A note to my Yarns from the Farm Readers—this is the third instalment of a series on biodiversity for our local newspaper. Biodiversity was the introduction, and the second was Biodiversity and Nutrition. Nan
In the world of Dr Seuss, weeds would be plain-belly sneetches. Their close relatives, the star-belly sneetches, would be the rest of the plants—the ones we think we want around. Of course, shyster McBean so mixes them up with his star-on, star-off machine that in the end the sneetches decide to quit worrying about who has stars on thars.
And that pretty much sums up the most useful approach we can take to weeds: with a very few exceptions, it matters not at all to the consumers of plants who has stars on thars.
If you run sheep or cattle, you may not realise just how sought-after most of our weeds are by your livestock, because, of course, they’ve eaten them. The best way to figure out what your animals are eating is to check out the differences between their paddocks and any ungrazed strips around you, like roadside verges.
I guarantee you will find dandelions, milk thistles, salsify, dock, thistles, gorse, broom and even Patterson’s Curse in those ungrazed strips, and probably not in your adjacent pastures.
Weeds are successful imports to an ecosystem, often exploiting weakness in our land management, like bare or disturbed ground. They have the wonderful secondary compounds that animals need for optimal nutrition, and in moderation provide a useful addition of biodiversity to animal diets. Because most of our weeds are forbs—broad-leafed plants rather than grasses—their blossoms are often the most sought-after part of the plant.
If you get a chance, keep an eye on a paddock full of dandelion blossoms that isn’t being grazed. Then when sheep or cattle are allowed in, see how long it takes for the blossoms to disappear. I recently did this with a paddock across the highway from me. It only took a few hours for several hundred sheep to clear all the dandelion flowers from a hundred or so acres.
Weeds only become intractable when they are allowed to take over large areas, effectively decreasing the biodiversity to nothing. Just as you spinach-lovers would baulk at spinach all day, every day, so do livestock get tired of eating just one thing.
So weed management is really about keeping the weed levels in your system to a few percent of the total plant biomass. And the trick to that is grazing, but not overgrazing—not always an easy balance to find or maintain.
When you get it just right, grazing enhances biodiversity without creating bare ground—which is where annual weeds get their start. Most of our weeds are annuals (excepting woody weeds like gorse or broom). Encouraging perennial plants through moderate grazing is an important part of this approach.
Getting the grazing pressure just right also means there are enough weeds in the system for your animals to learn about them—where they are, how much of them to eat, when to stop eating a particular species, and what medicinal value they might have. Briar rose hips, for instance, are high in Vitamin C, and are devoured avidly by my sheep in autumn when they ripen.
Perhaps the hardest part of maintaining weeds as valuable additions to biodiversity is our training to “weed” out “undesirables” and to keep the system looking tidy. If you can get your head around the idea that weeds are just sneetches like all the other sneetches—no more or less undesirable—it might be easier to let go of the feeling you need to kill them off.