10-YEAR DIAMETER AND BASAL AREA GROWTH OF TREES SURROUNDING SMALL-GROUP SELECTION OPENINGS

The effects of small openings in forest stands has interested silvicul turists and ecologists for years. Interest generally has centered on t he vegetation in the openings, not on that immediately outside of them . Quantitative information on the growth of trees adjacent to group-se lection openings, although often mentioned in forestry textbooks as co ntributing to cost effectiveness, is scant. Five conifer and three har dwood species bordering 9-, 18-, and 27-m diameter openings in the nor thern Sierra Nevada of California were examined for diameter growth 10 years before and 10 years after an initial group selection cutting. T en-year diameter growth at breast height of various combinations of sp ecies and diameter classes did not differ significantly (P > 0.05) amo ng opening sizes 10 years after cutting. But mean basal area growth of pines (ponderosa and sugar) 10 years after cutting was significantly greater (P < 0.05) than that before cutting in 18- and 27-m openings. This difference also was found for shade-tolerant conifers (Douglas-fi r, incense-cedar, and California white iir) bordering all opening size s. Mean basal area growth of hardwoods (California black oak, tanoak, Pacific madrone) did not differ before and after cutting for any openi ng size.