Freezing induces an increase in leaf spectral transmittance of forest understorey and alpine forbs

• Published in: Photochemical & Photobiological Sciences
• Main Authors: Solanki, Twinkle, García-Plazaola, José Ignacio, Robson, T Matthew, Fernandez-Marin, Beatriz
• Other Authors: Organismal and Evolutionary Biology Research Programme, Biosciences, Canopy Spectral Ecology and Ecophysiology, Faculty of Biological and Environmental Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: Royal Society of Chemistry 2022
• Subjects: ARCTIC EVERGREENS; Extreme climatic events; FROST-RESISTANCE; Frozen leaves; GROWING-SEASON; ICE NUCLEATION; LEAVES; Leaf optical properties; Leaf pigments; OPTICAL-PROPERTIES; PHOTOSYNTHESIS; PLANTS; Photoprotection; SEXUAL REPRODUCTION; Spectral reflectance; WINTER WARMING EVENTS; 11831 Plant biology; 1184 Genetics; developmental biology; physiology; Arctic
• Online Access: http://hdl.handle.net/10138/346702

Evergreen plants growing at high latitudes or high elevations may experience freezing events in their photosynthetic tissues. Freezing events can have physical and physiological effects on the leaves which alter leaf optical properties affecting remote and proximal sensing parameters. We froze leaves of six alpine plant species (Soldanella alpina, Ranunculus kuepferi, Luzula nutans, Gentiana acaulis, Geum montanum, and Centaurea uniflora) and three evergreen forest understorey species (Hepatica nobilis, Fragaria vesca and Oxalis acetosella), and assessed their spectral transmittance and optically measured pigments, as well as photochemical efficiency of photosystem II (PSII) as an indicator of freezing damage. Upon freezing, leaves of all the species transmitted more photosynthetically active radiation (PAR) and some species had increased ultraviolet-A (UV-A) transmittance. These differences were less pronounced in alpine than in understorey species, which may be related to higher chlorophyll degradation, visible as reduced leaf chlorophyll content upon freezing in the latter species. Among these understorey forbs, the thin leaves of O. acetosella displayed the largest reduction in chlorophyll (−79%). This study provides insights into how freezing changes the leaf optical properties of wild plants which could be used to set a baseline for upscaling optical reflectance data from remote sensing. Changes in leaf transmittance may also serve to indicate photosynthetic sufficiency and physiological tolerance of freezing events, but experimental research is required to establish this functional association. Peer reviewed