Opportunities for improving plantation productivity. How much? How quickly? How realistic?

Biomass production may be increased through greater utilization of existing resources, planting more area, and by implementing intensive silvicultural practices. This paper reviews the potential of intensive silviculture to increase productivity of short and longer rotation hardwood and conifer plantations. Some silvicultural treatments produced long-term growth and site improvements: species and provenance choice, tree breeding, improving rooting volume, applying high rates of fertilizers, and irrigation, all showed this potential. Short-term gains resulted from changes to stocking rates, rotation length, planting practices, tillage, weed control, and applying starter doses of fertilizer or nitrogenous fertilizer to pole stands. The largest gains came from site selection, species and provenance choice, draining wet sites and correcting nutrient deficiencies, followed by tree breeding and irrigation. Choice of stocking level and rotation length, planting practices, weed control, and fertilizing pole stands gave potentially large benefits (>25% gains) for short-rotation crops (<12–15 years). They produced lower benefits for longer rotation plantations. Starter fertilizers, tillage and utilizing thinnings had relatively low gains. Disease and insect control were difficult to assess. Managers should consider their current management level and practices, costs and benefits, social and environmental factors, practicality, and the time required for the benefits to be achieved. Further, growth improvements measured in research studies typically are not achieved in the field, with 15–25% reductions being commonly experienced. Quality control could reduce these losses.