Maintaining a pine legacy in itasca state park

Abstract

Itasca State Park, located in the northern central portion of Minnesota, is challenged with maintaining a pine forest covertype, yet regeneration failures may allow much of the park to succeed to northern hardwoods. Efforts to improve pine regeneration and growth have included deer exclosures and prescribed burning to reduce competing vegetation. We revisited Itasca's Mary Lake deer exclosure 66 years after establishment to compare stand development, structure, and white pine (Pinus strobus L.) regeneration and growth with that of adjacent plots that have been: (1) untreated and (2) recently repeatedly under-burned. Overstory structure and composition was similar among all three treatments, and midand understory structures were similar in the treatments subject to deer browse. Sapling and midstory white pine were only present in the exclosure. White pine regeneration was present in all treatments and most abundant in the burned treatment, but was restricted to the smallest height class and consistently overtopped by the shrub layer. Regeneration, sapling, and midstory layer tree densities were highest within the deer exclosure, as was white pine height growth. The untreated plot lacked young pine and will likely succeed to northern hardwoods with a shrub understory. The three-fire sequence of the burned treatment increased the abundance of white pine regeneration at this site, but may require additional measures to control competing vegetation to allow that regeneration to ascend into the sapling layer.