Ecosystem metabolism estimates from the National Ecological Observatory Network (NEON) stream and river sites

Abstract

Expanded availability of estimates of ecosystem metabolism and gas exchange from the worlds streams and rivers is rapidly revising estimates of river contributions to global carbon budgets. Here, we present estimates of gross primary production, ecosystem respiration, and gas exchange from 27 streams and rivers across North America, including Puerto Rico, using data from the National Ecological Observatory Network (NEON). Further, we explore how aggregating and processing input data influences model outputs, expanding the methodological knowledge in approaching sensor collection and manipulation for ecosystem-scale modelling. We apply filters to input data to determine how different approaches to quality control of raw data influence the quantity and precision of estimates of ecosystem metabolism. Model estimates are high priority measures of ecosystem function that integrate additional NEON data products that will allow further understanding of stream and river biogeochemistry and ecosystem function across time and space.

Fig. 1

Locations of 27 wadable and non-wadable stream and river sites in the National Ecological Observatory Network (NEON). Sites are sized and color ramped proportional to watershed area.

Fig. 2

Schematic of workflow to determine ecosystem metabolism from NEON sites. Green boxes represent the components of the data citation, numbered at the top of each box. Yellow boxes indicate specific functions within the neonMetabolismHelpers R package, with brief description of the arguments. See the github repository and the README.md of neonMetabolismHelpers for more details.

Fig. 3

Visualization of the number of models run for each NEON stream and river site for each water year.

Fig. 4

Site-specific gas exchange – discharge relationships determined using ecosystem metabolism estimates. Points are paired values of mean daily discharge and modelled estimates of gas exchange, K₆₀₀ (d⁻¹) and blue lines are LOESS fits to the point cloud.

Fig. 5

(a) Comparison of mean daily GPP and ER for NEON sites, showing net heterotrophy (GPP < ER) for all sites. The dashed line is a 1:-1 and points are colored by watershed area, with smaller watershed area sites in purple and larger area sites in yellow. (b) Evaluation of flow variability and light availability on mean GPP across NEON sites. Points are identified by the NEON site code, with size and color proportional to mean daily GPP.