Abstract
The purpose of this article was to determine whether natural regeneration or planted seedlings should be used in group-selection openings. The answer depends on the survival and growth rate of both types of seedlings, and that could depend on the size of the openings and the effect of trees on their edge. In this side-by-side study, the natural pine seedlings originated from the 1988 seed crop and the 1–0 nursery-grown seedlings were outplanted in spring 1989. Openings ranged from 0.01 to 0.65 ha. The plant community consisted of many species of shrubs, forbs, and grasses with manzanita having the highest density and greatest development. After 9 years, manzanita had an average density of 13,870 plants/ha, 2,050 m2/ha of foliar cover, and was 125 cm tall. From 1990 to 1997, planted ponderosa pine seedlings were taller (P < 0.05) than natural seedlings, and from 1995 to 1997, mean stem diameter at 30 cm of planted seedlings was larger than natural counterparts (P < 0.05). Development for 1 year in the nursery apparently gave the planted seedlings a growth advantage over the natural seedlings. For natural seedlings, distance from opening edge had little effect on pine height or diameter growth regardless of opening size. Planted seedlings, however, appeared to increase in height and diameter growth with both opening size and distance from edge.
Response of ponderosa pine plantations to competing vegetation control in Northern California, USA: a meta-analysis
