CLIMATIC WATER SUPPLY FOR
MOSS (Polytrichum commune Hedw.) SURFACE MOISTURE
-Rethinking of Koke-Niwa (moss gardens) based on long-term climatic analysis -IIDA Yoshihiko
Key Words: Polytrichum commune Hedw., microclimatic observation, dewfall, rainfall days, nocturnal clear calm days
1.
INTRODUCTION
Japanese moss gardens of Kyoto have been matured by both climate and traditional skills of landscape management, however, closely be in a decay in recent years. Primary research is needed based on interrelation between atmosphere and moss. The aim of this paper is to clarify the dynamics of moss surface moisture according to microclimatic observation in a naturally rain-supplied habitat of Polytrichum commune Hedw. and more to analyze climatic function for water supply in long-term.
2.
METHOD
Microclimatic observation in fall 2008 include three different vertical heights of temperature and relative humidity, radiation budget and wind speed / direction on the canopy of habitat in which was installed hydro-probes and thermometers inside moss turf, at Kita-Shirakawa Experimental Site, Kyoto University. Quantifying moss surface moisture (MSM) was manually carried out for totally 33 days. All data was compared with precipitation, wind and cloud conditions at Kyoto Local Meteorology Observatory.
3.
RESULTS AND DISCUSSION
In this duration, there are 5 days when is
measured over 0.2g/102cm2 of MSM on a
canopy (Fig.1). Following after rainfall on the Oct 14th , it was observed that nocturnal radiation cooling due to clear calm condition occurred and temperature decreased and specific humidity was stable in the early morning of Oct 16th. During the late night of Oct 30th and Nov 1st the decreasing of positive soil heat flux and clear condition persisted so
that dewfall was measured due to cooling effect considerably.
The differences of relative humidity between KSES observation data near the site and the measurement was 5% at the height of 1.5m and more significant about 15% at the level of 0.05m. During no rainfall periods when diurnal moisture change of hydro-probes in exposed turf was distinctly more varied than that under obstacles and was closely related to successive rainfall events of KLMO and KSES. Therefore, the rainfall data at KLMO may use for long-term assessment. Wind speed at the site was under 0.2m/s in the ratio of 51.4% of the total. It was seen of the increase of cloudy days and the decrease of calm days at KLMO.
4.
FORWARD BETTR MANAGEMENT OF MOSS GARDENS
The dewfall and distillation process on moss surface in clear calm condition after rainfall, as water supply function for a habitat of Polytrichum commune Hedw., would be corrupted in some gardens of Kyoto in this decade. It should be emphasized on artifices for accumulated and undisturbed damp cool air in the gardens.
日降水量
群落上
面水分量
京都大学北白川試験地 Ka aaa Epe e a Se
日降水量
群落上面水分量
