Can fog contribute to the nutrition of Chamaecyparis obtusa var. formosana? Uptake of a fog solute tracer into foliage and transport to roots

Electron microscopic observations of stomata, epicuticular waxes, and papillae in Chamaecyparis obtusa: Reconsidering the traditional concept of Y-shaped white stomatal bands

The foliar morphological characters of hinoki (Chamaecyparis obtusa) were revisited using optical and scanning electron microscopy. In C. obtusa, typical Y-shaped white stomatal bands were evident on the abaxial leaf surfaces. Two facial leaves and two lateral leaves were observed at the same node. Waxy papillae and oval stomata were arranged in two or three rows with protuberant rims on the abaxial leaf surfaces. Higher magnifications revealed the deposition of epicuticular waxes (tubules) on the Y-shaped white stomatal bands. Given the absence of stomatal bands after dewaxing with organic solvents, the white stomatal bands in C. obtusa were related to the epicuticular waxes rather than the presence of aggregated stomata alone. In contrast to C. obtusa, a single median leaf and two lateral leaves were observed at the same node of oriental arborvitae (Platycladus koraiensis). Neither stomatal bands nor papillae were observed on P. koraiensis leaves. The stomatal density and epicuticular waxes in the stomatal regions of C. obtusa were higher than those of P. koraiensis. This study suggests that the traditional concept of Y-shaped white stomatal bands in C. obtusa should be revised to describe the arrangement of the aggregated waxy stomata that occur in rows.

Scaling Erica arborea transpiration from trees up to the stand using auxiliary micrometeorological information in a wax myrtle-tree heath cloud forest (La Gomera, Canary Islands)

We investigate evapotranspiration, sap flow and top soil water content variations in a wax myrtle-tree heath ('fayal-brezal' in Spanish) cloud forest in the Garajonay National Park (La Gomera, Canary Islands) over a 1-year period. We provide transpiration estimates for one of the representative species, the shrubby needle-like Erica arborea L., present in this relict subtropical forest. An ad hoc tree up to the stand scaling method that combines the sap flow and auxiliary reference evapotranspiration data is illustrated, showing to be useful when sap flow in a limited number of trees has been monitored. Individual daily-based scaling curves of the Gompertz type were necessary to explain the observed sap flow variability in E. arborea during the 1-year period investigated (r(2) ≥ 0.953 with mode of r(2) = 0.9999). The mean daily sap flow of an E. arborea individual amounted to 8.37 ± 5.65 kg day(-1) tree(-1), with a maximum of 20.48 kg day(-1) tree(-1), yielding an annual total of 3052.89 kg tree(-1). A comparison of the computed daily transpiration with the continuous micrometeorological time series monitored in the studied plot suggested that solar radiation was the main driving force of transpiration in E. arborea (cross correlation index = 0.94). Fog may also affect tree transpiration via its reduction of radiation and temperature, such that during foggy periods the mean daily water loss estimate of E. arborea was 5.35 ± 4.30 kg day(-1) tree(-1), which sharply contrasted with the 2.4-fold average transpiration values obtained for fog-free days, i.e., 12.81 ± 4.33 kg day(-1) tree(-1). The annual water balance rendered a 288 mm year(-1) water input to the forest and evidenced the need for accurately quantifying the contribution of fog water dripping from the canopy.

Compact x-ray microtomography system for element mapping and absorption imaging

We have designed and built a compact x-ray microtomography system to perform element mapping and absorption imaging by exploiting scanning fluorescence tomography and full-field transmission microtomography, respectively. It is based on a low power microfocus tube and is potentially appropriate for x-ray diagnostics in space. Full-field transmission tomography yields the three-dimensional inner structure of an object. Fluorescence microtomography provides the element distribution on a virtual section through the sample. Both techniques can be combined for appropriate samples. Microradiography as well as fluorescence mapping are also possible. For fluorescence microtomography a small and intensive microbeam is required. It is generated using a polycapillary optic. Operating the microfocus tube with a molybdenum target at 12 W, a microbeam with a full width at half maximum lateral extension of 16 microm and a flux of about 10(8) photonss is generated. As an example of application, this beam is used to determine the element distribution inside dried plant samples. For full-field scanning tomography, the x-ray optic is removed and the sample is imaged in magnifying projection onto a two-dimensional position sensitive detector. Depending on the sample size, a spatial resolution down to about 10 microm is possible in this mode. The method is demonstrated by three-dimensional imaging of a rat humerus.