As atmospheric carbon levels inch higher each year and habitat loss reduces species counts and diversity at unprecedented rates, finding ways to mitigate the effects of climate change becomes ever more pressing. New research from Stanford University suggests that wild animals are doing some of the work for us — merely by existing.
Trees are already credited with removing greenhouse gases from the air by “breathing” them in and storing them in their trunks and roots. The analysis (“Mammal diversity influences the carbon cycle through trophic interactions in the Amazon”), published in Nature in 2017 by Stanford University researchers, reveals that vertebrate animals are also efficient carbon sinks. Three years of environmental surveys and more than a million records of animal activity in the Amazon contributed to this research, which shows that carbon levels in soil are significantly higher in places where animal populations are most diverse.
Though we’ve long known that animals sequester carbon by breathing, digesting their food, and decomposing, these new findings are surprising. They highlight the massive impact animals have on the carbon cycle, and suggest that species diversity might be more important than population size.
The scale of this analysis is also unprecedented; an enormous amount of data is needed to explore the relationships among animals, plants, and soil carbon levels. The Stanford team relied on the knowledge and guidance of people from the indigenous Makushi, Wapishana, and Wai-wai nations to better identify subtle traces of animals in the diverse topography. During data collection, a team of over 70 technicians measured the size and diversity of trees every month and estimated the number and diversity of mammals, birds, reptiles, and amphibians present.
These data were then cross-referenced with carbon levels from six months of soil samples to track any correlations between the two. The researchers found that the regions with the highest carbon concentrations were also the places that supported more diverse animal species. They hypothesized that a greater diversity of species increased feeding interactions, in turn creating more organic material to be decomposed and added to the total carbon load of the soil.
While this research looked only at a tropical environment, these findings are likely to be consistent across the globe. Animal diversity in ecosystems affects everything from plant diversity to water retention rates, so it’s likely to be positively correlated with carbon sequestration too. This research also suggests that supporting the species richness of an ecological region might be one of the best ways to improve its carbon retention rate.
