Can Q’eqchi’ Maya swidden agriculture enhance Tropical forest biodiversity at intermediate levels of disturbance? Evidence from high-resolution multi-spectral drone imagery from the Toledo District, Belize

Background/Question/Methods

In this study we investigate whether the spatial pattern of disturbance in a tropical forest that results from Q’eqchi’ Maya swidden agriculture contains a quantitative signature of ecosystem enhancement. While swidden cultivation (aka ‘slash-and-burn') is widely believed to have significant negative impacts on tropical forests, there is growing appreciation that indigenous forager societies can enhance ecosystem structure and function to increase the frequency of culturally important species without devastating ecosystem functioning, for example in species density of sand lizards (Bliege-Bird et al. 2008) and kangaroos in aboriginal fire mosaics in Australia (Codding et al. 2014), and of mollusks in Northwest clam gardens (Cox et al. 2019). In 2018, we began to test whether ecosystem enhancement can occur in indigenous swidden agricultural settings. We scanned ~18,000 acres around two Q’eqchi’ Maya villages in southern Belize using a drone equipped with a 5-band multi-spectral sensor and collected ground-truthed GPS land-use data and biodiversity surveys with local assistants and a community-based parabiologist. We analyzed these data using a high-performance computing workflow that include supervised and unsupervised land-use classification, a principal-components analysis of spectral species abundance and diversity (Féret 2020), and 2nd-order polynomial Bayesian statistical models.

Results/Conclusions

Class-level landscape fragmentation analysis indicates a wide range of land uses including extensive pastures, primary forest, and a full range of seral stages. Landscape-scale analysis indicates clear patterns of spectral variation and diversity that appear to be associated with different temporal and spatial patterns of swidden clearing. Our preliminary statistical modeling results suggest that the biodiversity levels are maximized at intermediate levels of landscape fragmentation. This suggests Q’eqchi’ swidden cultivation in this study area has limited forest clearing to a spatial scale that has not degraded ecosystem structure and function, while increasing it to a level that enhances the diversity of canopy tree species. We suggest that this may occur because the scale of disturbance provides a greater level of niche partitioning that provides enhanced opportunities for recruitment of species that dominate in early successional stages. Overall, we suggest that our study provides evidence that Q'eqchi’ Maya swidden cultivation may enhance the tropical forest biodiversity at intermediate levels of disturbance.