Fascicle Nutrient and Biomass Responses of Young Loblolly Pine to Control of Woody and Herbaceous Competitors
Individual fascicle mass and foliar nutrient content and concentration of young loblolly pine (Pinus taeda L.) wen evaluated on 13 locations of a regionwide competition study in the southeastern United States. The study included a factorial combination of two levels of weed control txatmalt (none, treated) and two levels of woody treatment (none, treated) following site preparation. At pine age 2 years, herbaceous treatment (HT)and woody treatment (WT) had a positive effect on individual fascicle biomass and content of N, P, and K at nearly all and at least half of the locations, respectively. In general these effects mirrored responses noted for seedling diameter and height. N concenration increased and P concentration decreased at about half of the locations, while Ca and Mg concentrations decreased nearly all locations with HT. By age 6 years, effects of HT and WT on fascicle mass and nutrient concentrations and contents became neutral or more neutral across the locations. This is atttributed in part to the greater nutrient demand of larger crop pines and associated competition components. A notable exception from neutml effects at age 6, typically occurring on sites with high levels of woody vegetation, was the positive response in K concentration or content and negative response in Ca and Mg concentrations with WT.