Temperature is a primary environmental control on ecological systems and processes at a range of spatial and temporal scales. The surface temperature of organisms is often more relevant for ecological processes than air temperature, which is much more commonly measured. Surface temperature influences—and is influenced by—a range of biological, physical, and chemical processes, providing a… More

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Canopy temperature Tcan is a key driver of plant function that emerges as a result of interacting biotic and abiotic processes and properties. However, understanding controls on Tcan and forecasting canopy responses to weather extremes and climate change are difficult due to sparse measurements of Tcan at appropriate spatial and temporal scales. Burgeoning observations of… More

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The proliferation of digital cameras co‐located with eddy covariance instrumentation provides new opportunities to better understand the relationship between canopy phenology and the seasonality of canopy photosynthesis. In this paper we analyze the abilities and limitations of canopy color metrics measured by digital repeat photography to track seasonal canopy development and photosynthesis, determine phenological transition… More

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The seasonal pattern of the carbon isotope content (δ13C) of atmospheric CO2 depends on local and nonlocal land‐atmosphere exchange and atmospheric transport. Previous studies suggested that the δ13C of the net land‐atmosphere CO2 flux (δsource) varies seasonally as stomatal conductance of plants responds to vapor pressure deficit of air (VPD). We studied the variation of… More

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Carbonyl sulfide (OCS) has recently emerged as a tracer for terrestrial carbon uptake. While physiological studies relating OCS fluxes to leaf stomatal dynamics have been established at leaf and branch scales and incorporated into global carbon cycle models, the quantity of data from ecosystem-scale field studies remains limited. In this study, we employ established theoretical… More

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Diurnal and vertical patterns of carbonyl sulfide (OCS) and CO2 mixing ratios above and within a 60‐m‐tall old‐growth temperate forest are presented. Canopy air from four different heights was sampled in situ using a continuous integrated cavity output spectroscopy analyzer during August–September 2014. Measurements revealed large vertical gradients in OCS, from which we inferred ecosystem… More

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Aerodynamic canopy height (ha) is the effective height of vegetation canopy for its influence on atmospheric fluxes and is a key parameter of surface‐atmosphere coupling. However, methods to estimate ha from data are limited. This synthesis evaluates the applicability and robustness of the calculation of ha from eddy covariance momentum‐flux data. At 69 forest sites,… More

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Carbon dioxide (CO2) exchange was measured above the forest floor of a temperate Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) and Western Hemlock (Tsuga heterophylla (Raf.) Sarg.) old-growth forest in southern Washington State. Continuous flux measurements were conducted from July 1998 to December 2003 using the eddy-covariance technique. Maximum observed fluxes were +6 mmol m2 s1 on… More

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This study examines how stand age affects ecosystem mass and energy exchange response to seasonal drought in three adjacent Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. The sites include two early seral (ES) stands (0-15 years old) and an old-growth (OG) (~ 450-500 years old) forest in the Wind River Experiment Forest, Washington, USA. We use… More

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