From Primary Production to Growth and Harvestable Yield and Vice Versa

Abstract

This chapter draws a link between the volume-oriented forestry measures and the biomass measures used in production ecology. Tools and rules of thumb will be provided to convert the forestry growth and yield values into primary productivity and production efficiencies, and vice versa. In ecological studies in the temperate zone of central Europe, direct physiological measurements of the gas exchange in plants, and indirect estimations based on energy balances, litter production or evaporation rates provide approximate values for gross primary production (GPP) of 20–40 tons ha^-1 year^-1 or 2–4 kg m^-2 year^-1 and net primary production (NPP) of 10–20 tons ha^-1 year^-1 or 1–2 kg m^-2 year^-1 respectively. Forest inventories and long-term experimental plots, on the other hand, report an average growth of merchantable wood volume of 10–20 m³ ha^-1 year^-1. This chapter explains how to convert wood volume growth data to NPP through multiplication with the specific wood density, biomass expansion factors and turnover rates, and to GPP by adding respiration.