{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T16:21:21Z","timestamp":1774369281680,"version":"3.50.1"},"reference-count":54,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2017,7,5]],"date-time":"2017-07-05T00:00:00Z","timestamp":1499212800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Tree species in the boreal forest cycle between periods of active growth and dormancy alter their photosynthetic processes in response to changing environmental conditions. For deciduous species, these changes are readily visible, while evergreen species have subtler foliar changes during seasonal transitions. In this study, we used remotely sensed optical indices to observe seasonal changes in photosynthetic activity, or photosynthetic phenology, of six boreal tree species. We evaluated the normalized difference vegetation index (NDVI), the photochemical reflectance index (PRI), the chlorophyll\/carotenoid index (CCI), and steady-state chlorophyll fluorescence (FS) as a measure of solar-induced fluorescence (SIF), and compared these optical metrics to gas exchange to determine their efficacy in detecting seasonal changes in plant photosynthetic activity. The NDVI and PRI exhibited complementary responses. The NDVI paralleled photosynthetic phenology in deciduous species, but not in evergreens. The PRI closely paralleled photosynthetic activity in evergreens, but less so in deciduous species. The CCI and FS tracked photosynthetic phenology in both deciduous and evergreen species. The seasonal patterns of optical metrics and photosynthetic activity revealed subtle differences across and within functional groups. With the CCI and fluorescence becoming available from satellite sensors, they offer new opportunities for assessing photosynthetic phenology, particularly for evergreen species, which have been difficult to assess with previous methods.<\/jats:p>","DOI":"10.3390\/rs9070691","type":"journal-article","created":{"date-parts":[[2017,7,5]],"date-time":"2017-07-05T11:26:04Z","timestamp":1499253964000},"page":"691","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":69,"title":["Parallel Seasonal Patterns of Photosynthesis, Fluorescence, and Reflectance Indices in Boreal Trees"],"prefix":"10.3390","volume":"9","author":[{"given":"Kyle","family":"Springer","sequence":"first","affiliation":[{"name":"Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada"}]},{"given":"Ran","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada"}]},{"given":"John","family":"Gamon","sequence":"additional","affiliation":[{"name":"Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada"},{"name":"Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada"},{"name":"School of Natural Resources, University of Nebraska, Lincoln, NE 68583, USA"}]}],"member":"1968","published-online":{"date-parts":[[2017,7,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1126\/science.263.5144.185","article-title":"Carbon pools and flux of global forest ecosystems","volume":"263","author":"Dixon","year":"1994","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"988","DOI":"10.1126\/science.1201609","article-title":"A large and persistent carbon sink in the world\u2019s forests","volume":"333","author":"Pan","year":"2011","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"891","DOI":"10.1890\/1051-0761(2002)012[0891:FCSITN]2.0.CO;2","article-title":"Forest carbon sinks in the Northern Hemisphere","volume":"12","author":"Goodale","year":"2002","journal-title":"Ecol. 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