Abstract:

The transpiration variation and relationship between supply and demand of water for the Cornus officinalis plantations in the rocky mountainous area of north China were analyzed through the experimental data of the C. officinalis plantations sap flow and rainfall, which was measured by thermal dissipation sap flow velocity probe and meteorology automatic monitoring system respectively .The trees were 15 years old. The experiment was conducted in April to September of 2005 and 2006. The aim of this study is to provide the essential evidence about water ecology for developing C. officinalis plantations in the area. The results as follows: 1) The daily variations of transpiration(Tr) is characterized with that Tr rises gradually in April, and reaches a peak during about June, falls down readily in July. In 2005 and 2006, the total Tr (ToTr) was 265.3 and 194.9 mm in the main season(April to September),respectively. In April, May, June, July, August and September, the ratio of the monthly Tr to ToTr is 10.7%, 22.3%, 21.6%, 21.2%, 12.9% and 11.2% in 2005. Respectively, 16.2%, 20.2%, 20.3%, 17.9%, 13.6%and 11.2% in 2006. 2) In all months during the growth season of 2005 and 2006, Tr showed significantly compound correlated with the solar radiation (R_a), air temperature, humidity, and wind speed over the canopy(α=0.01), and R_a is the most important micro-meteorology factor effecting on Tr through comparing the partial coefficient; 3) In terms of an whole growth season, the ratio of rainfall to transpiration is more than 1.0. So, there was no water supply and demand conflict, or water shortage and water stress as for the main growth season in the experiment area.

Key words: Cornus officinalis plantations, transpiration, relationship between supply and demand of water