Are optical indices good proxies of seasonal changes in carbon fluxes and stress-related physiological status in a beech forest?

0488992 - ÚVGZ 2019 RIV NL eng J - Journal Article
Nestola, E. - Scartazza, A. - Di Baccio, D. - Castagna, A. - Ranieri, A. - Cammarano, M. - Mazzenga, F. - Matteucci, G. - Calfapietra, Carlo
Are optical indices good proxies of seasonal changes in carbon fluxes and stress-related physiological status in a beech forest?
Science of the Total Environment. Roč. 612, jan (2018), s. 1030-1041. ISSN 0048-9697. E-ISSN 1879-1026
Research Infrastructure: CzeCOS II - 90061
Institutional support: RVO:86652079
Keywords : photochemical reflectance index * gross primary production * sub-alpine grassland * higher-plant leaves * leaf-area index * vegetation indexes * chlorophyll content * remote estimation * spectral indexes * canopy-scale * Chlorophyll fluorescence * Fagus sylvatica L. * Heat stress * Net ecosystem exchange
OECD category: Environmental sciences (social aspects to be 5.7)
Impact factor: 5.589, year: 2018

This study investigates the functionality of a Mediterranean-mountain beech forest in Central Italy using simultaneous determinations of optical measurements, carbon (C) fluxes, leaf eco-physiological and biochemical traits during two growing seasons (2014-2015). Meteorological variables showed significant differences between the two growing seasons, highlighting a heat stress coupled with a reduced water availability in mid-summer 2015. As a result, a different C sink capacity of the forest was observed between the two years of study, due to the differences in stressful conditions and the related plant physiological status. Spectral indices related to vegetation (VIs, classified in structural, chlorophyll and carotenoid indices) were computed at top canopy level and used to track CO2 fluxes and physiological changes. Optical indices related to structure (EVI 2, RDVI, DVI and MCARI 1) were found to better track Net Ecosystem Exchange (NEE) variations for 2014, while indices related to chlorophylls (SR red edge, CL red edge, MTCI and DR) provided better results for 2015. This suggests that when environmental conditions are not limiting for forest sink capacity, structural parameters are more strictly connected to C uptake, while under stress conditions indices related to functional features (e.g., chlorophyll content) become more relevant. Chlorophyll indices calculated with red edge bands (SR red edge, NDVI red edge, DR, CL red edge) resulted to be highly correlated with leaf nitrogen content (R-2 > 0.70), while weaker, although significant, correlations were foundwith chlorophyll content. Carotenoid indices (PRI and PSRI) were strongly correlated with both chlorophylls and carotenoids content, suggesting that these indices are good proxies of the shifting pigment composition related to changes in soil moisture, heat stress and senescence. Our work suggests the importance of integrating different methods as a successful approach to understand how changing climatic conditions in the Mediterranean mountain region will impact on forest conditions and functionality.
Permanent Link: http://hdl.handle.net/11104/0283485