J Plant Ecol ›› 2019, Vol. 12 ›› Issue (6): 982-992.DOI: 10.1093/jpe/rtz033

• Research Articles • Previous Articles     Next Articles

Hydrologic balance, net primary productivity and water use efficiency of the introduced exotic Eucalyptus grandis × Eucalyptus urophylla plantation in south-western China

Yanting Hu1, Ping Zhao1,2,*, Yuqing Huang3, Liwei Zhu1, Guangyan Ni1, Xiuhua Zhao1 and Zhihong Huang4   

  1. 1Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou 510650, China
    2Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou 510650, China
    3Key Laboratory of Beibu Gulf Environment Change and Resource Use, Ministry of Education and Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation, Nanning Normal University, 175 Mingxiu East Road, Nanning, Guangxi 530001, China
    4Department of Forest Ecology, College of Life Science and Technology, Central South University of Forestry and Technology, 498 Shaoshan South Road, Changsha, Hunan 410004, China
    *Correspondence address. South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou 510650, China. Tel: +86 20 37252881; Fax: +86 20 37252831; E-mail: zhaoping@scib.ac.cn
  • Received:2019-04-23 Revised:2019-05-19 Accepted:2019-07-20 Published:2019-12-01

Abstract:

Aims

Land cover changes can disrupt water balance and alter the partitioning of precipitation into surface runoff, evapotranspiration and groundwater recharge. The widely planted Eucalyptustrees in south-western China have the potential to bring about hydrologic impacts. Our research aims to elucidate the hydrologic balance characteristics of the introduced exotic Eucalyptus grandis× Eucalyptus urophylla plantation and to assess whether its high productivity results from high water use efficiency (WUE) or large water consumption.

Methods

A 400-m2 experimental plot was established in an E. grandis × E. urophylla plantation in south-western China. Water balance components, including stand transpiration (Tr), evapotranspiration (Et) and runoff (R) were obtained as follows: Tr was estimated based on sap flow measurements, Et was estimated as the average of surface transpiration and evaporation weighted by the fractional green vegetation cover using a modeling approach, and R was collected using the installed metal frame. Net primary productivity (NPP) was obtained from allometric equation and annual diameter at breast height (DBH) increment determination.

Important Findings

Annual Et and Tr were 430 ± 31 and 239 ± 17 mm, respectively. Annual Traccounts for 56 ± 8% of total evapotranspiration on average. WUE (NPP/Tr) of the E. grandis × E. urophylla was estimated to be 3.3–3.9 mmol·mol−1. Based on the comparative analysis of Tr and WUE, E. grandis × E. urophylla had a high productivity due to its high WUE without exhibiting prodigal water use. Meteorological factors including vapor pressure deficit and global solar radiation (Rs) were key factors regulating Et and Tr in our research site. Annual surface runoff, Etand canopy interception occupied 7%, 27–30% and 16% of total precipitation, while the remaining 46–50% of precipitation was used for sustaining groundwater recharge and altering soil water storage. The higher runoff coefficient (7.1%) indicated the weaker capability of E. grandis × E. urophylla to reserve water resource than natural forests and less disturbed plantations. The planting and protection of understory vegetation may decrease the surface runoff and exert beneficial effects on water conservation capacity of Eucalyptus plantation.

Key words: water balance, evapotranspiration, water use efficiency, sap flow, runoff