Effect of canal blocking on biodiversity of degraded peatlands: Insight from West Kalimantan

PLOS One | https://doi.org/10.1371/journal.pone.0334014 October 8, 2025 2 / 23 greenhouse gas (GHG) sequestration; thus, climate change mitigation [3]. However, due to the large scale of disturbances in peatland areas such as logging, forest clear- ance, and industrial plantations, instead of yielding benefits, peatlands may generate catastrophes. Converting peatlands into cultivation by draining peat water through canal building and clearing the land using the burning method, as well as logging, can lead to more carbon emissions, increased wildfire regimes, severe health prob- lems, and loss of biodiversity [4–11]. Tropical peatlands are unique and essential ecosystem holding many values towards human livelihoods and surrounding envi- ronments. The hydrological system allows peat water to be the source and supply of adjacent rivers and regulates the global and local water cycle, thus alleviating droughts and floods [12]. Indonesia holds 36% of the global area of peatland, with 485.6 ± 3.2 MtCO2e yr − 1 in carbon stocks [13,14]. However, many peatlands in Indonesia are threatened by land conversion, which also puts biodiversity throughout the tropics at risk [15,16]. In the Giam Siak Kecil-Bukit Batu Biosphere Reserve, the conversion of tropical peat- land into acacia and rubber plantations has resulted in lower bird diversity compared to natural peat forests [17]. Following a peat fire in Teluk Meranti, there has been a significant alteration and reduction in tree species diversity compared to the unburnt

forest [18]. In Kalimantan, the peatland fire of 2015 had repercussions on the behav- ior and survival rates of wildlife in both terrestrial and aquatic ecosystems [19]. Therefore, the impact of peatland degradation on biodiversity cannot be overlooked, especially considering recent long-term research findings and the increasing inter- est in biodiversity surveys which have revealed that tropical peatlands are home to diverse wildlife with few yet essential ecosystem endemic species [9,20–25]. With increasing global awareness of the importance of natural systems contribu- tions to the global climate crisis, the peatland crisis has gained much attention not only from scientists but also from the government [26,27]. In response to the dam- aging 2015 peatland fires across Indonesia, the Indonesian government showed its commitment to peatland restoration by establishing the Peatland Restoration Agency in 2016 (now known as Badan Restorasi Gambut dan Mangrove), mandated to accelerate peatland restoration. Several programs have been conducted to restore the degraded peatland, primarily through rewetting by raising groundwater levels, revegetation by establishing vegetation cover, and revitalization by empowering local communities through sustainable livelihood programs [28]. While the progress and outputs of rewetting, revegetation, and revitalization (e.g., groundwater level, vegeta- tion cover, seed survival, sustainable local businesses) are subjects of growing study, how biodiversity responds to these developments is still poorly understood [6,29–35].

However, given the pre-restoration disturbances, it is assumed that most wildlife species suffered due to scarce resources, isolation, or complete habitat loss [34,36]. Little research has been conducted on biodiversity in degraded peatlands and the research that exists is limited to just a few locations [25,37,38]. It is often assumed that survived or escaped wildlife will likely migrate back when the degraded habi- tat recovers [39–44]. In the long term, that returned wildlife could help restoration programs in peatlands by acting as seed dispersal and taking part in nutrient flux, Conservancy The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist.