Why Pinyons and Junipers Are Where They Are or Were Where They Were: Many Possibilities

This study says that PJ coming into sagebrush is not good for sage grouse. https://www.sciencedirect.com/science/article/pii/S1550742416300811

Last week I ran across two studies (a paper and a presentation) that both illustrate what I think it an important point. When we look at what happened in the past (usually from photos, or history books, or what’s there today) and see changes, we don’t know for sure if that is due to (1) previous people doing things (Natives and settlers), or (2) what happened when previous people stopped doing things, (3) vagaries of weather/climate or (4) other causes.

Last week I attended a Colorado State University featuring Dr. Marina Redmond, talking about pinyon-juniper woodlands and their expansion and contraction. The first point that she made is that there is an enormous range, and each situation/place is different. In some areas, PJ is expanding, and in other areas contracting, due to drought-induced mortality. According to this paper the mortality in pinyon is due to Ips species, and in juniper due to “plain old” drought stress.

If you just look at PJ expansion, you might think it’s due to fire suppression, which has changed over time. But it might also be caused by wetter conditions that were good for tree seedling establishment. Or it might even be that there was overgrazing in the past, which established conditions (little grass cover) in which PJs got a chance to take hold. It could even be a combination of several of these factors. Or in more generic terms, climate change (that is change mostly before what we call anthropogenic cc based on GHGS), post-disturbance recovery (I guess these would be “natural” disturbances, but perhaps these may not be obvious 100 years later), and changes due to human interventions (say, removing bison, adding cattle) and recovery from human interventions. Humans have a long history in the Southwest. Then, when you get into interactions among these, it seems like it would be hard to know for sure, and perhaps even harder to find (1) an ideal target NRV that people agree on (2) the FS can afford to intervene to produce and that (3) will be resilient to climate change.

It seems to me that keeping endangered species around (as in the study shown in the image above), producing useful things for wildlife and people (and cows) like forage and pinyon nuts, and at least thinking about resilience to climate change are challenging (and expensive) enough for land managers without introducing ideas like NRV or HRV. Perhaps the above observations in PJ are an example of what Millar and Woolfenden point out as “conceptual and practical” problems with ideas such as NRV.

While there are many important lessons to learn from the past, we believe that we cannot rely on past forest conditions to provide us with blueprints for current and future management (Millar et al 2007). In particular, the nature and scale of past variability in climate and forest conditions, coupled with our imprecise ability to fully reconstruct those conditions, introduce a number of conceptual and practical problems (Millar and Woolfenden 1999a). Detailed reconstructions of historical forest conditions, often dendroecologically based,
are very useful but represent a relatively narrow window of time and tend to coincide with tree recruitment in the generally cooler period referred to as the little ice age (figure 1). As such, manipulation of current forests to resemble past conditions may not produce the desired result when considering future climates.

This quote is from this paper by Stephens, Millar and Collins (2010). I’d only add to that list “the nature and scale of past variability in human actions and our imprecise ability to fully construct” them.

3 thoughts on “Why Pinyons and Junipers Are Where They Are or Were Where They Were: Many Possibilities”

  1. Why do I feel this is aimed at me? (Have you noticed nobody else seems to care much about NRV?) I’m not going to argue on behalf of the Forest Service, or the scientists that they listened to, when they proclaimed in the 2012 Planning Rule that natural range of variation (modified for expected future climate) is the best way to achieve required sustainability. It’s all in the record.

    If you are thinking back to the Pine Valley Project, I would just say this. They were proposing to get rid of large pine and juniper trees. That has to be based on a sustainable desired condition. They have to make their case for fewer trees based on something. They didn’t say what it was, but if it’s something other than NRV they’ve got some extra explaining to do.

    I could generalize and say that any active management must mean that the current condition is not the desired condition, and the manager is obligated to make the case that management is needed. And they have to do that within the existing legal framework, which is now NRV.

  2. No I am absolutely not talking about you.

    I don’t think people will care much about it until it is used to make decisions in forest plans that they disagree with (or travel management , or ??). At that point, depending on whose ox gets gored and whether they have a substantial litigation budget, we’ll see how it goes. I, like you, was involved in the development of the Rule, and know the record and participated in many discussions during the process.

    It’s either important and worth discussing, because it’s our current legal framework and the basis for National Forest management, or it’s not.

    What I’m trying to show is that some scientists believe that (magically?) NRV will provide ecological sustainability (the evidence seems to be citing papers that make those claims), and other scientists think it’s more complicated than that.

    I happen to belong to one of the more questioning disciplines, a view that seemed not adequately considered in my review of the documents.

    My concern, as a scientist, with this is that it is ultimately impossible to go back in time. We will choose some things to return and not other things. I’d like these to be informed not only by NRV, but more specifics as to what these interventions will do given today’s conditions, and which conditions/species are favored, which not, and why. I think those trade-offs and choices should be done transparently, with as much advice from as many different disciplines as possible and with the public weighing in on the trade-offs as well.


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