I love a good analogy. I find analogies can help me express ideas in ways other people can relate to. At the same time, I’m definitely guilty of sometimes fighting too hard to make an analogy fit, or relying too much on analogies to make a point that doesn’t need help being made. It kind of reminds me of when you go shoe shopping and the shoe you really want is only available in the half size below what you usually wear. It’s really tempting to just buy that smaller shoe, even though it doesn’t quite fit. Is there enough upside to getting that particular style of shoe to offset the costs of buying it and being uncomfortable? Also, how did I end up talking about shoes?
This week, as I was putting the final touches on a presentation, an idea popped into my head and I’ve been wrestling with it ever since. The presentation is about plants that are often labeled as weeds but are actually crucial role players in the recovery of prairies from disturbances. Those ‘opportunistic’ plants are always poised to respond quickly when fire, grazing, drought, or some other force temporarily weakens the dominant grasses and other vegetation in a prairie.
My objective for the presentation is to point out that these plants aren’t aggressive or in need of control. They are responding to a disturbance, not causing it. In a way, I realized, the process is similar to the way our body reacts when we cut ourselves. There’s a built-in response (blood clotting) that prevents the wound from continuing to bleed or get worse. Eventually, a scab forms and holds everything together while the wound heals. Those opportunistic plants are kind of like a scab…
Wait a minute, I thought. I’m trying to make these plants sound positive. Is equating them to a scab really the way to shine a positive light on them? It’s not like scabs are something most people celebrate. In fact, people tend to pick at them and pull them off… Oh. Oh! That’s even better!
Some landowners, when they see part of their pasture become ‘overrun’ with ragweed, annual sunflowers, or something similar, are tempted to try to kill off those ‘weeds’. Often, that involves something pretty drastic like broadcast herbicide spraying. It’s a counterproductive strategy because it removes the plants that were helping the plant community recover from the disturbance.
IT’S JUST LIKE PICKING A SCAB!
When you pick a scab, you reopen the wound, causing the pain and bleeding to restart. It’s better to just let the scab be and let the body do what it’s set up to do – heal itself. Besides, you’re not getting rid of the scab. It’s just going to re-form for the same reason it formed in the first place.
When you spray the ‘weeds’ that are stabilizing a disturbed plant community, you restart the disturbance. And what plants are going to respond best to that disturbance? The same ‘weeds’ you just killed – or other species that play the same kind of role.
That’s a pretty good analogy, if I do say so myself. There’s only one major flaw. Equating a flush of opportunistic plants to blood clotting and the formation of a scab makes it sound like disturbances like fire, grazing, or drought are somehow hurting the prairie, which is an idea I’ve tried to push back on. Those disturbances, including extended periods of grazing or drought, can be an important part of maintaining prairie diversity, both by keeping the plant community diverse and by providing a full range of habitat conditions for animals. Disturbances define prairies, they don’t harm them.
Over the years, I’ve legitimately angered some prairie people – especially botanists – by advocating for management that includes cycles of fairly intensive disturbance, followed by recovery. They disagree with my stance that those cycles bolster the biodiversity and resilience of prairies and argue that they degrade the quality of the plant community. It’s a healthy discussion and I’m not going to try to recap that whole argument here. Let’s just say that me equating prairie disturbances to injuries isn’t going to help my case.
…But it’s such a good analogy otherwise!
Just for fun, I went to Wikipedia and found a description of four basic stages of wound healing. Here they are (heavily paraphrased and simplified), along with some possible parallels from prairies and their recovery from disturbance:
Stage 1 – Hemostasis. This is when blood clotting starts to plug the break in the blood vessel and stop the bleeding. The resultant scab also covers the wound and facilitates the next steps of healing.
Prairie parallel: Seeds of annual and biennial plants germinate and quickly become established, taking advantage of the extra sunlight and reduced competition from surrounding plants. Some opportunistic perennial plants also respond positively to reduced competition, growing larger and blooming more prolifically than in previous years. All those plants create a canopy over bare soil and also spread their roots belowground, helping to prevent soil erosion, carry on nutrient cycling and provide important habitat for animals.
Stage 2 – Inflammation. White blood cells rush to the site and engulf/destroy bacteria and other pathogens, along with damaged cells.
Prairie parallel: High numbers of invertebrates are drawn to the disturbed site. They are attracted by both the habitat structure (sparse ground cover with a diffuse overhead cover of opportunistic plants) and the abundant resources (pollen, nectar, seeds, and more) provided by that copious new plant growth.
Stage 3 – Proliferation. The tissues damaged in the wound begin quickly re-growing. The wound is also contracted as the edges are gripped and pulled back together by myofibroblasts (there’s a word!).
Prairie parallel: The perennial grasses weakened by the disturbance begin quickly re-growing. The process starts slowly because the plants have depleted roots and energy reserves, but as their leaves grow they can pull in more energy, which allows for even faster growth. Spaces between perennial grasses contract as those plants send out rhizomes and re-expand their footprint.
Stage 4 – Maturation (remodeling). The structure of the tissues is re-established and cells that are no longer needed are removed by programmed cell death.
Prairie parallel: Competitive perennial plants re-establish their dominance and opportunistic plants fade away. Annuals and biennials die after they complete their life cycle (‘programmed cell death’?) and less competitive perennials hunker down and try to conserve energy until their next opportunity to thrive.
It’s good, isn’t it? The analogy fits well with the way prairies respond to disturbances, especially extended periods of drought or grazing that really set back dominant plants. I’m particularly happy with the ‘pulling off the scab’ part because it reinforces the idea that those opportunistic plants are doing an important job. They aren’t an injury, they’re a sign of healing from an injury caused by something else. Let them play their role. (Also, here I go again equating prairie disturbances to injuries…)
The prairies I’m most familiar with thrive under a management approach that includes extended periods of intensive grazing, followed by even longer periods of recovery. We have data that shows our plant communities are maintaining their diversity and we (and many others) have shown how animals benefit from the heterogeneous habitat created by that approach. You can read more on this topic here and here. Prairies are incredibly resilient. We just have to make sure we give them the opportunity to adapt to and recover (if that’s even the right word) from the periodic disturbances that created and have sustained these diverse, dynamic communities.
At the same time, that approach isn’t right for every prairie or situation. Smaller prairies and prairies that have rare populations of plants or other species need to be managed more carefully. The best long-term solution is to make those prairies bigger and more interconnected through restoration, but that’s easier said than done. In the meantime, management of those small prairies is fraught with difficulty, though trying to create some degree of habitat heterogeneity is probably still worth the effort. There is plenty of legitimate discussion to be had about how to balance all of that.
Regardless, when a prairie experiences a disturbance that temporarily reduces the vigor of dominant plants, it has an intrinsic process for responding. As it happens, that phenomenon has some similarities to the way our bodies respond to being wounded. In both cases, the best response is to let the process play out. Instead of fretting about ‘weeds’ or scabs, we should celebrate the roles they play within complex and beautiful systems that keep both prairies and humans healthy.