Modified photochemical reflectance index to estimate leaf maximum rate of carboxylation based on spectral analysis
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Modified photochemical reflectance index to estimate leaf maximum rate of carboxylation based on spectral analysis Ying Yu & Jinxin Piao & Wenyi Fan & Xiguang Yang
Received: 6 July 2020 / Accepted: 10 November 2020 # Springer Nature Switzerland AG 2020
Abstract The maximum rate of carboxylation in leaves (Vcmax) is an important parameter used to determine the photosynthetic rate. An accurate estimation of Vcmax is important for evaluating the photosynthetic capacity of vegetation productivity and the carbon budget of forest ecosystems. In this study, we measured the light use efficiency (LUE) and Vcmax of leaves and their corresponding spectral characteristics. Spectral analysis was used to find a modified photochemical reflectance index (PRI) of leaves to estimate LUE and thereby estimate leaf Vcmax. The results showed that the precision with which the modified ratio PRI index estimated LUE was significantly increased. The R2 of the estimation model was 0.69, and the root mean square error (RMSE) was 0.0024. The R2 of the model for estimating leaf Vcmax based on the LUE was 0.72, and the RMSE was 8.439 μmol/m2/s. The Vcmax values of conifer trees (Scots pine, Korean pine, and larch) were higher than those of broadleaf trees (white birch, Manchurian walnut, Siberian elm, Manchurian ash, Mongolian oak, Korean aspen, and Amur linden). This method avoids problem that conventional PRI is not sensitive to high leaf LUE Y. Yu : J. Piao : W. Fan : X. Yang School of Forestry, Northeast Forestry University, Harbin 150040 Heilongjiang, China Y. Yu : W. Fan (*) : X. Yang The Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, Harbin 150040 Heilongjiang, China e-mail: [email protected]
values and provides important parameter data for the quantitative estimation of the gross primary productivity of forest ecosystems. Keywords Photochemical reflectance index . Light use efficiency . Maximum carboxylation rate
Introduction The maximum rate of carboxylation (Vcmax) of leaves is an important parameter that describes the photosynthetic capacity of vegetation, and it is sensitive to dynamic changes in vegetation carbon and affects the uncertainty of the model’s prediction results (Knorr and Kattge 2005; Zaehle et al. 2005). Therefore, the accurate estimation of vegetation Vcmax plays an important role in photosynthesis calculations and the estimation and prediction of carbon fluxes. Currently, there are three main methods for estimating Vcmax. In the first method, Vcmax is directly measured in a laboratory by extracting leaf proteins to measure enzyme activity (Woodrow and Berry 1988). This method is time-consuming, complex, and not suitable for wide applications. In the second method, Vcmax is directly measured in situ. LI-6400 is used to measure the relationship between net photosynthetic rates of leaves and intercellular carbon dioxide concentration, and the relationship curve between these two variables is used to estimate Vcmax (Wullschleger 1993). T
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