Spectral characteristics of cyanobacteria soil crust in semiarid environments

Large areas of sand fields in and and semiarid regions are covered by cyano bacteria soil crusts. The objective of this article is to analyze (systemat ically throughout the VIS, NIR, and the SWIR regions of the spectrum) the u nique spectral features of cyanobacteria crust relative to bare sands mid u nder different moisture conditions. It was found that: 1) When biogenic soi l crusts a-re wet, their NDVI value can reach 0.30 units due to their photo synthetic activity; 2) the chaser the red edge inflection point is to the l onger wavelengths, the higher the relative abundance and distribution of th e microphytic community; 3) the phycobilin pigments, which are unique to cy anobactria, contribute to higher reflectance in the blue region relative to the sand substrate; 4) a crust index based on this uncommon spectral featu re can be useful for detecting and mapping, from remote sensing imagery, di fferent lithologic/morphologic units; 5) although most dune sand areas are generally made of quartz, other notable features appear on their spectra. I n the study area, there are absorption features representing minerals (iron oxides at 860 nm and clay minerals at 2200 nm) and biogenic crusts (chloro phyll at 670 nm and organic matter at 1720 nm, 2180 mn, and 2309 nm). (C) E lsevier Science Inc.