Radial variation in sap flux density (SFD) as a function of sapwood thickness is of importance in accurately estimating sap flux through sapwood area which, in turn, decides the precision of heat pulse application. Ho...Radial variation in sap flux density (SFD) as a function of sapwood thickness is of importance in accurately estimating sap flux through sapwood area which, in turn, decides the precision of heat pulse application. However, until now, only a few studies have evaluated the magnitude and significance of sampling errors associated with radial gradients in SFD, which were based on the small monitoring measurement data from a few trees. Based on one year of heat pulse observation of two 3 - 4 years old Eucalyptus urophylla S. T.,P Blake plantations in Leizhou Peninsula, Guangdong Province, China, a way of data processing was developed to treat with the lots of SFD data measured from 39 trees. It was found that the radial variation in SFD as a function of sapwood thickness in the two eucalyptus plantation sites could be expressed as y = 3. 667 5x(3) - 7.295 5x(2) + 3.682 6x + 0. 567 4 (R-2 = 0. 939 1, n = 80, P = 0.01), where y is the ratio of SFD of a sensor to the average of four data in different depths, x is the ratio of a sensor depth to tire radial sapwood thickness. It was the same (as in the following equation) in Jijia site, y = 5.006 2x(3) - 9.116 1x(2) + 4. 454 4x + 0.463 4 (R-2 = 0. 806 9, n = 72, P = 0.01) in Hetou site. From cambium to heartwood, SFD showed some increases at first and then decreases continuously. However, because die trees were very young, the maximum SFD was only 0. 33 - 0. 36 times more than the minimum.展开更多
通过研究降雨条件下森林土壤的入渗规律,入渗与降雨强度的关系以及影响入渗的因素,认为地表击实层降低了土壤渗透性,裸露地土壤渗透系数降低到4.84%;湿润锋面在不同的土壤层次里以不同的速度下移时,降雨稳渗率 fc 与降雨强度 i 近似地...通过研究降雨条件下森林土壤的入渗规律,入渗与降雨强度的关系以及影响入渗的因素,认为地表击实层降低了土壤渗透性,裸露地土壤渗透系数降低到4.84%;湿润锋面在不同的土壤层次里以不同的速度下移时,降雨稳渗率 fc 与降雨强度 i 近似地呈直线相关,并与森林土壤具有很大的渗透容量有关;并指出,森林土壤积水时间同降雨强度的关系与理论推算值之间有很大差别。文中对有关过程做了数学描述。展开更多
文摘Radial variation in sap flux density (SFD) as a function of sapwood thickness is of importance in accurately estimating sap flux through sapwood area which, in turn, decides the precision of heat pulse application. However, until now, only a few studies have evaluated the magnitude and significance of sampling errors associated with radial gradients in SFD, which were based on the small monitoring measurement data from a few trees. Based on one year of heat pulse observation of two 3 - 4 years old Eucalyptus urophylla S. T.,P Blake plantations in Leizhou Peninsula, Guangdong Province, China, a way of data processing was developed to treat with the lots of SFD data measured from 39 trees. It was found that the radial variation in SFD as a function of sapwood thickness in the two eucalyptus plantation sites could be expressed as y = 3. 667 5x(3) - 7.295 5x(2) + 3.682 6x + 0. 567 4 (R-2 = 0. 939 1, n = 80, P = 0.01), where y is the ratio of SFD of a sensor to the average of four data in different depths, x is the ratio of a sensor depth to tire radial sapwood thickness. It was the same (as in the following equation) in Jijia site, y = 5.006 2x(3) - 9.116 1x(2) + 4. 454 4x + 0.463 4 (R-2 = 0. 806 9, n = 72, P = 0.01) in Hetou site. From cambium to heartwood, SFD showed some increases at first and then decreases continuously. However, because die trees were very young, the maximum SFD was only 0. 33 - 0. 36 times more than the minimum.
文摘通过研究降雨条件下森林土壤的入渗规律,入渗与降雨强度的关系以及影响入渗的因素,认为地表击实层降低了土壤渗透性,裸露地土壤渗透系数降低到4.84%;湿润锋面在不同的土壤层次里以不同的速度下移时,降雨稳渗率 fc 与降雨强度 i 近似地呈直线相关,并与森林土壤具有很大的渗透容量有关;并指出,森林土壤积水时间同降雨强度的关系与理论推算值之间有很大差别。文中对有关过程做了数学描述。
