Insights for Restoration: Reconstructing the Long-Term Responses and Resilience of Vegetation, Hydrology and Peat Conditions to Fire Events in a Tropical Peatland in Central Kalimantan

Fire events in tropical peatlands often relate to dry peat conditions associated with climate variability (drought) and anthropogenic-driven ecosystem degradation. However, drought is not the only driver of long-term fire events and peatland ecosystem changes. This study used palaeoecological and geochemical proxies to investigate the long-term drivers in fire severity (FS) and the associated responses of the peatland ecosystems in Central Kalimantan, Indonesia. The results showed FS has increased from ~2300 cal. yr BP to present, and possible drivers include changes in sea level, increased frequency of El Niño events, increased biomass, and anthropogenically-driven ecosystem degradation. In response, the vegetation composition changed from a mix of peat swamp forest (PSF) and open vegetation (OV) during the late Holocene (2284 to 1129 cal. yr BP), to predominantly PSF from 1128 to 375 cal. yr BP, dry lowland mixed with swamp forest (LMS) and open vegetation (OV) from 374 to 135 cal. yr BP, and predominantly OV and freshwater swamp forest (FSF) from 134 to -62 cal. yr BP. The possible drivers of the vegetation turnover were hydrological conditions and the availability of peat nutrients, while the responses of vegetation turnover affected the accumulation and decomposition of recalcitrant organic matter in peat. The resilience of the peatland ecosystems over longer-term timeframes provided the following restoration insights: 1) PSF species (i.e. Eurya and Ilex) were resilient to high FS (charcoal influx in peat) tolerances of up to ~23 mm2cm-3yr-1 while LMS and OV species increased at lower FS threshold of ~13 mm2cm-3yr-1; 2) PSF species expanded during periods of wet conditions and high peat nutrients (i.e. TN- enriched); and 3) Future revegetation in the region can focus on tree taxa such as Euphorbiaceae, Apocynaceae plumeria, Arenga, Ficus, and Trema as they were historically able to thrive in high FS and dry hydrological conditions.