Colorado State University Fort Collins, CO, United States
Background/Question/Methods Growing scientific evidence indicates that soil fauna and the ecosystem functions and services they provide are threatened by global environmental changes such as those related to climate and land use. These threats affect species diversity and functional groups in belowground food webs, impacting ecosystem services that all life depends on. A better understanding of global change impacts to food-web interactions among soil fauna communities and plants, as well as to physical and geochemical processes driven by soil fauna will enhance our ability to predict changes at the ecosystem level. This presentation will discuss studies investigating how soil fauna responses to climate and land-use changes can drive soil and ecosystem functioning from tropical to temperate ecosystems. The first study assessed how climate change affects soil nematodes, and how nematode responses feedback to temperate grasses. The second study explored how soil macrofauna regulate land-use effects on the physical structure and carbon stocks in tropical soils.
Results/Conclusions In the first study, temporal reductions in precipitation disrupted the balance between the abundance of root-feeding nematodes, which are major constraints to ecosystem primary production, and their predators in favor of the root feeders. These nematode responses increased in magnitude from arid to moist environments, and further aggravated the effects of drought on grassland primary productivity and above-belowground plant biomass partitioning. Results from the second study showed that, over a range of soil textures (16–66% clay), soil engineering by macro-invertebrates indirectly mediated changes in soil carbon storage following land-use change by controlling the physical protection of low-humified organic matter occluded in soil aggregates, a fraction that accounted for most of the change in total soil carbon stocks following the conversion of native tropical forests. Together, data from these investigations indicate that soil fauna responses may challenge aboveground-based predictions of ecosystem functioning under global change.