Flooding and Drainage Effects on Slash Pine Loblolly Pine Seedlings

SL•.s• •,i•v.(Pinus elliottil vat.elliottll Engelm.) and loblolly pine (P.taeda L.) seedlings appear to have a high degree of tolerance to poor drainage and flooding.This tolerance is important in the silviculture of the southeastern Coastal Plain flatwoods where imperfectly drained Bladen clay loam and related soils predominate.Approximately 75 percent of the area in these soils, in which both surface and internal drainage are poor, is devoted to woodlands.Pines are the most valuable species, yielding high quality timber, pulpwood, and naval stores.Generally, the pines are restricted to the better drained sites while less valuable hardwoods are the dominant species in low-lying, poorly drained zones.Throughout this region, extensive areas occur in which, when drained, stands of pine develop from natural seedfall.Both stocking and growth of pines may be substantially increased by providing adequate drainage.Trousdell and Hoover (1955) are mindful that "in years with heavy spring rainfall, it may be difficult to regenerate pine stands on some poorly drained sites by clearcutting systems because of standing water on the prospective seedbed during the germination period."Wet conditions also result in death of residual seed trees.In addition to silvicultural implications, high water causes costly and unpredictable logging operations.Heavy machinery makes logging roads impassable, and the puddling of soil by compaction reduces productivity of a site.No major research has been directed at determining effective and economical drainage coefficients for woodlands and, therefore, the full benefit of particular water removal rates to both tree growth and logging remain speculative.Agricultural and civil engineers requested to design woodland drainage systems have little data on which such designs may be based.Nevertheless, there is much active interest in woodland drainage and engineers are receiving an increasing number of requests for assistance in the layout of water-removal systems.This paper presents the results of an effort to determine the effect of (1) continuous flooding, (2) continuous drainage,