Changes in Water-Use Efficiency of Eucalyptus Plantations and Its Driving Factors in a Small County in South China.

Ecosystem water-use efficiency ( W U E ) has been central in revealing the variability in terrestrial carbon and water cycles. Short-rotation plantations such as Eucalyptus plantations can simultaneously impact net primary production ( N P P ) and actual evapotranspiration ( E T a ), components of W U E , resulting in changes in terrestrial carbon and water cycles. However, there are few detailed studies on the changes in the W U E of Eucalyptus plantations at the catchment scale with high spatial remote sensing imagery. Here, we present the changes in the W U E of Eucalyptus plantations and its driving factors (i.e., N P P and E T a ) using satellite-based models combined with 5-m spatial resolution RapidEye imagery in a small county in South China. The increases in E T a of Eucalyptus plantations are primarily the result of climate warming and result in low W U E of Eucalyptus plantations. The management practice used (short rotation in this study) can enhance the effect of climate warming on W U E by varying the N P P of Eucalyptus plantations. A high value of N P P leads to a high W U E of Eucalyptus plantations at the end of a short rotation, while a low value of N P P results in a low W U E at the beginning of another short rotation. Changes in the W U E of Eucalyptus plantations indicated large spatial and temporal variability, associated with climate warming and short-rotation practices. [ABSTRACT FROM AUTHOR]