Spectrometry for ecologists

Abstract

Sunlight is a mixture of electromagnetic radiation at wavelengths ranging from 300 to 2500 nm at the surface of the earth. Interactions between electromagnetic waves and matter change with the wavelength. Ultraviolet and visible light (330−760 nm) is absorbed by photoreceptor proteins in the eyes of animals, providing them with ‘visible’ information. Photosynthetically active radiation (400−700 nm) is essential for many plants, while near-infrared light (700–2500 nm) is absorbed by water and organic compounds. Therefore, measurements of the features of these reflection spectra can be useful for studying both the vision of animals and physiological functions of plants. Spectrometers are used to measure the electromagnetic spectrum and conventionally most have been large instruments installed indoors. Recent technological developments have produced handheld spectrometers that can measure the spectrum at a pinpoint anywhere. Moreover, imaging spectrometers, which spectrally disperse the incident light at each pixel, continue to be improved and can provide spectroscopic images at any scale. This review explains spectrometry and introduces ecological studies using the latest spectrometers. The recent application of spectrometry to field studies should reveal new relationships between organisms and light.