EGU2020-1786
https://doi.org/10.5194/egusphere-egu2020-1786
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Evaluating drought-induced mortality risk for Robinia pseudoacacia plantations along the precipitation gradient on the Loess Plateau

Zhongdian Zhang1,2, Mingbin Huang2,3, Yingnan Yang1,2, and Xiaofang Zhao1,2
Zhongdian Zhang et al.
  • 1College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China
  • 2State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A & F University, Yangling 712100, China
  • 3CAS Center for Excellence in Quaternary Science and Global Change, Xian, Shaanxi 710061, China

Extensive afforestation with exotic species like Robinia pseudoacacia on the Chinese Loess Plateau are facing high drought-induced mortality risk due to the large fluctuations in annual precipitation and severe soil desiccation. The aim of this study was to assess the risk of drought-induced mortality for R. pseudoacacia plantations on the Loess Plateau based on plant hydraulics. We modified the routines of soil-plant-atmosphere water transfer in the Biome BioGeochemistry model (Biome-BGC) using a plant hydraulic model based on the supply-demand theory. The modified model efficiently captured the dynamics of canopy transpiration, soil moisture, leaf water potential, and regional variation in leaf area index in R. pseudoacacia stands on the Loess Plateau. We simulated the 50-year (1968-2017) plant hydraulic dynamics at 14 sites along a precipitation gradient on the Loess Plateau. The results indicated that annual average percentage loss of whole-plant hydraulic conductance (APLK) showed strong temporal variation due to climatic variability, which was positively correlated with annual potential evapotranspiration (PET) and the aridity index (the ratio of PET to annual precipitation). Along the precipitation gradient, the maximum APLK increased linearly with decreasing mean annual precipitation (MAP) and could exceed 60% at sites with MAP <446.1 mm. The sustainable growth of R. pseudoacacia plantations at these sites would face a severe threat. We analyzed the effect of soil desiccation on drought-induced mortality risk further. Soil desiccation increased the sensitivity of plant hydraulic safety to precipitation variability considerably, and the effect was more significant in areas with lower MAP. These quantitative findings should be helpful for evaluating and promoting the sustainability of plantation forests on the Loess Plateau.

How to cite: Zhang, Z., Huang, M., Yang, Y., and Zhao, X.: Evaluating drought-induced mortality risk for Robinia pseudoacacia plantations along the precipitation gradient on the Loess Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1786, https://doi.org/10.5194/egusphere-egu2020-1786, 2019