If a Tree Falls in the Forest, and There’s No One Around to Hear It, Does It Still Affect You?

Abstract

The Amazon rainforest, the largest forest ecosystem in the world, has continuously been under threat of land use conversion. Cattle pasture establishment is responsible for approximately 68% of deforestation with documented consequences to animal, plant, and microbial diversities. Inventory studies broadened our understanding of biological diversity losses, but have not been able to resolve questions about altered biogeochemical process rates and the associated nutrient cycling in this continental size ecosystem. In 2008, the Amazon Rainforest Microbial Observatory was established to study the effects of forest-to-pasture conversion on soil microbial communities and the ecological services they provide. Using a combination of high throughput sequencing of nucleic acids and in situ gas emission measurements, as well as soil physicochemical parameters, we observed increases in the process of biological nitrogen fixation with corresponding increased emissions of methane gas in pastures, which were reversed with rainforest regrowth. These biogeochemical processes were explained by elevated concentrations of labile carbon, measured as permanganate-oxidizable carbon. Our metabolomics results corroborated the above results with statistically significant increases of certain mono- and disaccharides. Metagenomic results indicated that genes for carbohydrate utilization were significantly more diverse and abundant in pasture samples relative to forest soils. 

Brief Biography

Jorge Mazza Rodrigues is a professor in the Department of Land, Air, and Water Resources at University of California - Davis. He graduated at the top of his class with an Agronomical Engineering degree from the University of Sao Paulo, Brazil and earned dual Ph.D. degrees from Michigan State University. He was recognized as a UC Davis Faculty Leadership Fellow in 2022 and currently a member of the First-Generation Faculty Learning Community. Research in his laboratory lies at the interface of soil microbial genomics and ecology and focuses on sustainable solutions for biodiversity maintenance in tropical forests and agricultural fields under increased world food demand. Jorge uses a combination of molecular and physiological experimental data to study microbial phylogenetic and functional diversification and their consequences to global biogeochemical cycles.  Results from this work have broad implications from basic research in evolutionary biology and ecology to applied aspects, such as conservation policies for natural ecosystems.