Response of Live Oak Regeneration to Planting Density, Fertilizer, and Mulch

Abstract

Maritime forests are coastal ecosystems that stabilize coastlines, recharge aquifers, and provide protection against storm surges. The range of these forests has been decreasing due to threats such as urban expansion, clearing for agriculture, climate change, and an influx of native but competitive loblolly pine (Pinus taeda L.) from pine plantations. To restore maritime forests, southern live oak (Quercus virginiana Mill.) should be established as the dominant canopy species; however, knowledge of how to grow live oak in a restoration setting is limited. We planted southern live oak seedlings into a clearcut experimental site that was formerly a loblolly pine plantation. Our goal was to test how planting density (1, 2, or 3 m), mulch, and fertilization at planting impacted the initial growth of seedlings over the course of four growing seasons. The application of fertilizer had an initial positive effect on seedling diameter (36%) after the first growing season. The application of mulch increased seedling height in years 2 through 4 (25.6% to 22.7%), diameter in years 3 and 4 (20.9% to 19.3%), and crown width in year four (8.5%). Planting density had no consistent effect over the first four years. These results demonstrate the potential benefits of incorporating fertilizer and mulch into restoration prescriptions to promote seedling field establishment. Planting density should continue to be monitored through canopy closure for potential effects of plant facilitation. Integrating silvicultural treatments such as planting density, soil amendments, and vegetation control may inform cost-effective management recommendations for maritime forest restoration.