Research Article: Estimations of evapotranspiration in an age sequence of Eucalyptus plantations in subtropical China

Date Published: April 11, 2017

Publisher: Public Library of Science

Author(s): Wenfei Liu, Jianping Wu, Houbao Fan, Honglang Duan, Qiang Li, Yinghong Yuan, Hao Zhang, Julia A. Jones.

http://doi.org/10.1371/journal.pone.0174208

Abstract

Eucalyptus species are widely planted for reforestation in subtropical China. However, the effects of Eucalyptus plantations on the regional water use remain poorly understood. In an age sequence of 2-, 4- and 6-year-old Eucalyptus plantations, the tree water use and soil evaporation were examined by linking model estimations and field observations. Results showed that annual evapotranspiration of each age sequence Eucalyptus plantations was 876.7, 944.1 and 1000.7 mm, respectively, accounting for 49.81%, 53.64% and 56.86% of the annual rainfall. In addition, annual soil evaporations of 2-, 4- and 6-year-old were 318.6, 336.1, and 248.7 mm of the respective Eucalyptus plantations. Our results demonstrated that Eucalyptus plantations would potentially reduce water availability due to high evapotranspiration in subtropical regions. Sustainable management strategies should be implemented to reduce water consumption in Eucalyptus plantations in the context of future climate change scenarios such as drought and warming.

Partial Text

Forests occupy approximately 4.1 billion hectares of the earth’s land surface [1] and play an important role in providing ecological services [2, 3]. In China, forests cover an area of 208 million hectares [4], of which reforested or afforested plantations account for more than one-third of the area. Reforested or afforested plantations have been performing important ecological function and service, which can absorb a large amount of CO2 and provide wood products [5, 6]. To meet increasing demands for timber and pulp, fast-growing tree species are widely planted in tropical and subtropical regions to boost regional economy [7, 8]. For instance, Eucalyptus, due to its characteristics of fast-growing, high productivity and good adaptability, has been extensively grown in South China [9]. By 2010, the plantation of Eucalyptus has been expanded to more than ten provinces across China, occupying an area of 3.68 million hectares. Hence, Eucalyptus plantations are of great significance to ecological and economic benefits in South China [9].

The efficient evaluation of Eucalyptus evapotranspiration was performed by combining evaporation model and micro-lysimetric measurements in an age sequence of Eucalyptus plantations. First, the total stand transpiration (including interception losses) increased with plantation ages from 2 to 6 years old, which implies the shorter rotation duration (i.e. < 6 years) would diminish the negative effects of Eucalyptus plantations on soil water sustainability. We also found that Eucalyptus plantations may easily suffer drought threat because of their high evapotranspiration. Therefore, policy makers should implement a rational distribution for Eucalyptus plantations to minimize the negative hydrological effects in the context of future climates characterized by rising temperatures and more intense droughts.   Source: http://doi.org/10.1371/journal.pone.0174208

 

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