Tale of Two Milkweeds
Milkweed pods on the ‘not grazed’ patch, about to burst with seeds.
Land stewardship is an ever-continuing cycle: observation>management choices>more observation, over and over. Sometimes the observations are subtle and perhaps too complex to communicate to someone else. Sometimes, there's not enough context to draw conclusions. Sometimes, they are clear enough to be noticed by the casual observer! That is the case with two patches of milkweed on the main Belliar driveway and this scenario shines a light into the complexity of the systems we manage and the variety of effects our actions may have on them.
We have grazed the "Barn Field" -- the hill rising up behind the Barn Store -- twice this season so far. Once in March and once in June. For the March graze, milkweed would not have been sprouted just yet. For the June graze, I remember the milkweed having already gone into full flower and being covered with bees and insects before the cattle came into the field. Most of the blooms were past prime when the cattle actually moved in.
When the cattle were in the field, to my suprise, they actually grazed on the milkweed pretty hard! I had always heard of people saying "they don't like it because it's bitter," and there are some fear-mongering internet warriors who insist it is toxic enough to kill cattle and so you must spray it or pull it from your hay fields and pastures. In my and Nat's experience grazing the way we do, we have so much less risk for toxicity (of almost any species, not just milkweed) for several reasons: 1) the cattle have other options in our fields to eat AND they are moved frequently, so the "toxic" plant can only make up a certain percentage of their diet, 2) plants have different levels of certain chemicals during certain parts of their lifecycle. There are MANY plants that can be eaten of heartily by livestock when there is new growth but not when the plants are fully mature. And most importantly, 3) the cattle have survival instincts that I trust. They will eat something when their body is telling them to and they will stop before it becomes a problem.
So the cattle ate back the milkweed patch along with much fescue and other species in the field. At the end of ~2 days of grazing, the milkweed plants were knocked back about half and still had some lower leaves. This part is important, I think! I remember being surprised about the cattle eating the milkweed, was intrigued about that, and was glad that it had had time to fully flower (read: feed early pollinators) before they did! I made a mental note to watch this area later this summer.
Fast forward to now in August. I've been watching the milkweed grow all summer as I drive in and out of the farm. We have a perfect "control" patch of milkweed that was at the same stage of growth as the grazed patch before it was grazed. Comparing the patches now, there's a huge difference!
The patch that was not grazed (above left) has notably leathery, yellowing leaves and is loaded down with seed pods. The patch that was grazed (above right) has grown back with fresh green vegetal growth. It's not as large nor has as many blooms on it as it originally did (remember-- it FULLY flowered out once already this year!). There are milkweed beetles and milkweed bugs in both patches. However, there is only evidence of caterpillar usage and monarchs flying around in the young, green patch.
Bonus: Tickseed Trefoil (the bushy plant with smaller leaves nestled between the milkweed patches). This plant is also grazed by cattle when it is young and edible and avoided when it is older. In other parts of the farm, tickseed trefoil is already in full bloom and making tons of its sticky seeds. Here among the June-grazed milkweed, it is just exiting vegetal phase and making its first flowers! The grazing had the same effect for this species as it did the milkweed!
Part of understanding this management choice's impact on the ecosystem is understanding the monarch life cycle. As a migratory species, they require food for themselves (nectar) and for their caterpillars (milkweed leaves) for the full length of their journey south. What I've learned is that the caterpillars need young, new growth! So from a perspective of monarch migration, it's good to have grazed the milkweed!
But wait! It's never as simple as that, is it? You might assume you can just mow in June to get the same effect, but no! I really don't think so. A mow in late April or May? Maybe more likely. A mow in June would, in my opinion, probably have been too severe of a cut. Remember how I said there were lower leaves left? I believe those served an important purpose in giving the plant enough reserve power to re-sprout in the way that it did and I think if mowed in June, the plants would not have come back from that. So mowing is not an equivalent management choice to grazing.
Furthermore, there's the fact that monarch migration is not the only factor we might be managing for! If we always managed for that, then we would not have very much milkweed go to seed ever and we could lose the patch entirely!
As you can see, it's so much to think about even with one species and one management choice. It can be overwhelming to go down these mental rabbit holes. But it's important to note that with each choice is another chance to wait, observe, and change tactics. For our goals, of broad conservation of grassland ecosystems in combination with productive pasture, a VARIED management strategy is more important than making the "correct" choice at any given moment. If we graze a patch, skip a patch, graze another patch twice, mow yet another patch, then we will have a landscape as varied as our work! In general, this diversified approach will yield diversity in the landscape and its species.
For me, I think the most fun part of this little observation was the definitive nature of it all. Usually I'm having to make mental extrapolations or assumptions about what "would" be happening if we'd chosen a different path. In this case, we have the "evidence" right there as a comparison since the grazed vs ungrazed areas both had milkweed patches that were the same age! Very cool to me, and I hope you as well!