title: Quantifying the effect of nitrogen-induced physiological and structural changes on poplar growth using a carbon-balance model.
abstract: We evaluate the importance of changes in photosynthetic capacity, respiration rates, root shoot ratio, pipe model parameters and specific leaf area in the early-growth response of hybrid poplar to nitrogen availability. Juvenile growth simulations for trees with three different levels of leaf nitrogen concentration (N(leaf)) (low (1.2%), medium (2.4%) and high (3.6%)) were conducted with the carbon-balance model CROBAS. Five-year growth simulations showed the diameter and height of poplar trees to be, respectively, four and three times larger in plants with 2.4% N(leaf) compared with those with 1.2% N(leaf). Increasing N(leaf) from 2.4 to 3.6% resulted in 34 and 16% higher diameter and height growth of trees. According to the model, changes in the photosynthetic capacity accounted for most of the differences in growth between trees with different levels of N(leaf); the other parameters were much less influential. This suggests that in fast-growing early-successional broadleaved species such as poplars, physiological rather than allocational and morphological traits predominate in determining growth, at least under non-limiting light conditions.
authors.affiliation: Centre Tecnològic Forestal de Catalunya (CTFC), Ctra Sant Llorenç de Morunys km. 2, 25280 Solsona, Spain. lluis.coll@ctfc.cat
authors.forename: Lluís
authors.initials: L
authors.lastname: Coll
authors.forename: Robert
authors.initials: R
authors.lastname: Schneider
authors.forename: Frank
authors.initials: F
authors.lastname: Berninger
authors.forename: Susy
authors.initials: S
authors.lastname: Domenicano
authors.forename: Christian
authors.initials: C
authors.lastname: Messier
mesh_terms: D002170:Canada; D002244:Carbon / Q000378:metabolism; D002678:Chimera / Q000254:growth & development / Q000502:physiology; D003198:Computer Simulation; D008027:Light; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D010101:Oxygen Consumption; D010788:Photosynthesis; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development / Q000502:physiology; D018520:Plant Shoots / Q000254:growth & development / Q000502:physiology; D032107:Populus / Q000254:growth & development* / Q000502:physiology; D013997:Time Factors
chemical_list: D002244:Carbon; D009584:Nitrogen