The effect of forest floor manipulation on nitrogen status and tree growth in an eastern Ontario jack pine ecosystem

Abstract

Four forest floor manipulation treatments were applied to an eastern Ontario jack pine (Pinusbanksiana Lamb.) ecosystem. These included a one-time complete removal of the forest floor to mineral soil; annual removal of the total forest floor to mineral soil; one-time removal of the forest floor, ashing of the material, and broadcast spreading of the ash onto exposed mineral soil; and an untreated control. Eight years after treatment radial tree growth on the treated plots showed a 30% reduction compared with the untreated plot. Annual removal of the forest floor caused most severe nitrogen depletion in jack pine foliage, forest floor, and mineral soil. Effects of one-time removal and burning treatments were less severe, but significant. Any interference with the normal buildup of the forest floor during stand development should be avoided if site quality is to be maintained for tree growth.