Effects of climate on growth traits of river red gum are determined by respiration parameters

Abstract

Temperature is the major uncontrollable climate variable in plantation forestry. Matching plants to climate is essential for optimizing growth. Matching is usually done with field trials because of the lack of a predictive relation between laboratory measurements of physiological responses and climatic factors affecting growth. This paper evaluates the potential of using respiration parameters for selection of appropriate drainage or seed sources within a drainage for superior growth in a particular climate. The growth traits measured are tree height, stem diameter and stem volume. The respiratory parameters measured are respiratory heat rate, rate of CO₂ production, and temperature dependence of respiratory heat rate. Five open-pollinated families from each of nine seed sources of river red gum (Eucalyptus camaldulensis Dehnh.) were studied following selection from a larger set of seed sources planted at three plantations in California. The three plantations differ in climate, particularly in extreme temperatures, diurnal temperature variability and total rainfall. Within each plantation, growth and respiration parameters show high genetic variation [overall coefficient of variation (CV) = 14–58%, family CV = 11–33%], with at least one of these traits showing significant (P < 0.10) difference due to drainage, or source within drainage, or families within source. The relationship of growth to respiration for each trait differs, depending on testplantation, origin drainage, source or family, suggesting a unique pattern for each trait. Correlation of drainage level averages between growth and respiration were strongly negative and significant (P = 0.10–0.01). Rankings for drainages between paired plantations were strong and significant (P = 0.10–0.05) only for respiration, but not for growth traits.