A highly portable, rapidly deployable system for eddy covariance measurements of CO2 fluxes Page: 2 of 29
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INTRODUCTION
A central question in the study of global climate change is the influence of land use and land use
management on climate. While much research in carbon and energy balance has been done in forested
ecosystems, only recently have similar studies begun in grasslands. Grassland and rangeland ecosystems
dominate the Great Plains region of North America, and extend from central Canada, south to Texas and
from eastern Nebraska, west to the Rocky Mountains. Within these ecosystems, land use variability and
management practices create stark heterogeneity in vegetation cover, soil moisture, and other surface
properties. Many of these differences can be observed over distances as short as hundreds of meters.
Additionally, climatic, edaphic, and management practice variations can produce heterogeneity within
similar vegetation types, again over short distances. Because the first priority of most flux networks has
been to characterize "representative" ecosystems, there are few replicates within any given vegetation type
or management regime. As a result, researchers using these data must assume that they are representative
of all areas, and have no empirical estimate of site-to-site variability.
Currently, information about these ecosystems comes from heavily instrumented, permanent (or
semi-permanent) flux tower sites. By their very nature, they can only explore the rather limited
surrounding landscape. A further complication exists for taller towers (above 10 meters). The footprint
seen by a flux tower under typical unstable conditions is usually about 100 times the height of the
measuring instrumentation above the canopy. In these cases, footprints can extend out for several
kilometers and encompass numerous, distinct flux zones. These "tall tower" systems thus sample a
weighted average of several different flux regimes. To address these issues, a portable, high precision flux
system is needed that can be set up and taken down quickly and easily and that can run without the
expensive and limiting infrastructure usually associated with flux installations. By deploying several of
these systems, simultaneously, differences in plot-level fluxes will be revealed.
Existing portable flux systems have shown the utility of this concept. One portable system is
currently being used to cross calibrate carbon flux sites within the AmeriFlux program (Evans, 2000).
While it makes precision flux measurements (using the eddy covariance technique) and is easily
transported and set up, it requires the tower and power infrastructure of an existing flux site. An earlier
system was used to examine spatial and climatic heterogeneity of fluxes from arctic ecosystems (Eugster et2
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Billesbach, David P.; Fischer, Marc L.; Torn, Margaret S. & Berry, Joe A. A highly portable, rapidly deployable system for eddy covariance measurements of CO2 fluxes, article, September 19, 2001; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc780022/m1/2/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.