Last week, I attended a science and stewardship conference of The Nature Conservancy in Madison, Wisconsin. It was an inspiring and thought-provoking week. There were a lot of topics that will provide fodder for future blog posts, but I wanted to start with an issue that came up in several sessions. The topic had to do with setting appropriate objectives for conservation strategies, and for land management in particular. In short, it’s really important to make sure we’re not setting objectives that are focused on strategies rather than outcomes.
Here’s an illustration of what I mean. If I was planning a vacation for next summer, I probably wouldn’t start with the following question: “What mode of transportation should I take on my vacation next year?”
Clearly, it’s tough to answer that question without knowing more about the ultimate objectives of the vacation. Where do I want to go? What time of year am I going? How many people are going with me? If I’m planning to travel from Nebraska to Ireland, I probably won’t be able to do that by bus. I could conceivably travel by motorcycle (if I had one) to the Rocky Mountains, but probably not if I was going during the winter or planning to take little kids with me.
It seems silly to start by thinking about how to get somewhere before deciding where to go, but as land managers, it’s easy to fall into exactly that mindset. We sometimes set objectives about using fire or grazing, for example, instead of first defining the outcome we want and then thinking about what tools and strategies might get us there (which may or may not include fire or grazing). In this post, I’ve provided examples of how this trap can present itself, both to managers of conservation land and private landowners, and some thoughts about how to avoid the trap.
Significant research has helped us understand the kinds of fire and grazing patterns under which North American prairies developed. For example, in many places, we have a pretty good idea how often a particular site burned, on average, before European settlement. We also have reasonably good information on the presence, abundance, and behavior of historic grazers. Based on that information, a land manager could decide that the best management for their prairie would be to reinstate, as closely as possible, the timing and intensity of historic fire and grazing that site likely evolved under.
Patch-burn grazing is often described, for example, as “mimicking historic fire and grazing patterns.” Mob grazing advocates trumpet (though I’m skeptical) that their system replicates the way bison moved across a landscape. Some in the Upper Midwest region of North America point to research showing high populations of indigenous people and scarce evidence of abundant bison and argue that their prairies should be managed only with fire. We can argue about all three of those examples – and many more – but the bigger point is that none of those arguments should determine our management strategies. Again, we shouldn’t be setting objectives about the strategy we want to use without first identifying the outcome we want.
To make a clunky return to my vacation travel analogy, it would be silly of me to choose horseback as my preferred mode of transportation across the Great Plains to the Rocky Mountains just because it’s what worked several hundred years ago. Today’s landscape is broken up into countless fenced off private land parcels, which would make cross-country horse travel difficult, to say the least. In addition, there is a pretty nice set of modern opportunities (roads and vehicles) I can take advantage of nowadays.
Likewise, our prairies exist within a different world today, with a new set of challenges and opportunities. Mimicking historic disturbance regimes won’t necessarily keep prairies in good shape in a world with habitat fragmentation, massive invasive species pressure, climate change, nitrogen deposition, and other factors. And speaking of good shape, our first and primary concern should really be to define what “good shape” is, right? Are we managing for plant diversity or a few rare plants? Are we trying to sustain diverse bird populations? Habitat heterogeneity? Is ecological resilience the goal? If so, what are the factors driving resilience, and how to we sustain those? There are countless reasonable goals for land managers to choose from, many dependent upon scale, but those goals should be based on the outcome we want.
I feel it’s important to say this here: I am a big proponent of both fire and grazing as management tools – you can find myriad examples of that by searching through my previous blog posts. However, while I think combining fire and grazing can create some fantastic results, those strategies/results don’t fit all objectives. More importantly, your particular site may or may not respond well to those kinds of fire and grazing combinations.
Let’s say your primary objective is to provide habitat for as many species of grassland birds as possible. First, you’ll need a pretty big swath of land – many bird species have minimum habitat size requirements. Assuming you’ve got sufficient land, the major factor grassland nesting birds respond to is habitat structure. Some birds prefer tall thatchy structure, others like short/sparse vegetation, and others want something in-between. A reasonable outcome-based objective might be that you want to provide all three of those habitat types across your prairie each year (and you’ll want to make sure the habitat are being successfully used by a diverse bird community). Perfect. Now, how will you create those habitat types?
Fall or spring fires can create short habitat structure that some birds really like to nest in. However, some bird species (e.g., grasshopper sparrows) usually like short habitat with a little more thatch in the ground layer than is usually found in recently burned prairies. Also, while burned areas are short and unburned areas are tall, it’s difficult to create in-between height/density habitats using only fire. This is where other tools such as mowing and grazing might be helpful. Mowing can reduce the height of tall vegetation and create short or mid-height structure that grasshopper sparrows, meadowlarks, and other species prefer. Grazing can do the same and can have the advantage that cattle or bison are selective grazers, eating some plants and leaving others. This can create structure with both tall and short vegetation mixed together and can also help suppress grasses and allow for greater expression of forbs (broadleaf plants) – something birds such as dickcissels often prefer.
If we’re trying to create optimal bird habitat, then, fire, mowing and grazing might all be useful tools to consider. It’s important to understand how each tool can be used to affect habitat structure, as well as the potential risks of using each (fire can sometimes kill aboveground animals and stimulate invasive plants, grazers can sometimes target vulnerable plants and create issues via trampling). With all of that information, you can start putting together strategies that employ the right tools, and then test those strategies against the OUTCOMES you desire. Notice that the process I’ve just described is independent of the kinds of historic fire returns for your area or whether or not you think grazing was a significant factor in the evolution of regional plant communities. Define your objective by the outcomes you want and test/adapt strategies based on that objective.
Other examples: At my family prairie, we aren’t using prescribed fire because we’ve been able to use grazing to meet our objectives of habitat heterogeneity and increasing plant diversity, and we use loppers/herbicide to successfully control woody invasion. In small prairies where preserving particular plant species is the objective, a strategy using only fire or mowing could be most appropriate. If that small prairie has rare insects or reptiles that are especially vulnerable to fire, maybe mowing is the best tool. Regardless, the right tools and strategies depend upon the outcome-based objective.
For ranchers and farmers who manage prairies, this same objective setting process should apply, but of course those prairies also have to help provide sufficient income to keep a family or business thriving. Even in those cases, however, it’s still important to start with outcome-based objectives. Those objectives can include a certain amount of needed income but should also include specific habitat or other ecological objectives. Once you’ve decided, for example, that you really want to manage in a way that provides a certain amount of quail habitat or provides consistent pollinator resources through the season, you can look for ways to accomplish that while still providing the needed income. When a conflict between income and habitat objectives arises, you can make the decisions that make sense to you, but at least you’re making those decisions with all the information needed to fully consider the options.
There are plenty of reasonable prairie management objectives to choose from, but they should be based on outcomes rather than on tools and strategies. Employing more frequent prescribed fire is not a good objective. However, using more frequent prescribed fire might be a great strategy to reach a particular outcome. (It could also be a terrible strategy, depending upon your objective.) Don’t fall into the trap of choosing your transportation method before you know where you want to go.
P.S. I’m sure some of you are thinking it, so let me address what might appear to be a weakness of my vacation transportation analogy. Yes, it’s perfectly fine to start vacation planning by deciding that you want to take a cruise ship or motorcycle if the OUTCOME you really want is to ride on a ship or motorcycle. If you don’t care where you go, the destination isn’t the outcome, it’s just a by-product of your mode of travel. Fine. But I think you understand what I was trying to say, right? Sure, you could argue that conducting prescribed fires could be your objective if all you want is a legal way to light things on fire and watch them burn. If that’s your objective, though, you’re not managing prairies, you’re lighting things on fire – and there’s a big difference. Ok? Ok.