Next Article in Journal
The Evaluation of Small- and Medium-Stream Carbon Pools in the Riparian Forests in Latvia
Previous Article in Journal
Chemical and Kraft Pulping Properties of Young Eucalypt Trees Affected by Physiological Disorders
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Forests
Volume 13
Issue 4
10.3390/f13040505
forests-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Rewetting Tropical Peatlands Reduced Net Greenhouse Gas Emissions in Riau Province, Indonesia

by
Iska Lestari
1,
Daniel Murdiyarso
1,2,* and
Muh Taufik
1
1
Department of Geophysics and Meteorology, Faculty of Mathematics and Natural Sciences, IPB University Campus Dramaga, Bogor 16680, Indonesia
2
Center for International Forestry Research, Jl. CIFOR, Situ Gede, Sindang Barang, Bogor 16115, Indonesia
*
Author to whom correspondence should be addressed.
Forests 2022, 13(4), 505; https://doi.org/10.3390/f13040505
Submission received: 15 January 2022 / Revised: 17 March 2022 / Accepted: 18 March 2022 / Published: 24 March 2022
(This article belongs to the Section Forest Meteorology and Climate Change)
Browse Figures
Review Reports Versions Notes

Abstract

:
Draining deforested tropical peat swamp forests (PSFs) converts greenhouse gas (GHG) sinks to sources and increases the likelihood of fire hazards. Rewetting deforested and drained PSFs before revegetation is expected to reverse this outcome. This study aims to quantify the GHG emissions of deforested PSFs that have been (a) reforested, (b) converted into oil palm, or (c) replanted with rubber. Before rewetting, heterotrophic soil respiration in reforested, oil palm, and rubber plantation areas were 48.91 ± 4.75 Mg CO2 ha−1 yr−1, 54.98 ± 1.53 Mg CO2 ha−1 yr−1, and 67.67 ± 2.13 Mg CO2 ha−1 yr−1, respectively. After rewetting, this decreased substantially by 21%, 36%, and 39%. Conversely, rewetting drained landscapes that used to be methane (CH4) sinks converted them into CH4 sources; almost twice as much methane was emitted after rewetting. Nitrous oxide (N2O) emissions tended to decrease; in nitrogen-rich rubber plantations, N2O emissions halved; in nitrogen-poor reforested areas, emissions reduced by up to a quarter after rewetting. Overall, rewetting reduced the net emissions up to 15.41 Mg CO2-eq ha−1 yr−1 (25%) in reforested, 18.36 Mg CO2-eq ha−1 yr−1 (18%) in oil palm, and 28.87 Mg CO2-eq ha−1 yr−1 (17%) in rubber plantation areas.

1. Introduction

Being carbon-rich reservoirs, peat swamp forests (PSFs) can shift from sequestering to emitting carbon, thus contributing to climate change. A net atmospheric carbon exchange of ~0.14 Gt C yr−1 is equal to ~1% of human-driven fossil fuel emissions or 3–10% of the current net sink for terrestrial natural ecosystems [1,2]. Tropical PSF, which accounts for 10% of the world’s peatland and stores around 50–350 Gt C [3,4], is therefore a major ecosystem in the world’s carbon budget.
With 15–21 Mha of PSF [5], Indonesia stores a large amount of carbon, around 57 Gt C [3]. However, peatland degradation in Indonesia, as a consequence of PSF conversion, is causing greenhouse gas (GHG) concentrations in the atmosphere to rise [6]. Previous studies showed that, over the last 25 years, as much as 427 Mg C ha−1 [7,8,9] has been released into the atmosphere due to peatland conversion. Other damaging consequences of peatland being converted for agriculture and export-orientated commodities like oil palm, pulp, and paper are a biodiversity loss [10], as well as drained peatland, due to lower groundwater levels (GWL) [11], which can lead to peat fires, especially during the dry season [12,13].
Being naturally waterlogged ecosystems, improving water management has been one of the most effective actions to halt further peatland degradation and GHG emissions. This also reduces fire hazards and creates conditions for restoring vegetation [14]. In recent years, increasing efforts have been made to restore the hydrological function of degraded peatlands by blocking and backfilling existing canals. This practice significantly reduces the outflow of surface runoff, increasing the GWL and storage capacity of degraded peatlands [15,16,17,18,19].
Extensive research on the impact of peatland drainage (following deforestation) and rewetting on GHG emissions have been conducted in Indonesia over the last decade. A range of methods have been used, from close chamber [20,21,22,23] to flux tower [24], for sample collection [20,21,22,23] and direct measurements [21,22,23,24]. These methods have enabled the assessment of total respiration [20,24], as well as the segregation of autotrophic and heterotrophic respiration [21,22,23].
Riau is one of the provinces prioritized for peatland restoration by the Indonesian Peatland Restoration Agency, which aimed to rewet and revegetate the landscape and support socioeconomic revitalization. In this study, the authors ask how does the singular impact of rewetting differ when compared with the combined impact of rewetting and revegetating the landscape? What type of vegetation cover is ideal for restoration efforts? Specifically, we are interested to know the effects of GHG emissions, as the fluxes of each GHG differ in response to rewetting, let alone when interacting with different revegetation treatments.
Quantifying the net effects of rewetting and revegetation based on the global warming potential of each GHG is more realistic than just accounting for rewetting alone. Raising the GWL up to 10 cm from the surface would also have a net cooling effect [25]. We expect the study results will allow for the recommendation of suitable management options in line with national and subnational efforts to reduce GHG emissions, so as to meet the emission reduction targets in the context of nationally determined contributions.

2. Materials and Methods

2.1. Study Site

Field data were collected from permanent research plots in the village of Tanjung Leban, Bengkalis Regency, Riau Province (Figure 1). This area, which has an altitude of 1–6.1 m above the mean sea level, holds the remnants of lowland peat swamp forests (PSFs). Approximately 80% of the landscape is dominated by deep peat (>3 m thick).
The plots are made up of community-initiated reforested area (RA; 5 years old), an oil palm plantation (OP; 11 years old), and rubber tree plantations (RP; 15 years old). The RA consists of a mix of native peat swamp species, like Dyera polyphylla, Callophylum lowii, Shorea uliginosa, Cratoxylum arborescens, and Mezettia parviflora. The OP was planted in a 9 × 9 m2 in a triangular pattern with low tillage. The RP was not planted regularly but occasionally fertilized (Figure 2).
Two parallel drainage canals were constructed by the logging company whose operations are located upstream. These canals have been causing substantial drawdown of the groundwater levels during the dry season. The local community planted native species in peat swamp areas in 2013 after a peat fire incidence occurred in 2010.
According to the long-term records of a nearby weather station in Bukit Batu (see Figure 1), the region has an average annual rainfall of 2443 mm. The wettest month is November, with a monthly rainfall of 375 mm, while the driest month is June, with a monthly rainfall of 161 mm. The monthly air temperature does not fluctuate much, and the annual temperature averages at 26.9 °C (https://en.climate-data.org/location/579424/; accessed on 15 December 2021).

2.2. Measurements of Greenhouse Gas Emissions

We adopted the closed-chamber method, which is widely used in carbon cycle studies, as well as other areas of environmental research [26,27]. Measurements of CO2 emissions were carried out using an Infrared Gas Analyser (IRGA), LI-COR, Model LI-840A. A small amount of air was circulated in the dynamic chamber to measure the CO2 concentration (ppm) and CO2 flux (mg m−2 h−1). Total respiration (SRt), which includes autotrophic (SRa) and heterotrophic respiration (SRh), was measured in untrenched plots and to separate heterotrophic respiration, which signifies microbial activity in peat decomposition, measurements carried out in trenched plots of 100 × 100 × 100 cm3. The soil respiration was measured in 4-month intervals.
Emissions of methane (CH4) and nitrous oxide (N2O) from soil were obtained using the static closed chamber system [28]. Samples were collected with four replicates for each land cover type in September 2018 to represent the conditions before rewetting. Samples that represent the rewetted conditions were collected in August 2019. Prior to gas sampling, the chamber was fanned gently for about 10 s to mix the air inside the chamber. Gas samples were collected at the closure of 0, 10, 20, and 30 min later using a 50-mL polypropylene syringe. The height of each chamber was measured at each sampling date at four different positions to calculate the headspace volume. The syringe was prepared with a three-way stopcock and connected to the outlet of the chamber hood with silicone tubes. The syringe was also equipped with a barometer as a leak indicator during air sample collections. To prevent leakage during transportation to the laboratory, the stopcocks were sealed with polycarbonate caps.
The gas samples were analyzed within 30 days with a gas chromatograph using an Electron Capture Detector (ECD) for N2O analysis and with a Flame Ionization Detector (FID) for CH4 analysis [29], Shimadzu, Model GC-14A. Soil N2O and CH4 fluxes were quantified from the rate of concentration change in the chamber hood, determined by linear regression of the change in gas concentration as a function of the incubation time. A negative rate indicated an uptake of atmospheric GHG, while a positive rate expressed GHG emissions from the peat. The slope of the best linear fit was expressed in mass units per space by using the ideal gas law [28]. The flux rate of CH4 and N2O per unit area was determined by the rate of gas concentration change (dc/dt) over a 10-min sampling interval. This rate is represented by the slope of CH4 and N2O concentration linear regression with time. The slope was related to the flux through the following equation [30]:
ϕ = Γ M   V N 0   A   δ θ δ t
where ϕ denotes flux (mg m−2 h−1), M is the molecular weight (g mol−1), N0 is Avogadro’s number (molecule mol−1), Γ demonstrates air density (molecule cm−3), A is the surface area covered by the chamber (cm−2), V expresses the effective volume of the chamber (cm−3), and δ θ δ t is a rate of increased concentration inside a chamber (ppbv/min). The air density inside the chamber was corrected with the average air temperature inside the chamber over the 30-min sampling period (ᴦ):
Γ = 0.34848   P 237 + T N 0 M a i r
where P is pressure (millibar), and T is the average temperature inside the chamber (°C).
The calculation of the GHG emissions, expressed in CO2 equivalents, is based upon 100 years of perspective in global warming potential of 28 for CH4 and 265 for N2O [31].

2.3. Monitoring of the Groundwater Level

A semipermanent U-notch weir was constructed in December 2018 to block the canal and control the groundwater level (GWL) at 40 cm below the peat surface. The construction was designed for a medium lifetime of 2–5 years using durable-grade wood (Figure 3). Plastic sacks containing a mixture of sands and mineral soils were placed deep into the weir body to stabilize the structure and prevent water leakage and peat erosion at the bottom and sides of the canal body. The weir is maintained regularly to prevent unnecessary damage and make sure the GWL is controlled.
The GWL was automatically recorded using data loggers (Model HOBO™ U20-001-02-Ti, Onset Computer Corporation, Bourne, MA, USA) with 0.3–0.6 cm of accuracy and 0.14 cm of resolution. The sensor was set to record GWL fluctuations at 30-min intervals. The data loggers were installed in piezometers in the three land covers, with five points in RA, four points in OP, and four points in RP. The distribution of the piezometer was perpendicular to the canal.

2.4. Statistical Analysis

Shapiro–Wilk tests were used to verify the normality of data distribution for the soil GHG fluxes (CO2, CH4, and N2O) and groundwater level among the different land cover types. Differences in the variables among the land cover types (if data were normally distributed) were tested with analysis of variance (ANOVA). The Kruskal–Wallis H test was used for abnormally distributed data. A multiple linear regression model was applied to see the relationship between soil respiration before and after rewetting and the correlation with the groundwater levels in three land covers. The Pearson’s correlation analysis was used to find out the correlation of the groundwater level and CH4 or N2O fluxes. IBM SPSS statistical software (22.0 Version) was used for all statistical analyses. All graphs were prepared using SigmaPlot (12.5 Version) and Microsoft Excel (2019 Version). To capture the range of uncertainty in the findings, a 95% confidence interval was used.

3. Results

3.1. Effects of Rewetting on Greenhouse Gas Fluxes

Figure 4 shows the fluctuation of GWL over a one-year observation period and its effect on the CO2 fluxes. Our data generally shows that, after a drainage canal is blocked, peatland rewetting reduces CO2 fluxes in the form of total respiration (SRt) and heterotrophic respiration (SRh). Statistically, the reduction was significant for both SRt and SRh values (p < 0.05). Although the effect on the SRt values was not significantly different across the different land cover types (p > 0.05), there was a significant difference in SRh between the land cover types (p < 0.05). This suggests that differences between the land cover types may be due to diverse combinations of both the quantity and quality of organic carbon produced by standing vegetation and microbial activities in decomposing organic materials.
As shown in Table 1, the proportion of SRh in the reforested and oil palm areas (48.91 ± 4.75 and 54.98 ± 1.53 Mg CO2 ha−1 yr−1, respectively) to SRt (49.68 ± 6.84 and 55.71 ± 5.54 Mg CO2 ha−1 yr−1, respectively) was as high as 98% before rewetting. Even after rewetting, it was still relatively high (85% and 83%, respectively). This indicates an abundance of organic materials. However, it is rather peculiar to report that the SRh value in the rubber plantation (67.67 ± 2.13 Mg CO2 ha−1 yr−1) was higher than the SRt value (61.36 ± 7.28 Mg CO2 ha−1 yr−1). It is very likely that fertilizer applied in the rubber plantation has enhanced the mineralization of organic matter in the untrenched plots and increased SRh, while, in the trenched plots, SRh has been up taken by roots and reduced SRt, as was found in an earlier study of the fertilizer’s effects on respiration [32].
Table 2 shows the effect of rewetting on CH4 and N2O fluxes. In the reforested area (RA) and rubber plantation (RP), the increased GWL of rewetted peatlands, which stimulated the activity of soil microbes, including methanogenic bacteria, enhanced the release of CH4 into the atmosphere more than 100 times. In RA, CH4 release increased from −0.10 ± 6.46 to 8.02 ± 3.28 mg m−2 h−1 (p > 0.05); in OP, it increased from 0.34 ± 3.06 to 5.36 ± 8.67 mg m−2 h−1 (p > 0.05); and in RP, it increased from −0.19 ± 3.82 to 3.47 ± 7.93 mg m−2 h−1 (p > 0.05). These relatively low emissions were confirmed by a large body of literature from the tropics, which conclude an average CH4 release rate around 3 mg m−2 h−1 [33].
While no significant differences in CH4 fluxes were seen across the land cover types before or after rewetting, the correlation between GWL and increased CH4 fluxes was weak in RA (r2 = 0.14, p > 0.05) but strong in OP (r2 = 0.76, p > 0.05) and very strong in RP (r2 = 0.99, p > 0.05). Before rewetting, both RA and RP were sinks for CH4, but OP remained a CH4 source, although not a particularly strong one.
Likewise, in the case of N2O fluxes, no significant differences were seen between RA, OP, and RP either before rewetting (0.40 ± 0.84, 1.70 ± 1.33, and 7.25 ± 2.28 mg m−2 h−1, respectively) or after rewetting (−0.20 ± 0.52, −0.45 ± 1.52, and 4.68 ± 2.31 mg m−2 h−1, respectively) (p > 0.05). Our findings also suggest that the correlation between N2O flux and GWL was stronger after rewetting. Using Pearson’s correlation analysis, the coefficients of correlation (r2) for RA, OP, and RP were 0.57, 0.50, and 0.69, respectively (p > 0.05), before rewetting, while, after rewetting, were 0.57 and 0.64 in RA and OP, respectively, with a strong but negative correlation of 0.73 in RP. This could be due to the fact that rubber plantation was occasionally fertilized with urea.

3.2. Global Warming Potential and Net Greenhouse Gas Emissions

The contributions of CO2, CH4, and N2O emissions to soil GHG emissions were calculated based on their Global Warming Potential (GWP). Following Reference [31], we adopted 28 for CH4 and 265 for N2O over a time horizon of 100 years. The contribution of each gas and the total emissions (in Mg CO2-eq) are shown in Table 3. Statistically, these fluxes were not significantly different from those of the conditions before rewetting (p > 0.05), but a decrease of 25%, 18%, and 17% in RA, OP, and RP, respectively, is worth considering when the revegetation program is to be implemented to control GHG emissions.

4. Discussion

4.1. The Interplay between Vegetation and Anoxic Soil Environment

The CO2 fluxes found in this study in drained and rewetted peatland fall within the range of similar studies in other places in Indonesia; with oil palm, acacia, and rubber plantations being commonly studied manmade ecosystems [32,34,35,36,37,38,39]. Native species have been suggested to be the best vegetation choice for peatland restoration [40]. Most recently, the practice has been to follow the system of paludiculture, as improving hydrology is a prerequisite, especially in naturally waterlogged environments [40]. Combining native species would not only contribute towards halting GHG emissions; this would also enhance local livelihoods, as species such as Jelutung (Dyera polyphylla) have long been known to be economically important, as well as a secure biodiversity [40,41,42].
While the specific figures varied greatly between this and previous studies [43,44,45]—since the control mechanism between rewetting and draining can neither be made simple nor identical, our findings similarly demonstrated that soil respiration was controlled by GWL. This study shows that increasing GWL reduced the respiration by around 21–39%; meanwhile, a decrease in GWL was seen to increase respiration by 40–75% [22]. Overall, a positive impact was demonstrated when using canal blocking to maintain the GWL and, hence, control CO2 emissions.
The fact that heterotrophic respiration dominated emissions from both drained and rewetted peatland is also consistent with other studies [14]. These suggest that the interplay between vegetation or land cover types and emissions from an anoxic environment or rewetted peatland matters. With around 80% of respiration being heterotrophic, rewetting even shrubby or completely deforested PSF would be a wise first step to take, especially in socially and biophysically fire-prone regions like Riau.

4.2. Net Emissions and Global Warming

This study shows that, in drained conditions, peatlands were sinks of CH4, but the flux was substantially increased when GWL was elevated. In natural systems, CH4 emissions from peat soils are strongly affected by the groundwater levels; emissions were found to be at their maximum rates during the rainy months in pristine Kalimantan peatlands when GWL is close to the peat surface [46]. In addition, CH4 fluxes from wet, low-lying hollows were observed to be higher than those of dry, higher hummocks in the pristine peat forests of Indonesia and the Peruvian Amazon [46,47,48]. However, such relatively small emissions are overridden by largely reduced CO2 emissions, even if CH4 has a larger global warming potential.
Emissions of N2O are more complex. A number of abiotic factors, including mineralized organic matter, used nitrogen fertilizer, and deposited lateral fixation, may affect emissions, in addition to biotic factors like plant–microbial interactions and abiotic factors like soil humidity and temperature, which influence the production of soil N2O [49]. While this study demonstrated an increase in N2O fluxes when the GWL was elevated, natural peatland with high water levels is not a source of N2O due to low nitrogen mineralization and nitrification activities and high denitrification activity in reductive conditions [50]. However, by draining peatland for agricultural use, N2O emissions increase, along with CO2 emissions [51]. In the rainy season, N2O peat flows were found to be more elevated in Indonesian peatlands than during the dry season [52].
It is therefore considered to be more practical to consider the net effects of rewetting on the overall GHG emissions, expressed in CO2 equivalents by considering the global warming potential of each GHG. Although reforesting with native forest species is the most effective way to reduce global warming effects (25%), compared with oil palm plantation (18%) and rubber plantation (17%), the choices around what to plant on degraded peatland will also be influenced by the socioeconomic context.

4.3. Subnational Mitigation Actions

Among other approaches to mitigate climate change, we find ‘nature-based solutions’ (NbS). This approach involves working with nature, such as with unique yet threatened ecosystems like peatlands, to address human well-being, including local livelihoods, as well as to promote biodiversity conservation. Peatland restoration efforts that reduce GHG emissions through replanting with native species that are economically important for society, as we discuss here, could be good candidates for NbS that are within reach of all stakeholders.
Indonesia can use its position as the top-ranked tropical country for using nature, especially wetlands, to resolve climate change mitigation in a cost-effective manner [53] to promote peatland conservation and restoration. The government of Riau Province is in a good position to take the lead in promoting its vast peatland ecosystems as subnational contributions to the national climate agenda. Internal trading and financial compensation may also be generated through recently enacted regulations around carbon economic values. Initiatives can equally go beyond national emission reduction targets when programs are interlinked with transboundary issues, like fire emissions and haze pollution.

5. Conclusions

It is too simplistic to assume that, just because the CO2 flux is affected by the groundwater levels, rewetting will reduce emissions; Indonesia’s mass peatland restoration efforts must also introduce socially, economically, and environmentally appropriate vegetation at the same time. Vegetation grown on converted peat swamp forest has a significant role when it comes to supplying organic materials. In this case, restoration with native peat species seems to have the potential to control GHG emissions when peatland is rewetted. Communities in affected areas should therefore benefit from restoration programs.
Although it will not zero CO2 emissions, rewetting degraded peatlands has a substantial positive effect on net GHG emissions. All kinds of efforts to increase groundwater levels should therefore be supported, without jeopardizing the economic development objectives. Global agendas with national and local implications, like the Nationally Determined Contributions, should be supported through broader stakeholder participation. Climate change mitigation measures could be implemented at the subnational level, including in Bengkalis Regency and Riau Province.

Author Contributions

I.L. carried out the fieldwork, contributed to the data analysis, and wrote the original draft; D.M. conceived and conceptualized the ideas, supervised the fieldwork, reviewed and edited the original draft, and acquired the funding; and M.T. supervised the work and reviewed the draft. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Directorate General of Higher Education in the Republic of Indonesia’s Ministry of Education, Culture, Research and Technology through the PMDSU Scholarship. Additional support was received from the United States Agency for International Development (USAID) (AID-BFS-G-11-00002) through the Sustainable Wetlands Adaptation and Mitigation Program (SWAMP) of the Center for International Forestry Research (CIFOR).

Data Availability Statement

Data sharing is not applicable.

Acknowledgments

We sincerely acknowledge and thank the landowners in Tanjung Leban Village; their support and assistance were coordinated by Muhammad Nur. Without them, this long-term field work would not have been possible.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of the data; in the writing of the manuscript; or in the decision to publish the results.

References

  1. Gallego-Sala, A.V.; Charman, D.J.; Brewer, S.; Page, S.E.; Prentice, I.C.; Friedlingstein, P.; Moreton, S.; Amesbury, M.J.; Beilman, D.W.; Björck, S.; et al. Latitudinal limits to the predicted increase of the peatland carbon sink with warming. Nat. Clim. Chang. 2018, 8, 907–913. [Google Scholar] [CrossRef] [Green Version]
  2. Loisel, J.; Gallego-Sala, A.V.; Amesbury, M.J.; Magnan, G.; Anshari, G.; Beilman, D.W.; Benavides, J.C.; Blewett, J.; Camill, P.; Charman, D.J.; et al. Expert assessment of future vulnerability of the global peatland carbon sink. Nat. Clim. Chang. 2021, 11, 70–77. [Google Scholar] [CrossRef]
  3. Page, S.E.; Rieley, J.O.; Banks, C.J. Global and regional importance of the tropical peatland carbon pool. Glob. Chang. Biol. 2011, 17, 798–818. [Google Scholar] [CrossRef] [Green Version]
  4. Gumbricht, T.; Roman-Cuesta, R.M.; Verchot, L.; Herold, M.; Wittmann, F.; Householder, E.; Herold, N.; Murdiyarso, D. An expert system model for mapping tropical wetlands and peatlands reveals South America as the largest contributor. Glob. Chang. Biol. 2017, 23, 3581–3599. [Google Scholar] [CrossRef] [Green Version]
  5. Page, S.; Rieley, J. Tropical peat swamp forests of Southeast Asia. In The Wetland Book; II: Distribution, Description and Conservation; Springer: Dordrecht, The Netherlands, 2018; pp. 1753–1761. [Google Scholar] [CrossRef]
  6. Hooijer, A.; Page, S.; Jauhiainen, J.; Lee, W.A.; Lu, X.X.; Idris, A.; Anshari, G. Subsidence and carbon loss in drained tropical peatlands. Biogeosciences 2012, 9, 1053–1071. [Google Scholar] [CrossRef] [Green Version]
  7. Hergoualc’h, K.; Verchot, L.V. Stocks and fluxes of carbon associated with land use change in Southeast Asian tropical peatlands: A review. Glob. Biogeochem. Cycles 2011, 25, 1–13. [Google Scholar] [CrossRef] [Green Version]
  8. Hergoualc’h, K.; Verchot, L.V. Greenhouse gas emission factors for land use and land-use change in Southeast Asian peatlands. Mitig. Adapt. Strateg. Glob. Chang. 2014, 19, 789–807. [Google Scholar] [CrossRef]
  9. Eickenscheidt, T.; Heinichen, J.; Drösler, M. The greenhouse gas balance of a drained fen peatland is mainly controlled by land-use rather than soil organic carbon content. Biogeosciences 2015, 12, 5161–5184. [Google Scholar] [CrossRef] [Green Version]
  10. Giesen, W.; Sari, E.N.N. Tropical Peatland Restoration Report: The Indonesian Case; Berbak Green Prosperity Partnership/Kemitraan Kesejatheraan Hijau (Kehijau Berbak): Wageningen, The Netherlands, 2018; Available online: https://www.researchgate.net/publication/323676663_Tropical_Peatland_Restoration_Report_the_Indonesian_case?channel=doi&linkId=5aa3a4c745851543e63d9011&showFulltext=true (accessed on 28 February 2018).
  11. Taufik, M.; Minasny, B.; Mcbratney, A.B.; Van Dam, J.C.; Jones, P.D.; Van Lanen, H.A.J. Human-induced changes in Indonesian peatlands increase drought severity. Environ. Res. Lett. 2020, 15, 084013. [Google Scholar] [CrossRef]
  12. Taufik, M.; Setiawan, B.I.; Van Lanen, H.A.J. Increased fire hazard in human-modified wetlands in Southeast Asia. Ambio 2019, 48, 363–373. [Google Scholar] [CrossRef]
  13. Taufik, M.; Widyastuti, M.T.; Sulaiman, A.; Murdiyarso, D.; Santikayasa, I.P.; Minasny, B. An improved drought-fire assessment for managing fire risks in tropical peatlands. Agric. For. Meteorol. 2022, 312, 108738. [Google Scholar] [CrossRef]
  14. Murdiyarso, D.; Lestari, I.; Hanggara, B.B.; Saragi-Sasmito, M.; Basuki, I.; Taufik, M. Managing Water Regimes. In Wetland Carbon and Environmental Management; American Geophysical Union: Washington, DC, USA, 2021; pp. 355–369. [Google Scholar] [CrossRef]
  15. Ritzema, H.; Limin, S.; Kusin, K.; Jauhiainen, J.; Wösten, H. Canal blocking strategies for hydrological restoration of degraded tropical peatlands in Central Kalimantan, Indonesia. Catena 2014, 114, 11–20. [Google Scholar] [CrossRef] [Green Version]
  16. Dohong, A.; Abdul Aziz, A.; Dargusch, P. A Review of techniques for effective tropical peatland restoration. Wetlands 2018, 38, 275–292. [Google Scholar] [CrossRef]
  17. Sutikno, S.; Rinaldi, R.; Saputra, E.; Kusairi, M.; Saharjo, B.H.; Putra, E.I. Water management for hydrological restoration and fire prevention in tropical peatland. IOP Conf. Ser. Mater. Sci. Eng. 2020, 933. [Google Scholar] [CrossRef]
  18. Urzainki, I.; Laurén, A.; Palviainen, M.; Haahti, K.; Budiman, A.; Basuki, I.; Netzer, M.; Hökkä, H. Canal blocking optimization in restoration of drained peatlands. Biogeosciences 2020, 17, 4769–4784. [Google Scholar] [CrossRef]
  19. Rixen, T.; Baum, A.; Wit, F.; Samiaji, J. Carbon leaching from tropical peat soils and consequences for carbon balances. Front. Earth Sci. 2016, 4, 74. [Google Scholar] [CrossRef] [Green Version]
  20. Jauhiainen, J.; Limin, S.; Silvennoinen, H.; Vasander, H. Carbon dioxide and methane fluxes in drained tropical peat before and after hydrological restoration. Ecology 2008, 89, 3503–3514. [Google Scholar] [CrossRef]
  21. Hergoualc’h, K.; Hendry, D.T.; Murdiyarso, D.; Verchot, L.V. Total and heterotrophic soil respiration in a swamp forest and oil palm plantations on peat in Central Kalimantan, Indonesia. Biogeochemistry 2017, 135, 203–220. [Google Scholar] [CrossRef] [Green Version]
  22. Murdiyarso, D.; Saragi-Sasmito, M.F.; Rustini, A. Greenhouse gas emissions in restored secondary tropical peat swamp forests. Mitig. Adapt. Strateg. Glob. Chang. 2019, 24, 507–520. [Google Scholar] [CrossRef]
  23. Swails, E.; Hergoualc’h, K.; Verchot, L.; Novita, N.; Lawrence, D. Spatio-temporal variability of peat CH4 and N2O fluxes and their contribution to peat GHG budgets in Indonesian forests and oil palm plantations. Front. Environ. Sci. 2021, 9, 48. [Google Scholar] [CrossRef]
  24. Hirano, T.; Segah, H.; Kusin, K.; Limin, S.; Takahashi, H.; Osaki, M. Effects of disturbances on the carbon balance of tropical peat swamp forests. Glob. Chang. Biol. 2012, 18, 3410–3422. [Google Scholar] [CrossRef]
  25. Evans, C.D.; Peacock, M.; Baird, A.J.; Artz, R.R.E.; Burden, A.; Callaghan, N.; Chapman, P.J.; Cooper, H.M.; Coyle, M.; Craig, E.; et al. Overriding water table control on managed peatland greenhouse gas emissions. Nature 2021, 593, 548–552. [Google Scholar] [CrossRef]
  26. Norman, J.M.; Garcia, R.; Verma, S.B. Soil surface CO2 fluxes and the carbon budget of a grassland. J. Geophys. Res. 1992, 97, 845–853. [Google Scholar] [CrossRef]
  27. Davidson, E.A.; Savage, K.; Verchot, L.V.; Navarro, R. Minimizing artifacts and biases in chamber-based measurements of soil respiration. Agric. For. Meteorol. 2002, 113, 21–37. [Google Scholar] [CrossRef]
  28. Verchot, L.V.; Davidson, E.A.; Cattânio, J.H.; Ackerman, I.L.; Erickson, H.E.; Keller, M. Land use change and biogeochemical controls of nitrogen oxide emissions from soils in eastern Amazonia. Glob. Biogeochem. Cycles 1999, 13, 31–46. [Google Scholar] [CrossRef]
  29. Loftfield, N.; Flessa, H.; Augustin, J.; Beese, F. Automated gas chromatographic system for rapid analysis of the atmospheric trace gases methane, carbon dioxide, and nitrous oxide. J. Environ. Qual. 1997, 26, 560–564. [Google Scholar] [CrossRef]
  30. Husin, Y.A.; Murdiyarso, D.; Khalil, M.A.K.; Rasmussen, R.A.; Shearer, M.J.; Sabiham, S.; Sunar, A.; Adijuwana, H. Methane flux from Indonesian wetland rice: The effects of water management and rice variety. Chemosphere 1995, 31, 3153–3180. [Google Scholar] [CrossRef]
  31. Myhre, G.; Shindell, D.; Bréon, F.-M.; Collins, W.; Fuglestvedt, J.; Huang, J.; Koch, D.; Lamarque, J.-F.; Lee, D.; Mendoza, B.; et al. Anthropogenic and natural radiative forcing. In Climate Change 2013—The Physical Science Basis, Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change; Cambridge University Press: Cambridge, UK, 2013; pp. 659–740. [Google Scholar] [CrossRef]
  32. Comeau, L.P.; Hergoualc’h, K.; Hartill, J.; Smith, J.; Verchot, L.V.; Peak, D.; Salim, A.M. How do the heterotrophic and the total soil respiration of an oil palm plantation on peat respond to nitrogen fertilizer application? Geoderma 2016, 268, 41–51. [Google Scholar] [CrossRef]
  33. Couwenberg, J.; Dommain, R.; Joosten, H. Greenhouse gas fluxes from tropical peatlands in south-east Asia. Glob. Chang. Biol. 2010, 16, 1715–1732. [Google Scholar] [CrossRef]
  34. Husnain, H.; Wigena, I.G.P.; Dariah, A.; Marwanto, S.; Setyanto, P.; Agus, F. CO2 emissions from tropical drained peat in Sumatra, Indonesia. Mitig. Adapt. Strateg. Glob. Chang. 2014, 19, 845–862. [Google Scholar] [CrossRef]
  35. Marwanto, S.; Agus, F. Is CO2 flux from oil palm plantations on peatland controlled by soil moisture and/or soil and air temperatures? Mitig. Adapt. Strateg. Glob. Chang. 2014, 19, 809–819. [Google Scholar] [CrossRef]
  36. Khasanah, N.; van Noordwijk, M. Subsidence and carbon dioxide emissions in a smallholder peatland mosaic in Sumatra, Indonesia. Mitig. Adapt. Strateg. Glob. Chang.. 2019, 24, 147–163. [Google Scholar] [CrossRef] [Green Version]
  37. Batubara, S.F.; Agus, F.; Rauf, A.; Elfiati, D. Impact of soil collar insertion depth on microbial respiration measurements from tropical peat under an oil palm plantation. Mires Peat 2019, 24, 1–11. [Google Scholar] [CrossRef]
  38. Swails, E.; Hertanti, D.; Hergoualc’h, K.; Verchot, L.; Lawrence, D. The response of soil respiration to climatic drivers in undrained forest and drained oil palm plantations in an Indonesian peatland. Biogeochemistry 2019, 142, 37–51. [Google Scholar] [CrossRef]
  39. Wakhid, N.; Hirano, T.; Okimoto, Y.; Nurzakiah, S.; Nursyamsi, D. Soil carbon dioxide emissions from a rubber plantation on tropical peat. Sci. Total Environ. 2017, 581–582, 857–865. [Google Scholar] [CrossRef] [Green Version]
  40. Tata, H.L. Mixed farming systems on peatlands in Jambi and Central Kalimantan provinces, Indonesia: Should they be described as paludiculture? Mires Peat 2019, 25, 1–17. [Google Scholar] [CrossRef]
  41. Posa, M.R.C.; Wijedasa, L.S.; Corlett, R.T. Biodiversity and conservation of tropical peat swamp forests. Bioscience 2011, 61, 49–57. [Google Scholar] [CrossRef]
  42. Harrison, M.E.; Rieley, J.O. Tropical peatland biodiversity and conservation in southeast Asia: Foreword. Mires Peat 2018, 22, 1–7. [Google Scholar] [CrossRef]
  43. Wösten, J.H.M.; Clymans, E.; Page, S.E.; Rieley, J.O.; Limin, S.H. Peat-water interrelationships in a tropical peatland ecosystem in Southeast Asia. Catena 2008, 73, 212–224. [Google Scholar] [CrossRef]
  44. Carlson, K.M.; Goodman, L.K.; May-Tobin, C.C. Modeling relationships between water table depth and peat soil carbon loss in Southeast Asian plantations. Environ. Res. Lett. 2015, 10, 74006. [Google Scholar] [CrossRef]
  45. Saragi-Sasmito, M.F.; Murdiyarso, D.; June, T.; Sasmito, S.D. Carbon stocks, emissions, and aboveground productivity in restored secondary tropical peat swamp forests. Mitig. Adapt. Strateg. Glob. Chang. 2019, 24, 521–533. [Google Scholar] [CrossRef] [Green Version]
  46. Jauhiainen, J.; Takahashi, H.; Heikkinen, J.E.P.; Martikainen, P.J.; Vasander, H. Carbon fluxes from a tropical peat swamp forest floor. Glob. Chang. Biol. 2005, 11, 1788–1797. [Google Scholar] [CrossRef]
  47. Ishikura, K.; Darung, U.; Inoue, T.; Hatano, R. Variation in soil properties regulate greenhouse gas fluxes and global warming potential in three land use types on tropical peat. Atmosphere 2018, 9, 465. [Google Scholar] [CrossRef] [Green Version]
  48. Hergoualc’h, K.; Dezzeo, N.; Verchot, L.V.; Martius, C.; van Lent, J.; del Aguila-Pasquel, J.; López Gonzales, M. Spatial and temporal variability of soil N2O and CH4 fluxes along a degradation gradient in a palm swamp peat forest in the Peruvian Amazon. Glob. Chang. Biol. 2020, 26, 7198–7216. [Google Scholar] [CrossRef]
  49. Butterbach-Bahl, K.; Baggs, E.M.; Dannenmann, M.; Kiese, R.; Zechmeister-Boltenstern, S. Nitrous oxide emissions from soils: How well do we understand the processes and their controls? Philos. Trans. R. Soc. B Biol. Sci. 2013, 368, 20130122. [Google Scholar] [CrossRef]
  50. Kolb, S.; Horn, M.A. Microbial CH4 and N2O consumption in acidic wetlands. Front. Microbiol. 2012, 3, 78. [Google Scholar] [CrossRef] [Green Version]
  51. Mu, Z.; Huang, A.; Ni, J.; Xie, D. Linking annual N2O emission in organic soils to mineral nitrogen input as estimated by heterotrophic respiration and soil C/N ratio. PLoS ONE 2014, 9, e96572. [Google Scholar] [CrossRef] [Green Version]
  52. Jauhiainen, J.; Silvennoinen, H.; Hämäläinen, R.; Kusin, K.; Limin, S.; Raison, R.J.; Vasander, H. Nitrous oxide fluxes from tropical peat with different disturbance history and management. Biogeosciences 2012, 9, 1337–1350. [Google Scholar] [CrossRef] [Green Version]
  53. Griscom, B.W.; Busch, J.; Cook-Patton, S.C.; Ellis, P.W.; Funk, J.; Leavitt, S.M.; Lomax, G.; Turner, W.R.; Chapman, M.; Engelmann, J.; et al. National mitigation potential from natural climate solutions in the tropics. Philos. Trans. R. Soc. B Biol. Sci. 2020, 375, 20190126. [Google Scholar] [CrossRef] [Green Version]
Forests 13 00505 g001 550
Figure 1. Study site located in Tanjung Leban Village, Bengkalis Regency (shaded area), Riau Province, Indonesia. Dumai is an industrialized zone with oil refinery and crude palm oil shipping harbor. Bukit Batu is a township with a weather station.
Figure 1. Study site located in Tanjung Leban Village, Bengkalis Regency (shaded area), Riau Province, Indonesia. Dumai is an industrialized zone with oil refinery and crude palm oil shipping harbor. Bukit Batu is a township with a weather station.
Forests 13 00505 g001
Forests 13 00505 g002 550
Figure 2. General features of community-initiated revegetation in degraded peatland following deforestation, fires, and drainage in (a) a reforested area (RA) with mixed native species, (b) an oil palm plantation (OP), and (c) a rubber plantation (RP).
Figure 2. General features of community-initiated revegetation in degraded peatland following deforestation, fires, and drainage in (a) a reforested area (RA) with mixed native species, (b) an oil palm plantation (OP), and (c) a rubber plantation (RP).
Forests 13 00505 g002
Forests 13 00505 g003 550
Figure 3. The standard design of a U-notch weir to block canals adopted to ensure a constant groundwater level of 40 cm (Source: Sutikno, Personal communication).
Figure 3. The standard design of a U-notch weir to block canals adopted to ensure a constant groundwater level of 40 cm (Source: Sutikno, Personal communication).
Forests 13 00505 g003
Forests 13 00505 g004 550
Figure 4. CO2 flux responses to the groundwater levels in reforested, oil palm, and rubber plantation areas of rewetted peatlands in Bengkalis Regency, Riau Province, Indonesia.
Figure 4. CO2 flux responses to the groundwater levels in reforested, oil palm, and rubber plantation areas of rewetted peatlands in Bengkalis Regency, Riau Province, Indonesia.
Forests 13 00505 g004
Table
Table 1. Annual CO2 fluxes in the form of total soil respiration (SRt) and heterotrophic soil respiration (SRh) across three different land covers before and after rewetting.
Table 1. Annual CO2 fluxes in the form of total soil respiration (SRt) and heterotrophic soil respiration (SRh) across three different land covers before and after rewetting.
Land Cover TypesCO2 Flux (Mg CO2 ha−1 yr−1)
Before RewettingAfter Rewetting
SRtSRhSRtSRh
Reforested Area49.68 ± 6.8448.91 ± 4.7545.18 ± 2.0238.51 ± 2.13
Oil Palm Plantation55.71 ± 5.5454.98 ± 1.5342.49 ± 3.1835.17 ± 1.81
Rubber Plantation61.36 ± 7.2867.67 ± 2.1341.84 ± 2.3141.26 ± 2.94
Table
Table 2. CH4 and N2O fluxes in reforested area (RA), oil palm (OP), and rubber plantation (RP) before and after rewetting (mean ± SE; n = 4).
Table 2. CH4 and N2O fluxes in reforested area (RA), oil palm (OP), and rubber plantation (RP) before and after rewetting (mean ± SE; n = 4).
Land Cover TypeCH4 Flux (mg m−2 h−1)N2O Flux (mg m−2 h−1)
Before RewettingAfter RewettingBefore RewettingAfter Rewetting
Reforested Area−0.10 ± 6.468.02 ± 3.280.40 ± 0.84−0.20 ± 0.52
Oil Palm Plantation0.34 ± 3.065.36 ± 8.671.70 ± 1.33−0.45 ± 1.52
Rubber Plantation−0.19 ± 3.823.47 ± 7.937.25 ± 2.284.68 ± 2.31
Table
Table 3. Total net greenhouse gas emissions expressed in CO2 equivalent in the reforested area (RA), oil palm (OP), and rubber plantation (RP) before and after rewetting (mean ± SE).
Table 3. Total net greenhouse gas emissions expressed in CO2 equivalent in the reforested area (RA), oil palm (OP), and rubber plantation (RP) before and after rewetting (mean ± SE).
Land Cover
Type		CO2 CH4N2OTotal Net GHG Emissions
Mg CO2-eq ha−1 yr−1
Before
Rewetting		After
Rewetting		Before
Rewetting		After
Rewetting		Before
Rewetting		After
Rewetting		Before
Rewetting		After
Rewetting
RA49.68 ± 6.8445.18 ± 2.02−19.67 ± 8.0523.69 ± 8.0231.20 ± 9.28−17.17 ± 7.4761.21 ± 8.0751.70 ± 2.57
OP55.71 ± 5.5442.49 ± 3.1810.32 ± 4.5925.22 ± 17.2739.52 ± 21.6126.07 ± 14.41105.55 ± 31.7493.78 ± 34.86
RP61.36 ± 7.2841.48 ± 2.31−16.03 ± 1.5029.52 ± 10.5898.60 ± 33.1350.59 ± 20.05143.93 ± 38.91121.59 ± 32.94
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Lestari, I.; Murdiyarso, D.; Taufik, M. Rewetting Tropical Peatlands Reduced Net Greenhouse Gas Emissions in Riau Province, Indonesia. Forests 2022, 13, 505. https://doi.org/10.3390/f13040505

AMA Style

Lestari I, Murdiyarso D, Taufik M. Rewetting Tropical Peatlands Reduced Net Greenhouse Gas Emissions in Riau Province, Indonesia. Forests. 2022; 13(4):505. https://doi.org/10.3390/f13040505

Chicago/Turabian Style

Lestari, Iska, Daniel Murdiyarso, and Muh Taufik. 2022. "Rewetting Tropical Peatlands Reduced Net Greenhouse Gas Emissions in Riau Province, Indonesia" Forests 13, no. 4: 505. https://doi.org/10.3390/f13040505

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop