关键词: 西藏柏木, 巨柏, 物种多样性, 物种组成, 建群种

Abstract: In this study, we used the data of field meteorological observation of late rice in low hilly red soil region and analyzed the distribution characteristics with typical diurnal and monthly variation of the actual evapotranspiration of rice field at different growth stages. At the same time, the influences of meteorological factors on the actual evapotranspiration were studied by using the path analysis method and Beven’s sensitivity formula. The results indicated that the actual value of evapotranspiration during the whole growth period was 290.61 mm and the measured evapotranspiration value was the largest at transplantingtillering stage, which was 96.91 mm, accounting for 33.3% of the whole growth period. The evapotranspiration of paddy field in the whole growth period showed a tendency to increase first and then decrease gradually. The peak appeared in the later stage of rice tillering. The change of rice field evapotranspiration in one day showed the low intensity in the morning and evening but high at the noon, which just liked a ‘reverse’ U. Weather conditions and the duration of growth period also had some influences on evapotranspiration. Path analysis and sensitivity analysis showed that net radiation and relative humidity had higher total contribution coefficient and sensitivity coefficient, which means these two factors were the main meteorological factors that affected the evapotranspiration of paddy field. The three temperature factors (the highest temperature, lowest temperature, average temperature) were in the next place, and the wind speed’s effects on evapotranspiration were little. There was a significant time scale difference for the relationship between evapotranspiration and meteorological factors. The effect of each meteorological factor on the actual evapotranspiration was more significant at daily scale than at hourly scale.

Key words: Cupressus torulosa, C. gigantea, species composition, species diversity, constructive species