Global vegetation models require the photosynthetic parameters, maximum carboxylation capacity (V[subscript cm]), and quantum yield (alpha) to parameterize their plant functional types (PFTs). The purpose of this work is to determine how much the scaling of the parameters from leaf to ecosystem level through a seasonally varying leaf area index...
Terrestrial biosphere models can help identify physical processes that control carbon
dynamics, including land–atmosphere CO₂ fluxes, and have great potential to predict the terrestrial
ecosystem response to changing climate. The skill of models that provide continental-scale carbon flux
estimates, however, remains largely untested. This paper evaluates the performance of continental-scale...
Earth system processes exhibit complex patterns across time, as do the models that seek to replicate these processes. Model output may or may not be significantly related to observations at different times and on different frequencies. Conventional model diagnostics provide an aggregate view of model–data agreement, but usually do not...
Accurately simulating gross primary productivity (GPP) in terrestrial ecosystem models is critical because errors in simulated GPP propagate through the model to introduce additional errors in simulated biomass and other fluxes. We evaluated simulated, daily average GPP from 26 models against estimated GPP at 39 eddy covariance flux tower sites...
The eddy-covariance method often underestimates fluxes under stable, low-wind conditions at night when turbulence is not well developed. The most common approach to resolve the problem of nighttime flux underestimation is to identify and remove the deficit periods using friction-velocity (u*) threshold filters (u*[superscript Th]). This study modifies an accepted...
A globally integrated carbon observation and analysis
system is needed to improve the fundamental understanding
of the global carbon cycle, to improve our ability to
project future changes, and to verify the effectiveness of policies
aiming to reduce greenhouse gas emissions and increase
carbon sequestration. Building an integrated carbon observation...
Ecosystem process models are important tools for determining the interactive effects of global change and disturbance on forest carbon dynamics. Here we evaluated and improved terrestrial carbon cycling simulated by the Community Land Model (CLM4), the land model portion of the Community Earth System Model (CESM1.0.4). Our analysis was conducted...
The exchange of carbon dioxide is a key measure of ecosystem metabolism and a critical intersection
between the terrestrial biosphere and the Earth’s climate. Despite the general agreement that
the terrestrial ecosystems in North America provide a sizeable carbon sink, the size and distribution
of the sink remain uncertain. We...
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Predicting the net effects on the carbon and water
balance of semi-arid forests under future conditions depends
on ecosystem processes responding to changes in
soil and atmospheric drought. Here we apply a combination
of field observations and soil–plant–atmosphere modeling
(SPA) to study carbon and water dynamics in a regenerating
ponderosa...
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tial measured at pre-dawn and midday and sap flow mea-
sured between 11–13 h (Irvine et al., 2004
We investigated an alternative means for quantifying daytime ecosystem respiration from eddy-covariance data in three forests with different canopy architecture. Our hypothesis was that the turbulent transport by coherent structures is the main pathway for carrying detectable sub-canopy respiration signals through the canopy. The study extends previously published work by...