How eddy covariance flux measurements have contributed to our understanding of Global Change Biology

Abstract

A global network of long‐term carbon and water flux measurements has existed since the late 1990s. With its representative sampling of the terrestrial biosphere's climate and ecological spaces, this network is providing background information and direct measurements on how ecosystem metabolism responds to environmental and biological forcings and how they may be changing in a warmer world with more carbon dioxide. In this review, I explore how carbon and water fluxes of the world's ecosystem are responding to a suite of covarying environmental factors, like sunlight, temperature, soil moisture, and carbon dioxide. I also report on how coupled carbon and water fluxes are modulated by biological and ecological factors such as phenology and a suite of structural and functional properties. And, I investigate whether long‐term trends in carbon and water fluxes are emerging in various ecological and climate spaces and the degree to which they may be driven by physical and biological forcings. As a growing number of time series extend up to 20 years in duration, we are at the verge of capturing ecosystem scale trends in the breathing of a changing biosphere. Consequently, flux measurements need to continue to report on future conditions and responses and assess the efficacy of natural climate solutions.

Net carbon ecosystem exchange during 24 years in the Sorø Beech Forest – relations to phenology and climate

“…The annual increase of 12 g C m -2 d À1 of CUP is somewhat higher than the global average increase (6 g C m -2 d À1 ) estimated by Baldocchi (2020).…”

“…(3) Long-term flux measurements are essential to identify trends and distinguish them from random noise. In consequence already established sites with long-term measurements need to continue operation (Baldocchi, 2020). Moreover, longterm flux measurements can provide a data base to distinguish between normal and extreme ecosystem responses to environmental drivers.…”

Canopy photosynthetic capacity drives contrasting age dynamics of resource use efficiencies between mature temperate evergreen and deciduous forests

“…The eddy covariance (EC) technique is the most common method of measuring net CO 2 and water vapor fluxes between terrestrial ecosystems and the atmosphere (Baldocchi, 2020). For the FLUXNET sites, the gap-filled and partitioned flux data and meteorological data were obtained from the FLUXNET2015 Dataset (http://fluxn et.fluxd ata.org/data/fluxn et201 5-datas et/).…”

Interannual variability of net ecosystem carbon production and its climatic and biotic mechanism during 2005-2018 in a rain-fed maize ecosystem

“…Meanwhile, there was a significant positive correlation between RE and GEP (Table S3) with a ratio of 0.75. The IAV of GEP was controlled by temperature at the regional scale and driven by moisture, LAI and residues as well as temperature at the single site scale [4,53]. Moreover, GEP was more sensitive to drought than RE in most ecosystems [15].…”

“…The Previous studies suggest that climatic and biotic drivers may ultimately cause the IAV of NEP by regulating phenological and physiological indicators [4,9,15]. Therefore, the IAV of NEP can be explained by indicators related to physiological (described by the carbon uptake or release peak) and phenological (described by the corresponding duration) processes of the plant [53]. The framework provides a new perspective on the explaining the causes of the IAV of NEP [8,14,15,23].…”