Lasers, forests, and birds

 

Understanding why some regions are higher in number of species than others is fundamental to protect our planet's biodiversity. One factor that seems to determine the number of species present in an area is environmental heterogeneity. A heterogeneous environment will have a higher number of habitats, conditions (such as temperature or humidity) or a higher number of resources. Habitat structure is another component of environmental heterogeneity. An area with a high variety of structures, such as vegetation forms or inanimate objects, will provide animal species a higher number of food resources, shelter, or even a higher number of microclimates. However, measuring vegetation structure, the main component of habitat structure, is not an easy task.

Lidar (Light detection and ranging), a remote sensing technology that uses pulses of laser to measure the height and density of the vegetation, is helping researchers to measure vegetation structure from the sky (and soon from the International Spatial Station!). This technology allows us to make vegetaion measurements for wide extents and avoids spending huge amounts of time and money in field surveys. Recently, I leaded a study, together with researchers from NIMBioS and the University of Tennessee, where we created 3D models of forests using Lidar, and studied how North American forests' structure determine the diversity of birds. We created different Lidar-derived structural metrics to study how the structure of a forest patch varies horizontally and vertically. We found that high heterogeneity of the horizontal component of the forest structure was especially important for enhancing diversity of birds. Forest patches with very high vertical heterogeneity presented less species than patches with intermediate levels of vertical heterogeneity, contrary to previous studies.

This type of study is very important for conservation, as we can identify the characteristics of those habitats that support high levels of biodiversity, and therefore prioritize our protection efforts. We could, for example, promote the maintenance of horizontal heterogeneity in forests to enhance their bird diversity. However, these effects might depend on the forest type, so our future work will look at how these relationships are affected by the typology of the forest, and how these effects can help us explain biodiversity patterns at continental scales.