Effects of site preparation treatments on early growth and survival of planted longleaf pine ( Pinus palustris Mill.) seedlings in North Carolina

Abstract

We tested the effects of eight site preparation treatments on early growth and survival of container-grown longleaf pine ( Pinus palustris Mill.) seedlings. Treatments included an untreated check, six combinations of two initial vegetation control treatments (chopping or herbicide) with three planting site conditions (flat [no additional treatment], mounding, or bedding), and a more intense treatment consisting of chopping, herbicide, and bedding. All plots were prescribed burned after site preparation and before planting. Seedling survival was not significantly different among treatments at either 12 ( p = 0.768) or 20 ( p = 0.881) months after planting. Both bedding and mounding increased root collar diameter after 20 months when compared to flat treatments ( p ≤ 0.002). Between the vegetation control treatments, herbicides increased root collar diameter growth over chopping ( p = 0.002) while chopping did not significantly differ from the check. The most root collar growth occurred on the chopping/herbicide/bedding and herbicide/bedding treatments, with the least on the flat (check) and chopping/flat treatments. The percentage of seedlings in height growth 20 months after planting was higher on bedding and mounding treatments when compared to flat treatments ( p ≤ 0.003). Herbicide was also significantly better than chopping with respect to the percentage of seedlings in height growth ( p = 0.016). The treatments with the most seedlings in height growth were chopping/herbicide/bedding followed by herbicide/bedding and herbicide/mounding.