Carbon Capture and Productivity of Plantation Forests in North-eastern Australia

Approximately 130,000 ha of hardwood plantations have been established in north-eastern Australia in the last 15 years. As a result of poor taxa selection approximately 25,000 ha have failed due to drought, pest and disease or extreme weather events (drought and cyclones). Given the predicted impacts of climate change in northeastern Australia (reduced rainfall, increased temperatures and an increase in extreme weather conditions, particularly drought, storms and cyclones), selection of the right taxa for plantation development is even more critical as the taxon planted needs to be able to perform well under the environments experienced at planting as well as those that may develop over in 30 years time as a result of changing climate. Data was compiled from 37 taxa trials within a network established across the subtropics of eastern Australia with trials selected using taxa linkage, stocking rates, age (10 ±2 years) and regional (climatic) representation. Significant differences in survival, height, diameter, basal area, volume MAI, stem borer incidence, carbon sequestration rates and pulp productivity were observed at age 10 years. Across all regions, at age 10 years, the largest volume increment (30 m3/ ha/y) was observed in E. pellita in the North Tropical Coast whilst the largest average breast height diameter (19.6 cm) was observed in E. dunnii in the Northern Rivers region. In the case of E.dunnii, this equates to 274 tonnes of CO2 equivalents or 74 tonnes of pulp per hectare at age 10. Of the 65 taxa included in the study, those that were the most robust (based on volume growth, survival and carbon sequestration rates) under the drought conditions experienced in north-eastern Australia, during the study period were Corymbia citriodora subsp. variegata (CCV), Eucalyptus dunnii, E. longirostrata and E. argophloia. Of these species only CCV and E. argophloia had low borer attack, making them potentially suitable for solid wood production.Analysis of the climatic conditions resulted in key climatic drivers for individual taxa being identified with E. dunnii performing best on sites with a higher incidence of raindays and higher mean annual rainfall, while E. argophloia performed best on sites with higher daily minimum temperatures