emporal variation in sap-flow-scaled transpiration and cooling effect of a subtropical Schima superba plantation in the urban area of Guangzhou

hermal dissipation probes were used to measure xylem sap flux density for a Schima superba plantation growing in the urban area of Guangzhou city, South China. Stand transpiration was calculated by multiplying mean sap flux density by total sapwood area. The peak of sap flux density occurred later in wet season than in dry season. The maximum of daily sap flux density was the highest of 59 g m-2 s-1 in July and August, and the lowest of 28 g m-2 s-1 in December. During November 2007- October 2008 and during November 2008-October 2009, the stand transpiration was 263.2 and 291.6 mm, respectively. In the study periods, stand transpiration in wet season (from April to September) could account for about 58.5% and 53.8% of the annual transpiration, respectively. Heat energy absorbed by tree transpiration averaged 1.4×108 and 1.6×108 kJ per month in the Schima superba plantation with the area of 2885 m2, and temperature could be reduced by 4.3 and 4.7 oC s-1 for 10 m3 air.