Frequently Asked Questions

Email questions regarding DecAID to Put "DecAID Question" in the subject line. Answers to frequently asked questions will be posted here.

Question: What is the minimum size of an analysis area when using information in DecAID for project planning?

Answer: The minimum scale of 20 square miles is necessary if using the vegetation inventory data. In the case of large fires or insect outbreaks, a larger analysis area may be necessary. At a watershed scale it may appear that there is an excess of dead wood because many disturbances are as large, or larger, than the watershed scale. But, it may still be a rare occurrence at the regional or sub-regional scale, the scale at which the vegetation data were collected.

If you are just using the wildlife data, you can use a smaller scale. The wildlife data were collected at the stand scale to describe stand or plot level habitat use. However, use of the vegetation inventory data give you much more flexibility in applying snag and down wood densities to a project area than just using the wildlife data.

Question: Should we still be using the concept of Biological Potential for analysis?

Answer: The eastside screens still mention biological potential but also state that we need to use the best available science - the biological potential model does not meet the "best available science" standard. The NW Forest Plan also refers to biological potential, but uses it as a placeholder until better information can be developed. The LRMP standards based on biological potential still need to be met as a minimum, but this shouldn't conflict with use of the best available science. Clearly state that you are meeting your LRMP standards as a minimum, but also clearly state what the best available science indicates for snag management.

Question: Can data from unharvested inventory data be used as a reference condition given that unharvested does not equal unmanaged? Fire suppression has affected many of our forests.

Answer: Data from unharvested plots can be used as a reference condition to approximate natural or historic conditions of dead wood. However, there is a caveat to using this approach in eastside dry forests. On the eastside in particular, current levels of dead wood may be elevated above historical conditions due to fire exclusion and increased mortality, and may be depleted below historical levels in local areas burned by intense fire or subjected to repeated salvage and firewood cutting. Plot data from unharvested forests on the westside, where fire return intervals are longer, may provide a reasonable approximation of historical conditions.

There is debate among professionals on the impact fire exclusion has on dead wood relative to natural or historic conditions. Thus, DecAID also presents information in the summary narratives from research studies and inventories about natural and/or historic conditions where available. This additional information can be used to assess appropriateness of using data from unharvested plots to determine reference conditions, and to help identify knowledge gaps and areas of needed research.

Even with the caveats associated with applying inventory data to eastside forests to determine reference conditions, we still recommends using the data because:

  • They are still some of the best data available to assess natural or historic conditions of dead wood, even in eastside dry forests.
  • They are the only available data showing distribution and variation in snag and down wood amounts across the landscape.
  • The data from unharvested stands are in the range of other published data on natural and historic levels of dead wood even in the drier vegetation types.

For a full discussion see HRV Dead Wood Comparison

Question: What is the appropriate S-Class to use for bug-killed lodgepole pine and mixed conifer stands that are > 10 years post-disturbance?

Answer: This is a challenging situation ... there are no good data for these stands. Post-fire wildlife habitat information for EMC stands is not applicable to this situation ... all those data points are from stands < 10 years and most < 5 years post-disturbance. And there is no post-disturbance wildlife data for LP. For the other structural conditions, the BBWO and TTWO data from Goggans et al. (1988) doesn't give snag densities so that doesn't help either. If canopy closure in LP is >10% the stands would fall into the LP Small/medium tree class. That leaves marten (AMMA) data as the only data for wildlife, though there is inventory data for this type

The best solution is to rely on the information available on life history of BBWO and TTWO indicating that they use high densities of recently dead trees (while beetle populations are high). Also discuss AMMA use of snags, but mostly down wood. Use the literature on these species that are in DecAID to help with this discussion.

In addition, show how other areas of the landscape are providing habitat for these species. Compare these data to the distribution histograms to show if there are adequate areas with high densities of snags and down wood on the landscape.

Back to Top