BACKGROUND AND AIMS Maximizing photosynthesis at the canopy level is important for enhancing crop yield, and this requires insights into the limiting factors of photosynthesis. Using greenhouse cucumber (Cucumis sativus) as an example, this study provides a novel approach to quantify different components of photosynthetic limitations at the leaf level and to upscale these limitations to differe...

RESUME The main limitation in the application of spaceborne SAR to large-scale forest biomass mapping is the variability in canopy structure and vegetation density. It causes signal saturation and a large residual error in the parameter estimates. A problem in defining retrieval algorithms for forest biomass is that microwaves respond to the shapes, sizes, orientations and dielectric properties...

Fire in the boreal region is the dominant agent of forest disturbance with direct impacts on ecosystem structure, carbon cycling, and global climate. Global and biome-scale impacts are mediated by burn severity, measured as loss of forest canopy and consumption of the soil organic layer. To date, knowledge of the spatial variability in burn severity has been limited by sparse field sampling and...

A strong positive correlation between vegetation canopy bidirectional reflectance factor (BRF) in the near infrared (NIR) spectral region and foliar mass-based nitrogen concentration (%N) has been reported in some temperate and boreal forests. This relationship, if true, would indicate an additional role for nitrogen in the climate system via its influence on surface albedo and may offer a simp...

Radiative-transfer physically-based studies have previously demonstrated the relationship between leaf water content and leaf-level reflectance in the near-infrared spectral region. The successful scaling up of such methods to the canopy level requires modeling the effect of canopy structure and viewing geometry on reflectance bands and optical indices used for estimation of water content, such...

Managers of the nearly 0.5 million ha of public lands in North and South Dakota, USA rely heavily on manual measurements of canopy height in autumn to ensure conservation of grassland structure for wildlife and forage for livestock. However, more comprehensive assessment of vegetation structure could be achieved for mixed-grass prairie by integrating field survey, topographic position (summit, ...

Soybean [Glycine max (L) Merrill] is one of the most important leguminous crops and ranks fourth after to rice, wheat and maize in terms of world crop production. Soybean contains abundant protein and oil, which makes it a major source of nutritious food, livestock feed and industrial products. In Japan, soybean is also an important source of traditional staples such as tofu, natto, miso and so...

The projected rise in atmospheric CO2 concentration is expected to increase growth and yield of many agricultural crops. The magnitude of this stimulus will partly depend on interactions with other components of the atmosphere such as tropospheric O3. Elevated CO2 concentrations often lessen the deleterious effects of O3, but the mechanisms responsible for this response have received little dir...

A growing number of studies have focused on evaluating vegetation indices in terms of their sensitivity to vegetation biophysical parameters as well as to external factors affecting canopy reflectance. In this context, leaf and canopy radiative transfer models have provided a basis for understanding the behaviour of such indices, particularly their resistance to external perturbing effects rela...

Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentration of CO(2) ([CO(2)]) have been shown to decrease stomatal conductance (g(s)) for a wide range of species under numerous conditions. Less well understood, however, is the extent to which leaf-level responses translate to changes in ec...