Performance of Pinusponderosa and Pinusjeffreyi provenances in New Zealand

Abstract

Provenance trials were assessed at age 22–24 years at four sites: (1) moist oceanic; (2) moist, semicontinental; and (3–4) dry, semicontinental. The trials at sites 2 and 3 were the main ones, involving nearly 40 provenances of Pinusponderosa Laws. and five of Pinusjeffreyi Grev. & Balf. The P. ponderosa covered from 36°N northwards in the west of its natural range, with 12 provenances in northern and central Sierra Nevada. Past data on Dothistroma blight came from two additional sites. Large provenance differences reflected both relatively discrete races and superimposed clinal patterns. The main divisions of P. ponderosa were (in addition to the eastern variety, scopulorum) as follows: the North Plateau race, east of the Cascade Range extending northwards therefrom; and the Pacific race, in the Sierra Nevada, Coast Ranges, and western Cascade Range. However, there was an apparent transition zone east of the southern Cascade Range, with some Pinuswashoensis Mason & Stockwell south of there. Apart from previously reported differences, the North Plateau race showed better Dothistroma resistance and abundant anthocyanin in cones. Within the Pacific race, Sierra Nevada material suffered more Dothistroma blight, while the northern provenances had more cone anthocyanin. Strong provenance–site interaction occurred for growth, which related largely to differences among races in relative performance at different sites. On the moist sites, height showed very close negative correlations with altitude of origin adjusted for latitude, low-altitude provenances from Sierra Nevada and the Coast Ranges being the tallest. Stem diameter at those sites, while also showing close negative correlations with latitude-adjusted altitude, showed additional effects of race, North Plateau tending to have smaller diameters relative to adjusted altitude. However, at the dry site 3, where growth was less, North Plateau provenances ranked much better; they survived well and included the tallest lot, although diameters still were less than in the Pacific race. Wood density averaged ca. 350 kg/m3 in rings 6–15 from the pith, with very minor differences between sites; this being less than in rings 1–5 and much less than in outer-wood of adjoining Pinusradiata D. Don. The North Plateau race had slightly higher density, particularly in rings 11–15. Some between-provenance variation existed within races, but with no clear pattern. Provenance–site interaction was generally minor. The P. jeffreyi provenances were always among the slowest growing. The one Coast Ranges provenance was distinct from others. Also it grew better relative to the others on the moister sites and had evidently hybridized with P. ponderosa.