Rates and spatial variability of peat subsidence in Acacia plantation and forest landscapes in Sumatra, Indonesia

Evans, Chris; Williamson, Jennifer; Kacaribu, Febrio; Irawan, Denny; Suardiwerianto, Yogi; Hidayat, Muhammad Fikky; Laurén, Ari; Page, Susan

doi:10.1016/j.geoderma.2018.12.028

Cited by 110 publications

(155 citation statements)

References 46 publications

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“…The simulated annual CO 2 emissions of section 3.3 are within the range of the values in the literature for peatlands in the same region Evans et al, 2019). Relatively speaking, building 80 blocks to the whole 931 km 2 area mitigates only 2.24% of the CO 2 emissions.…”

Section: Implication To Co 2 Emissions 380supporting

confidence: 74%

“…Figure 9). However, the simulated daily WTD of Figure 10 are in the same range and show similar dynamics as those reported earlier for drained peatlands in similar areas Hooijer et al, 2012;Evans et al, 2019), and for natural peatland forests in Great Sunda islands (Cobb et al, 2017;Evans et al, 2019). Thus, we assume that WTD in Figure 10 and the consecutive CO 2 emissions, discussed in section 4.3, are plausible.…”

supporting

confidence: 82%

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Canal blocking optimization in restoration of drained peatlands

Urzainki¹,

Laurén²,

Palviainen³

et al. 2020

Preprint

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Abstract. Drained peatlands are one of the main sources of carbon dioxide (CO2) emissions globally. Emission reduction and, more generally, ecosystem restoration can be achieved by raising the water table using canal or drain blocks. When restoring large areas, the number of blocks becomes limited by the available resources, which raises the following question: in which exact positions should a given number of blocks be placed in order to maximize the water table raise throughout the area? There is neither a simple nor an analytic answer. The water table response is a complex phenomenon that depends on several factors, such as the topology of the canal network, site topography, peat hydraulic properties, vegetation characteristics and meteorological conditions. We developed a new method to position the canal blocks based on the combination of a hydrological model and heuristic optimization algorithms. We applied this approach to a large drained peatland area (931&#8201;km2) in Sumatra, Indonesia. Our solution consistently improved the performance of traditional block locating methods, indicating that drained peatland restoration can be made more effective at the same cost by selecting the positions of the blocks using the presented scheme.

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Section: Implication To Co 2 Emissions 380supporting

confidence: 74%

supporting

confidence: 82%

Canal blocking optimization in restoration of drained peatlands

Urzainki¹,

Laurén²,

Palviainen³

et al. 2020

Preprint

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“…The surface peat pH is 3.4 ± 0.1. GWLs in plantation are actively managed to support the required level of productive growth via an extensive network of topographically defined water management zones, controlled by outlet sluices, and supported by large‐scale and continuous rainfall and water level monitoring (Evans et al, ). Water management zones comprise of ditches and canals (also used for transportation).…”

Section: Methodsmentioning

confidence: 99%

Impact of forest plantation on methane emissions from tropical peatland

Deshmukh¹,

Julius²,

Evans

et al. 2020

Global Change Biology

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Tropical peatlands are a known source of methane (CH4) to the atmosphere, but their contribution to atmospheric CH4 is poorly constrained. Since the 1980s, extensive areas of the peatlands in Southeast Asia have experienced land‐cover change to smallholder agriculture and forest plantations. This land‐cover change generally involves lowering of groundwater level (GWL), as well as modification of vegetation type, both of which potentially influence CH4 emissions. We measured CH4 exchanges at the landscape scale using eddy covariance towers over two land‐cover types in tropical peatland in Sumatra, Indonesia: (a) a natural forest and (b) an Acacia crassicarpa plantation. Annual CH4 exchanges over the natural forest (9.1 ± 0.9 g CH4 m−2 year−1) were around twice as high as those of the Acacia plantation (4.7 ± 1.5 g CH4 m−2 year−1). Results highlight that tropical peatlands are significant CH4 sources, and probably have a greater impact on global atmospheric CH4 concentrations than previously thought. Observations showed a clear diurnal variation in CH4 exchange over the natural forest where the GWL was higher than 40 cm below the ground surface. The diurnal variation in CH4 exchanges was strongly correlated with associated changes in the canopy conductance to water vapor, photosynthetic photon flux density, vapor pressure deficit, and air temperature. The absence of a comparable diurnal pattern in CH4 exchange over the Acacia plantation may be the result of the GWL being consistently below the root zone. Our results, which are among the first eddy covariance CH4 exchange data reported for any tropical peatland, should help to reduce the uncertainty in the estimation of CH4 emissions from a globally important ecosystem, provide a more complete estimate of the impact of land‐cover change on tropical peat, and develop science‐based peatland management practices that help to minimize greenhouse gas emissions.

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“…Drainage creates an aerated upper soil layer which increases soil respiration by enabling microbes to decompose the peat (Astiani et al, 2017). A study summarizing data from pulp and paper plantations reports subsidence rates of 4.3 cm/year in plantations of Acacia grown on drained tropical peat swamps, due primarily to peat oxidation, and closely correlated with groundwater depth (Evans et al, 2019). Similarly, eddy covariance measurements have demonstrated that ecosystem‐level respiration depends greatly on groundwater depth (Hirano et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

“…Repeat lidar studies typically create a single DTM by combining point clouds or by selecting the higher density survey (Silva et al, 2017). We created separate DTMs because peat subsidence occurs in drained areas of the peat swamp, so the DTM varies with time in a complex way: a recent review has reported an average subsidence rates in drained peatlands of 4.3 cm/year (Evans et al, 2019), so the altitude of the DTM close to large canals could have fallen by roughly 13 cm between surveys, while regions with unaltered hydrology would have changed very little. Another reason for keeping the DTMs separate was a concern about a 170 cm vertical offset apparent between surveys.…”

Section: Methodsmentioning

confidence: 99%

Dynamics of a human‐modified tropical peat swamp forest revealed by repeat lidar surveys

Wedeux

Dalponte

Schlund

et al. 2020

Global Change Biology

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Tropical peat swamp forests (PSFs) are globally important carbon stores under threat. In Southeast Asia, 35% of peatlands had been drained and converted to plantations by 2010, and much of the remaining forest had been logged, contributing significantly to global carbon emissions. Yet, tropical forests have the capacity to regain biomass quickly and forests on drained peatlands may grow faster in response to soil aeration, so the net effect of humans on forest biomass remains poorly understood. In this study, two lidar surveys (made in 2011 and 2014) are compared to map forest biomass dynamics across 96 km2 of PSF in Kalimantan, Indonesia. The peatland is now legally protected for conservation, but large expanses were logged under concessions until 1998 and illegal logging continues in accessible portions. It was hypothesized that historically logged areas would be recovering biomass while recently logged areas would be losing biomass. We found that historically logged forests were recovering biomass near old canals and railways used by the concessions. Lidar detected substantial illegal logging activity—579 km of logging canals were located beneath the canopy. Some patches close to these canals have been logged in the 2011–2104 period (i.e. substantial biomass loss) but, on aggregate, these illegally logged regions were also recovering. Unexpectedly, rapid growth was also observed in intact forest that had not been logged and was over a kilometre from the nearest known canal, perhaps in response to greater aeration of surface peat. Comparing these results with flux measurements taken at other nearby sites, we find that carbon sequestration in above‐ground biomass may have offset roughly half the carbon efflux from peat oxidation. This study demonstrates the power of repeat lidar survey to map fine‐scale forest dynamics in remote areas, revealing previously unrecognized impacts of anthropogenic global change.

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Rates and spatial variability of peat subsidence in Acacia plantation and forest landscapes in Sumatra, Indonesia

Cited by 110 publications

References 46 publications

Canal blocking optimization in restoration of drained peatlands

Canal blocking optimization in restoration of drained peatlands

Impact of forest plantation on methane emissions from tropical peatland

Dynamics of a human‐modified tropical peat swamp forest revealed by repeat lidar surveys

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