Ecohydrological feedbacks in peatlands: an empirical test of the relationship among vegetation, microtopography and water table

Abstract

AbstractCurrent models and theories of the formation and maintenance of microtopography in ombrotrophic peatlands (bogs) assume autogenic feedbacks between vegetation composition, water table depth (WTD) and microtopography. A hypothesized outcome of autogenic feedbacks is a strong association among spatial variations in vegetation composition, WTD and microtopography. We tested and corroborated this hypothesis using fine spatial scale (<2 × 2 m2) data from two 20 × 20 m2 plots at Mer Bleue, a temperate bog. Furthermore, we partitioned the spatial variation of plant communities into portions explained by WTD as well as fine‐scale and broad‐scale spatial structures using distance‐based Moran's eigenvector maps. We hypothesized that plant distributions are more strongly related to WTD than to microtopography and found that this hypothesis was supported in only one of the two sampled plots, suggesting that the feedbacks among WTD, vegetation and microtopography could be dependent on location within a bog. A plot closer to the centre (apex) of the bog showed stronger relationships among WTD–microtopography and vegetation than a plot closer to the margin. Our results support current models and theories of the development of bogs wherein plant communities, water table and microtopography are strongly associated because of underlying ecohydrological feedbacks but highlight that strength and direction of feedbacks may vary by location within a bog. Affirming the presence of these structural relationships and identifying variability in them is a key step towards better understanding peatland carbon cycling, especially in the context of increasing anthropogenic and natural disturbances to peatlands. Copyright © 2016 John Wiley & Sons, Ltd.