Wetland chronosequence as a model of peatland development: Vegetation succession, peat and carbon accumulation

Abstract

Model validation experiments are fundamental to ensure that the peat growth models correspond with the diversity in nature. We evaluated the Holocene Peatland Model (HPM) simulation against the field observations from a chronosequence of peatlands and peat core data. The ongoing primary peatland formation on the isostatically rising coast of Finland offered us an exceptional opportunity to study the peatland succession along a spatial continuum and to compare it with the past succession revealed by vertical peat sequences. The current vegetation assemblages, from the seashore to a 3000 year old bog, formed a continuum from minerotrophic to ombrotrophic plant communities. A similar sequence of plant communities was found in the palaeovegetation. The distribution of plant functional types was related to peat thickness and water-table depth (WTD) supporting the assumptions in HPM, though there were some differences between the field data and HPM. Palaeobotanical evidence from the oldest site showed a rapid fen–bog transition, indicated by a coincidental decrease in minerotrophic plant functional types and an increase in ombrotrophic plant functional types. The long-term mean rate of carbon (C) accumulation varied from 2 to 34 g C/m2 per yr, being highest in the intermediate age cohorts. Mean nitrogen (N) accumulation varied from 0.1 to 3.9 g N/m2 per yr being highest in the youngest sites. WTD was the deepest in the oldest sites and its variation there was temporally the least but spatially the highest. Evaluation of the HPM simulations against the field observations indicated that HPM reasonably well simulates peatland development, except for very young peatlands.

Lateral expansion and carbon exchange of a boreal peatland in Finland resulting in 7000 years of positive radiative forcing

“…By ~8500 cal B.P., the initial rich fen was replaced by poor fen, dominated by E. vaginatum (Figure ). This phase commonly precedes ombrotrophication [ Hughes and Barber , ; Tuittila et al , ; Väliranta et al , ]. By 2500 years (following initiation) the peatland had covered an area of 0.15 km 2 (Figure a).…”

“…In general, long‐term vertical peat accumulation results in a successional change where hydrological conditions and vegetation structure change over the course of time [ Hughes , ; Tuittila et al , ]. In Finland, early stage peatlands are predominantly characterized by sedge‐dominated fen vegetation, high CH 4 emissions [ Leppälä et al , ], and relatively slow C accumulation rates [ Tolonen and Turunen , ].…”

Carbon storage and potential methane production in the Hudson Bay Lowlands since mid-Holocene peat initiation

“…Since this time, land has been emerging from the Hudson and James Bays at GIA rates that are among the fastest globally [4][5][6] . Today, a nearly continuous peat cover over low relief deposits of glacio-marine sediments 7 stretches from the shoreline of Hudson and James Bays inland to the margin of the upland Precambrian Shield.…”

Towards Developing a Functional-Based Approach for Constructed Peatlands Evaluation in the Alberta Oil Sands Region, Canada

“…NPP is a function of the photosynthetic efficiency of plants (Fig. 3), therefore varies among different peatland PFTs (Laine et al 2012;Tuittila et al 2013). A study of peatland NPP suggests that among the PFTs present during northern peatland succession, minerotrophic sedges have the highest NPP, while ombrotrophic forbs have the lowest (Frolking et al 2010).…”

“…Thus, a continuous increase in catotelm peat thickness gradually isolates the acrotelm from the minerotrophic groundwater, resulting in ombrotrophic (nutrient-poor) conditions (Vitt 2006). The appearance of Sphagnum mosses is a floristic indicator of ombrotrophy, a final stage in peatland succession (Mitsch and Gosselink 2000;Tuittila et al 2013). Ombrotrophication is biogeochemically associated with reduced mineralization rates and NPP (Bayley et al 2005), lower CH 4 and N 2 O emission, with CO 2 being the major GHG (Martikainen 1996;Regina et al 1996), and high acidity and production of allelochemical that slows the rate of nutrient cycling (Bradley et al 2008).…”