Premium
Photosynthetic stimulation under long‐term CO 2 enrichment and fertilization is sustained across a closed Populus canopy profile (EUROFACE)
Author(s) -
Liberloo Marion,
Tulva Ingmar,
Raïm Olaf,
Kull Olevi,
Ceulemans Reinhart
Publication year - 2007
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2006.01926.x
Subject(s) - photosynthesis , canopy , leaf area index , carbon sink , photosynthetic capacity , nutrient , human fertilization , coppicing , sink (geography) , agronomy , carbon dioxide , botany , carbon cycle , biology , woody plant , ecosystem , ecology , cartography , geography
Summary• The long‐term response of leaf photosynthesis to rising CO 2 concentrations [CO 2 ] depends on biochemical and morphological feedbacks. Additionally, responses to elevated [CO 2 ] might depend on the nutrient availability and the light environment, affecting the net carbon uptake of a forest stand. • After 6 yr of exposure to free‐air CO 2 enrichment (EUROFACE) during two rotation cycles (with fertilization during the second cycle), profiles of light, leaf characteristics and photosynthetic parameters were measured in the closed canopy of a poplar ( Populus ) short‐rotation coppice. • Net photosynthetic rate ( A growth ) was 49% higher in poplars grown in elevated [CO 2 ], independently of the canopy position. J max significantly increased (15%), whereas leaf carboxylation capacity ( V cmax ), leaf nitrogen (N a ) and chlorophyll (Chl a ) were unaffected in elevated [CO 2 ]. Leaf mass per unit area (LMA) increased in the upper canopy. Fertilization created more leaves in the top of the crown. • These results suggest that the photosynthetic stimulation by elevated [CO 2 ] in a closed‐canopy poplar coppice might be sustained in the long term. The absence of any down‐regulation, given a sufficient sink capacity and nutrient availability, provides more carbon for growth and storage in this bioenergy plantation.