Monday, October 7, 2013

The Ecologists' Dilemma


Sitting on the tailgate of the Forest Service pickup, affectionately known as the “Weed Truck” by other employees, the first thing I noticed that day while eating lunch was all the insect activity. It had been cool for several days, and so everyone had been hunkered down, waiting for the weather that was today. The days’ sunshine brought the whole of the northwoods back to life; what flowers were left were photosynthesizing again, and they had a captive audience. If you were an insect, you were out looking for sweet yummy goodness in the form of nectar. From the tailgate, I could see that there was one creature in particular that was having eating buffet-style at this gravel pit in the middle of the woods. I recognized them from afar, and soon noticed they were everywhere, dozens of them within sight, flying madly from flower to flower trying to get their business done before another cold spell. Agopostimon are a genus of bees that I first saw and learned at springs in Arizona, while working in Grand Canyon National Park. In Northern Wisconsin, they are one of the last hangers-on at the end of Summer and are a harbinger of the next season. As they flitted drunkenly from one oasis to the next, they glinted like brilliant-green emeralds in the waning afternoon sun. 

Its a wonder how these creatures ended up looking the way they do, blessed by some stroke of evolutionary luck to be the hands-down winner of any bee beauty pageant. They are the only Family of bees to have this brilliant green sheen, while all the others toil in the traditional yellow-and-black-striped regalia of all their other honey-making cousins. There are a few beetles that might be as spectacular as Agopostimon, but they are the Bootsie Collins of the flying-insect world; the guy everyone else wants to be (pun intended). 

 First I had noticed that the busy little critters were Agopostimon, then that there were hundreds of them. The sinking feeling in my stomach followed immediately; absolutely every flower these poor fools were nectaring on belonged to our nemesis and arch rival for the day, Spotted Knapweed. Known to professionals such as ourselves, or other such plant-nerds, as Centaurea bimaculata, it made its way to the states years ago from Eastern Europe. Reminiscent of a smallish thistle, the little purple flowers are indeed showy, meaning they are pretty enough to look at; but it's all a hoax. Its their obnoxious-neighbor behaviour that has earned them a trip to the top of the DNR A-List of Non-Native Invasive species (NNIS).  If they would just mind thier own business, they’d be fine, but, like plenty of others from Europe, they like to take over any and every dry, sandy habitat all for themselves.  

My job with the Forest Service is to lead a crew of two others in ridding our precious public lands of NNIS. As many of you know, our federal government loves its acronyms. NNIS, in this context anyway, are Non-Native Invasive Species, and we spend a good bit of money on keeping a list of prioritized bad-guys in-check. The Forest Service identifies and prioritizes its most-wanted list based on two main criteria. First, and most obviously, the plant must have first originated OUTSIDE the continental United States, hence the first part of the acronym, Non-Native. Secondly, you must be invasive, and this is where the definition becomes a bit more, well, technical. To be invasive, the plant offender must, without disturbance to the soil or ground layer, be able to invade a site and displace a large percentage of the native species within the site. When Spotted Knapweed colonizes a roadside or ditch, it is displacing other weedy, non-native species; in this case, we leave it alone, untreated. Where Knapweed does warrant treatment, in particular, is in Jackpine Barrens. The dry, sandy soils characteristic of this habitat type make it extremely vulnerable to invasion by Spotted Knapweed, and as this is a globally-rare ecosystem, active management is mandatory against such a threat. The bigger-picture idea here is in the directive of the Forest Management Plan and the Endangered Species Act to protect biodiversity. 

Which is exactly the quandary on this particular day. Today, in this gravel pit, our job is to spray all of the Knapweed with a broadleaf-specific herbicide. The idea as that when the Forest Service needs a load of gravel from this pit as fill for a culvert after a spring gulley-washer, they wont be spreading any of the billions of Knapweed seeds that have worked their way down into the gravel and sand, to other parts of the Forest. This is the “contain” part of what I’m trying to do on a day-to-day basis. This day, though, is a balancing act. It’s a paradox really, kill one to foster the life of others? The Ecologists’ dilemma, of sorts. As its late in the season for flowering plants, the knapweed takes advantage by flowering later than its neighbors can and thereby gets its pollen moved around, spreading its evil veil further the following year. The Agopostimon are about to be collateral-damage in the war on NNIS; painted blue with a deadly cocktail sure to put a damper on their punch-drunk nectar party. They are so gorgeous; how can I spray these damn weeds and not kill every last good guy? The guilt is a stone in my gut. I decide to do my best to spray JUST the basal rosettes; they will drink up the poison, the damn weed will die, and the bees will be saved. All is hunkey-dorey in our NNIS mission. Well, at least that’s the theory. In my minds’ eye though, there will be too many dead bees to count. More than likely, there will be many casualties. But this day, as I said, is a balancing act. I think of it this way; If it weren’t for the abundance of Late-Flowering non-native Knapweed in this gravel pit, there wouldn’t be any Agopostimon either. Not trying to sound like a therapist, the flowers are enabling the bees to work later than they normally would in the season. Without them, they’d have died with the last native Goldenrod gone to seed. Of natural causes, unlike today.