Estimation of the net primary productivity of even-aged stands with a carbon-allocation model

The estimation of the time-course of net primary productivity (NPP) is of g eneral ecological interest. Solutions of Pipestem, a model of carbon alloca tion and growth, show a waxing and waning of NPP in even-aged stands of Pin us taeda between establishment and maturity. Peak productivity occurs at th e time of stand closure. Estimation of NPP is inextricably linked with esti mation of the production and loss of components of dry matter (foliage, fee der roots, and woody tissues). The fraction of available carbon allocated t o the production of each of these components varies considerably over the c ourse of stand development. Analyses also indicate that the increasing conc entration of atmospheric CO2 is elevating the NPP of stands of P. taeda. (C ) 1999 Elsevier Science B.V. All rights reserved.