Spacing and provenance effects on the performance of shore pine (Pinus contorta var. contorta): 20-year test results
1995
Xie, C.Y. (British Columbia Ministry of Forests, Victoria, CB, Canada.) | Johnstone, W.D. | Ying, C.C.
Spacing and provenance effects on the performance of shore pine (Pinus contorta var. contorta) at a frost-prone site in coastal British Columbia were investigated with respect to mortality, growth, stem defects, and disease and insect damages in a trial with six seed sources that were assigned to seven spacing regimes from 749 to 2990 stems per hectare. Twenty-year test results indicate that mortality was low (2.3% on average) and not significantly influenced by spacing. However, spacing effects on the other traits were significant. Increasing planting density reduced the proportion of stem defected and disease- and insect-damaged trees, slowed diameter and stem volume growth of individuals, and stimulated height growth. Height growth responded to planting density earlier than diameter growth, but diameter growth became more affected as trees grew. The total volume per hectare increases with planting density, but the rate of increase declined as the test proceeded. Response to planting density was homogeneous among provenances with respect to all the traits investigated. However, large and significant regional and provenance differences in mortality, growth, and disease and insect susceptibility were detected. Northern and outer coast provenances demonstrated higher mortality, slower growth, and larger proportions of disease- and insect-damaged trees. Clearly, determining appropriate spacing levels and selecting suitable seed sources are both important for the success of reforestation with shore pine at difficult sites
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