In separate comments published in the journal Science, two groups of researchers from Oregon State University and the USDA Forest Service will exchange perspectives on the issue of post-wildfire salvage logging, forest regeneration and fire risk that were the source of considerable controversy earlier this year.
In a publication last January by researchers from OSU and the Forest Service, based on a study of areas burned in Oregon's Biscuit Fire in 2002, researchers had concluded that post-fire logging resulted in significant mortality of natural conifer regeneration, and created conditions that could lead to fires of greater intensity in the near-term future.
That paper and its findings were the subject of a significant debate in recent months, including Congressional committee hearings. In particular, a second group of scientists in the OSU College of Forestry and the Forest Service Pacific Southwest Research Station questioned the methodology, interpretations and conclusions of the study as they were reported.
Those issues are being revisited in more depth by both groups in a peer-reviewed commentary and response to it in the upcoming, Aug. 4, issue of Science. A third commentary is also being provided in that publication by Washington Congressman Brian Baird.
The technical commentary was authored by six scientists from the OSU College of Forestry, two scientists from the Pacific Southwest Research Station and the retired lead ecologist from the Siskiyou National Forest where the Biscuit Fire occurred.
It says that the original paper did not adequately report forest management objectives for the sites being studied; did not describe the plant association, site variables, logging methods, weather, distance to seed crops, or extended delay in logging after the fire; made inappropriate assumptions about the survival of seedlings in the face of harsh conditions and competing vegetation; and said that some of the conclusions about future fire hazards are unsupported speculation, making interpretation for policy makers, the public and other scientists difficult.
"Caution is urged when projecting forest development from such early conifer survival results," the scientists said in their commentary. "Competing vegetation can develop rapidly after a disturbance in this region, and can dramatically affect small conifer seedling survival and growth."
Other points made in their paper included:
- Regeneration damage when prompt salvage is delayed was reported by others over 50 years ago.
- It is inappropriate to compare 1-2 year old seedling density with the "free to grow" stocking standards required by regulatory agencies, which by definition refers to larger, older trees, and their distribution.
- In this case, little effort was made in postfire harvest to avoid seedling damage, since the management plan called for prompt salvage and subsequent replanting. Logging equipment and practices are available to reduce seedling damage if that is a goal of the harvest.
- Artificial reforestation practices are science based and well tested in this region, and the performance of planted seedlings commonly exceeds that of natural seedlings.
- Management objectives called for increasing downed wood during salvage logging on some sites, and some of the increases in downed wood after logging may have been an intended result for purposes of soil protection and wildlife habitat. However, from the original report it is not possible to discern this.
- Conclusions about fuel loadings did not adequately consider fuel continuity or projected fire behavior, and the statement, as reported, that future fire hazard is less from deteriorating standing trees than from post-salvage downed wood is not supported scientifically.
The response to the technical commentary was authored by five scientists from the Department of Forest Science and Department of Fisheries and Wildlife at OSU, and a fire ecologist from the Forest Service Pacific Southwest Research Station. It provided additional details of the research setting and its scope, and emphasized the strength of the study design and conclusions.
It says that short-term data from well designed studies such as the original paper can be very valuable; that caution should be exercised when extrapolating what we know about live-tree harvest to post-wildfire situations; that strong study designs such as this effectively isolate the response to post-fire logging, by itself, from the reponse to multiple post-fire treatments; that the original study focused on early conifer establishment and its importance, not long term conifer survival; and that high intensity fire, which is a major management concern in this area, is directly related to fine downed-wood loads.
"Although Newton and Baird provide no compelling evidence to refute our findings, we are pleased with the opportunity for dialogue and to expand on our article," the researchers said in their reply. "We reported that post-fire logging 2-3 years after the 2002 Biscuit Fire was associated with significant mortality in natural conifer regeneration and elevated potential fire behavior in the short term. We did not draw further conclusions about long-term effects of postfire logging."
Other points made in their response included:
- The original study was one part of a larger, longer-term project.
- The comments made about the original paper provide no data or compelling evidence that diminish or refute the original findings.
- Multiple independent reviews by professional statisticians confirmed the conclusions of the original study.
- The reference made to stocking standards in the original paper was meant as a benchmark for comparison only; in addition, under federal stocking definitions, it's quite acceptable to count young trees, not just those that are older and free to grow.
- The effects of logging on regeneration they reported were similar to results published before and after their original paper, including studies of both prompt and delayed salvage.
- In conclusions about fire intensity, the original paper referred primarily to higher levels of downed fuel after logging, not fuel continuity -- but in any case, fuel continuity is generally implied in standard fire models.
- The suggestion that leaving dead trees standing could result in lower fire hazard is a reasonable hypothesis, in part because no scenario produces a larger pool of fine fuels than a single one-time input from felling of all trees shortly after a fire.
- Their objective was not to assess the management plan, but to quantify the effects of post-fire logging on fuel loads.
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