Forests play a significant role in the global carbon (C) cycle. Variability in weather, species, stand age, and current and past disturbances are some of the factors that control stand-level C dynamics. This study examines the relative roles of stand age and associated structural characteristics and weather variability on the exchange of carbon dioxide between… More
Comparisons were made among Douglas-fir forest, aspen (broad leaf deciduous) forest and wheatgrass (C3) grassland for ecosystem-level water-use efficiency (WUE). WUE was defined as the ratio of photosynthetic CO2 assimilation rate and evapotranspiration (ET) rate. The ET data measured by eddy covariance were screened so that they overwhelmingly represented transpiration. The three sites used in… More
The internal conductance from intercellular spaces to the sites of carboxylation (gi) has only been measured in a few tree species and not in conifers, despite the fact it may impose a large limitation on photosynthesis. The present study provides the first estimates of gi for a coniferous species, and examines variation in gi with… More
Two years of continuous eddy covariance measurements were used to characterize the seasonal and annual variability of the latent and sensible heat fluxes above a 50-year-old, 33 m tall coastal Douglas-fir forest on the east coast of Vancouver Island, Canada. The total annual evaporation was found to be very conservative for this temperate coniferous rainforest despite… More
CO2 exchange was measured on the forest floor of a coastal temperate Douglas-fir forest located near Campbell River, British Columbia, Canada. Continuous measurements were obtained at six locations using an automated chamber system between April and December, 2000. Fluxes were measured every half hour by circulating chamber headspace air through a sampling manifold assembly and… More
We analyzed 17 months (August 2005 to December 2006) of continuous measurements of soil CO2 efflux or soil respiration (RS) in an 18-year-old west-coast temperate Douglas-fir stand that experienced somewhat greater than normal summertime water deficit. For soil water content at the 4 cm depth (θ) >0.11 m3 m−3 (corresponding to a soil water matric potential of −2 MPa),… More