Eucalyptus

The Eucalyptus genus yields high rates of productivity and can be grown across a wide range of site types and climates for products such as pulp, fuelwood, or construction lumber. In addition, many eucalypts have the ability to coppice, making this genus an ideal candidate for use as a biofuel feedstock. However, the water use of Eucalyptus is a controversial issue, and the impacts of these fast-growing trees on water resources are well documented. Regardless, the demand for wood products and water continues to rise, providing a challenge to increase the productivity of forest plantations within water constraints. This is of particular relevance for water-limited countries such as South Africa which relies on exotic plantations to meet its timber needs. Research results from water use studies in South Africa are well documented and legislation restrictions limit further afforestation. This paper outlines techniques used to quantify the water use of eucalypt plantations and provides recommendations on where to focus future research efforts. Greater insights into the water use efficiency of clonal material are needed, as certain eucalypt clones show fast growth and low water use. To better understand water use efficiency, estimates should be combined with monitoring of stand canopy structure and measurements of physiological processes

Eucalyptus and Water Use in South Africa

The Eucalyptus genus yields high rates of productivity and can be grown across a wide range of site types and climates for products such as pulp, fuelwood, or construction lumber. In addition, many eucalypts have the ability to coppice, making this genus an ideal candidate for use as a biofuel feedstock. However, the water use of Eucalyptus is a controversial issue, and the impacts of these fast-growing trees on water resources are well documented. Regardless, the demand for wood products and water continues to rise, providing a challenge to increase the productivity of forest plantations within water constraints. This is of particular relevance for water-limited countries such as South Africa which relies on exotic plantations to meet its timber needs. Research results from water use studies in South Africa are well documented and legislation restrictions limit further afforestation. This paper outlines techniques used to quantify the water use of eucalypt plantations and provides recommendations on where to focus future research efforts. Greater insights into the water use efficiency of clonal material are needed, as certain eucalypt clones show fast growth and low water use. To better understand water use efficiency, estimates should be combined with monitoring of stand canopy structure and measurements of physiological processes

Tamm Review: Light use efficiency and carbon storage in nutrient and water experiments on major forest plantation species

International audienceWe used published data from nine sites where nutrient and water optimization studies had been installed in a 2 × 2 factorial design to determine maximum biomass production in response to a simple set of treatments. We tested for site and treatment effects on the relationships between stem, aboveground (stem, branches, foliage) and total (aboveground + roots) biomass production versus intercepted light (light use efficiency, LUE). We also estimated the additional carbon stored as a result of treatment. The sites were located in Australia (Pinus radiata), Brazil (Eucalyptus grandis × urophylla), France (Pinus pinaster), the United States in Georgia and North Carolina (Pinus taeda) and Hawaii (Eucalyptus saligna), Portugal (Eucalyptus globulus), South Africa (E. grandis), and Sweden (Picea abies). We hypothesized that site, treatment and their interaction would significantly affect LUE; however, we rejected our hypothesis because stem, aboveground and total LUE were not affected by site or treatment. The stem, aboveground and total LUE values were 1.21, 1.51, and 0.85 g MJ−1, respectively. The total LUE value was lower than that for stem and aboveground LUE because a different population was used for the analysis (only five of the nine sites had total production data), and the total LUE relationship had a zero intercept whereas the stem and aboveground LUE relationships had a negative intercept. The average amount of additional carbon that would be stored by the irrigation, fertilization, and fertilization plus irrigation treatments was 3.9, 6.8 and 13.4 Mg CO2 equivalents ha−1 yr−1, respectively. These additional carbon storage estimates, based on these research studies with annual nutrient and water applications, were similar to results obtained in operational settings with less intensive nutrient applications