ELSEVIER Agricultural and Forest Meteorology 88 (1997) 169-179 AGRICULTURAL F&kiT METEOROLOGY Applicability of the radiation-use efficiency concept for simulating growth of forest stands H.H. Bartelink a, *, K. Kramer b, G.M. J. Mohren b a Wageningen Agricultural Uniuersiry, Dept. of Forestry, Wageningen, Netherlands b Institute for Forest and Nature Research IBN-DLO, Netherlands Received 27 February 1996; revised 15 May 1997; accepted 17 May 1997 Abstract The aim of the study was to estimate the radiation-use efficiency (RUE) and investigate its suitability as a tool to simulate growth of mixed forest stands. We applied a mechanistic forest growth model (FORGRO), (1) to investigate differences between RIJE of deciduous broadleaved trees (beech) and evergreen conifers (Douglas-fir), and (2) to analyze the effects of stand structure and stand composition on RUE in mixed species forests. With FORGRO, RUE under optimum growing conditions was calculated. Based on comparison of net primary production (NPP) rates estimated by FORGRO with data from the literature, we concluded that using FORGRO to estimate RUE was legitimate. Sensitivity analysis showed that RUE is relatively insensitive to changes in values of photosynthetic parameters. Temperature had some effect, depending on the species. Hence, species-specific responses to temperature can be expected to affect competitive interrelationships in case of climate change. Though RUE showed large daily variability, RUE derived from cumulative absorbed photosynthetically active radiation (APAR) and NPP was virtually constant throughout the year and over a lo-yr period, in both monospecies and mixed-species stands. It was concluded that the RUE-concept is a useful tool in simulating forest growth. 0 1997 Elsevier Science B.V. Keywords: Radiation-use efficiency; Forest growth; FORGRO; Simulating forest growth 1. Introduction Based on results of many productivity studies, Monteith (1977) proposed the concept of radiation- use efficiency (RUE:), stating that the ratio between the amount of absorbed photosynthetically active radiation (APAR: 400-700 nm) and the amount of dry mass produced would be a conservative parame- ter. In many productivity studies, a linear relation- ship between APAR and crop growth has been found * Corresponding author. since, both in agricultural crops (e.g., Gallagher and Biscoe, 1978; Stockle and Kiniry, 1990), and in tree species (e.g., Jarvis and Leverenz, 1983; Cannell et al., 1988). Landsberg (1986) and Cannell et al. (1987) concluded that under non-limiting growing condi- tions (ample supply of water and nutrients) RUE may be constant for a single species: when RUE refers to total dry mass production it is likely to be a conservative value for C3-crops growing in similar temperature and radiation environments (Cannel1 et al., 1988). In many situations, however, RUE will be lower than the theoretical maximum of about 3 g MJ- ’ 0168-1923/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved. HZ SO168-1923(97)00041-5