|Ares, Adrian - WEYERHAEUSER COMPANY|
Submitted to: North American Agroforestry Conference
Publication Type: Proceedings
Publication Acceptance Date: April 7, 2005
Publication Date: June 12, 2005
Citation: Ares, A., Brauer, D.K., Burner, D.M. 2005. Growth of southern pines at different stand configurations in silvopastoral practices. North American Agroforestry Conference. Center for Integrated Natural Resources and Agricultural Management, St. Paul, Minnesota. 2005 CDROM. Interpretive Summary: Many farmers could possibly increase the overall productivity and sustainability of their operations by combining tree production with livestock grazing systems, but adoption of these silvopastoral practices in North America has been limited by a lack of scientific data for optimal designs. Research was conducted to assess the effects of number of rows of trees and alley widths between trees on growth of southern pines in silvopastures. Contrary to earlier reports, tree growth as measured by basal area was similar for single and double tree row designs, and was superior to designs with three or more tree rows. The study is of interest to scientists, foresters, extension personnel, and producers because the results identify the most productive spatial arrangements for pines in silvopasture systems designed to increase overall farm productivity.
Technical Abstract: Predictions of economic outputs from silvopastoral practices in the southern United States remain uncertain because of scarce baseline information. Silvopastoral trials have mainly included single- or multiple-tree rows separated by alleys with (1) constant stand density or (2) constant alley width. For constant density trials, (a) basal area of 18-yr-old slash pine (Pinus ellioti Engelm.) in northern Florida was similar in single- and double-row configurations, and decreased 44% with a 3.6-fold increase in alley width for the double-row configuration; (b) basal area of 32-yr-old slash pine in double-row configuration in central Florida decreased 46% for a 2.1-fold increase in alley width; (c) basal area of 18-yr-old slash pine and loblolly pine (Pinus taeda L.) in single-row configurations in central Louisiana was 37-41% greater than in triple-row configuration with a 2.3-fold increase in alley width, and (d) basal area of 11-yr-old loblolly pine in a double-row configuration in western Arkansas was 20% greater than in a quadruple-row arrangement. For a constant alley width of 14.6 m in central Arkansas, basal areas of 18-yr-old loblolly pine in single, double and quadruple-row configurations were 20, 27, and 46 m2/ha. In this study, basal areas in the silvopastures were similar or greater than those of an adjacent spacing trial for similar stand densities but bole biomass for a given tree diameter was likely 2653% lower in the silvopasture because of differences in allometric relationships. Decisions on tree spatial arrangements in silvopastures should consider the combined effects of basal area accumulation, biomass partitioning and wood quality.