The world is changing. Over the next 50 years, ecosystems will be exposed to rising atmospheric [CO2], warming, and increasingly variable precipitation patterns, in addition to weather that’s just plain ‘weird’. In order to understand and model current and future ecosystem responses to atmospheric and climatic change, ecologists are endeavoring to develop a more holistic view of ecosystem processes by linking plant traits with biogeochemical cycling. However, some of the least understood processes remain hidden in the ground beneath our feet. Fine roots are narrow in diameter, short-lived, and key to the cycling of carbon, water, and nutrients within an ecosystem. We have been focused on quantifying the responses of fine roots to changing environmental conditions across a number of diverse biomes. Our goals are to advance our understanding of fine-root trait variation, make meaningful linkages among above- and belowground traits, and develop predictive relationships among belowground plant traits and ecosystem processes. Improving our understanding of the hidden processes beneath our feet can improve the coarse representation of fine-root processes and associated parameters in terrestrial biosphere models and fill gaps in our understanding of ecosystem processes, now and in the future.
Results/Conclusions
Over the last decade, we have quantified the role of belowground plant traits in ecosystem responses to changing environmental conditions across three diverse ecosystems: (1) a temperate forest in eastern Tennessee exposed to elevated [CO2] for 12 growing seasons, where elevated [CO2] resulted in increased fine-root production and rooting depth with consequences for soil carbon and nitrogen cycling; (2) a boreal, black-spruce bog in northern Minnesota, where large-scale warming is increasing soil nutrient availability and decreasing moisture availability, resulting in non-linear shifts in belowground carbon allocation; (3) the tundra of northern Alaska, where the interplay between shifting plant community composition, species-specific root traits, and soil nutrient availability throughout the soil profile leads to shifting patterns in ecosystem carbon cycling. Combined with the newly-released second version of the Fine-Root Ecology Database (FRED 2.0), observations across these three important biomes can help to scale potential linkages between belowground plant traits and ecosystem carbon, water, and nutrient cycling across the globe. In turn, these relationships inform model conceptualization, parameterization, and evaluation of ecosystem responses to changing environmental conditions.