PRIMARY PRODUCTION OF THE BIOSPHERE - INTEGRATING TERRESTRIAL AND OCEANIC COMPONENTS

Integrating conceptually similar models of the growth of marine and te rrestrial primary producers yielded an estimated global net primary pr oduction (NPP) of 104.9 petagrams of carbon per year, with roughly equ al contributions from Land and oceans. Approaches based on satellite i ndices of absorbed solar radiation indicate marked heterogeneity in NP P for both Land and oceans, reflecting the influence of physical and e cological processes. The spatial and temporal distributions of ocean N PP are consistent with primary I.imitation by Light, nutrients, and te mperature. On Land, water limitation imposes additional constraints. O n Land and ocean, progressive changes in NPP can result in altered car bon storage, although contrasts in mechanisms of carbon storage and ra tes of organic matter turnover result in a range of relations between carbon storage and changes in NPP.