VEGETATION TRENDS IN A YOUNG PONDEROSA PINE PLANTATION TREATED BY MANUAL RELEASE AND MULCHING

On an above-average site in northern California, a complex plant commu nity was treated by manual release in 2- and 5-foot radii, one and thr ee times. Mulching with a small (3-foot square) paper ! asphalt mulch and a control were additional treatments. Results for a 10-year period are presented for shrubs, a subshrub (whipplea), ferns, forbs, and gr asses. No single category of competing vegetation dominated during the study, and competition to planted ponderosa pines was from all vegeta tion combined. In spite of large amounts of competing vegetation, the pines dominated in all trials, especially if the treated area was larg e and the treatment was often. Ponderosa pine seedlings in plots grubb ed to a 5-foot radius three times had statistically larger diameters a nd heights than counterparts in almost all other treatments. The cost of applying this treatment was $402 per acre, the highest of all treat ments, but reasonable compared to similar application in other plant c ommunities. Much information on density, foliar cover, and height of e ach category of vegetation is presented, which in turn portrays change s in a developing plant community in a young ponderosa pine plantation .