As a result of landuse, 50%
or more of forests in the Northern Hemisphere mid-latitudes are in hilly to
mountainous terrain, accounting for half or more of the mid-latitude Gross
Primary Productivity. The mid-latitude sink observed in the atmosphere may
reflect carbon dynamics occurring in complex terrain. This is challenging: these regions are
inherently highly heterogeneous and currently reflect complex land use
histories, and atmospheric techniques for estimating spatially integrated
carbon fluxes don’t work well in sloping terrain. Consequently, the impacts of
climate, harvesting regimes, disturbances and fire/pest management on carbon
exchange are poorly constrained in mountains. While mountains are
heterogeneous, the orientation of slopes to incident radiation and
gravitational flows of air and water result in organization of the variability
that can be exploited. Analysis using model-data fusion techniques of long-term
eddy covariance data showed 1) mid-aged Rocky Mountain forests are sinks, 2)
most of the net uptake occurs in the spring when melting snow provides moisture
for photosynthesis but low soil temperatures inhibit respiration and 3)
interannual variability is mainly due to GEE and is largely driven by spring
temperature and precipitation, which both determine spring fluxes and set the
stage for mid-summer soil moisture conditions.
Author: David Schimel, Britton Stephens, Russell Monson, et al (schimel at ucar dot edu)
Filesize: 37.34 Kb