Abstract: Sap flow velocities of Tilia amurensis, Acer mono and Pinus koraiensis in a broad-leaved Korean pine forest of Changbai Mountain were continuously measured from June to September of 2009 using Granier’s thermal dissipation sap flow probe method, with simultaneous measurements of environmental factors. Diurnal and monthly variations of sap flow velocities for the three species and the effects of environmental factors were analyzed. The results showed that diurnal variations of sap flow velocities for three species all displayed singlepeaked curves, and their starting time and peak time were the same. However, their end time showed a difference, and the diurnal end time of sap flow for T. amurensis was the latest. The monthly dynamics of sap flow velocities for the three species also showed a similar pattern, with their maximums appearing in August and minimums in June. Among the three species, the daily average sap flow velocity of T. amurensis was the highest in each month, with the lowest for P. koraiensis. Sap flow velocities of the three species were mainly affected by the photosynthetically active radiation and vapor pressure deficit. Stepwise regression models for predicting sap flow velocities of the three species based on environmental factors were established in each month.

Key words: nitrogen, water and nitrogen productivity, Coffea arabica, drought stress, regression analysis, rewatering, yield