McCulloh Katherine A, Winter Klaus, Meinzer Frederick C, Garcia Milton, Aranda Jorge, Lachenbruch Barbara
Department of Wood Science and Engineering, Oregon State University, Corvallis, OR 97331, USA.
Tree Physiol. 2007 Sep;27(9):1355-60. doi: 10.1093/treephys/27.9.1355.
Use of Granier-style heat dissipation sensors to measure sap flow is common in plant physiology, ecology and hydrology. There has been concern that any change to the original Granier design invalidates the empirical relationship between sap flux density and the temperature difference between the probes. Here, we compared daily water use estimates from gravimetric measurements with values from variable length heat dissipation sensors, which are a relatively new design. Values recorded during a one-week period were compared for three large pot-grown saplings of each of the tropical trees Pseudobombax septenatum (Jacq.) Dugand and Calophyllum longifolium Willd. For five of the six individuals, P values from paired t-tests comparing the two methods ranged from 0.12 to 0.43 and differences in estimates of total daily water use over the week of the experiment averaged < 3%. In one P. septenatum sapling, the sap flow sensors underestimated water use relative to the gravimetric measurements. This discrepancy could have been associated with naturally occurring gradients in temperature that reduced the difference in temperature between the probes, which would have caused the sensor method to underestimate water use. Our results indicate that substitution of variable length heat dissipation probes for probes of the original Granier design did not invalidate the empirical relationship determined by Granier between sap flux density and the temperature difference between probes.
在植物生理学、生态学和水文学中，使用格拉尼尔式散热传感器来测量液流是很常见的。有人担心，对原始格拉尼尔设计的任何改变都会使液流通量密度与探头之间的温差之间的经验关系无效。在这里，我们将重量测量得出的每日水分利用估计值与可变长度散热传感器的值进行了比较，可变长度散热传感器是一种相对较新的设计。对热带树木盾柱木（Pseudobombax septenatum (Jacq.) Dugand）和长叶红厚壳（Calophyllum longifolium Willd.）的三株大型盆栽幼树，比较了一周内记录的值。在六个个体中的五个中，比较这两种方法的配对t检验的P值范围为0.12至0.43，实验周内每日总水分利用估计值的差异平均<3%。在一株盾柱木幼树中，相对于重量测量，液流传感器低估了水分利用。这种差异可能与自然存在的温度梯度有关，温度梯度降低了探头之间的温差，这会导致传感器方法低估水分利用。我们的结果表明，用可变长度散热探头替代原始格拉尼尔设计的探头并没有使格拉尼尔确定的液流通量密度与探头之间的温差之间的经验关系无效。
