Milestones and millstones: a retrospective on 50 years of research to improve productivity in loblolly pine plantations.

摘要

The productive potential of plantations together with the expansion of the pulp and paper industry in the region prompted a broadly based programme of research and development in southern pine (Pinus (southern)) plantation establishment and management. The first major research contribution to pine plantation forestry in the South was the USDA-Forest Service Publication, Agricultural Monograph No. 18, Planting the Southern Pines by P.C. Wakeley. This publication summarized 30 years of research by Wakeley and his colleagues at the Southern Forest Experiment Station and served as a road map for essentially every agency and organization, public and private that wished to establish and manage plantations of southern pine. In 1951, the Texas Forest Service and Texas A&M University established the first southern pine tree improvement programme. This programme not only introduced a new area of forest research in the South, it established a new way to conduct research through the creation of a forest industry-university-government research cooperative. The passage of the McIntire-Stennis Cooperative Forestry Research Act of 1962 greatly expanded the forestry research potential at state universities and soon thereafter a number of cooperatives were formed in pine tree improvement, forest fertilizer application, competing vegetation management, forest biology, nursery management, growth and yield, hardwood tree improvement, and hardwood silviculture. These cooperative endeavors fostered creativity and innovation and provided a network for the rapid testing and dissemination of ideas and discoveries. Naturally regenerated second growth stands of southern pine typically had a mean annual increment of 2-3 m3 ha-1 year-1. Today, operational plantations of genetically improved loblolly pine (Pinus taeda) with basic site preparation will produce 9-12 m3 ha-1 year-1 over a 25-year rotation while experimental plantations with complete competition control and annual fertilizer application have achieved mean annual increments as high as 34 m3 ha-1 year-1 by age 12 years. In 1999, planted forests accounted for only 11% of the South's total growing-stock volume, but contributed 41% of the softwood net annual growth and 29% of the softwood harvest. These figures are forecast to increase during the first half of the 21st century..