Natural Range of Variation in the southern Sierra national forests

So what did the Sierra, Sequoia and Inyo do to apply this planning rule requirement to terrestrial ecosystems?  I’ve just reviewed the draft plan and DEIS, and I don’t think I’ve got a good answer.  They don’t directly say what NRV is or how they determined it (at least in the places I’ve looked).

The Bio-Regional Assessment says this (p. 39):  “NRV only was not used because at this time conditions are far removed from them in terms of fire regime, and even a modest shift toward that level of resiliency would benefit ecological integrity and is more feasible in a short period of time. The planning rule specifically provides for using ecological integrity based on measures other than NRV where this is the case.”

This view is supported by the Planning Handbook (1909.12 FSH 12.14b) (but again, the Handbook does not appear to be supported by the Planning Rule): “In some situations, there is not enough information to understand the natural range of variation under past disturbance regimes for selected key ecosystem characteristics or the system is no longer capable of sustaining key ecosystem characteristics identified as common in the past based upon likely future environmental conditions. In these cases, the Interdisciplinary Team should establish an alternative ecological reference model for context for assessing for integrity by identifying the conditions that would sustain these key ecosystem characteristics.”  However no “alternative ecological reference model” was documented.

For terrestrial vegetation the Bio-Regional Assessment then apparently ignores itself (p. 98):  “Under the 2012 Planning Rule, “natural range of variability” is a key means for gauging ecological integrity. Ecosystem sustainability is more likely if ecosystems are within the bounds of natural variation, rather than targeting fixed conditions from some point in the past (Wiens et al. 2012, Safford et al. 2012). Safford et al. (2013a) compiled comprehensive, scientific literature reviews on natural range of variability, and these are the primary basis for the summary below.”  The summaries conclude whether ecosystems are within or outside of NRV, but they don’t say what NRV is.

The Sierra Assessment says this (p. 17):  “Comprehensive, scientific literature reviews on natural range of variability were compiled. The following is an overview. Consistent with trends across the entire assessment area, terrestrial ecosystems in the Sierra NF are predominantly outside the natural range of variability (NRV) for key indicators of ecological function, structure, and composition. First, nearly half (44 percent) of the area of the Sierra NF dominated by woody vegetation (or 76 percent of montane coniferous forests) is in a highly departed condition with respect to the historic fire return interval, burning at frequencies that are significantly longer than pre-settlement fire regimes (Safford and van de Water 2013). The Sierra NF has missed an average of three to four fire return intervals across all vegetation types dominated by trees or shrubs (Safford and van de Water 2013). Subalpine forests are the exception, burning at intervals that within one or two fire return intervals.”

The Bio-Regional Assessment describes fire history on p. 33, and the Sierra Assessment appears to use historic fire intervals as a reference, but what are the vegetation conditions that would produce the desired fire intervals (which would be the NRV for vegetation)?  I didn’t find a document that says what what vegetation NRV is or how it was determined, or even what the “key indicators” are.  The draft plan does have desired conditions for vegetation, and the DEIS says those are or are based on NRV.  The quickest way to get a feel for these DC=NRV is Tables 1-7 in the draft revised forest plan.

What is NRV for vegetation characteristics?  Are they based on the best available science? Did they properly use historic reference conditions?  What was the reference period? Did they consider climate change?  Are these sustainable desired conditions?  Do they comply with the requirement for ecological integrity?   Do they provide conditions needed for at-risk species? You’d think the answers to these important questions would be easier to find, but I’m out of time.  Maybe someone else can find some answers on the revision website somewhere.


  1. Jon, thanks for digging this up. I don’t have time to dive in for very long.

    FWIW, here’s a paragraph from the Sierra draft plan, Chapter 2. Vision, under Desired Conditions, Terrestrial Ecosystems:

    Forestwide (TERR-FW-DC)
    “Vegetation conditions, particularly structure and composition, are resilient to climate
    change and to the frequency, extent and severity of ecological processes. These include
    fire in fire-adapted systems, drought, and flooding in riparian systems. Functioning
    ecosystems retain their essential components, processes and functions. Native insect and
    disease populations are generally at endemic levels with occasional outbreaks. Vegetation
    structural diversity usually restricts the scale of insect and disease outbreaks to local

    This is aspirational, of course, but at some point ecosystems will regain and retain their essential components, processes and functions. It may be that it won’t have much ponderosa pine, and a lot less sugar pine. Maybe the Sierra will be an oak- and chaparral-dominated forest, and maybe that will be resilient to climate change and to the frequency, extent and severity of ecological processes.

    In any case, maybe the three forests should stop the forest-plan process and shift staff and funding to dealing with the mortality — and future fires and other effects.

  2. Jon,
    You asked:. “What is NRV for vegetation characteristics? Are they based on the best available science? Did they properly use historic reference conditions? Did they consider climate change? Are these sustainable desired conditions? Do they comply with the requirement for ecological integrity? Do they provide conditions needed for at-risk species? ”
    I think I mentioned I participated in a couple of those collaboration groups everyone hates, and everyone from preservationist to commercial logger was asking similar or same. The fact is, I think, is the USFS lacks the resources to answer every question with even a small measure of scientific certainty ( if such a thing exists).
    What we did was to take the “ologists” best guess (sometimes referred to as best available science) for NRV, factored for at-risk species (which nearly always conflicted with each other) and then overlaid the many other Forest Plan directives for everything from slope to riparian.
    It was a morass of conflicting management directives and only best guesses from well meaning specialists.
    After a very long time there was agreement on a proposal that included a wide range of vegetative treatments.
    I’m embarrassed to admit that the whole process makes me wonder if there isn’t substantial merit to Andy’s KISS idea.
    But the point I wanted to emphasize is that I don’t think that the agency can provide satisfactory answers to your questions.
    So if most folks agree that moving from a highly modified unsustainable condition towards a more “natural” one would be a good thing… How do we write a Forest Plan that makes that happen?

  3. Brian, I have actually written something that was intended to help answer these questions:

    I should first point out that your experience sounds like project planning, and this is about forest planning. The main difference is that plans are where you decide what the desired conditions are, and projects are where you figure out how to achieve them. But your question about whether the Forest Service is up to the task is relevant regardless, and the above planning guide doesn’t really try to answer that question.

    What is NRV for vegetation characteristics? The Sierra forests have apparently done the hard work for this, reviewing the research. They just need to say what NRV is. Other forests have done so.

    Is this based on the best available science? Again, they’ve clearly looked at the science (and we’ll assume that includes competing views); they just need to meet the requirement in the planning rule to document why it is the “most accurate, reliable, and relevant.”

    Did they properly use historic conditions? What was the reference period? How did they consider climate change? Again, a documentation task.

    The last three questions are harder because they are about compliance with the substantive requirements of the planning rule. The fundamental assumption is that if you answer these first questions right, you get the last ones right. But the Forest Service can’t assume environmental consequences; it has to evaluate them.

    This is where planning teams seem to hit the wall, but it really requires only two things. First, project future vegetation outcomes (considering both wildfire and management actions and constraints). There are tools to do this (look at Appendix B of the Kootenai National Forest revised plan EIS for their methodology). Then consider the effects of those vegetation conditions on at-risk wildlife (Example I, p. 27 of “Planning for Diversity” shows how this might look).

    The weakest link is probably the knowledge of the relationship between ecological conditions and many species. But that is the essence of the coarse filter strategy that the Forest Service has embraced, so they have to finish the game. They need to project habitat and species outcomes using the best information available in a way that helps decide among alternative approaches. They can’t just punt. And I would add that the uncertainty revealed by this process is a reason why they can not trust everything to the coarse filter, and pretend that it can be a complete substitute for protective standards in a forest plan.

  4. Jon, thanks for the response and clarification. I have questions!!

    You wrote :. ” What is NRV for vegetation characteristics? The Sierra forests have apparently done the hard work for this, reviewing the research. They just need to say what NRV is. Other forests have done so.”

    Isn’t NRV supposed to be defined at a watershed level? If yes, and the agency has actually done this, then I am genuinely impressed and will consider taking back all the bad things I’ve said about Forest planners.
    Second question is on climate change. Has the agency actually specified how they expect the climate to change on a scale that can be measured at the forest level? I admit to being out of the loop for a few years now, but last I knew the agency didn’t have enough past data and usable future predictions ( my term… I’m sure it’s not right…. please forgive and insert correct term) to say.

    Anyway… I didn’t mean to disagree with your original point. Indeed, I think your questions become most relevant in the implementation level.

    In my collaboration experience, when the answer was ‘we don’t have enough data to say what the natural variation/ sustainable/ pre European/ pre modified condition was for this particular watershed, but we * think * it’s ( fill in vegetative class here), oh and by the way, that veg class conflicts with one or two mandates for the special status species currently inhabiting the area….’. Well, that was when we all did a sort of choreographed face-palm!

    • Ecological integrity is the “quality or condition of an ecosystem,” and it is required for “terrestrial and aquatic ecosystems and watersheds.” Again, since the Sierra forests did not document NRV, I can only assume that the research they used was ecosystem-based (based on the fact that desired conditions are specified for terrestrial ecosystems). The Flathead assessment has an extensive discussion of NRV for different characteristics of terrestrial ecosystems (based on an analysis completed in 1999, and relies heavily on HRV). The Forest Service is much less forthcoming about NRV for aquatic systems, rephrasing it as “properly functioning conditions,” but not telling us what those are for different kinds of aquatic systems. From what I’ve seen, downscaling climate change to something that is relevant to forest plans is occurring, but I’m not sure it’s being integrated into NRV (you could also look at how the Flathead addressed this).

      Your last paragraph highlights the whole point forest planning. It was because the original forest plans did not identify desired conditions that you had to do it for each project. If forest plans make that decision for ecosystems, then project planning can be based on “departures” from NRV/desired conditions.

      Rant #1. Now we’re seeing revised plan language that puts off identifying NRV (or desired conditions) until project decisions. That is wrong in so many ways. What have we accomplished with the time and money spent on forest plans if they don’t make this decision? More to the point, plans that don’t make decisions needed to provide ecological integrity aren’t likely to be legal.

      Rant #2. This project “collaboration experience” sounds like the typical Forest Service approach. They pick a spot they want to manage and ask how to manage it (consistent with the forest plan). The answer might be that it’s the wrong spot. The real range of alternatives includes other areas, and collaboration should start at that beginning.

      (A correction to what I said about “Planning for Diversity.” It WAS intended to address the practicality of accomplishing requirements of the planning rule by using examples of “best practices” to date from existing forest planning documents.)

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