Distance decay in spectral space in analysing ecosystem β‐diversity

The use of spectral distance for explaining the phenomenon of distance decay in species similarity between two sites (based on the niche difference model) is presented here. Distance decay is based on the first law of geography: ‘the similarity between two sites decays with increasing the distance between them’. From an ecological point of view, this could be expressed as: ‘the β‐diversity between two sites should increase with an increase in spatial distance’. Beta‐diversity is defined as the amount of turnover in species composition from one site to another; and it plays a key role in biodiversity management and conservation, as it allows the detection of spatial gradients that act functionally in determining the spatial variation in species composition. This work demonstrates how the celebrated distance decay pattern achieved by means of spatial distance can be attained even with spectral distance, measured on Landsat near‐infrared images. It is argued that spectral heterogeneity represents a good proxy of β‐diversity of an area, becoming a valuable tool in biodiversity characterization at regional and global scales.