Palaeoecological data of KTG core, Katingan, Central Kalimantan, Borneo, Indonesia

Southeast Asian peatlands, along with their various important ecosystem
services, are mainly distributed in the coastal areas of Sumatra and
Borneo. These ecosystems are threatened by coastal development, global
warming and sea level rise (SLR). Despite receiving growing attention for
their biodiversity and as massive carbon stores, there is still a lack of
knowledge on how they initiated and evolved over time, and how they
responded to past environmental change, i.e., precipitation, sea level and
early anthropogenic activities. To improve our understanding thereof, we
conducted multi-proxy palaeoecological studies in the Kampar Peninsula and
Katingan peatlands in the coastal area of Riau and Central Kalimantan,
Indonesia. The results indicate that the initiation timing and environment
of both peatlands are very distinct, suggesting that peat could form under
various vegetation as soon as there is sufficient moisture to limit
organic matter decomposition. The past dynamics of both peatlands were
mainly attributable to natural drivers, while anthropogenic activities
were hardly relevant. Changes in precipitation and sea level led to shifts
in peat swamp forest vegetation, peat accumulation rates, and fire regimes
at both sites. We infer that the simultaneous occurrence of El
Niño-Southern Oscillation (ENSO) events and SLR resulted in synergistic
effects which led to the occurrenceere fires in a pristine coastal
peatland ecosystem, however, it did not interrupt peat accretion. In the
future, SLR, combined with the projected increase in frequency and
intensity of ENSO, can potentially amplify the negative effects of
anthropogenic peatland fires. This prospectively stimulates massive carbon
release, thus could, in turn, contribute to worsening the global climate
crisis especially once an as yet unknown threshold is crossed and peat
accretion is halted, i.e., peatlands lose their carbon sink function.
Given the current rapid SLR, coastal peatland managements should start
develop fire risk reduction or mitigation strategies.