D8 Remote Sensing and Ecosystem Monitoring

Topic

The state and function of plant ecosystems can be measured at scales ranging from a few meters to entire continents, and a suite of measurement tools allows this entire range of spatial scales to be covered, each at its own specific scale.

At the most local scale, flux towers—which utilize the eddy covariance technique—directly record the ecosystem's net carbon exchange between the surrounding vegetation and the atmosphere; each tower quantifies whether the specific portion of the ecosystem it monitors is acting as a carbon sink or a carbon source at any given moment.

Moving up in scale from the individual flux tower to the surrounding landscape, an airborne or drone-mounted laser sensor—known as airborne LiDAR—scans the three-dimensional structure of the vegetation over areas spanning many kilometers, enabling estimates of leaf area index and biomass for each part of the landscape with a resolution of a few meters.

Scaling up further—from the landscape covered by airborne laser sensors to regional and global levels—satellite-based optical and radar sensors perform similar measurements of leaf area index, biomass, and ecosystem disturbances across entire continents; these satellite measurements also allow for the estimation of gross primary productivity of vegetation at these same regional and global scales.

Combining point measurements from flux towers, landscape-level measurements from airborne laser sensors, and regional-to-global measurements from satellite sensors requires big data analysis supported by cloud computing platforms like Google Earth Engine, which process these three data sources in tandem. This big data analysis makes it possible to integrate individual-level physiology—measured by flux towers and airborne laser sensors at the scale of meters—with ecosystem-level metabolism, measured by satellite sensors at the scale of continents. Taken together, flux towers, airborne laser sensors, satellite-based optical and radar sensors, and big data analysis enable the quantification of gross primary productivity, net ecosystem carbon exchange, leaf area index, biomass, and ecosystem disturbances across scales ranging from meters to continents; this coverage of scales ultimately integrates individual physiology with ecosystem metabolism within the context of the state and function of plant ecosystems.

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