Influence of tree shelters on seedling success in an afforested riparian zone

Abstract

The restoration of a natural riparian ecosystem is a key component to improving water quality and restoring stream health in a disturbed watershed. The rate and degree of riparian restoration, and hence stream restoration, depends in part upon afforestation practices. Successful afforestation is determined largely by the rates of survivorship and growth of the tree species planted or recruited in a riparian zone. This study was part of a project involving the restoration of a channelized section of Wilson Creek located in the Bernheim Arboretum and Research Forest, Nelson County, Kentucky. Riparian restoration activities focused on reestablishing a native riparian corridor using American sycamore (Platanus occidentalis), green ash (Fraxinuspennsylvanica var. subintegerrima), and pin oak (Quercus palustris). This study evaluated techniques for improving the growth and survivorship of planted seedlings along Wilson Creek. Specifically, two tree shelter types (Tubex® vs. continental mesh), with or without herbicide treatments, were compared. Additionally, the influence of these techniques on debris retention within the riparian zone was also examined. Results showed that use of tree shelters significantly increased the growth of seedlings (but not survivorship), provided physical protection especially during heavy flooding events, and accelerated woody debris retention. Both Tubex® and continental mesh tree shelters were effective in enhancing seedling growth, with Tubex® shelters yielding significantly better growth when combined with herbicide to control competing vegetation. Thus, the most cost effective choice may depend on the environmental setting and ability to combine the shelters with other growth enhancing treatments.