Abstract
Although grass lands occur in drier areas than forests, net production of the grass lands is no less than that of the seasonal forests, mainly due to the fact that respiration consumes much of forest gross production. However, grass biomass degrades quickly. By well-managed forestation of such area, net production can be converted to wood. This is an effective way of the atmospheric CO2 sequestration.
To improve forest net production in the global change area of high atmospheric CO2 concentrations, understanding of the sink-source relationship of tree growth is indispensable. We found that, in two Acer species, the growth of branches depended not only on their photosynthetic production but on their ranks in growth priority. Even the branches of similar light interceptions showed marked differences in branch growth, depending, for example, on the abundance of long shoots within the branch.
