Effects of intensive fertilization, complete competition control and site quality on aboveground net primary production (ANPP) dynamics of loblolly pine plantations

Changes in aboveground net primary production (ANPP) are relevant to forest management, ecosystem ecology and carbon budget. It is believed that ANPP reaches a maximum young stands then gradually declines as age. Intensive silvicultural treatments such competing vegetation control fertilization have been widely used pine plantations the southern US shown large early growth gains. The effects of site quality on long-term patterns remain be studied. These were rigorously tested by examining their parameters an ANPP-age model for loblolly pine, using 33-year data from field experiment containing factorial arrangement complete competition (H) intensive (annually until age 12 years biennially 28 years). Site significantly affect magnitude timing ANPP; substantially alter pattern relationship, but does not. Under better conditions will reach greater at earlier ages. Non-fertilized achieve smaller thereafter no obvious decline ANPP, while intensively fertilized quickly sharply lower level than non-fertilization stands. repeated enhances rates stands, continuous application mid- or late-rotation reduces older Our results showed nutrient limitations not responsible age-related US.