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采用Granier热扩散方法(TDP)测定了尾巨桉2个径向深度(0~2和2~4 cm)的液流速率,探讨液流径向变化对树木蒸腾估算产生的影响、不同个体大小的估算误差以及估算误差与光合有效辐射(PAR)和水汽压亏缺(VPD)的关系.结果表明:尾巨桉的日蒸腾量在单点径向深度0~2 cm条件下估算值最大,两点综合估算值次之,单点径向深度2~4 cm最小,单点径向0~2 cm和径向2~4 cm所得的日蒸腾量分别较两点综合估算值高估了32.9%和低估了58.7%;用单点径向0~2 cm估算蒸腾量时所产生的误差随胸径的递减而减少,胸径为17.7、12.9和9.8 cm的树木产生的估算误差分别为51.7%、33.0%、18.0%,而单点径向2~4 cm所产生的估算误差则没有明显的径级差异;PAR和VPD都与单点径向0~2 cm估算误差有较好的正相关性,相比较VPD而言,PAR与单点径向0~2 cm估算误差的相关性更好.相比传统的仅用单一深度液流速率估算单株蒸腾耗水量的方法,两点估算方法一定程度上提高了日蒸腾量计算的精度,为尾巨桉人工林森林耗水量估算提供了可靠依据.
Granular thermal diffusion method (TDP) was used to determine the flow velocities at two radial depths (0 ~ 2 and 2 ~ 4 cm) of Eucalyptus urophylla, and the effect of radial flow on tree transpiration estimation was studied. The results showed that the daily transpiration of Eucalyptus urophylla was the largest at 0-2 cm under the single point radial depth, and the correlation between the estimated error and the photosynthetically active radiation (PAR) and vapor pressure deficit (VPD) The integrated value of the two points is the second, the single point radial depth of 2 ~ 4 cm minimum, single point radial 0 ~ 2 cm and radial 2 ~ 4 cm obtained daily transpiration than the two points of the comprehensive estimate of an estimated 32.9 % And underestimation of 58.7%. The error of transpiration with single point diameter of 0 ~ 2 cm is decreased with the decrease of DBH. The estimation errors of tree with DBH of 17.7, 12.9 and 9.8 cm were 51.7% 33.0% and 18.0%, respectively. However, there was no significant difference between the diameters of 2 and 4 cm. The PAR and VPD had a good positive correlation with the single-point radial 0-2 cm estimation error , Compared with the VPD, PAR and single-point radial 0 ~ 2 cm estimation error correlation is better.Compared with the traditional single-only flow rate of a single estimate of transpiration water consumption The method improves the accuracy of transpiration estimation methods to calculate two points certain extent, provide a reliable basis for the E. grandis plantation forest water consumption tail estimates.