Skip to Main Content
Acute physiological stress and mortality following fire in a long-unburned longleaf pine ecosystemAuthor(s): J.J. O’Brien; J.K. Hiers; R.J. Mitchell; J.M. Varner; K. Mordecai
Source: Fire Ecology 6(2)1-12
Publication Series: Scientific Journal (JRNL)
Station: Southern Research Station
Download Publication (615.38 KB)
DescriptionOne important legacy of fire exclusion in ecosystems dependent upon frequent fire is the development of organic soil horizons (forest floor) that can be colonized by fine roots. When fire is re-introduced, the forest floor is often consumed by fire and heavy overstory mortality, often delayed by months, results. We hypothesized that the delayed post-fire tree mortality is a manifestation of a cascade of physiological stresses initiated by root damage that can also magnify the impact of other kinds of damage. We investigated the physiological impact of forest floor consumption on longleaf pines (Pinus palustris Mill.) subjected to a wildfire in 2005 in a long-unburned (>50 years) forest by measuring forest floor consumption, whole tree water use, and leaf chlorophyll content. Ten of the 23 study trees died within three years post fire. Post-fire sap flux was unrelated to crown scorch, but was negatively correlated with forest floor consumption. A segmented linear regression revealed declines in sap flux until a threshold of 31 % forest floor consumption, after which further consumption had no additional effect on tree water use. Trees with >30 % forest floor consumption beneath their crowns were more than 20 times as likely to die as those with less consumption. Chlorophyll content in needles that flushed post fire was negatively correlated with crown scorch (R² = 0.60, P = 0.009) though all trees with scorch also experienced varying degrees of forest floor consumption. Our results suggest that the consumption of the forest floor with the likely concomitant loss of roots initiated a decline spiral, driven by an inability to supply sufficient water to the crown. Though we did not measure loss of stored carbohydrates in consumed roots directly, we infer that this likely effect, coupled with decreased crown photosynthetic capacity, eventually resulted in substantial overstory tree mortality.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationO’Brien, J.J.; Hiers, J.K.; Mitchell, R.J.; Varner, J.M., III; Mordecai, K. 2010. In press. Acute physiological stress and mortality following fire in a long-unburned longleaf pine ecosystem. Fire Ecology 6(2)1-12.
Keywordschlorophyll, crown scorch, duff, forest floor consumption, Pinus palustris, transpiration
- Recent advances in understanding duff consumption and post-fire longleaf pine mortality
- Overstory tree mortality resulting from reintroducing fire to long-unburned longleaf poine forests: the importance of duff moisture.
- Development of post-fire crown damage mortality thresholds in ponderosa pine
XML: View XML