The transpiration and the spectral response of non-irrigated Haloxylon ammodendron at canopy scale

摘要

Transpiration, an essential component of surface evapotranspiration, is particularly important in the research of surface evapotranspiration in arid areas. The paper inverted the transpiration of non-irrigated Haloxylon ammodendron and its spectral responses at the canopy scale in the southern edge of the Gurbantunggut desert in Xinjiang, China. The results are as follows: The stem sap flow rate appeared biomadal or multi-peak course and maintained a certain flow in the night. The stem sap flow maintained at 0 ∼ 0.1 L/h, with a peak appearing at 12:00 ∼ 17:30, 0.316 L/h. "Noon peak" appeared from mid May to early September, at 14:00 ∼ 16:00. For monthly changes, the peak value appeared in June, with the value varying (0.32 ± 0.20) L / h, followed by July (0.30±0.16) L/h, then, May and August, the minimum value appeared in September (0.15±0.03) L/h. At the canopy scale, the optimal exponential model of the sap flow rate based on the hyperspectrum is y = 0.0015e, R = 0.806. © 2012 SPIE.