A continental-scale strategy to sample carbon and nutrient dynamics within and across air, land, and water systems

Background/Question/Methods

The construction of the National Ecological Observatory Network (NEON) across the U.S. creates the opportunity for researchers to study carbon and nutrient transformations and transfers within and across ecosystems at local-to-continental scales.  In this talk, we describe the biogeochemical sampling that will be conducted at 30-year core (n = 20) and 5-10-year relocatable (n = 40) NEON sites.  These sites occur across a range of ecoclimatic zones that are characterized by different hydrological regimes, including flashy rain-driven, shallow sub-surface (perched, pipe-flow, etc), and deep groundwater, which likely affect the chemical forms and quantities of reactive elements that are retained and/or mobilized across landscapes.  NEON’s biogeochemistry sampling approach employs a mixed strategy, whereby intensive (in time), spatially-limited measurements of inputs, ecosystem stocks, and biogeochemical transformations occur within the dominant vegetation type at each site, and are coupled to less frequent, extensive sampling of stocks, transformations, and hydrologic transfers in stratified (by vegetation type) random plots across each site.  These data collections will occur in conjunction with remotely-sensed observations (LiDAR and hyperspectral data), as well as data assimilation modeling to understand and predict changes to biogeochemical cycling at regional to continental scales.

Results/Conclusions

The measurement approach focuses on water and elemental inputs to the terrestrial system (atmospheric deposition, bulk precipitation), ecosystem stocks (nutrient contents in plant tissues and soils), microbially- and redox-mediated transformations, transfers (soil-water and groundwater sources/chemistry), and outputs (surface water, and evapotranspiration).  We discuss both data that will be collected as part of the current NEON design, as well as how the broader natural sciences community can conduct research collaboratively with the NEON project.  Current engagement with the ecological community is critical to NEON’s success, particularly in the initial years of sampling, to ensure that high-quality, standardized and useful data are made available and inspire further, cutting-edge research.