How pervasive is biotic homogenization in human-modified tropical forest landscapes?

Background

Land-cover change and ecosystem degradation often lead to biotic homogenization. Yet, there is knowledge gaps regarding this phenomena, which this study seeks to fill. Solar et al. (2015) monitor the change in biodiversity along a land use gradient ranging from primary forest to severely degraded and human dominated landscapes.

Goals & Methods

This study aims to understand how biotic homogenization plays out on multiple scales and for multiple taxa. The authors do this by collecting data on five taxa (birds, dung beetles, plants, orchid bees, and ants) sampled in 335 sites in 36 landscapes in two regions of the Brazilian Amazon. 

Conclusions & Takeaways

The study found that human land use is associated with biotic homogenization because the types of species that are resistant to degraded habitat and those that have robust dispersal mechanisms are more likely to colonize human-altered land. Solar et al. show that, as the land use gradient shifts from primary, undisturbed forest to mechanized agriculture, the percentage of beta diversity decrease contributed by nestedness (species loss) increases. This can be interpreted as the community composition changing to species more tolerant of human activity, rather than by species turnover (species replacement). Thus, the authors show that human land use is positively correlated with an increase in biotic homogenization.