EGU2020-5176
https://doi.org/10.5194/egusphere-egu2020-5176
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Ecophysiological Responses of desert shrub to rainfall addition for Reaumurica soongorica in desert ecosystem

Wei Li1 and Cicheng Zhang2
Wei Li and Cicheng Zhang
  • 1School of Land Resources and Urban & Rural Planning, Hebei GEO University, Shijiazhuang, China (liwei19870316@hotmail.com)
  • 2Department of Hydraulic Engineering, School of Civil Engineering, Tsinghua University, Beijing, China (cichengzhang@mail.bnu.edu.cn)

Desert environments are characterized by limited and highly variable rainfall, which is an intermittent source of water critical to the evolution of the structure and functioning of desert ecosystems. The present study was to assess the effects of different amounts of rainfall received through discrete rainfall events and of the ecophysiological responses for Reaumurica soongorica along multiple average precipitation (MAP) gradient. A field experiment was performed under seven simulated rainfall amounts (0 - 40 mm) with Reaumurica soongorica at respective High-P (120 mm), Middle-P (67 mm), and Low-P (35 mm) sites along middle and lower reach of Heihe River Basin in July, 2015. Pre-dawn plant water potential (ψpd), the rates of photosynthesis and stomatal conductance were measured synchronously. Results showed that: photosynthetic response of R.soongorica to rainfall pulse was significant different. The mean daily leaf gas exchange and maximum photosynthesis rate (Pn-max) of R.soongorica were decreased obviously with decreasing MAP. Vapour pressure deficit (VPD) was the predominant factor for gas exchange limiting. Under the control of VPD, stomatal conductance was pregressively reduced with decreasing ψpd, which was functioned as limiting Pn-max and further increasing water use efficiency (WUE). However, when MAP was declined below 35 mm, the response of stomatal conductance to ψpd was weakened, from which Pn-max began to increase again. 2 to 4 days hystereric response of R.soongorica ψpd to various rainfall events was found in High-P. Stomatal conductance was then increased linearly with increasing ψpd, from which Pn-max was also enhanced linearly. While weakly response of ψpd to similar rainfall events was observed in Low-P, where stomatal conductance and Pn-max was maintained stable after rain. Mentioned above, the effective rainfall pluse, induced by obvious physiological response of R. soongorica, was 3.63-6.73 mm and 6.73-10.09 mm for Linze and Ejina, respective. Our results provided comprehensively understanding in the consequences of long-term variability in rainfall for the physiology of desert plants and species dynamics in desert ecosystems.

How to cite: Li, W. and Zhang, C.: Ecophysiological Responses of desert shrub to rainfall addition for Reaumurica soongorica in desert ecosystem, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5176, https://doi.org/10.5194/egusphere-egu2020-5176, 2020