Effect of cattle grazing, seeded grass, and an herbicide on ponderosa pine seedling survival and growth.

On a site of above-average quality in northern California, an early shrub-forb-grass plant community was treated by artificially seeding two forage grass species at plantation age 3, cattle grazing with and without seeded grasses, and applying a soil-active chemical (Velpar). Planted ponderosa pines were part of this community. Results fur a 10-year period (1988-1997) are presented for planted pines, manzanita, other shrubs, forbs, and grasses (natural and seeded). In general, the pines, manzanita, and grasses were numerous and developing well after 10 years, and the other shrubs and forbs were declining in density or foliar cover or both. Velpar was the only treatment that significantly improved pine seedling growth. Grazing did not. The seeded (introduced) grasses, which were heavily grazed, probably reduced damage to the pines. The grasses also helped reduce manzanita foliar cover when grazed. No evidence was found that the introduced grasses served as a biological control in terms of reducing the density of manzanita or other shrubs.