.

Wang, Z., et al. (2018). "Mapping forest canopy nitrogen content by inversion of coupled leaf-canopy radiative transfer models from airborne hyperspectral imagery." Agricultural and Forest Meteorology 253-254: 247-260. Nitrogen map was validated by ground data and general pattern. The known pattern can validated remote sensing products spatially.

Skidmore, A. K., et al. (2010). "Forage quality of savannas — Simultaneously mapping foliar protein and polyphenols for trees and grass using hyperspectral imagery." Remote Sensing of Environment 114(1): 64-72. Canopy N was calculated just multiplying leaf N to LAI. In this paper, more precise estimate of canopy N was attributed to higher estimate of LAI. On leaf scale, the leaf structure itself did not account for leaf spectroscopy better than foliar traits. However, on UAV level, canopy structure affects to the spectroscopy directly.

Wang, Z., Skidmore, A. K., Wang, T., Darvishzadeh, R., & Hearne, J. (2015). Applicability of the PROSPECT model for estimating protein and cellulose+ lignin in fresh leaves.  Remote sensing of environment ,  168 , 205- Physical models also include empirical parts. PROSPECT does so, too. In the paper, leaf potein and lignin + cellulose were decoupled from LMA.

Dechant, B., et al. (2017). "Estimation of photosynthesis traits from leaf reflectance spectra: Correlation to nitrogen content as the dominant mechanism." Remote Sensing of Environment 196: 279-292. Photosynthetic traits has its mechanism by leaf internal components. Comparing the spectroscopic absorption of causing components and their traits, they can be detected and correlation. In the case of Vcmax, N dominantly controls it.

Li, F., et al. (2017). "Foliar nitrogen and phosphorus stoichiometry of three wetland plants distributed along an elevation gradient in Dongting Lake, China." Sci Rep 7(1): 2820. Species specific elemental ratio constraint its distribution partially. Then plants spatial distribution can be explained by their stoichiometry.

Nitrogen deficiency effects on plant growth, leaf photosynthesis, and hyperspectral reflectance properties of sorghum. European journal of agronomy 22.4 (2005) 391-403. Net photosynthetic rate per unit chlorophyll was higher in N deficient plant so that mitigated the stress partially. The decreased leaf area and net photosynthetic rate per unit area, however, limited plant growth and productivity.

Gara, Tawanda W., et al. Leaf to canopy upscaling approach affects the estimation of canopy traits. GIScience & remote sensing 56.4 (2019) 554-575. In remotely sensing, upper-most leaves are dominantly detected so they are usually measured for upscaling, assuming that sunlit leaves are representing the whole canopy. Short plants or plants with sparse leaves, however, cannot be seen dominated by sunlit leaves because of canopy vertical diversity. In that case, it is significantly better to measure sunlit and mid-layer leaves(approach B,D and E) more than to measure only sunlit leaves(C). Though r square in remotely sensing canopy chlorophyll was higher at C, there was no significant difference between 2-leaf and 1-leaf approach.