Eucalyptus genotypes water use and site interactions on water resource sustainability and productivity

Water use, water use efficiency and water use sustainability are challenging issues for expansion of Eucalyptus plantations around the world but in particular where climate change scenarios are projecting droughts and water scarcity. The fast-growing species have been negatively related to reduce water availability by social and environmental groups but also forest industry wonders about the impact of drier climates on productivity and the water sustainability of forest plantations. We evaluated growth, water use and water use efficiency response at canopy closure (3 to 4 years of age) of eight selected E.globulus, E.nitens and E. nitens x globulus (E.gloni) genotypes at 4 sites of contrasting climate (temperature & dry season length) and soil water holding capacity. Across sites and genotypes growth rate and water use ranged 35-70- m3/ha/yr and 350 to 900 mm ha-1. Despite specific genotype cases, our results showed similar water use vs productivity relationships for a single taxon (90 m3 of water per m3 of wood) but suggested large differences among taxas across sites. Also, our results suggest that hybrids may provide large productivity benefits but may need a more precise understanding on their physiological mechanisms. These results suggest that interesting opportunities exist for matching genotypes to sites in order to reduce environmental concerns on water resources use of Eucalyptus intensively managed plantations.