Benefit or Liability? The Ectomycorrhizal Association May Undermine Tree Adaptations to Fire After Long-term Fire Exclus
- PDF / 1,260,980 Bytes
- 16 Pages / 593.972 x 792 pts Page_size
- 0 Downloads / 146 Views
Benefit or Liability? The Ectomycorrhizal Association May Undermine Tree Adaptations to Fire After Long-term Fire Exclusion Dana O. Carpenter,1 Melanie K. Taylor,1,2 Mac A. Callaham Jr.,2 J. Kevin Hiers,3 E. Louise Loudermilk,2 Joseph J. O’Brien,2 and Nina Wurzburger1* 1
Odum School of Ecology, University of Georgia, Athens, Georgia 30602, USA; 2Center for Forest Disturbance Science, USDA Forest Service Southern Research Station, 320 Green Street, Athens, Georgia 30602, USA; 3Tall Timbers Research Station, 13093 Henry Beadel Drive, Tallahassee, Florida 32312, USA
ABSTRACT Long-term fire exclusion may weaken ecosystem resistance to the return of fire. We investigated how a surface wildfire that occurred after several decades of fire exclusion affected a southern Appalachian forest transitioning from a fire-adapted to a fire-intolerant state. Tree traits associated with fire adaptation often co-occur with traits for nutrient conservation, including the ectomycorrhizal (ECM) association. In the absence of fire, the ECM association may facilitate the accumulation of organic matter, which becomes colonized by fine roots that then become vulnerable to consumption or damage by fire. Therefore, a deeper organic horizon might make stands of fire-adapted, ECM trees less resistant to a surface wildfire than stands of arbuscular mycorrhizal (AM), fire-intolerant trees. To test this hypothesis, we established plots in stands that fall along a gradient of mycorrhizal tree
relative abundance both inside and outside the perimeter of the 2016 Rock Mountain wildfire. With increasing relative abundance of ECM trees, we found increasing organic horizon depth and mass and slower rates of decay, even for litter of ECM tree species. We calculated a major (73–83%) reduction in fine root biomass and length in the organic horizon following the wildfire. Over three years post-fire, we observed a higher probability of crown decline, basal sprouting and aboveground biomass mortality with increasing abundance of ECM trees. We propose that the biogeochemistry of mycorrhizal associations can help explain why fire exclusion makes stands of fireadapted trees less resistant to a surface wildfire than those with fire-intolerant trees. Key words: Wildfire; Disturbance; Reintroduction; Ecosystem resilience; Biogeochemistry; Mycorrhizal fungi; Plant functional traits.
Received 5 May 2020; accepted 12 September 2020 Electronic supplementary material: The online version of this article (https://doi.org/10.1007/s10021-020-00568-7) contains supplementary material, which is available to authorized users. Author Contributions NW, JJO and JKH conceived of the idea. All authors contributed to the design of the study. DOC and MKT performed the research. DOC and NW analyzed data. DOC and NW wrote the paper, with contributions from all authors. *Corresponding author; e-mail: [email protected]
HIGHLIGHTS Dominance of ectomycorrhizal trees was associated with a deeper organic horizon.
D. O. Carpenter and others A wildfire consumed fine roots in the organic
Data Loading...
