May 29, 2020
https://www.linkedin.com/posts/activity-6672104826991652865-Kbvq
Part 2 of 3 crop tree enhancement growth models is a crown width-diameter projection system for sweetgum. Initial data were obtained from 14-year-old stand on an abandoned agricultural field that was remeasured 9 years later. Treatments included fertilization, release, release with fertilization, and control. The crown width (CW) projection function uses initial CW, basal area of competing trees after treatment, and response to release only and release with fertilization. The dbh projection function uses initial dbh, periodic CW growth, and response to release with or without fertilization. The CW and dbh projection functions were fit as a system of seemingly unrelated regression (SUR) equations. Sweetgum exhibits a large growth response to release treatments, especially when fertilization is included. The response to treatments is greatest for trees with small initial CW and low basal area of competitors. Released trees have more resources available due to expansion into space previously occupied by competitors. A simple Shiny app was developed for this growth projection system.
Shiny app for sweetgum