Preprints
https://doi.org/10.5194/hess-2021-304
https://doi.org/10.5194/hess-2021-304

  23 Jun 2021

23 Jun 2021

Review status: this preprint is currently under review for the journal HESS.

Modelling the artificial forest (Robinia pseudoacacia L.) root-soil water interactions in the Loess Plateau, China

Hongyu Li1,2, Yi Luo1,2,3, Lin Sun1, Xiangdong Li4, Changkun Ma5, Xiaolei Wang1,2, Ting Jiang1,2, and Haoyang Zhu1,2 Hongyu Li et al.
  • 1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
  • 2University of Chinese Academy of Sciences, Beijing, 100049, China
  • 3Research Centre for Ecology and Environment of Central Asia, Chinese Academy of Sciences, Urumqi, 830011, China
  • 4Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science & Technology, Guangzhou, 510650, China
  • 5State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi'an University of Technology, Xi'an, 710048, China

Abstract. Plant root–soil water interactions are fundamental to vegetation–water relationships. Soil water availability and distribution impact the temporal–spatial dynamics of roots and vice versa. In the Loess Plateau (LP) of China, where semiarid and arid climates prevail and deep loess soil is dominant, drying soil layers (DSLs) have been extensively reported in artificial forest land; however, the underlying mechanism remains unclear. This study proposes a root growth model that simulates both the dynamic rooting depth and fine root distribution, coupled with soil water, based on cost–benefit optimisation. Evaluation of field data at an artificial forest site of black locust (Robinia pseudoacacia L.) in the southern LP positively proves its performance. Further, a long-term simulation was performed to address the DSL issues, which were forced by a 50-year climatic data series, under variations in precipitation. The results demonstrate that incorporating the dynamic rooting depth into the currently available root growth models is necessary for reproducing the drying soil processes. The top 2.0 m is the most active zone of infiltration and root water uptake, and below which the fractions of fine roots and uptake are small but cause a persistently negative water balance and consequent DSLs. The upper boundary of the DSLs fluctuates strongly with infiltration events, while the lower boundary extends successively owing to the interception of most infiltration by the top 2.0 m layer. Coupling the root–water interactions helps to reveal the intrinsic properties of DSLs, with the persistent extension of its thickness and rare opportunities for recovery from the drying state. This study may have negative implications for the implementation of artificial afforestation in this semiarid region, as well as in other regions of similar climate and soils.

Hongyu Li et al.

Status: open (until 18 Aug 2021)

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  • RC1: 'Comment on hess-2021-304', Anonymous Referee #1, 17 Jul 2021 reply

Hongyu Li et al.

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Short summary
Drying soil layers (DSLs) have been extensively reported in artificial forest land in the Loess Plateau of China, with limited water resources and deep loess. To address this issue relating to plant root–soil water interactions, this study developed a root growth model that simulates both the dynamic rooting depth and fine root distribution. Evaluation versus field data proved a positive performance. long-term simulation reproduced the evolution process of the DSLs and revealed its mechanisms.