The Spatial Heterogeneity of Vegetation, Hydrology and Water Chemistry in a Peatland with Open-Water Pools
Ombrotrophic bogs can comprise a mosaic of vegetation patches and open-water pools, with hydrological and biogeochemical connections between pools and the surrounding peat and vegetation. To establish these connections, we studied the spatial heterogeneity of hydrology and water chemistry in two zones of distinct vegetation assemblages in the subboreal Grande plée Bleue peatland, southern Québec, Canada. We show that seasonal water-level fluctuations are greater and organic C, N and P concentrations are higher in the peat pore water of a forested zone than in a neighboring open-bog zone; that vegetation is responsible for 69% of the spatial variations in hydrology and water chemistry. Vegetation also explains 31% of the temporal variation in water chemistry, with higher increases in C, N and P concentrations over the growing season in the forested peat and pools than in the open-bog zone. We also show that C, N and P concentrations and water-level fluctuations in pools, especially during precipitation events, were lower than in the surrounding peat. Our results suggest the existence of small “watersheds” to the pools with water flowing in during wet and out during dry periods. Localized patterns emerge from the vegetation–hydrology–water chemistry interactions, with pools influencing the persistence of trees in the central part of an ombrotrophic bog.
KeywordsPeatland Spatial Heterogeneity Vegetation Hydrology Water Chemistry Carbon Nitrogen Phosphorus
We would like to thank Jules Regard, Zeinab Khanafer, Jordan Paillard, Andy Hennebelle, Evrard Kouadio, Philippe Major, Mike Dalva and Hélène Lalande for their help in the field and in laboratory analysis. We also thank the Société de gestion et de mise en valeur de la Grande plée Bleue for granting access to the study site. The research was funded through a Fonds de recherche du Québec—Nature et Technologies (FRQNT) grant to JT.
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