Willow production as a function of radiation and temperature

Abstract

A simple model for growth of energy forests is constructed, in which the dominant variables for growth are air temperature and radiation. Processes included in the model are: photosynthesis; light penetration in the canopy; respiration; allocation between above- and below-ground parts; and allocation between stems and leaves. Other factors influencing growth are assumed to be close to optimal, e.g., water-supply and nutrition.

The model is tested on willow, using actual meteorological data and seasonal field measurements of growth of yearly coppied shoots in established stands. Good agreement between simulated growth and field measurements was obtained for two sites with different climates and plant densities expressed in stools m⁻².

For one-year-old shoots in 1981, the model predicted a maximal LAI of $\text{∼ 7}$ and an above-ground biomass production of $\text{∼ 14}$ tonnes ha⁻¹ for the southern part of Sweden (latitudes 55–60°N), and LAI and production of $\text{∼ 4}$ and 8.5, respectively, for the north-eastern coastal area (latitudes 63–66°N).