Email questions regarding DecAID to barbara.webb@usda.gov. Put "DecAID Question" in the subject line. Answers to frequently asked questions will be posted.
1. Should we still be using the concept of Biological Potential for analysis?
Rose et al. (2001) report that results of monitoring indicate that the biological potential models are a flawed technique (page 602). 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.2. How does DecAID address Forest Plan requirements such as “maintain primary excavator populations to at least 60 percent of their biological potential”?
DecAID is an advisory tool to help managers evaluate effects of forest conditions and existing or proposed management activities on organisms that use snags and down wood. DecAID also can help managers decide on snag and down wood sizes and levels needed to help meet wildlife management objectives (see “What is DecAID ?” on home page).
This tool provides a synthesis of the best available science on dead wood dependent species, dynamics/ ecology of dead wood, and regional vegetation inventory data in one website.
DecAID does not replace standards and guidelines within Forest Land and Resource Management Plans (LRMPs). It does not dictate or prescribe levels of snags and down wood to leave in a treatment unit, planning area or landscape. It does provide the scientific basis for management of decayed wood to meet objectives outlined in LRMPs and analyzing the effects of implementation of those standards and/or objectives (i.e., provide viable populations of dead wood associated MIS). Any deviations from Forest LRMPs must be justified and documented based on the best available science. Prescribing snag levels below existing LRMP levels would require either a non-significant LRMP amendment or a larger scale analysis during revision of the LRMP.
3. When is it appropriate to NOT go through a DecAID analysis – e.g. when we’re not cutting snags? At a certain project size/scope?
All forest vegetation management projects should include a dead wood analysis, even if no snags are being cut or removed. For example, thinning activities capture mortality and increase vigor of stands, thus impacting dead wood recruitment for decades.
There is no management direction requiring that an analysis use and/or reference the information in DecAID. There is management direction requiring the use of the best available science in our NEPA analyses - 36 CFR 219.3 Role of Science in Planning: “The responsible official shall use the best available scientific information to inform the planning process required by this subpart…” While this is technically within the Land Management Planning section (Forest Plan), based on the 2007 memo, it should apply to projects as well. http://fsweb.r6.fs.fed.us/resource-planning-monitoring/documents/20070621-chief-clarified-advice-best-science.pdf.
The information in DecAID synthesizes the best available science into a meta-analysis that can address landscape conditions with the needs of wildlife species. This method has been peer-reviewed and published in a scientific journal:
If you have other sources of information that adequately addresses LRMP standard and guidelines together with the anticipated effects of an action on important wildlife species, you are free to use them. Many users find it more convenient to use the DecAID tool that compiles the best available science, has been peer-reviewed, and stood up to appeals and litigation.
4. What kinds of action and anticipated effects will trigger a DecAID analysis?
If an action will impact a species that utilizes dead wood (snags or logs), it is recommended that the information in DecAID be considered.
If an action will impact the availability of dead wood, currently or in the future, so as to impact the availability of this habitat feature to an MIS, Sensitive or TE species, it is recommended that the information in DecAID be considered.
Examples include: salvage of snags or logs (i.e. the immediate removal of dead wood habitat), the thinning, sanitation, or regeneration harvest of green stands (i.e. the influencing of how soon a live tree dies and remains on landscape to provide snag and log habitat).
5. What is GNN and how is it derived?
GNN (Gradient Nearest Neighbor) is a raster based vegetation layer that covers all forested lands in Oregon, Washington and northern California. GNN used vegetation plot data from the FIA (Forest Inventory and Analysis) Program, Landsat imagery, and other spatial data including climate, geology, topography, and ownership. Through a statistical interpolation each raster (or pixel) is assigned a vegetation plot that is the nearest neighbor in gradient space (i.e., closest geographically, that most closely resembles all spatial attributes).
6. What are the pros and cons using GNN vs. forest-specific datasets?
Forest data sets, including MSN, are usually stand-based. The distribution histograms in DecAID use raster data. You lose the tails of the histograms when you use stand averages, and the tails are extremely important from a wildlife standpoint. We strongly recommend using GNN data to compare against the histograms because GNN is raster based data at the same resolution as the DecAID vegetation inventory data.
7. How big does an analysis area need to be?
Firstly, there is an important distinction between “project area” and “analysis area”. Project areas are usually delineated to encompass the area containing stands to be treated. These areas are usually too small to adequately analyze the impacts of the project on dead wood levels across the landscape. The analysis area needs to be large enough to represent the variation in snag habitat and distribution from which the inventory data were collected. If this is not possible, a comparison between the project area and the inventory data in DecAID is not appropriate. Thus, the analysis area for assessing dead wood will be larger than the project area.
The recommendation in DecAID for the size of the broad landscape is areas be at least 20 square miles in size [12,800 acres per Wildlife Habitat Type]."
8. What is the minimum size of an analysis area when using information in DecAID for project planning?
The minimum scale of 20 square miles (12,800 acres, 5,120 ha) per vegetation condition is necessary. 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. However, 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, using the vegetation inventory data gives you much more flexibility in applying snag and down wood densities to a project area than just using the wildlife data.
9. Can I have my stand exams tell me the current level of snags and logs?
Most stand exam data give you stand averages which aren’t very helpful to collect additional data for use in a DecAID assessment. The data in DecAID, both wildlife and inventory data, are plot level with the high variability of clumps of snags and plots with no snags retained in the information. For example, conventional stand exam data may not give you information on those high density clumps of snags used by wildlife species for nesting.
Also stand exams may be inherently biased towards areas with commercial value, and extra care would have to be taken to ensure no bias and a level of randomness in order to get information on a landscape scale. If you can assure you are capturing the variability (clumps, etc.) then there may be a way to use stand exams.
Although some feel that GNN data is not as good as stand exam data, it is important to remember that the GNN data in DecAID and its use with DecAID information has stood up in court and litigation.
10. What is the appropriate S-Class to use for bug-killed lodgepole pine and mixed conifer stands that are > 10 years post-disturbance?
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.
Urban myth: a story or statement that is not true but is often repeated and believed by many to be true (Cambridge Dictionary).
Urban myths regarding DecAID:
1. DecAID is only for salvage projects.
Untrue. DecAID can be used to inform the analysis regarding any impact to dead wood habitat (i.e. snags and logs) and the wildlife species that use it. It can be used for green sales and salvage sales. It can be used for any project that impacts the availability of snags and logs in the short or long-term.
2. Use of DecAID is required.
Untrue. DecAID is not direction. It is a tool to use that has stood up through litigation, and the information within it is updated with best available science. Its use is recommended.
3. DecAID is prescriptive; meaning it tells you what you need to leave regarding dead wood size and density.
Untrue. Data within DecAID is not the final word on what it to be left on the ground. It is information whereby rationales for effects and recommendations or mitigations are made stronger.
4. I’m not cutting any snags, so I don’t need to use DecAID.
Maybe. Use of DecAID is not mandatory, but not simply because you are not cutting snags. The information in DecAID can help with the analysis of any activity that impacts the availability and development of snags and logs (e.g. thinning, ladder fuels reduction).
5. There is so much dead wood habitat out there from previous mortality events that it’s not a concern.
Maybe. What does that amount of dead wood mean for the wildlife species you are analyzing? Are these high densities of dead wood common on the larger landscape? DecAID can help you answer these questions and verify/support the conclusion that dead wood habitat may not be a concern.
6. DecAID is a model.
Untrue. A model implies that data is entered and a result is generated. DecAID serves as a compilation of statistical summary, review of published literature, and statistical synthesis available in one website.