DIURNAL CHANGES IN THE RADIUS OF A SUB-ALPINE NORWAY SPRUCE STEM - THEIR RELATION TO THE SAP FLOW AND THEIR USE TO ESTIMATE TRANSPIRATION
DIURNAL CHANGES IN THE RADIUS OF A SUB-ALPINE NORWAY SPRUCE STEM - THEIR RELATION TO THE SAP FLOW AND THEIR USE TO ESTIMATE TRANSPIRATION
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DOI：
10.1007/bf00192189
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发表时间：
1995-12-01
影响因子：
2.3
通讯作者：
THUM, R
中科院分区：
文献类型：
--
作者：
HERZOG, KM;HASLER, R;THUM, R
对亚高山地区成熟挪威云杉树干半径的日变化和木质部液流进行了同步观测。土壤基质势>-35kPa。流动的动力学是密切相关的茎半径的变化所造成的耗尽其可伸展的组织。茎的半径每天都在振荡，并且与此相当独立，在几天内波动。日干缩量（Δ S-d）与树冠基部日流量（Q（d））相关，当树冠在雨天蒸腾量较少且接近饱和时，Δ S-d相对于Q（d）有增大的趋势。使用线性关系，Δ S-d的流量估计值与热平衡测量值的偏差小于+/-10%，前提是其干雨天比率的校准周期与估计值相当。如果这两个时期在这方面不同，流量的估计偏差高达42%。二次关系产生的估计值较少依赖于天气。它将最大偏差降低到+/-22%。由于Δ S-d还可以比Q（d）更好地代表每日蒸腾的时间模式，因此分析茎半径的变化可以补充或部分取代茎中液流的测量。
Diurnal changes in the stem radius of a subalpine mature Norway spruce were measured simultaneously with the flow of sap in xylem. Matric potentials in the soil were >-35 kPa. The kinetics of the flow were closely related to the changes in the radius of the stem resulting from depletion of its extensible tissues. The radius of the stem oscillated daily and, fairly independently of this, fluctuated over several days. The daily shrinkage (Delta S-d) was correlated with the daily flow through its base (Q(d)), When the crown transpired little and was nearly saturated during rainy days, Delta S-d tended to increase relative to Q(d). Using a linear relation, the estimates of flow by Delta S-d deviated less than +/-10% from the values measured by heat balance, provided that the periods of calibration in their ratio of dry to rainy days were comparable to those estimated. If the two periods differed in this respect, the estimates of flow deviated up to 42%. A quadratic relation yielded estimates that depended less on weather. It reduced maximal deviations to +/-22%. Since Delta S-d additionally may represent the time pattern of the daily transpiration better than Q(d), analysing changes in the radius of stems may supplement or partly replace measurements of sap flow in stems.