) over a 2-week period during early summer. R stem and Q were measured at two positions (1.3-m or BH, and base of live crown—BLC), and R soil was measured using 15 open-system chambers on each plot. E L before and after treatment was estimated using Q measured at BLC with estimates of A L before and after scorching. We expected Q to decrease in scorched trees compared with controls resulting from reduced A L. We expected R stem at BLC and BH and R soil to decrease following scorching due to reduced leaf area, which would decrease carbon supply to the stem and roots. Scorching reduced A L by 77%. Prior to scorching, Q at BH was similar between scorch and control trees. Following scorching, Q was not different between control and scorch trees; however, E L increased immediately following scorching by 3.5-fold compared to control trees. Changes in E L in scorched trees corresponded well with changes in VPD (D), whereas control trees appeared more decoupled over the 5-day period following treatment. By the end of the study, R stem decreased to 15–25% in scorched trees at both stem positions compared to control trees. Last, we found that scorching resulted in a delayed and temporary increase in R soil rather than a decrease. No change in Q and increased E L following scorching indicates a substantial adjustment in stomatal conductance in scorched trees. Divergence in R stem between scorch and control trees suggests a gradual decline in stem carbohydrates following scorching. The absence of a strong R soil response is likely due to non-limiting supplies of root starch during early summer.

  • Citation: Clinton, Barton D.; Maier, Chris A.; Ford, Chelcy R.; Mitchell, Robert J. 2011. Transient changes in transpiration, and stem and soil CO2 efflux in longleaf pine (Pinus palustris Mill.) following fire-induced leaf area reduction. Trees DOI: 10.1007/s00468-011-0574-6.

Requesting Print Publications

Publication requests are subject to availability. Fiscal responsibility limits the hardcopies of publications we produce and distribute. Electronic versions of publications may be downloaded, distributed and printed.

Please make any requests at pubrequest@fs.fed.us.

Publication Notes

  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
  • Our online publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unusable.
  • To view this article, download the latest version of Adobe Acrobat Reader.