Does anyone else remember the old Atari game Missile Command? It came out in the early 1980’s – back when computer graphics consisted of pixels roughly the size of the keys on the keyboard I’m using to write this. For those unlucky people too young or too old to remember the game, here’s a quick summary…
In the game, the player’s job was to defend six cities (consisting of about 8 pixels each) from an increasing number of missiles coming out of the sky above. Those missiles were represented by long jagged lines that lengthened inexorably toward the cities below. To save the cities, the player had to place the cursor below the “missiles” and push the button on the joystick at just the right time to create an explosion (consisting of about 8 pixels) that would destroy the missile. There was limited ammunition available each round, so too many misses and the player had to watch helplessly while the remaining missiles destroyed his/her cities.
Each round of the game was increasingly difficult, with more and more missiles falling from the sky at higher and higher rates of speed. There was no winning the game (at least for me); the hope was to get through as many rounds as possible before the inevitable destruction of the poor cities below. It wasn’t the most enjoyable game I’ve ever played, but there weren’t a lot of other video game choices back then so I played it quite a bit.
Why am I writing about a 1980’s video game on a prairie blog? Well, I was reminded of the game the other day while listening to a conference presentation about tree encroachment in prairies. Dirac Twidwell, from the University of Nebraska-Lincoln was making the case that we should be directing conservation funding to prevent trees from becoming abundant in parts of Nebraska where they are still relatively scarce. Instead, we often focus on helping landowners clear trees from landscapes already full of trees in all directions. In those heavily infested places, the fight to prevent trees from invading prairies (or reinvading previously-cleared prairies) becomes really difficult. Hordes of seeds can come into those prairies from all directions and often overwhelm the most valiant efforts to stay ahead of them.
That’s when Missile Command popped into my head. It seemed a perfect (ok, pretty good) metaphor for the effort to prevent woody encroachment in prairies embedded within a landscape full of trees and shrubs. My mind wandered from what Dirac was saying (sorry Dirac!) and I decided to see how far I could take that video game metaphor. This blog post is the result.
There are three points I’d like to make about Missile Command and prairie conservation (that’s a sentence I never thought I’d write). The first is that I agree with Dirac’s main point. We need to be focusing much more effort on landscapes where tree encroachment has not yet become extreme. In those areas, the number of missiles (new trees or shrubs) coming at us is still manageable, and we can make it even more manageable by working to reduce the number of seed sources.
Eastern red cedar expansion is a big problem in Nebraska, and is exacerbated by the fact that we still plant cedar trees for windbreaks and shelterbelts, providing bases from which bird-dispersed seeds (missiles) can spread into the surrounding countryside. It would be great if we could stop planting cedars, of course, but if we are going to continue planting them, we should at least get more serious about killing off their progeny while they’re still small and relatively easy to destroy. The longer we wait, the more it becomes like later rounds in Missile Command, trying to catch more and more new trees with limited capacity.
There are landscapes in Nebraska and other prairie states where the scenario already resembles the latter rounds of Missile Command. There are numerous trees and shrubs in all directions, including eastern red cedar, but also many others like Siberian elm, honey locust, Russian and autumn olives, sumac, dogwood, and more. Keeping a quarter section of prairie free of trees is an intensely difficult job because missiles constantly bombard the area from all directions. In that situation, we have to stop trying to fight with the same strategies we used when trees were much less abundant. In video game parlance, we have to find a cheat code.
That’s my second point. When we’re in situations where tree and shrub invasion feels overwhelming, we need to change tactics. Trying to keep increasing the time we spend on old strategies isn’t sustainable.
For example, prescribed fire can be much more efficient at killing large numbers of eastern red cedar trees than cutting every individual tree with a pair of loppers, chainsaw, or skidsteer-mounted tree shear. Fire isn’t the easiest strategy to employ, but it sure can hit a lot of trees at once. If deciduous shrubs like sumac or dogwood are the problem, burning on a three or four year frequency (because we’ve decided that was the average historic frequency) probably isn’t going to be successful, at least here in Nebraska. More frequent and more intense fires might be needed, and/or herbicide application will need to be part of the equation.
At heavily infested sites, it might be time to switch from carefully applying herbicide to individual trees to broadcasting chemicals across entire patches of woody plants. In some cases, deploying bigger equipment (dozers, excavators, etc.) to remove patches of big trees can be a lot faster than trying to eliminate them with hand tools. Sure, there’s going to be more collateral damage with these approaches, but as in cancer treatment (because why not bring in a new metaphor?), sometimes something drastic like chemotherapy is needed to deal with the problem before it kills the patient.
Most importantly, we need to stop working on the control of trees (and other invasives) on a site by site basis when those prairies are embedded within a landscape full of invaders. Trying to protect one city from an ever-increasing barrage of missiles isn’t sustainable. Trust me, I tried it many times when I was a kid.
Success will only come if we can start building partnerships with surrounding landowners and taking a neighborhood approach to woody plant control. By working collaboratively on eradicating trees and shrubs from sections, townships, and even larger areas, we can greatly reduce the invasive pressure in the interior portions of those control zones. That means all the partners can then work together to defend and expand the outer boundaries of those zones. It’s not the way most of us have worked in the past, but look at where that’s gotten us.
My third point is one I don’t really want to make, but it’s one I’ve been thinking more and more about. The world is quickly changing around us – including continual habitat fragmentation, increasing dominance of woody plants and other invaders within grassland landscapes, and increasing nitrogen deposition, just to name a few examples. When you add the rapidly changing climate to that mix, it gets pretty difficult to see how we’re going to hold the line in every prairie that stands in the way of those changes. It’s probably time that we start talking about how we can preserve as much biological diversity and ecological function as possible within selected sites that are inexorably transitioning from prairies to shrublands or other community types.
If you haven’t had this conversation with yourself or others, I’d encourage you to broach the topic. It’s not one I’m going to explore here at the end of an already-too-long blog post, but it is one I’ll return to in the future. I’d be curious to hear from others who are already ruminating on the subject and have helpful thoughts.
To wrap this up, however, let’s return to my youth. I often found myself staring blearily at the screen as the last of my 8 pixel cities was destroyed. Either my ammunition had run out or I just couldn’t keep up with the overwhelming barrage. I can remember those feeling of helplessness and frustration very clearly, and they are similar to the feelings I sometimes get today when I think about the threats to prairies.
When I was a kid, I didn’t have any way to reprogram the Missile Command game on my computer and give myself a better chance of success. There’s no such limitation on us as prairie conservationists, however. Just because some of our current approaches are becoming inadequate as trees and other invaders increasingly press in on us doesn’t mean we have to lose the game. With some creativity and teamwork, we’ve still got a chance to create our own cheat codes and win at least some of the time.