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SummaryPinus radiata(GF27- and Guadalupe-based intraspecific hybrids) and Pinus pinasterwere trialled to examine the potential for commercial deployment on three lower-rainfall sites within the 500–800 mm rainfall zone of New South Wales. All three ex-pasture sites were considered to be dry for P. radiata; two lower-elevation sites to the west of Gundagai being more challenging than a high-elevation site near Bombala. Cuttings and seedlings of genetically improved P. pinasterand P. radiataand a Guadalupe × routine cross seedlot of P. radiatawere planted at three stockings (625, 1250 and 1850 stems per hectare (sph)) and were assessed for survival, growth (diameter at breast height, height, volume), form (straightness, malformations, branch size, branch angle) and number of commercially acceptable trees per hectare up to age 8 years.Survival in P. pinasterdidn’t decline after minor post-establishment mortality and was not affected by stocking or plant type. In contrast, survival in P. radiatacontinued to decline over time at 1250 and 1850 sph stockings at the two low-rainfall, low-elevation sites. Guadalupe-based seedlings had better survival than GF27 cuttings, but both present a high risk under dryland or drought conditions.Site and stocking affected growth of the two species differently. P. radiatagrew larger than P. pinasterat all sites. The combination of survival and growth resulted in site volume production that increased with stocking and site quality for P. pinaster. P. radiataexhibited a similar pattern but with reduced volume production at higher stockings on the high-quality Bombala site due to poor survival.The form and branching of P. pinasterwas better than that of P. radiataon all sites except the high-rainfall Oak Range. Form of P. pinastercuttings was better than of seedlings. Form and branch size were improved by higher stockings and were worse on higher quality sites for both species. However, branch angle was better for P. radiatathan for P. pinaster.P. pinasterwas reasonably productive on the best performing of the low-rainfall, lower-elevation sites. Given periods of very low rainfall since the establishment of these trials, the productivity of 6–7 m3 ha–1 y–1at age 8 years at stocking of 1250–1875 suggests that 12–15 m–3 ha–1 y–1may be possible when mean annual increment (MAI) peaks at a later age. Although P. radiatagrowth rate was high, the poor survival and form of GF27, and to a lesser extent the Guadalupe cross, suggest it presents a high risk on these sites. Continued monitoring of the sites is therefore suggested. Further work could look at more drought-resistant taxa of P. radiata. |
