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Goats, Sheep and Thistle

Goats and Sheep provide a practical method for the reduction and mitigation of invasive plants including the extensive list of non -native thistles which degrade habitat and spread prolifically.

What makes the goat and in many cases sheep(depending on the breed) a superbly effective tool in the reduction and elimination of thistle infestation and monocultures, is the ruminant animals ability to both reduce seed production, alter soil chemistry and finally, the ability kill the plant altogether.

First, how does a goat reduce seed production? Grazers target plant seed heads as they contain the highest nutritive value for the animal. If a plant has produced a seed head the goat will find this part of the plant most palatable, and consume it first. Second, How does a goat effect soil chemistry, and why is this advantageous? Through the elimination processes goats alter both soil ph and N, K, P levels. Certain varieties of thistle thrive under certain conditions; for example—Italian Thistle, a resilient invasive annual thistle prefers potassium deficient soils. Understanding the unique/peculiar preferences of invasive/undesirable plants allows insight into intensity and duration of grazing application, as soil dynamics can be changed through animal impact so as to promote specific conditions, favorable or unfavorable to different plants and microorganisms.

Finally, and most essentially, a grazer can kill a plant. The mechanical process of grazing can destroy a plants ability to deliver nutrients to itself, to photosynthesize and can damage a plants ability to derive a store nutrients and water from itself and the soil.

It is because the grazer works on multiple biological and physical levels that grazing is effective. What’s more, is a grazers ability to stimulate desirable ecological conditions such that soil, plant community and hydrological conditions are conducive to balance.