Performance of a two-leaf light use efficiency model for mapping gross primary productivity against remotely sensed sun-induced chlorophyll fluorescence data

2018 ◽  
Vol 613-614 ◽  
pp. 977-989 ◽  
Author(s):  
Mei Zan ◽  
Yanlian Zhou ◽  
Weimin Ju ◽  
Yongguang Zhang ◽  
Leiming Zhang ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Primary Productivity ◽  
Remotely Sensed ◽  
Gross Primary Productivity ◽  
Light Use Efficiency ◽  
Use Efficiency ◽  
Light Use Efficiency Model

scholarly journals Modeling the Effects of Global and Diffuse Radiation on Terrestrial Gross Primary Productivity in China Based on a Two-Leaf Light Use Efficiency Model

2020 ◽  
Vol 12 (20) ◽  
pp. 3355
Author(s):  
Yanlian Zhou ◽  
Xiaocui Wu ◽  
Weimin Ju ◽  
Leiming Zhang ◽  
Zhi Chen ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Primary Productivity ◽  
Meteorological Data ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Gross Primary Productivity ◽  
Light Use Efficiency ◽  
Remotely Sensed Data ◽  
Use Efficiency ◽  
Light Use Efficiency Model

Solar radiation significantly affects terrestrial gross primary productivity (GPP). However, the relationship between GPP and solar radiation is nonlinear because it is affected by diffuse radiation. Solar radiation has undergone a shift from darker to brighter values over the past 30 years in China. However, the effects on GPP of variation in solar radiation because of changes in diffuse radiation are unclear. In this study, national global radiation in conjunction with other meteorological data and remotely sensed data were used as input into a two-leaf light use efficiency model (TL-LUE) that simulated GPP separately for sunlit and shaded leaves for the period from 1981 to 2012. The results showed that the nationwide annual global radiation experienced a significant reduction (2.18 MJ m−2 y−1; p < 0.05) from 1981 to 2012, decreasing by 1.3% over this 32-year interval. However, the nationwide annual diffuse radiation increased significantly (p < 0.05). The reduction in global radiation from 1981 to 2012 decreased the average annual GPP of terrestrial ecosystems in China by 0.09 Pg C y−1, whereas the gain in diffuse radiation from 1981 to 2012 increased the average annual GPP in China by about 50%. Therefore, the increase in canopy light use efficiency under higher diffuse radiation only partially offsets the loss of GPP caused by lower global radiation.

scholarly journals Tree–grass phenology information improves light use efficiency modelling of gross primary productivity for an Australian tropical savanna

2017 ◽  
Vol 14 (1) ◽  
pp. 111-129 ◽  
Author(s):  
Caitlin E. Moore ◽  
Jason Beringer ◽  
Bradley Evans ◽  
Lindsay B. Hutley ◽  
Nigel J. Tapper
Keyword(s):  
Primary Productivity ◽  
Vegetation Index ◽  
Temporal Dynamics ◽  
Seasonal Pattern ◽  
Gross Primary Productivity ◽  
Perennial Grasses ◽  
Light Use Efficiency ◽  
Tropical Savanna ◽  
Flux Tower ◽  
Use Efficiency

Abstract. The coexistence of trees and grasses in savanna ecosystems results in marked phenological dynamics that vary spatially and temporally with climate. Australian savannas comprise a complex variety of life forms and phenologies, from evergreen trees to annual/perennial grasses, producing a boom–bust seasonal pattern of productivity that follows the wet–dry seasonal rainfall cycle. As the climate changes into the 21st century, modification to rainfall and temperature regimes in savannas is highly likely. There is a need to link phenology cycles of different species with productivity to understand how the tree–grass relationship may shift in response to climate change. This study investigated the relationship between productivity and phenology for trees and grasses in an Australian tropical savanna. Productivity, estimated from overstory (tree) and understory (grass) eddy covariance flux tower estimates of gross primary productivity (GPP), was compared against 2 years of repeat time-lapse digital photography (phenocams). We explored the phenology–productivity relationship at the ecosystem scale using Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices and flux tower GPP. These data were obtained from the Howard Springs OzFlux/Fluxnet site (AU-How) in northern Australia. Two greenness indices were calculated from the phenocam images: the green chromatic coordinate (GCC) and excess green index (ExG). These indices captured the temporal dynamics of the understory (grass) and overstory (trees) phenology and were correlated well with tower GPP for understory (r2 =  0.65 to 0.72) but less so for the overstory (r2 =  0.14 to 0.23). The MODIS enhanced vegetation index (EVI) correlated well with GPP at the ecosystem scale (r2 =  0.70). Lastly, we used GCC and EVI to parameterise a light use efficiency (LUE) model and found it to improve the estimates of GPP for the overstory, understory and ecosystem. We conclude that phenology is an important parameter to consider in estimating GPP from LUE models in savannas and that phenocams can provide important insights into the phenological variability of trees and grasses.

scholarly journals Measured and modeled interactive effects of potassium deficiency and water deficit on gross primary productivity and light‐use efficiency in E ucalyptus grandis plantations

2015 ◽  
Vol 21 (5) ◽  
pp. 2022-2039 ◽  
Author(s):  
Mathias Christina ◽  
Guerric Le Maire ◽  
Patricia Battie‐Laclau ◽  
Yann Nouvellon ◽  
Jean‐Pierre Bouillet ◽  
...  
Keyword(s):  
Water Deficit ◽  
Primary Productivity ◽  
Potassium Deficiency ◽  
Gross Primary Productivity ◽  
Interactive Effects ◽  
Light Use Efficiency ◽  
Use Efficiency
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