Increasing survival probability, height growth, and diameter growth of 1-0 shortleaf pine seedlings through genetic selection, site preparation, and vegetation control

Abstract

Natural regeneration of shortleaf pine (Pinus echinata Mill.) has proven difficult due to slow growth, high mortality, and lack of competitive ability. Consequently, artificial regeneration is frequently used for reforestation, although regeneration failures are common. We examine how genetic selection, in conjunction with extensive site preparation and understory vegetation control, can increase reforestation success. We used data from three long-term studies in southeastern Missouri to examine survival of 5,500 1-0 shortleaf pine seedlings. One site contained 2,000 full-sib plus 1,000 orchard-run 1-0 containerized seedlings planted on a mechanically cleared hillslope. Herbicide was applied at initial planting and 1 year after planting to 2,000 seedlings, while 1,000 seedlings received no herbicide. In addition, 2,500 orchard-run bareroot seedlings were planted at two similar sites: one utilizing herbicide understory control for 10 years, and one underplanting in an existing forest with no site preparation or herbicide. Seedling survival after 7 years on sites with no vegetation control was 30 percent. With herbicide treatments before and after planting, survival of orchard-run seedlings was 60 percent 7 years after planting. When pedigreed seedlings were planted on mechanically prepped and herbicide-treated sites, average survival increased to 85 percent after 7 years. Survival of planted shortleaf pine seedlings increased as site preparation intensity and understory competition control increased. Long-term survival was reduced by underplanting seedlings in an existing hardwood stand, where overstory and understory competition was present.

Parent Publication

• Proceedings of the 20th Biennial Southern Silvicultural Research Conference

Citation

Lyczak, Stephen J.; Kabrick, John M.; Dey, Daniel C.; Knapp, Benjamin O.; Larsen, David R.; Walter, William D. 2020. Increasing survival probability, height growth, and diameter growth of 1-0 shortleaf pine seedlings through genetic selection, site preparation, and vegetation control. In: Bragg, Don C.; Koerth, Nancy E.; Holley, A. Gordon, eds. 2020. Proceedings of the 20th biennial southern silvicultural research conference. e–Gen. Tech. Rep. SRS–253. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 309-317.