Contributions of climate, leaf area index and leaf physiology to variation in gross primary production of six coniferous forests across Europe: a model-based analysis.

Gross primary production (GPP) is the primary source of all carbon fluxes in the ecosystem. Understanding variation in this flux is vital to understanding variation in the carbon sink of forest ecosystems, and this would serve as input to forest production models. Using GPP derived from eddy-covariance (EC) measurements, it is now possible to determine the most important factor to scale GPP across sites.

Fruit development, not GPP, drives seasonal variation in NPP in a tropical palm plantation.

We monitored seasonal variations in net primary production (NPP), estimated by allometric equations from organ dimensions, gross primary production (GPP), estimated by the eddy covariance method, autotrophic respiration (R(a)), estimated by a model, and fruit production in a coconut (Cocos nucifera L.) plantation located in the sub-tropical South Pacific archipelago of Vanuatu. Net primary production of the vegetative compartments of the trees accumulated steadily throughout the year.

The human footprint in the carbon cycle of temperate and boreal forests.

Temperate and boreal forests in the Northern Hemisphere cover an area of about 2 x 10(7) square kilometres and act as a substantial carbon sink (0.6-0.7 petagrams of carbon per year).

Respiration as the main determinant of carbon balance in European forests.

Carbon exchange between the terrestrial biosphere and the atmosphere is one of the key processes that need to be assessed in the context of the Kyoto Protocol. Several studies suggest that the terrestrial biosphere is gaining carbon, but these estimates are obtained primarily by indirect methods, and the factors that control terrestrial carbon exchange, its magnitude and primary locations, are under debate. Here we present data of net ecosystem carbon exchange, collected between 1996 and 1998 from 15 European forests, which confirm that many European forest ecosystems act as carbon sinks.

Transpiration of a 64-year old maritime pine stand in Portugal : 2. Evapotranspiration and canopy stomatal conductance measured by an eddy covariance technique.

The sensible and latent heat losses of a maritime pine stand (Pinus pinaster Aiton) and of its understorey were measured in Portugal, in conditions of mild water stress, using an eddy covariance technique (monodimensional sonic anemometer coupled with a thin thermocouple and a fast-response hygrometer) at two levels above and under the canopy: canopy exchanges were estimated by difference. This paper first discusses the corrections to be made to the raw fluxes, then shows that, over a 24-h interval, the energy balance closure was very satisfactory, as well as the comparison between estimations of canopy evaporation by eddy covariance and sap flow. Moreover, the phase shift between the two methods was small when sap flow was measured just at the base of the canopy.