[Comparison and application of calculation methods for water consumption of tree transpiration]. / æž—æœ¨è’¸è ¾è€—æ°´é‡æµ‹ç®—æ–¹æ³•çš„æ¯”è¾ƒä¸Žåº”ç”¨.

In this study, the concept, research value, and research advances of tree transpiration were concisely narrated. From the perspective of measurement and estimation, we summarized the main calculation methods for water consumption of tree transpiration. By comparing the advantages, disadvantages, applicability, limitations, application status, and applicable scale of different methods, we showed that the measurement methods could be applied to the measurement of water consumption at multiple spatial scales, and that the estimation methods were often applied to the measurement of evapotranspiration at large spatial scales. As the measurement method was the basis of the estimation method, it is necessary to carry out reasonable quality control and evaluation of the measured results of measurement methods, in order to provide data basis for the estimation results of the correction estimation method. Whether it was at a particular large spatial scale or at different spatial scales, the combination of measurement methods and estimation methods could improve the accuracy of evapotranspiration measurement. Improving the accuracy of calculating the dispersion of trees at a large spatial scale in complex underlying surface and harsh climate environments would become a research hotspot but may also be a difficulty in the future. With the continuous progress of science and technology, both measurement devices and methods would be improved, and new methods for accurately measuring the water consumption of forest transpiration would be available.

[Physiological responses of Salix rehderiana and Populus cathayana grafted seedlings to nitrogen deficiency]. / å·æ»‡æŸ³ä¸Žé’æ¨å±žé—´å«æŽ¥å¹¼è‹—å¯¹æ°®ç´ ç¼ºä¹çš„ç”Ÿç†å“åº”.

Morphological and physiological responses of Salix plants are different from Populus to nitrogen (N) deficiency. In this study, grafting technology was used in S. rehderiana and P. cathayana to investigate the graft compatibility of Salix and Populus, and whether grafting could improve the resistance to N deficiency in Salicaceae plants. The survival rate, growth, biomass accumulation and allocation, gas exchange parameters and non-structural carbohydrates (NSCs) were measured to evaluate the resistance to N deficiency among different grafting combinations. The results showed that the graft compatibility between S. rehderiana and P. cathayana was quite high. The survival rate was 74% and 96% in S/P (S. rehderiana was used as scions and P. cathayana as rootstocks) and P/S (P. cathayana was used as scions and S. rehderiana as rootstocks) combinations, respectively. N deficiency reduced the survival rate in all grafting combinations, which were 53.3% and 86.7% in S/P and P/S, respectively. The survival rate of S/P was lower than that of the other grafting combinations. Under control and N-deficient conditions, the height, basal diameter, biomass and net photosynthetic rate (Pn) of P/P and P/S combinations were higher than those of S/S and S/P combinations. N deficiency significantly reduced growth rate, biomass accumulation and Pn in all grafting combinations. The rate between root biomass and aboveground biomass of S. rehderiana rootstock combinations (S/S and P/S) was significantly higher than those of P. catha-yana rootstock combinations (P/P and S/P) under both control and N-deficient conditions. It indicated that more photosynthates might be allocated to belowground in S. rehderiana, while to aboveground in P. cathayana. The NSCs in roots of all grafting combinations were more sensitive to N deficiency than in stems and leaves. Except for the S/P combination, the starch, fructose, sucrose and total soluble sugar concentrations were significantly increased in roots in P/P, S/S and P/S combinations. Additionally, under N-deficient condition, the NSCs contents were significantly higher in P/P and P/S combinations than in S/S and S/P combinations.