Assessing the potential of the downscaled far-red solar-induced chlorophyll fluorescence from canopy to leaf level for drought monitoring in winter wheat
- 1State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and the Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing, China (202031051047@mail.bnu.edu.cn; qiushen@mail.bnu.edu.cn)
- 2Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, Beijing, China (zhaowenhui@mail.bnu.edu.cn)
- 3Faculty of Geographical Science, Beijing Normal University, Beijing, China (corresponding author: jjwu@bnu.edu.cn)
- 4College of Grassland Science and Technology, China Agricultural University, Beijing, China (leizhenliu@cau.edu.cn)
Solar-induced chlorophyll fluorescence (SIF) from the ground, airborne to satellite-based observations has been increasingly used in drought monitoring recently, due to its close relationship with photosynthesis. SIF emissions do respond rapidly to drought, relative to the wide used vegetation indices (VIs, e.g., Normalized Difference Vegetation Index (NDVI)), thus indicating its potential for early drought monitoring. The response of SIF to drought can be attributed to the confounding effects of both physiology and canopy structure. In order to reduce the re-absorption and scattering effects, total emitted SIF (SIFtot) was proposed and served as a better tool to estimate GPP compared with top-of-canopy SIF (SIFtoc) in some studies. However, the response time and response magnitude of SIFtot to drought and its relationships with environmental parameters and soil moisture, that is, the knowledge of drought monitoring using SIFtot remains unclear. Here the continuous ground data of F760toc (SIFtoc at 760 nm) in nadir view that was downscaled to F760tot (SIFtot at 760 nm), surface soil moisture at 20cm soil layer (SM), meteorological and crop growth parameters, were measured from four winter wheat plots with different intensities of drought (well-watered treatment, moderate drought, severe drought and extreme drought) over two months. By analyzing these data, we found that F760tot was indeed more closely related to physiological and was less subjected to canopy structure than that of F760toc, but this relationship was reversed under extreme drought. It was more closely correlated with SM than VIs at short time lags, but weaker at longer time lags. The daily mean values of F760tot were able to distinguish the differences in drought gradients and respond quickly to the onset of drought, especially for the moderate drought, which appears to have the most decrease. These results demonstrate that F760tot has potential for early drought monitoring.
How to cite: Lin, J., Shen, Q., Wu, J., Liu, L., and Zhao, W.: Assessing the potential of the downscaled far-red solar-induced chlorophyll fluorescence from canopy to leaf level for drought monitoring in winter wheat, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1474, https://doi.org/10.5194/egusphere-egu22-1474, 2022.
