The cohesion-tension theory of water transport states that hydrogen bonds hold water molecules together and that they are pulled through the xylem under tension. This tension could cause transport failure in at least two ways: collapse of the conduit walls (implosion), or rupture of the water column through air-seeding. The...
This study investigated the mechanisms involved in the
regulation of stomatal closure in Douglas-fir and evaluated
the potential impact of compensatory adjustments in
response to increasing tree height upon these mechanisms.
In the laboratory, we measured leaf hydraulic conductance
(Kleaf) as leaf water potential (Yl) declined for comparison
with in...
Despite renewed interest in the nature of limitations on maximum tree height, the mechanisms governing ultimate and species-specific height limits are not yet understood, but likely involve water transport dynamics. Tall trees experience increased risk of xylem embolism from air-seeding because tension in their water column increases with height due...
Disturbance events strongly affect the composition, structure, and function of forest ecosystems; however, existing US land management inventories were not designed to monitor disturbance. To begin addressing this gap, the North American Forest Dynamics (NAFD) project has examined a geographic sample of 50 Landsat satellite image time series to assess...
Evidence of shifting dominance among major forest disturbance agent classes regionally to globally has been emerging in the literature. For example, climate-related stress and secondary stressors on forests (e.g., insect and disease, fire) have dramatically increased since the turn of the century globally, while harvest rates in the western US...
Hatchery supplementation of anadromous salmon is extensive across the Pacific Northwest region with millions of juvenile salmon stocked annually. The influence of hatchery-origin fish as prey items in recipient ecosystems has been explored, but influences of these fish on broader stream nutrient dynamics has not been well-studied. Salmon-derived nutrients (SDN)...
Worldwide measurements of nearly 130C3 species covering all
major plant functional types are analysed in conjunction with
model simulations to determine the effects of mesophyll
conductance (gm) on photosynthetic parameters and their
relationships estimated from A/Ci curves. We find that an
assumption of infinite gm results in up to 75%...
Worldwide measurements of nearly 130C3 species covering all major plant functional types are analysed in conjunction with model simulations to determine the effects of mesophyll conductance (gm) on photosynthetic parameters and their relationships estimated from A/Ci curves. We find that an assumption of infinite gm results in up to 75%...
The effect of various wood characteristics on decomposition of metham sodium to methylisothiocyanate in sixteen North American and Southeast Asian hardwoods and softwoods was investigated. While marked differences were noted in the degree of decomposition among some species, the relationship between decomposition and lignin content, extractive levels, wood pH, or...
Virtual water trade is increasingly recognized as a useful metaphor for thinking about freshwater resources in an international context. Its legitimacy in terms of economic theory has been questioned by a number of authors, however. In this article I develop new theoretical results that place the virtual water concept on...