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Sustainable biomass production in eucalypt plantations under climate changes: insights from a throughfall exclusion experiment

Laclau J.P.. 2016. In : IUFRO Regional Congress for Asia and Oceania 2016: Forests for sustainable development the role of research. Beijing : IUFRO, p. 42-42. IUFRO Regional Congress for Asia and Oceania 2016, 2016-10-24/2016-10-27, Beijing (Chine).

The frequency of drought periods should increase under climate changes in many tropical regions. A large-scale throughfall exclusion experiment was set up in Brazil to study the interaction between water status and potassium (K) or sodium (Na) availability on the ecophysiology of Eucalyptus trees. Across the water supply regimes, the stemwood biomass at the harvest age was 2.7 and 1.6 times higher in trees fertilized with KCl and NaCl, respectively, than in trees with no K and Na addition. Excluding 1/3 of the rainfall reduced stemwood production only for trees fertilized with K, as a result of low water requirements of K-deficient trees. Gas exchange water used efficiency (WUE) estimates were not correlated with WUE for wood production. The allocation pattern in response to nutrient and water supply appeared to be a major driver of WUE for stemwood production. Phloem sap and leaf ä13C were not valuable proxies of WUE for wood production, which suggests a weak interest for breeding programs. The strong interaction between water and nutrient availabilities on tree functioning in this study suggests that a slight decrease in fertilization rates could help reduce the risks of mortality of Eucalyptus trees under conditions of extreme water deficit.

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