{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,21]],"date-time":"2026-01-21T05:22:22Z","timestamp":1768972942948,"version":"3.49.0"},"reference-count":0,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2024,5,24]],"date-time":"2024-05-24T00:00:00Z","timestamp":1716508800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Fundamental Research Funds of the Central Public Welfare Scientific Research Institutes","award":["CAFYBB2023PA00102"],"award-info":[{"award-number":["CAFYBB2023PA00102"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Monitoring drought stress is crucial for estimating productivity and assessing the health status of forest ecosystems under global climate change. Solar-induced chlorophyll fluorescence (SIF) is mechanistically coupled to photosynthesis and has advantages over greenness-based vegetation indices in detecting drought. In recent years, SIF has commonly been used in monitoring drought stress in crop ecosystems. However, the response of tower-based SIF to drought stress in forest ecosystems remains unclear. In this study, we investigated the potential of tower-based SIF to monitor drought, which was quantified using the plant water stress index (PWSI) in a Chinese cork oak plantation. The results show the negative effect of drought on SIF, and afternoon depression of SIF emission under drought stress was observed. Canopy SIF (F) exhibited a nonlinear relationship with PWSI, while the quantum yield of SIF (\u03a6F) exhibited a significant linear relationship with PWSI at 687 nm and 760 nm (\u03a6F687: R2 = 0.90; \u03a6F760: R2 = 0.85). Incident radiation (PAR) and canopy structure affected the response of SIF to drought stress, with PAR as the main factor causing the nonlinear relationship between F and PWSI. Afternoon depression was described as the afternoon\/morning ratio (AMR). AMRF and AMR\u03a6F exhibited a negative linear response to PWSI. AMRF was less affected than F by PAR and canopy structures, and AMR\u03a6F was more physiologically representative than \u03a6F. Moreover, AMR\u03a6F was sensitive to VPD and REW, and it might be a good indicator of drought. Red SIF was more sensitive to drought than far-red SIF, as the R2 of PWSI with AMR\u03a6F687 (R2 = 0.89) was higher than that with AMR\u03a6F687 (R2 = 0.84). These results highlight the potential of tower-based SIF, especially red SIF, for drought monitoring in a plantation, and consideration of the physiological diurnal variation in SIF under drought stress is crucial for improving the accuracy of drought stress monitoring.<\/jats:p>","DOI":"10.3390\/rs16111897","type":"journal-article","created":{"date-parts":[[2024,5,24]],"date-time":"2024-05-24T11:17:52Z","timestamp":1716549472000},"page":"1897","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["The Afternoon\/Morning Ratio of Tower-Based Solar-Induced Chlorophyll Fluorescence Can Be Used to Monitor Drought in a Chinese Cork Oak Plantation"],"prefix":"10.3390","volume":"16","author":[{"given":"Qingmei","family":"Pan","sequence":"first","affiliation":[{"name":"Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China"},{"name":"Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China"},{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiangfen","family":"Cheng","sequence":"additional","affiliation":[{"name":"Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China"},{"name":"Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China"},{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1570-0555","authenticated-orcid":false,"given":"Meijun","family":"Hu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China"},{"name":"Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China"},{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Linqi","family":"Liu","sequence":"additional","affiliation":[{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"},{"name":"Jiangxi Academy of Forestry, Nanchang 330013, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xin","family":"Wang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China"},{"name":"Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China"},{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jinsong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China"},{"name":"Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China"},{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhipeng","family":"Li","sequence":"additional","affiliation":[{"name":"Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China"},{"name":"Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China"},{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wenwen","family":"Yuan","sequence":"additional","affiliation":[{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"},{"name":"Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou 311400, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiang","family":"Gao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China"},{"name":"Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China"},{"name":"Henan Xiaolangdi Forest Ecosystem National Observation and Research Station, Jiyuan 454650, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,5,24]]},"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/11\/1897\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:48:23Z","timestamp":1760107703000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/11\/1897"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,5,24]]},"references-count":0,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2024,6]]}},"alternative-id":["rs16111897"],"URL":"https:\/\/doi.org\/10.3390\/rs16111897","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,5,24]]}}}