Smith W K, Geller G N
Botany Department, University of Wyoming, 82071, Laramie, WY, USA.
Oecologia. 1980 Sep;46(3):308-313. doi: 10.1007/BF00346257.
The influence of variations in the boundary air layer thickness on transpirtion due to changes in leaf dimension or wind speed was evaluated at a given stomatal resistance (r ) for various combinations of air temperature (T ) and total absorbed solar energy expressed as a fraction of full sunlight (S ). Predicted transpiration was found to either increase or decrease for increases in leaf size depending on specific combinations of T , S , and r . Major reductions in simulated transpiration with increasing leaf size occurred for shaded, highly reflective, or specially oriented leaves (S =0.1) at relatively high T when r was below a critical value of near 500 s m. Increases in S and decreases in T lowered this critical resistance to below 50 s m for S =0.7 and T =20°C. In contrast, when r was above this critical value, an increase in leaf dimension (or less wind) resulted in increases in transpiration, especially at high T and S . For several combinations of T , S , and r , transpiration was minimal for a specific leaf size. These theoretical results were compared to field measurements on common desert, alpine, and subalpine plants to evaluate the possible interactions of leaf and environmental parameters that may serve to reduce transpiration in xeric habitats.
在给定的气孔阻力（r）下，针对不同的气温（T）组合以及以全日照比例表示的总吸收太阳能（S），评估了边界空气层厚度变化对因叶片尺寸或风速变化而产生的蒸腾作用的影响。结果发现，根据T、S和r的特定组合，随着叶片尺寸的增加，预测的蒸腾作用可能会增加或减少。当r低于约500 s/m的临界值时，对于遮荫、高反射或特殊取向的叶片（S = 0.1），在相对较高的T下，随着叶片尺寸增加，模拟蒸腾作用会大幅降低。对于S = 0.7和T = 20°C，S的增加和T的降低将该临界阻力降低至50 s/m以下。相反，当r高于该临界值时，叶片尺寸增加（或风速降低）会导致蒸腾作用增加，尤其是在高T和S时。对于T、S和r的几种组合，特定叶片尺寸下的蒸腾作用最小。将这些理论结果与常见沙漠、高山和亚高山植物的田间测量结果进行比较，以评估叶片和环境参数之间可能的相互作用，这些相互作用可能有助于减少旱生栖息地的蒸腾作用。
