Management of structure and productivity of boreal and subalpine forests

McKeand, S.E. & Bridgewater, F.E. 1993. Provenance and family variation for juvenile growth characteristics of Pinus taeda L. and the impact on early selection for growth. In Management of structure and productivity of boreal and subalpine forests (ed. S. Linder & S. Kellomaki). Stzrdin Forestalia Suecica 191. 94 pp. ISSN 0039-3150, ISBN 91-576-4822-0. Stem elongation in first-and second-year Loblolly pine (Pima taeda L.) seedlings has reliably predicted 8to 12-year heights of half-sibs in Atlantic Coastal Plain provenances. However, stem elongation traits may not be useful for early selection with other provenances. For western provenances, shoot dry weight at 4-6 months is used to predict field performance, but dry weight has not been a good predictor for the Atlantic Coastal provenances. A study with 13 to 16 open-pollinated families from each of five provenances was established to test for differences among them for early selection. Ranks of stem elongation traits for the five provenances were as expected with the southern and lower coastal plain sources growing the fastest. Heritabilities for most traits in most provenances were moderate to high. Elongation traits were most strongly related to 5-year heights of older half-sibs in other trials for the Atlantic Coastal, Middle-Upper Gulf, and Marion County, Florida provenances, but the relationships were weaker for the Lower Gulf and the Gulf Hammock, Florida provenances. Thus, there is evidence that early selection based on firstand secondyear stem elongation traits may be effective only for certain provenances of Loblolly pine.