Genotypic and Silvicultural Controls on Wind Damage, Failure Mode, and Productivity in a Radiata Pine Trial Following Cyclone Gabrielle

Storm damage poses an increasing risk to radiata pine (Pinus radiata D. Don) plantations in New Zealand as extreme wind events intensify under climate change. This study quantified wind damage following ex-tropical Cyclone Gabrielle in a seven-year-old genetics trial comprising 12 genotypes grown under four stand configurations defined by contrasting stocking (833 and 1282 stems/ha) and cultivation (with and without cultivation) treatments. The genotypes comprised a Pinus attenuata × P. radiata var. cedrosensis hybrid, ten anonymised radiata pine clones and an industry-standard radiata pine seedlot. Field assessments and unmanned aerial vehicle UAV laser scanning were used to classify damage into stem breakage and overturning and to derive structural metrics, including tree diameter, height, slenderness, volume, crown width and crown volume. Overall, 16.7% of trees were damaged, with stem breakage (10.2%) occurring more frequently than overturning (6.5%). Averaged across the four treatments, total damage significantly ranged from 10.4% in the high stocking cultivated treatment to 23.5% in the low stocking no cultivation treatment. Variation between the 12 genotypes was highly significant, with breakage, overturning and total damage ranging from 3.3%–25.4%, 1.4%–15.0% and 6.6%–29.5%, respectively, between the 12 genotypes. Two radiata pine clones with high growth rates and low to moderate wind damage had the highest post-storm total stem volume per hectare, which greatly exceeded that of the hybrid or the widely planted radiata pine seedlot. These findings highlight the potential of clones that combine high growth rates and resistance to wind damage to maintain high productivity under a changing climate with a greater frequency of extreme weather events.