The three domains of life (Archaea, bacteria and eukarya) are well-represented and active in soil systems. Much of the metabolic activity in soils is microbially-mediated and faunally-influenced. Because agroecosystems are the most amenable to experimental manipulation of any terrestrial ecosystems, many experiments on them have provided intriguing results. Using conservation and no-tillage techniques, we have measured increases in biotic diversity and enhanced carbon sequestration in soils worldwide. Methods to enhance carbon sequestration at micro-, meso- and macro-scales are being pursued.
Questions remain about the primary causal factors of biodiversity in cropped, forested and rangelands. Results from a cross-ecosystem study of microbial biodiversity have yielded counterintuitive information, with agroecosystems having greater diversity than forests on similar soil types in the southeastern USA. Other speakers in this symposium will address similar topics in sites ranging from polar to temperate and tropical regions.