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Forskningsartikel2006Vetenskapligt granskad

Simulation of willow productivity based on radiation use efficiency, shoot mortality and shoot age

Sannervik AN, Eckersten H, Verwijst T, Kowalik P, Nordh NE


Process-based models usually are complex and require a large number of input data, which restrain their use for prediction of forest growth. To overcome those difficulties, efforts have been made towards their simplification by integrating both empirical and mechanistic elements at the same hierarchical level. In this study, we investigated the reliability of such a model for projecting productivity in willow coppice systems. Willow forest growth was assumed proportional to the global radiation intercepted by the canopy during the vegetation period. The radiation use efficiency concept was combined with mortality functions based on self-thinning to simulate the accumulated biomass. The model was calibrated against annual stem biomass data from a fertilised and irrigated experimental stand situated near Uppsala (central Sweden) and validated against data from several other fertilised stands located in central and southern Sweden, all representing close to optimal nitrogen conditions. The model was able to explain 81% of the observed variations in standing biomass of 1-year-old shoots, almost none of the variations after the second year, and 52% for 3-year-old shoots. Thus, willow productivity of especially shoots older than I year was only partially possible to reproduce based on incident radiation, shoot age and shoot mortality. This might be explained by low performance of the radiation interception and mortality estimations, as well as, the assumption of optimum conditions being maintained throughout the period may not have been met. (c) 2005 Elsevier B.V All rights reserved

Publicerad i

European Journal of Agronomy
2006, Volym: 24, nummer: 2, sidor: 156-164