We have several goals for this project. First, we want to eliminate the poison oak (or at least reduce it). Second, we want to reduce the invasive thistles on the site. Finally, we want to reduce the fine fuel load, which is comprised mostly of annual grasses. These goals require somewhat different approaches. For the poison oak, we'll need to repeatedly defoliate it, which will eventually stress the plants enough to kill them. For the thistle, grazing it at this stage won't kill it, but it will reduce the number of viable seeds produced by each plant. This will reduce the amount of thistle next year. For the fine fuels, we want to consume them or trample them.
Livestock have 3 impacts on plants, each of which can help us achieve these goals. First, obviously, the sheep and goats consume the plants. Second, they walk on them. By trampling them, the animals help incorporate organic matter into the soil and speed the decomposition of dead plant material. Finally, animals do what animals do after they eat and drink: they deposit manure and urine, which aids in the cycling of nutrients in this system.
The best place to see these impacts, for me, is to look down a fenceline. This photo shows grazed vegetation on the left and ungrazed vegetation on the right.
To accomplish these goals, we need very portable systems. We use portable electric fencing and portable livestock water systems. We also use herding dogs extensively. Our border collies help us keep animals controlled and help us move them quickly, efficiently and humanely.