This work is intended as a review of gas exchange processes between the atmosphere and the terrestrial vegetation, which have been known for more than two centuries since the discovery of photosynthesis. The physical and biological mechanisms of exchange of carbon dioxide, water vapour, volatile organic compounds emitted by plants and air pollutants taken up by them, is critically reviewed. The role of stomatal physiology is emphasised, as it controls most of these processes. The techniques used for measurement of gas exchange fluxes between the atmosphere and vegetation are outlined.

Vertical profiles of the leaf area density (LAD) of a Japanese zelkova canopy were estimated by combining airborne and portable ground-based light detection and ranging (lidar) data and using a voxel-based canopy profiling method. The profiles obtained by the two types of lidars complemented each other, eliminating blind regions and yielding more accurate LAD profiles than could be obtained by using each type of lidar alone. In the combined results, the mean absolute errors (MAEs) of LAD ranged from 0.20 to 0.42 $ hbox{m}^{2} hbox{m}^{-3}$, and the mean absolute percentage errors (MAPEs) of the leaf area index (LAI) ranged from 22.3%to 27.2%, for ground areas from 4 to 32 $hbox{m}^{2}$ , respectively. A laser beam coverage index $Omega$ incorporating the lidar's beam settings and a beam attenuation factor was proposed. This index showed general applicability to explain the LAD estimation error for LAD measurements using different types of lidars and with different beam settings. Parts of the LAD profiles that were underestimated even when data from both lidars were combined were interpolated by using a Gaussian function. The interpolation yielded improved results for ground areas of 16 and 32 $hbox{m}^{2}$; the respective MAEs of LAD were 0.17 and 0.11 $hbox{m}^{2} hbox{m}^{-3}$, and the respective MAPEs of LAI were 8.0%and 9.4%. The proposed method improves lidar-derived LAD estimation and is adapted to broadleaved canopies. The index $Omega$ was tested against an actual canopy scenario and could be used to determine appropriate lidar measurement settings -

To parameterize stomatal conductance or ozone uptake modeling in the Eastern Asian tree species Zelkova serrata, measurements of stomatal conductance were carried out in several Japanese sites across the growing season. The new parameterization improved the stomatal conductance model performance relative to a previously proposed model. The results were used to compare the spatial distribution of AOT40 and Z. serrata stomatal ozone uptake in Japan. Including a soil moisture function improved the model in the short periods with low precipitation. In addition, elevated vapor pressure deficit and soil moisture deficit due to high temperature, and high ozone exposure induced stomatal closure. The consequent decoupling of stomatal ozone uptake from high ozone exposure suggests caution in using AOT40 as a standard for Z. serrata protection in Japan.