Pastures provide food and space for domesticated animals to grow and thrive in. They also
provide an ideal habitat for weeds to grow and thrive in. Many weed species possess
significant nutritive value, a concept not lost on the grazing animals as they eat them
along with the cultivated pasture species. Other weeds are less attractive to grazing
animals, and they can ruin a good pasture quickly.
A good example of this can be seen below in this ragged pasture in Michigan. Animals have
grazed the lush desirable vegetation, leaving the bull thistle, which has taken over quite
a bit of this pasture habitat. The bull thistle in this pasture is flowering, indicating
it is in the second year of its biennial life cycle. The white flowering plants in the
foreground are probably wild carrot.
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The gentle rolling landscape below is home to not only the fine cows in the foreground, but the enlightened citizens of Holy Cross, Iowa. This looks to me like a well managed pasture, with no weeds in evidence. The bristling silos dotted copiously across the countryside attest to the richness of this land. Residents of northeast Iowa fondly refer to their region as "Little Switzerland". Holy Cross is also the location where the first triazine resistant Pennysylvania smartweed population was discovered. For more about this nasty byproduct of herbicide use see the chemical weed management section.
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The very large flowering Canada thistle plant below is not something even the goats in the backround want to eat. Once out of their pen and into the pasture serving as habitat to the Canada thistle plant, they will seek more tasty plants. The thistles as a group of species seem to possess leaf adaptations that help them escape grazing, including nasty and pokey spines.
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The Michigan pasture below is home to millions of dandelion plants in flower. Although they make the pasture appear very weedy, much research indicates they interfer little with the pasture's productivity. This is a good example of farmer attitudes about the presence of weeds independent of the yield losses the weeds cause. For more about farmer attitudes, and how expectations of growers influence their weed management systems, see the section on weed management.
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Below is another pasture littered with dandelion plants preparing to disperse their wind-blown seed across the landscape. If this Ontario pasture was near a residential area, the local homeowners may be concerned about dispersal and spread of dandelion seed onto their managed lawns and yards. Golf course managers would also be concerned about these wind dispersed seeds. Myself, I find this a lovely picture.
