Influence of reproduction cutting methods on structure, growth and regeneration of longleaf pine forests in flatwoods and uplands

Abstract

a b s t r a c tThough longleaf pine (Pinus palustris Mill.) forests have been primarily managed with even-aged methods, interest is increasing in uneven-aged systems, as a means of achieving a wider range of stewardship goals. Selection silviculture has been practiced on a limited scale in longleaf pine, but difficulty with using traditional approaches and absence of an evaluation across a range of site types has left managers in doubt concerning its suitability. This study was conducted to quantify the effects on stand dynamics of applying single-tree selection, group selection, irregular shelterwood and uniform shelterwood in longleaf pine forests on flatwoods and uplands of the southeastern United States. Selection treatments reduced stand basal area to $11.5 m 2 ha À1 and shelterwood treatments left a basal area of $5.8 m 2 ha À1 . In spite of initial decreases in tree density and standing volume, growth rates were normal in all stands (1-5% per year), as were subsequent increases in basal area and tree density. Despite the continuing abundance of saw-palmetto (Serenoa repens W. Bartram) cover and absence of prescribed fire during the eight post-treatment years, significant increases in pine regeneration were observed in all treated stands in the flatwoods. Because of a multi-year drought in the uplands, pine seedling numbers dramatically declined, no matter which reproduction approach was employed. Although seedling numbers eventually began to recover, they were again precipitously depressed by a wildfire in 2013. Even with such losses, sufficient pine seedlings remained in each treatment to foster successful stand regeneration. Single-tree selection produced less overall change in the forest ecosystem than group selection, which caused less alteration than shelterwood treatment. Single-tree selection appears to be an effective way for achieving stand regeneration, while maintaining a continuous canopy cover that aids in the control of woody competitors and supports an array of resource values. Selection silviculture seems to be a lower risk approach for guiding forests along a trajectory of gradual improvement, with adjustments provided by frequent surface fires and periodic tree harvest. Long-term observation will be required to verify that selection can sustain forest ecosystems on sites characterized by differing environments.Published by Elsevier B.V.

Improving Ecological Restoration to Curb Biotic Invasion—A Practical Guide

“…Different thinning intensities (i.e., variable retention among forest trees) can be used to increase the spatial heterogeneity in overstory vegetation (Franklin et al 2007). Uneven-aged silvicultural systems, such as single-tree selection and group selection (Brockway et al 2014), can also improve overstory structure while increasing the species diversity, richness, and evenness of native understory plants (Brockway and Outcalt 2015, 2017). Herbicides: Use of chemicals to control undesirable plant competitors or invaders is viewed as a less favorable option, because of the potential adverse effects posed to desirable species present in local and regional habitats.…”

Seed depredation negates the benefits of midstory hardwood removal on longleaf pine seedling establishment

“…Creating favorable conditions for longleaf pine regeneration may involve a series of silvicultural manipulations on fire-suppressed sites. Light availability is increased by reducing overstory density through a variety of harvesting techniques (Boyer & Farrar 1981;Mitchell et al 2006;Brockway & Outcalt 2017). Additional mechanical, chemical, or prescribed fire treatments are often used to eliminate midstory hardwoods to restore the historical savanna structure and create a more flammable understory for the reintroduction of fire (Provencher et al 2001;Kush et al 2004;Jose et al 2010).…”

Height-diameter Relationships in Longleaf Pine and Four Swamp Tree Species

“…Overstory pines here ranged from 48 to 74 years in age. Site index at these study sites is fairly consistent, ranging from 21 to 24 m at 50 years (Brockway & Outcalt, 2017 …”