Am J Bot. 1998 Apr;85(4):592.
Eriophorum vaginatum and E. angustifolium are dominant arctic sedges of the well-drained tussock tundra and the permanently flooded wet-sedge tundra, respectively. We determined diurnal courses of gas exchange and water relations of the two species in their natural habitat and compared their responses to changes in light, air temperature, and humidity. Mean photosynthetic response to light was similar between E. angustifolium and E. vaginatum and carbon gain in both species was light limited during most of the growing season. On sunny and dry days, both species closed stomata in response to high leaf-to-air vapor pressure deficits. Even though E. angustifolium was growing in standing water, it exhibited a tighter control of transpirational water loss and had lower hydraulic conductivity in the soil-root-shoot pathway than E. vaginatum. The different response pattern between the two species is discussed in the context of differences in habitat conditions.
羊胡子草和窄叶羊胡子草分别是排水良好的丘状冻原和永久性积水湿地冻原的优势北极苔草。我们在其自然栖息地测定了这两个物种的气体交换和水分关系的昼夜过程，并比较了它们对光照、空气温度和湿度变化的响应。羊胡子草和窄叶羊胡子草的平均光合响应相似，在生长季节的大部分时间里，两种物种的碳增益都受到光照限制。在阳光明媚和干燥的日子里，两种物种都会因叶片与空气之间的蒸汽压差过高而关闭气孔。尽管窄叶羊胡子草生长在静止的水中，但它对蒸腾水损失的控制更为严格，在土壤-根-茎途径中的水力传导率也低于羊胡子草。在生境条件的差异背景下，讨论了这两个物种之间不同的响应模式。
