lower density planting

While we historically thought that tree height in our pine plantations was independent of the planting density, recent research by the Texas A&M Forest Service (TAMFS) seems to indicate otherwise at low density spacing. So although tree height is unaffected by high densities between 700 or 800 tress per acre, the TFS found that the tree height was influenced by the spacing when they compared their data from plantings varying from 300 to 500 plus trees per acre.
The TAMFS planted four densities of control mass pollinator (both parent tree sources are known) loblolly pine at Fairchild State Forest in 2018: 360 (10’ X 12’), 435 (10’ X 10’), 545 (10’ X 8’) and 726 (10’ X 6’) trees per acre. While the 435 and 726 densities had a total height of about 27-28’ in 2024, the 545 spacing had a total height of over 29’ and the 360 spacing had a total height of a bit over 30’. The research results, however, were influenced by a large volume of volunteer pines that seeded in from the adjoining natural stand.
www.FS.USDA.gov
While further research is needed to duplicate these studies, this project is opening a discussion regarding whether our standard 726 trees per acre plantings are excessive. The average diameter at breast height (dbh) was greater at the lower densities, but total volume per acre is dependent on survival and survival is most crucial in the lower density plantings. So will the TAMFS lower their planting density recommendations in the future. Time (and more research) will tell!