Paludification is the most common process of peatland formation in boreal regions. In this study, we investigated the autogenic (e.g., topography) and allogenic (fire and climate) factors triggering paludification in different geomorphological contexts (glaciolacustrine silty-clayey and fluvioglacial deposits) within the Québec black spruce (Picea mariana)–moss boreal forest. Paleoecological analyses were conducted along three toposequences varying from a forest on mineral soil to forested and semi-open peatlands. Plant macrofossil and charcoal analyses were performed on basal peat sections (≤50 cm) and thick forest humus (<40 cm) to reconstruct local vegetation dynamics and fire history involved in the paludification process. Results show that primary paludification started in small topographic depressions after land emergence ca. 8000 cal yr BP within rich fens. Lateral peatland expansion and secondary paludification into adjacent forests occurred between ca. 5100 and 2300 cal yr BP and resulted from low-severity fires during a climatic deterioration. Fires that reduced or eliminated entirely the organic layer promoted the establishment of Sphagnum in microdepressions. Paludification resulted in the decline of some coniferous species such as Abies balsamea and Pinus banksiana. The paleoecological approach along toposequences allowed us to understand the spatiotemporal dynamics of paludification and its impacts on the vegetation dynamics over the Holocene.

In the Monnikenberg estate, built in the mid-19th century in a Pleistocene coversand area to the south of Hilversum (the Netherlands), a depression with a small man-made mire was found to contain the remains of a complex peaty fill of a larger mire. Microfossil study and radiocarbon dating showed that its development started at the beginning of the third millennium BC through water stagnation on a podzol in combination with a high groundwater level, and about two millennia ago the vegetation had progressed from a mesotrophic mire to an ombrotrophic bog. Such origin, development and age are in conformity with the results for some other recently studied mires in the Het Gooi region (Gijzenveen; Van Geel et al., 2016). In the Monnikenberg mire, a discrepancy was found between the radiocarbon age of the upper part of the peaty fill and its clearly medieval or younger age as evidenced by its microfossil content, notably the occurrence of pollen of buckwheat (Fagopyrum) and cornflower (Centaurea cyanus). These species were first introduced in the Netherlands during the late Middle Ages. From further observations in a large pit in the former border zone of the mire, it is concluded that this discrepancy and the unique sedimentary structures, observed in this pit, result from peat exploitation and contemporary reworking of its sandy overburden during the Late Middle Ages or Early Modern Times. This is the first evidence for local early peat exploitation for such mires in Het Gooi. The results underpin the importance of microfossil analyses for proper interpretation of radiocarbon data, when studying mire fills. Additionally, they provide further proof for the development of podzols and ericaceous vegetation prior to and independent of early prehistoric agriculture in the Dutch Pleistocene coversand areas, and for the early (pre-medieval) start of wind erosion and deposition of drift sands.

Macrofossil analyses were used to reconstruct long-term vegetation successions within ombrotrophic peatlands (bogs) from the northern shorelines of the St. Lawrence Estuary (Baie-Comeau) and the Gulf of St. Lawrence (Havre-St-Pierre). Over the Holocene, the timing and the ecological context of peatland inception were similar in both regions and were mainly influenced by fluctuations in relative sea level. Peat accumulation started over deltaic sands after the withdrawal of the Goldthwait Sea from 7500 cal yr BP and above silt–clay deposits left by the Laurentian marine transgression after 4200 cal yr BP. In each region, the early vegetation communities were similar within these two edaphic contexts where poor fens with Cyperaceae and eastern larch (Larix laricina) established after land emergence. The rapid transitions to ombrotrophy in the peatlands of Baie-Comeau are associated with particularly high rates of peat accumulation during the early developmental stage. The results suggest that climate was more propitious to Sphagnum growth after land emergence in the Baie-Comeau area. Macrofossil data show that treeless Sphagnum-dominated bogs have persisted over millennia and that fires had few impacts on the vegetation dynamics. This study provides insight into peatland vegetation responses to climate in a poorly documented region of northeastern America.

A 7000-year record of local fire history was reconstructed from three ombrotrophic peatlands in the James Bay lowlands (northwestern Québec, Canada) using a high-resolution analysis of macroscopic charcoal (long axis≥0.5 mm). The impact of fire on vegetation changes was evaluated using detailed analysis of plant macrofossils. Compared to upland boreal forest, fire incidence in these Sphagnum-dominated bogs is rather low. Past fire occurrence seems to have been controlled primarily by internal processes associated with local hydroseral succession. Size of the peatland basin and distance from the well-drained forest soils also appear to be factors controlling fire occurrence. The impact of peatland fires on long-term vegetation succession appears negligible except in a forested bog, where it initiated the replacement of Sphagnum by mosses. In some circumstances, fire caused marked changes in the bryophyte assemblages over many decades. However, ombrotrophic peatland vegetation is generally resilient to surface fire.

We studied a Holocene peat fill of a small depression in Pleistocene coversand, in the western border zone of Het Gooi, to assess the early local and regional vegetation history in relation to sea-level rise, soil development and potential human impact. In the fourth millenium BC, a podzol which had formed in the depression became stagnative, leading to the development of a moorland pool. The local vegetation changed from dry heathland, through an amphibic vegetation type with, among others, Littorella uniflora and Lycopodiella inundata, to a permanently moist Sphagnum-dominated vegetation. The existence of moorland pools and the development of such habitats into Sphagnum-dominated vegetation are known from Late-Holocene anthropogenic, more or less open landscapes that were formed on a podzolising sandy soil under ericaceous vegetation. However, the recorded vegetation succession did not show any recognisable local human impact and therefore is attributed to natural succession. In the period concerned, sea level was still about 4 m below the land surface in the depression, implying that water logging occurred independent from a rise in sea level and associated groundwater level. It took until the Late Middle Ages before such rise led to significant water logging and peat growth in this border zone, but the mean groundwater level never reached to above NAP (Dutch Ordnance Datum).

This paper examines the floristic changes that occur following human disturbance in mid-montane forest in the Wau area in Papua New Guinea. The study was restricted to a 1600–2400 m altitudinal range on Mt Kaindi, with disturbed forest, and Mt Missim, with undisturbed forest. Special attention was given to the status of Nothofagus pullei which is locally dominant on Mt Kaindi.

A major change in floristic composition was observed between 1800 and 2000 m. The abundance and species composition of ferns and mosses above 2000 m characterizes the floristic differences. Nothofagus pullei was found to be a pioneer species with a long life-span, one which does not regenerate under its own cover. There were no other important floristic differences between Notho-fagus-dominated forest and mixed mid-montane forest. Nothofagus pullei locally dominates the canopy and thereby suppresses the growth of other trees.