Invasive Sheepcies Part II
Long-time readers of our farm blog will remember other things I’ve written about our ongoing cow-bro science experiment grazing bamboo (#1, #2, #3, #4). When I tell people that I planted bamboo on my farm to try using it as a forage crop to feed my animals (it is a large grass after all), usually one of the top three questions they ask has to do with invasiveness. The concern is that bamboo will create a monocultural thicket and gradually envelope a lot of land as it sometimes does in suburban neighborhoods. The attendant dislocations of a more “native” biology when a foreign plant moves in is generally framed as an unmitigated disaster whenever conservation agencies publish warnings about “invasive species”.
I just don’t see the world in such black and white terms these days. I think there are some foreign insects and fungi that are undeniably detrimental to a lot of native plants and animals - Emerald Ash Borers and Chestnut Blight spring to mind. If I could rewind history and prevent the arrival of those two pests in North America I would do so in a heartbeat. I love trees and the loss of the American Chestnut was truly a disaster for the forests of the eastern US. The current decimation of White Ash by Emerald Ash Borers is depressing to watch unfold.
Then there are the more middling examples - zebra mussels, earthworms. Earthworms are blamed for disrupting forest soil ecosystems just as they’re cooed over by gardeners everywhere for their help in decomposing organic material and their miraculous ability to make phosphorus more available to plants after passing soil through themselves. Zebra mussels are hated on ferociously for clogging up drain pipes and ruining boat hulls, but what I see in their case is the arrival of a species that is best adapted to a highly artificial environment (man-made). Even with all the environmental progress that has been made since the 1970s the Great Lakes are only an ecological shadow of their former selves. I’m not convinced Zebra Mussels would have caused many waves if they’d arrived 400 years ago, but in disturbed and polluted water they can clearly thrive. If I’m correct in my assessment, then the cause of their proliferation is more about the habitat humans have made for the mussels in the lake rather than some inherent potency of the mussels themselves.
And finally there are manifold examples of plants and animals that move into new ground and either capitalize on human caused disruption or slip into the ecosystem and add diversity without driving anything else extinct. Just a few examples - Paulownia trees, Amur Honeysuckle, Coyotes, Purple Loosestrife, Clovers, all the cool season grasses in your lawn… Lawn grass is a good example of the principle I’m driving at because it dominates ground given the right conditions of fertile soil, plenty of moisture, and frequent clipping. Humans create an environment in which the most highly adapted plants proliferate. Stop mowing for a year and the lawn turns to a field, stop for a decade or two and it will be scrubland. Stop for a century and it’ll be forest. This is instructive because the timescale is short enough for even our device distracted modern human to notice. Some of the other “invasives” on the list operate over longer timeframes or more subtle disturbances than lawn grasses, so it’s more difficult to see that the reason they’ve attained hegemony in a given spot is some deeper-in-the-past disruption (cleared land for building a house, soil leached of vital nutrients by acid rain, logging of mature trees for lumber, the list often feels endless when one starts looking carefully).
My point is this - blaming all non-native plants and animals for our ecological ills is as myopic as blaming dietary fat for all obesity. Ecosystems are just as complex as human bodies that shift their metabolisms according stressors, microbiome, sleep patterns, hormones, diet composition, exercise, social connectedness, and emotional well-being. A disruption of one these domains may or may not cause over-weight in a person. Put a bunch of them on the wrong track and the likelihood goes way, way up. Similarly in an ecosystem, if it’s largely intact across a landscape, a 2 acre patch cut for lumber isn’t cause for concern. Plop a town or a superhighway down in it though and suddenly the habitat is completely and utterly fragmented by asphalt and roofs, wires, walls, and noise. Without placing a value judgement on which plants and animals are good and bad what we will inevitably see is the proliferation of life that is best adapted to the new environment. Mother Nature doesn’t care whether the life that succeeds evolved in situ for millenia or moved in from some other part of the globe yesterday. She just moves for ever more life.
I believe bamboo grazing gets me closer to supporting a more life-full world and helps me align a little more closely with Mother Nature. The thicket it grows into is fantastic habitat for rabbits and other small game. There are no other stands of bamboo anywhere for miles and miles around my farm. I help make a small dot of diversity with its planting. The dense mat of roots and woody biomass it grows fix carbon from the atmosphere, and even more important on the carbon front is that each pound of hay I offset by feeding bamboo is a pound of feed I didn’t have to burn diesel fuel (in a tractor) to make. If I can accomplish the same goal (fed animals) without making and hauling hay, that does a lot to create the ecologically sensitive agriculture I want to see in the world. Agriculture and industry, rightly, both get a bad rap for externalizing costs as much as possible. In this case I believe I can externalize a small environmental good (not-burning fuel) by growing bamboo. I see the production of perennial forages that animals transform into high quality animal proteins and fats as the best type of agriculture for my particular place. In this one small spot it is a good choice to use a non-native grass (bamboo), to feed a non-native mammal (sheep), that in turn feeds other non-native mammals (human).
Believe it or not I have even more to say on this topic, but blogposts that run too long get boring, so I’m going to break for now.