Eucalyptusand Water Use in South Africa

Abstract

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.

Extending periodic eddy covariance latent heat fluxes through tree sap-flow measurements to estimate long-term total evaporation in a peat swamp forest

“…An important observation, made over the three field campaigns, was that the average ET a measured during March 2010 (4.4 mm day −1 ) did not correspond to the period of highest R n (November 2009), which is commonly accepted to be one of the main driving variables in the process of ET a (Albaugh et al, 2013). This may indicate a lag in the ET a of the Nkazana PSF in relation to the maximum R n , possibly explaining the poor relationships observed between tree sap flow and climatic variables (such as R n ).…”

“…1) generally considered to control sap flow in trees such as solar irradiance (I s ) and VPD (Albaugh et al, 2013). Sap flow was also compared by multiple regression analysis to the micrometeorological parameters including I s , T air , RH and soil volumetric water content (θ ) to determine individual and combined drivers of sap flow.…”

Integrated Landscape Approaches for Africa’s Drylands

“…For example, commercial plantation forestry is classified in South Africa's Water Act as a stream flow reduction activity. This has resulted in land-cover changes in water-constrained watersheds with tree-free buffer zones being established close to permanent streams and public works programs removing invasive tree seedlings to improve stream flow (Cadman et al 2010;Albaugh, Dye, and King 2013). Similarly, dismantling inappropriate enclosures and reopening former stock routes may be required to ensure pastoral mobility and increase resilience of pastoral production systems (Wagkari 2009;IUCN 2012).…”

Physiological responses and soil water balance of clonal <i>Eucalyptus</i> under contrasting spacings and genotypes

“…For that seek a better understanding of the interaction genotype x spacing x water relations, it is crucial to the understanding of physiological variables such as transpiration, leaf area index, conductance canopy, leaf water potential and the use of efficiency water (ALBAUGH et al, 2013).…”

“…Many studies have focused on the influence of superior genotypes and silvicultural practices on increased productivity and water use efficiency, measured by the amount of biomass produced by the amount of water transpired (MYERS et al, 1996;LI, 2000;ALBAUGH et al, 2013;OTTO et al, 2014).…”