RESEARCH PAPER: 1 2 Estimation of Foliar Pigment Concentration in 3 Floating Macrophytes using Hyperspectral 4 Vegetation Indices 5 6 Cameron Proctor 1 , Yuhong He 2 7 Department of Geography, University of Toronto Mississauga, 3359 Mississauga Road N, 8 William G. Davis Bldg, L5L 1C6, Mississauga, Ontario, Canada 9 Department Fax: (905) 828-5273 10 1 cameron.proctor@utoronto.ca 11 2 yuhong.he@utoronto.ca 12 13 Abstract. Foliar pigment concentrations of chlorophylls and cartenoids are important indicators 14 of plant physiological status, photosynthesis rate and net primary productivity. Although the 15 utility of hyperspectral derived vegetation indices for estimating foliar pigment concentration has 16 been documented for many vegetation types, floating macrophytes have not been assessed 17 despite their ecological importance. This study surveyed 39 wetland species (12 floating 18 macrophytes (FM), 8 grasses/sedges/rushes (GSR) and 19 herbs/wildflowers (HWF)) to 19 determine whether foliar pigments concentrations could be estimated from hyperspectral 20 reflectance. Hyperspectral reflectance of samples was recorded using an ASD FieldSpec3 Max 21 portable spectroradiometer with the plant probe attachment or via a typical laboratory setup. A 22 semi-empirical relationship was established using either a linear, second-degree polynomial or 23 logarithmic function between 13 candidate vegetation indices and Chl-a, Chl-b, Car and Chl-a+b 24 pigment concentrations. Vegetation indices R-M, CI-Red and MTCI were strongly correlated 25 with foliar pigment concentrations using a linear fitting function. Chl-a+b and Chl-b 26 concentrations for all samples were reasonably estimated by the R-M index (R 2 : 0.66 and 0.64), 27 although Chl-a and Car concentration estimates using CI-Red were weaker (R 2 : 0.63 and 0.51). 28 Regression results indicate that pooled samples to estimate individual foliar pigments were less 29 correlated than when each type of vegetation type was treated separately. For instance, Chl-a+b 30 was best estimated by CI-Red for FM (R 2 : 0.80), MTCI for HWF (R 2 : 0.77) and R-M for GSR 31 (R 2 : 0.67). Although floating macrophytes feature unique adaptions to their aquatic environment, 32 their foliar pigment concentrations and spectral signatures were comparable to other wetland 33 vegetation types. Overall, vegetation indices that exploit the red-edge region were a reasonable 34 compromise that had good explanatory power for estimation of foliar pigments across the 35 sampled wetland vegetation types with CI-Red the best suited index for floating macrophytes. 36 37 Keywords: floating macrophyte, chlorophyll, vegetation indices, pigment concentration 38 estimation, wetland vegetation types 39 40 41