Timing and Duration of Release Affect Vegetation Development in a Young PonderosaPine Plantation

摘要

The density and development of greenleaf manzanita, other shrubs, and graminoidswere evaluated in a young ponderosa pine plantation on a poor site in northern California from 1988 through 1997. Manual grubbing to a 5-foot radius created treatment regimes that lasted for 3 to 6 years and vegetation recovery times of 4 to 10 years. The duration and timing of the grubbing constituted the treatments. Greenleaf manzanita was the dominant shrub in the former brushfield and again dominated after site preparation and release. In 1988 its density in the control averaged 123,500 plants per acre; in 1997 density had declined to 44,450 plants per acre and its height to 3.2 feet-values that were significantly larger than counterparts in any other treatment. Early release provided pine seedlings with a significant advantage in average height and diameter if continued each year for the first 3 years and first 6 years.