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Mechanisms for the Development of Microform Patterns in Peatlands of the Hudson Bay Lowland
Ecosystems ( IF 3.7 ) Pub Date : 2019-09-23 , DOI: 10.1007/s10021-019-00436-z
Lorna I. Harris , Nigel T. Roulet , Tim R. Moore

Spatial surface patterns of hummocks, hollows, ridges, and pools (microtopography) are common features of many northern peatlands and are particularly distinct within the vast peatlands of the Hudson Bay Lowland (HBL), Canada. Hypotheses and models describe how small-scale feedbacks among vegetation, hydrology, and nutrients cause spatial differences in peat accumulation that enable microforms and surface patterns to develop over time. Empirical tests of the predictions from theoretical models of these proposed feedback mechanisms are limited, particularly in large peatland complexes such as the HBL. We investigate feedbacks controlling peatland structure and function in an ombrogenous bog and a minerogenous fen in the HBL. Our sites represent surface patterns found in many northern peatlands, specifically spatially irregular hummocks and hollows, and parallel ridges and pools that are perpendicular to slope. We found the occurrence of different spatial patterns depends on position within a peat landform, with these differences attributed to the ecohydrological setting. In turn, the ecohydrological setting, with different water table depths, nutrient availability, and species composition, influences the strength and direction of feedback mechanisms at the microform scale. Our data support the prediction of a positive feedback between plant productivity and acrotelm thickness for peat accumulation and hummock growth and that this may be enhanced by water ponding on slopes to form ridge–pool tracks. We did not find evidence to support the proposed feedback among evapotranspiration-driven transport of water and nutrients for the development of hummocks. Our results suggest a combination of mechanisms operating at various temporal and spatial scales is associated with the development of surface patterns in northern peatlands.



中文翻译:

哈德逊湾低地泥炭地微形图案发育的机理

山岗,凹陷,山脊和水池(微观地形)的空间表面格局是许多北部泥炭地的共同特征,在加拿大哈德逊湾低地(HBL)的广阔泥炭地中尤为明显。假设和模型描述了植被,水文和养分之间的小规模反馈如何导致泥炭堆积的空间差异,从而使微缩形态和表面图案随时间发展。对这些提议的反馈机制的理论模型进行的预测预测的经验测试有限,特别是在大型泥炭地综合体(例如HBL)中。我们调查反馈的泥炭地结构和功能在HBL中的一个成虫沼泽和一个矿产中的反馈。我们的站点代表了在许多北部泥炭地中发现的表面模式,尤其是空间上不规则的山岗和凹陷,以及与坡度垂直的平行山脊和水池。我们发现不同的空间格局的发生取决于泥炭地貌的位置,这些差异归因于生态水文环境。反过来,具有不同地下水位深度,养分可利用性和物种组成的生态水文环境会影响微观形态尺度上反馈机制的强度和方向。我们的数据支持预测植物生产力与泥炭堆积和山岗生长的顶肢厚度之间的正反馈,并且可以通过在斜坡上积水以形成山脊-池径来增强。我们没有证据支持由蒸散驱动的水和养分的运输对山雀的发育提出的反馈意见。

更新日期:2019-09-23
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