Leaf spectral signatures differ in plant species colonizing habitats along a hydrological gradient

Aims We aimed at determining differences in the leaf spectral signatures of plant species groups growing in habitats along the hydrological gradient of an intermittent wetland and to define leaf traits that explain their variability.We want to contribute to the understanding of the causes for plant spectrum variability at leaf and community levels.Methods We measured leaf reflectance spectra(300-887 nm)of representative plant species from different habitats and analyzed spectral differences among species groups.To explain leaf spectra variability within a group,we performed detailed analyses of leaf morphological and biochemical traits in selected species.Important FindingsThe reflectance spectra of the different species groups differed most in the green,yellow and red spectral ranges.The reflectance spectra of submerged leaves of hydrophytes with simple structures were explained by their biochemical traits(carotenoids),while for more complex aerial leaves,morphological traits were more important.In submerged and natant leaves of amphiphytes,total mesophyll and spongy tissue thickness were the most important traits,and these explained 44%and 47%,respectively,of the spectrum variability of each plant group.In general,the redundancy analysis biplots show that samples of different plant species colonizing the same habitat form separate clusters and are related to the explanatory variables in different ways.The redundancy analysis biplots of helophytes and wet meadow species show clustering of graminoids and dicots into two distinct groups.Leaf encrustation(prickle hair properties and epidermis thickness)is important for graminoids,while leaf thickness and specific leaf area have more important roles in dicots.Our results show that knowledge of the species composition and leaf traits is necessary to interpret the reflectance spectra of such plant communities.