Regional and local patterns in depth to water table, hydrochemistry and peat properties of bogs and their laggs in coastal British Columbia

Abstract

Abstract. In restoration planning for damaged raised bogs, the lagg at the bog margin is often not given considerable weight and is sometimes disregarded entirely. However, the lagg is critical for the proper functioning of the bog, as it supports the water mound in the bog. In order to include the lagg in a restoration plan for a raised bog, it is necessary to understand the hydrological characteristics and functions of this rarely studied transition zone. We studied 13 coastal British Columbia (BC) bogs and identified two different gradients in depth to water table, hydrochemistry and peat properties: (1) a local bog expanse-bog margin gradient, and (2) a regional gradient related to climate and proximity to the ocean. Depth to water table generally increased across the transition from bog expanse to bog margin. In the bog expanse, pH was above 4.2 in the Pacific Oceanic wetland region (cooler and wetter climate) and below 4.3 in the Pacific Temperate wetland region (warmer and drier climate). Both pH and pH-corrected electrical conductivity increased significantly across the transition from bog expanse to bog margin, though not in all cases. Na + and Mg 2+ concentrations were generally highest in exposed, oceanic bogs and lower in inland bogs. Ash content in peat samples increased across the bog expanse-bog margin transition, and appears to be a useful abiotic indicator of the location of the bog margin. The observed variation in the hydrological and hydrochemical gradients across the bog expanse-bog margin transition highlights both local and regional diversity of bogs and their associated laggs.

Net Ecosystem Carbon Balance of a Peat Bog Undergoing Restoration: Integrating CO2 and CH4 Fluxes From Eddy Covariance and Aquatic Evasion With DOC Drainage Fluxes

“…The peat deposits vary in thickness and degree of decomposition within the bog. At the center of the bog, the peat thickness varies from 4 to 7 m, although there have been reports of depths up to 9 m (Hebda et al, ; Howie & van Meerveld, ). At the periphery, the peat is only 1 m thick (Hebda et al, ).…”

“…The current study explores the C balance of a raised dome peat bog ecosystem near Vancouver, Canada, that is undergoing restoration via ditch blocking to elevate the water table level (Howie et al, ; Howie & van Meerveld, ). Using measurements of (i) ecosystem‐scale fluxes of CO 2 and CH 4 determined by EC, (ii) evasion fluxes of CO 2 and CH 4 from the open water surface determined by headspace equilibration, and (iii) DOC fluxes (fDOCs) in water draining from the study site, we sought to evaluate the following aspects regarding C dynamics in the peatland system: (1) the seasonal dynamics of C fluxes and the annual C budget, (2) the significance of open water contribution to the ecosystem‐scale CO 2 and CH 4 fluxes, and (3) the contribution of DOC drainage flux to the NECB budget at annual and seasonal scales.…”

Classification of vegetative lagg types and hydrogeomorphic lagg forms in bogs of coastal British Columbia, Canada

“…EC values were compensated for H + concentrations using: EC corr = EC measured – EC H + , where EC H + = 3.49 × 10 5 x 10 ‐pH and 3.49 × 10 5 is the conversion factor for field measurements standardized to 25° C (Rydin and Jeglum ). Since concentrations in major cations tend to increase from the bog to the mineral forest (Bragazza et al ; Richardson et al ; Howie and van Meerveld ) and may reflect the relative influence of water from the mineral forest surrounding the bog in the lagg, water samples were collected from the LG piezometers using a low‐flow peristaltic pump and analyzed at the Pacific Environmental Science Centre in North Vancouver, BC, for Ca 2+ , Mg 2+ , and Na + concentrations using inductively coupled plasma spectrometry. Peat samples were collected at 0.10, 0.50, and 1.00 m below the surface at the LG piezometers and analyzed in the laboratory for ash content.…”

“…The concept of a hydrological protection zone for bogs has also been adopted in the United Kingdom (UK) (Morgan‐Jones et al ) and The Netherlands (Schouwenaars ; Tomassen et al ). In order to delineate the extent of an HPZ or lagg in the field, an understanding of the plant communities, hydrochemistry, and peat properties of different laggs in the region is important (Howie and van Meerveld ). A classification of laggs based on these parameters will improve our understanding of the variability in lagg types and assist land managers in making management decisions (e.g., hydrological restoration, delineation of HPZs, identification of plant communities for conservation).…”

Satellite Determination of Peatland Water Table Temporal Dynamics by Localizing Representative Pixels of A SWIR-Based Moisture Index

“…Larger scale topographical differences within peatlands can lead to differences in the amplitude of WTD fluctuations while remaining fluctuations well correlated. For example, a treeless central area may have a shallower WTD and lower amplitude of WTD fluctuations than the tree margins, where the deepest WTD and highest amplitudes are observed [27,40,41].…”