The ecohydrological and biochemical processes responsible for the globally significant stores of carbon in northern peatlands are largely controlled by the soil’s hydrophysical properties, in particular the relationship that soil water tension (ψ) has with soil water content (θ) and hydraulic conductivity (K). Despite the importance, little is known about how these relationships vary between species in different physiological Sphagnum microforms, such a hummock and hollow, as well as with depth within a profile. Complicating matters is that laboratory experiments to determine these relationships are almost always completed with 5 cm high samples, despite no real scientific evidence supporting this height. To address these shortcomings, we sampled 8 replicates/samples (moss surface to 15 cm depth) each from a S. magellanicum hollow and a S. fuscum hummock. We determined the K(ψ) and θ(ψ) relationships at various pressure heads (0 to –32 cm) and then sub-sectioned the 15-cm samples into 3x5-cm (top, middle, bottom) samples and repeated the tests. There were important differences in both K(ψ) and θ(ψ) relationships between the top, middle and bottom samples. Additionally, comparison of the average of the 3x5-cm samples versus the 15-cm samples suggested that the 15-cm samples were not a good representation due to not being fully compatible with the methodology, and that 3x5-cm samples were preferred. Using Hydrus-1D to simulate a 30-day drought period with local hydroclimatological data, we assessed whether the statistically significant differences were ecohydrologically significant when accounting for the different topographic niches of the two species. The different moss species responded differently, with S. fuscum becoming more water stressed than S. magellanicum, yet S. fuscum lost less water from soil water storage than S. magellanicum. This highlighted the critically important need to replicate the species’ niche in the landscape, and not give two distinct species the same hydrological modelling boundary conditions to compare results.

导致北部泥炭地全球重要碳储存的生态水文和生物化学过程在很大程度上受土壤水物理特性的控制，特别是土壤水分张力 ( ψ ) 与土壤含水量 ( θ ) 和水力传导率 ( K ) 的关系. 尽管很重要，但人们对这些关系如何在不同生理学泥炭藓中的物种之间变化知之甚少。缩微，如小丘和空心，以及轮廓内的深度。复杂的是，确定这些关系的实验室实验几乎总是用 5 厘米高的样品完成，尽管没有真正的科学证据支持这个高度。为了解决这些缺点，我们从S. magellanicum空心和S. fuscum小丘上采样了 8 个重复/样品（苔藓表面至 15 厘米深度）。我们确定了各种压头（0 到 –32 厘米）下的K ( ψ ) 和θ ( ψ ) 关系，然后将 15 厘米样品分成 3x5 厘米（顶部、中部、底部）样品并重复测试. 有两个重要的区别ķ( ψ ) 和θ ( ψ ) 顶部、中间和底部样本之间的关系。此外，将 3x5-cm 样品与 15-cm 样品的平均值进行比较表明，15-cm 样品由于与该方法不完全兼容而不是一个很好的代表，而 3x5-cm 样品是首选。使用 Hydrus-1D 以当地水文气候数据模拟 30 天干旱期，我们评估了在考虑两个物种的不同地形生态位时，统计学上的显着差异是否具有生态水文意义。不同的苔藓物种的反应不同，S. fuscum比S. magellanicum 对水分的压力更大，然而S. fuscum从土壤蓄水中流失的水分比S. magellanicum 少。这突出了在景观中复制物种生态位的至关重要的需求，而不是为两个不同的物种提供相同的水文建模边界条件来比较结果。