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Over the past two decades, the existence of intact peatlands in lowland Amazonia has been demonstrated, including a vast area of potential peat-forming vegetation of around 43,617 km2 in the Pastaza-Marañón Foreland Basin (PMFB), in the Loreto Department of north-east Peru. Peat sampling and floristic assessments have revealed the presence of peat in four ecosystem types in the PMFB: palm swamps, peatland pole forests, open peatlands, and, more rarely, in seasonally flooded forests. However, recent field investigations and palynological studies show that temporal changes in vegetation in peatlands may have been driven by changes in the degree of flooding, suggesting greater complexity in the controls on peatland development and in the spatiotemporal relationships between ecosystems than current conceptual models allow. Here we present new high-resolution palynological, geochemical and radiocarbon data from an open peatland sampled in the PMFB near San Roque village on the Marañón river. Our study aims to: (1) reconstruct past vegetation changes; (2) investigate the interaction between the fluvial system and the peatland’s vegetation dynamics over time; (3) determine how patterns of ecological and fluvial change at San Roque compare with records from other peatland types in the wider PMFB. Downcore palynology on the dated SAR_T3_03_B peat core provides a vegetation record spanning the last 4,300 years documenting changes in ecological associations over time. Between 4,300 and 3,180 cal yr BP, prior to peat accumulation, our data shows pronounced fluvial influence with high amounts of inorganic material and pollen assemblages from taxa related to open water conditions. Since the beginning of peat accumulation around 3,180 Cal yr BP, palynological and geochemical data suggest conditions related to predominantly herbaceous communities. Core scanning micro-XRF provides proxy evidence for episodes of fluvially-derived minerogenic input during the period of peat accumulation (3,180–440 Cal yr BP). Simultaneous increases in flood-tolerant taxa (e.g. Symmeria paniculata, Alchornea sp., Myrtaceae) support the inference of intervals with increased frequency and depth of river flooding. From around 440 Cal yr BP, we infer the establishment of M. flexuosa palms linked to lower flooding, which persists today. Compared with other regional sequences, the San Roque record is distinctive because of this notable influence of flooding regime on the ecosystem, which impacted on the vegetation succession through changes in flood levels and nutrient inputs. The dynamics of the sediment-laden Marañón River therefore emerges as a major driver in vegetation change and trajectory of peatland development during the last four millennia.

The recently described peatlands of northern Peruvian Amazonia are relatively intact compared with peatlands elsewhere in the tropics. They make an important contribution to regional biodiversity and, by sequestering carbon, to climate change mitigation. Research to date has focused on their physical and biological aspects, but peatlands are not simply natural phenomena: they are used, valued and understood socially and culturally in profoundly different ways by different groups of people.This research project used an interdisciplinary participatory approach, working with peatland communities and stakeholders in Peru, to bring together the different perspectives needed to produce a comprehensive understanding which the natural sciences cannot achieve alone. The three central aims of the project were to 1) characterise the ecology and sociocultural values of the ecosystem types identified by local communities; 2) identify the strategies and challenges around community management of natural resources; and 3) identify opportunities for peatland conservation and maintenance of livelihoods. We worked with five peatland forest communities, three mestizo and two indigenous, in the Pastaza-Marañón Basin, which is the largest peat-forming area in lowland Peru. To address our aims we used a range of methods, both ecological (plot-based vegetation survey, measuring peat properties) and sociological (participatory mapping, interviews, focus groups).A key outcome of this work is a better understanding of the multifaceted importance of peatlands to local communities. The resources and spaces provided by peatland ecosystems were important culturally and socioeconomically to all five communities, but with pronounced differences relating to the communities’ different sociocultural and economic experiences and contexts. Another striking finding was that the nature of communities’ relationships with external actors, and their exposure to different opportunities and challenges, varied very markedly from one community to the next. For example, our study communities have experienced different interventions, some more successful and enduring than others, by government agencies and NGOs focusing mainly on biodiversity conservation; the success or otherwise of these past projects is likely to shape the willingness of communities to engage with future conservation efforts. Some communities have been more heavily influenced than others by the expansion of regional markets and value chains for timber and non-timber forest products into remote peatland areas over recent decades; other communities have been profoundly affected by activities of multinational extractive industries, including the oil industry and plantation agriculture.We conclude that future peatland conservation efforts and sustainable development projects in Peruvian Amazonia will need to recognize the significant variations from one community to the next in terms of the ways in which they use and value the peatlands, and in terms of their wider socio-economic and cultural contexts. Long-term protection of the peatlands will only be possible by engaging with communities individually, taking into account the concerns, needs, desires, threats, and opportunities particular to each one.