A novel photographic approach for monitoring the structural heterogeneity and diversity of grassland ecosystems

Aims Studies that investigate the space-filling heterogeneity of biological structures in plant communities remain scarce. The main objective of this study was to evaluate the relationship between newly developed photographic measures of structural heterogeneity in digital images and plant species composition in the context of a long-term grassland experiment. Methods We tested a close-range photographic protocol using measures of structural heterogeneity in gray-tone images, namely mean information gain (MIG) and spatial anisotropy, to assess differences in the compositional (species richness) and functional characteristics (plant height and flowering) of 78 managed grassland communities. We also implemented a random placement model of community assembly to explore the links between our measures of structural complexity and the geometric pattern of plant communities. Important Findings MIG and spatial anisotropy correlated with the growth and species richness of grassland communities. Simulations showed that structural heterogeneity in gray-tone digital images is a function of the size distribution and orientation pattern of plant modules. This easy, fast and non-destructive methodological approach could eventually serve to monitor the diversity and integrity of various ecosystems at different resolutions across space and time