Environmental monitoring is critical for both understanding the world and developing policies to protect it. Environmental observatory networks (EONs) allow scientists to collect, share, and synthesize data to make new discoveries as well as informed policy decisions on regional to global scales. But observatory networks are not always evenly distributed; some regions of the world are better monitored than others. Therefore, researchers must assess the representativeness of EONs not only to increase their numbers in underrepresented regions but also to evaluate their applicability to research and policy questions.
In a new study, Villarreal and Vargas carried out just such an assessment of FLUXNET, an EON known as the “network of networks” that measures the exchange of matter—such as carbon dioxide, water, and methane—and energy between the land and the atmosphere. Although previous research has evaluated EONs using climate and vegetation parameters, here the authors assessed the representativeness of eddy covariance sites within FLUXNET using species distributions models. The team focused on Latin America, a biodiverse region with large impacts on carbon and water cycles far beyond its borders.
Despite its outsized ecological impact, the density of FLUXNET sites in Latin America is lower than in the United States or Europe. The team identified 41 eddy covariance sites registered with FLUXNET across Latin America as of 2018 and evaluated the network’s ability to monitor patterns of gross primary productivity (GPP), evapotranspiration, and variability in multiple environmental factors, including climate, topography, and soil. The authors then used a multivariate statistical technique to determine how many more FLUXNET sites are necessary across Latin America to improve the representativeness of the network for GPP and evapotranspiration.
They found that the existing FLUXNET sites represented nearly half of GPP and more than a third of evapotranspiration patterns. For climate, terrain, and soil properties, those numbers were 34%, 36%, and 34%, respectively. Unfortunately, data from these sites are not widely available. Currently, the authors note, models must rely on data from FLUXNET sites outside of Latin America to make predictions about patterns within the region.
The multivariate analysis showed that adding 200 study sites across Latin America could nearly double the overall representativeness of both GPP and evapotranspiration. However, with optimally located sites, the same increase could be achieved with just 60 sites, though the uncertainty would be much higher.
In the meantime, the authors call for more coordination and data sharing among researchers in Latin America and caution against “helicopter research,” in which researchers from institutions in developed countries collect data with little or no involvement from local researchers. Ultimately, local contributions will be critical for increasing the representativeness of FLUXNET sites across the region. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2020JG006090, 2021)
—Kate Wheeling, Science Writer