Fungal diversity and its functions in tropical peatlands as plant growth promoting microorganism or associated with green house emission

Indonesia’s tropical peatlands are an ecosystem of global significance. They contain immense stores of carbon and play a key role in regional and global climate systems. They provide habitat for iconic species such as the orangutan and Sumatran tiger, and they sustain the livelihoods of thousands of local people. Despite these values, Indonesia’s peatland ecosystems have been subject to extensive deforestation and degradation during the past two decades. Recurrent peatland fires related to these land use activities have caused smoke pollution across the region, resulting in substantial public health issues and political controversy. More than 50% of the nation’s 21 Mha of peatland can be considered as degraded. There is an urgent need to slow the rate of peatland degradation in Indonesia and to effectively restore the vast areas already damaged. A key consideration in this challenge is that tropical peatland restoration is an emerging field of scientific inquiry and little research has been published on the factors that constitute and influence successful restoration of tropical peatland ecosystems. This thesis addresses this gap in the broader ecosystem restoration literature by focusing on a case study of the so-called “Ex-Mega Rice Project” area of Central Kalimantan (an area previously subject to extensive degradation) and examining how successful peatland restoration can be achieved in Indonesia by: (1) reviewing the drivers of peatland degradation in the country in order to better understand the competing interests and broader socioecological context in which restoration activities need to be carried out; (2) studying previous restoration initiatives in Indonesia to better understand the restoration techniques used and the factors influencing their relative effectiveness; (3) analysing the specific tropical peatland restoration technique of “re-wetting” to better understand which elements of the technique best support effective restoration outcomes; (4) analysing the specific issue of illegal oil palm development on Indonesian peatland, including a consideration of what sorts of interventions are required to halt illegal oil palm development and control the associated recurrent fires that have been shown to substantially constrain the effectiveness of restoration initiatives; and (5) presenting an overarching conceptual framework of the factors that influence effective peatland restoration, which can be used by policy makers to devise restoration interventions that should have a greater probability of success. The drivers of peatland degradation in Indonesia can be categorised as direct and indirect. Direct drivers include logging, oil palm development and recurrent fires (mostly caused by large- and small-scale land use activities). Indirect drivers include climate change, the poverty and employment needs of local people, and the ineffective and sometimes perversely counter-productive land use governance systems. Techniques previously used to restore peatlands in Indonesia include rewetting through canal blocking, re-forestation through seedling transplanting, the development of seed-based tree seedling nurseries, and measures that support natural regeneration such as the strategic planting of seed trees and additional seed dispersal. Previous restoration measures in the case study area were typically “small and pilot-based” and, as such, their impact were limited. That noted, of these techniques, rewetting appears to be the most common and the most likely to result in larger-scale successful peatland restoration. A detailed analysis of rewetting activities in the case study area revealed that effective rewetting and peatland restoration can be achieved with or without spillways on “dam box” designs, and if special design consideration is given to dam crest elevation and dam spacing, and if the materials used to construct dams were sufficiently durable and appropriate. The case analysis also showed that rewetting dams built for restoration were frequently damaged, apparently by loggers and fishermen opposed to the restoration intervention in the area. A detailed analysis of the extent of illegal oil palm development in the case study area is also included in this thesis. Spatial analysis and emissions modelling revealed that around 86,700 ha of palm oil plantations had been developed on “deep” peatland in the case study area (2004 to 2012) in direct contravention of a range of applicable laws, rules, decrees and ordinances aimed at conservation of deep peatland. Our modelling suggests that these oil palm plantations have directly resulted in between 3.73 MtCO2e (minimum) to 8.67 MtCO2e (maximum) of emissions annually between 2004 and 2012. Laws and government policies protecting peatlands must be properly enforced in Indonesia to not only halt the damage caused by this illegal development, but also to allow restoration activities to be enacted with a reasonable chance of success. The final part of this thesis presents an assessment framework for evaluating the likelihood of success of different peatland restoration interventions in the tropics. The assessment framework includes a hierarchal structure that covers principal aspects, attributes, success indicators, standards for comparison, and decision criteria. The framework can be used by policy makers to improve the probability of success of future peatland restoration initiatives in Indonesia.

To evaluate the hypothesis that plant-mediated oxygen supplies decrease methane (CH4) production and total global warming potential (GWP) in a tropical peatland, the authors compared the fluxes and dissolved concentrations of greenhouse gases [GHGs; CH4, carbon dioxide (CO2) and nitrous oxide (N2O)] and dissolved oxygen (DO) at multiple peatland ecosystems in Central Kalimantan, Indonesia. Study ecosystems included tropical peat swamp forest and degraded peatland areas that were burned and/or drained during the rainy season. CH4 fluxes were significantly influenced by land use and drainage, which were highest in the flooded burnt sites (5.75 ± 6.66 mg C m−2 h−1) followed by the flooded forest sites (1.37 ± 2.03 mg C m−2 h−1), the drained burnt site (0.220 ± 0.143 mg C m−2 h−1), and the drained forest site (0.0084 ± 0.0321 mg C m−2 h−1). Dissolved CH4 concentrations were also significantly affected by land use and drainage, which were highest in the flooded burnt sites (124 ± 84 μmol L−1) followed by the drained burnt site (45.2 ± 29.8 μmol L−1), the flooded forest sites (1.15 ± 1.38 μmol L−1) and the drained forest site (0.860 ± 0.819 μmol L−1). DO concentrations were influenced by land use only, which were significantly higher in the forest sites (6.9 ± 5.6 μmol L−1) compared to the burnt sites (4.0 ± 2.9 μmol L−1). These results suggest that CH4 produced in the peat might be oxidized by plant-mediated oxygen supply in the forest sites. CO2 fluxes were significantly higher in the drained forest site (340 ± 250 mg C m−2 h−1 with a water table level of −20 to −60 cm) than in the drained burnt site (108 ± 115 mg C m−2 h−1 with a water table level of −15 to +10 cm). Dissolved CO2 concentrations were 0.6–3.5 mmol L−1, also highest in the drained forest site. These results suggested enhanced CO2 emission by aerobic peat decomposition and plant respiration in the drained forest site. N2O fluxes ranged from −2.4 to −8.7 μg N m−2 h−1 in the flooded sites and from 3.4 to 8.1 μg N m−2 h−1 in the drained sites. The negative N2O fluxes might be caused by N2O consumption by denitrification under flooded conditions. Dissolved N2O concentrations were 0.005–0.22 μmol L−1 but occurred at < 0.01 μmol L−1 in most cases. GWP was mainly determined by CO2 flux, with the highest levels in the drained forest site. Despite having almost the same CO2 flux, GWP in the flooded burnt sites was 20% higher than that in the flooded forest sites due to the large CH4 emission (not significant). N2O fluxes made little contribution to GWP.

Peatland degradation indicated by stable isotope depth profiles and soil carbon loss

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 of charcoal influx to identify local fires and examine the associated responses to the tropical peatland ecosystem in Central Kalimantan, Indonesia. The results showed local fire events increased after 756 cal. yr BP, and possible drivers of charcoal influx include changes in sea level, increased frequency of El Niño events, increased biomass, and anthropogenically-driven ecosystem degradation. However, the vegetation composition showed changes since ∼2300 cal. yr BP from a mix of peat swamp forest (PSF) and open vegetation (OV) during the late Holocene (∼2300 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 vegetation turnover affected the accumulation and decomposition of recalcitrant organic matter in peat. The thresholds of the peatland ecosystems over longer-term timeframes provided the following restoration insights: 1) PSF species (i.e. Eurya and Ilex) showed high fire tolerance and increased in abundance up to charcoal influx threshold of ∼23 grains mm−2 cm−3 yr−1 while LMS and OV species increased up to a lower threshold of ∼13 grains mm−2 cm−3 yr−1before declining; 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, Arenga, Ficus, and Trema as they were historically able to thrive in fire events and dry hydrological conditions.

QUANTIFYING PEATLAND CARBON DYNAMICS USING MECHANISTICALLY-BASED BIOGEOCHEMISTRY MODELS

Alterations in land use of a million hectares of peatlands in Central Kalimantan and other regions, without an understanding of the characteristics of tropical peatlands, have led to land degradation. This study aimed to determine the effect of land-use changes on plant diversity and soil characteristics of peatlands in Central Kalimantan, Indonesia. The conversion of secondary forests to critically degraded land, acacia forest, agroforestry land, rubber gardens, and palm oil plantations by clear-cutting and fire converted organic materials to available nutrients and increased soil pH at the soil surface. However, the nutrients are easily leached by high rainfall intensity thus resulted in a more degraded land at long-term periods. Land-use change resulted in high humic acid levels, aromatic area, hydrophobic surface area, but low water storage capability. This condition made it easily burn during the dry season and is prone to flooding during the rainy season. The Shannon indexes for all tropical peatland land uses at all levels of plant growth categorized plant diversity and number of individuals as low to moderate due to waterlogging, low pH, low soil fertility, high metal toxicity, and fire. Land with oil-, sap- and litter-producing plants, which resist decomposition, and monoculture plantations tended to contain higher amounts of humic acid, hydrophilic areas, aromatic areas, and bulk density than naturally regenerated forests, although these land uses had lower organic C, available N, and water-holding capacity. Closed cycles of organic matter, carbon, water, nutrient, energy, production, and crops should be maintained for rehabilitation of peatland.

Indonesia declared an ambitious plan to restore its degraded and fire‐prone peatlands, which have been a source of significant greenhouse gas and haze. However, the progress has been slow and the plan cannot succeed without sustained social supports and political will. Although many previous studies argued for the need to see ecological restoration in socio‐economic contexts, empirical assessments have been lacking for how restoration is operationalized on the ground. We interviewed 47 key informants involved in four different projects in Central Kalimantan, Indonesia, and assessed their definitions, goals, and practices of peatland restoration. Most of the actors we interviewed defined peatland restoration primarily in an ecological context following the global concept of ecological restoration. However, all four restoration projects were designed without determining reference and trajectory conditions. Their intermediate goals and practices were more focused on engaging local communities and developing sustainable livelihood options than improving the ecological conditions of peatlands. To be internally consistent, peatland restoration needs to recognize a social dimension in its process, as well as in its goal. Setting clear trajectory conditions is also important to clarify achievable goals and measurable intermediate outcomes. We propose the following definition of peatland restoration: a process of assisting the recovery of degraded peatland ecosystems to achieve the appropriate trajectories defined through multi‐stakeholder collaboration within social‐ecological contexts. We hope to generate healthy debates to further refine the definition that encompasses both social and ecological dimensions to generate broader support for sustaining and expanding peatland restoration projects in Indonesia.

Land use change and forest fire covering millions ha of peat-land in Central Kalimantan are the main factor contribute on forest peatland degradation. This study aimed to determine the impact of forest peatland fire severity level on the plant diversity and soil chemical properties of wet tropical peatland in Central Kalimantan, Indonesia. The severe peat fire extremely decreased diversity, number of individuals as well as number of plant species. The accumulation of ashes in forest peat fires impacted area instantly increased pH, organic matter, humic acid content, hydrophobicity, available-N and available-K. However, their availabilities had only been temporary as they were easily diminished and washed way which result in long-term land degradation. An opened and dried peatland had low water holding capability and, hence, it was relatively easy to burn during the dry season but flooded during the rainy season. Tropical forest peats fires significantly reduced plant diversity and changed soil chemical properties. This forest peat fire potentially loss its function, particularly moisture storage, carbon, nutrients and biodiversity.

Reducing CO2 emissions and supporting food security in Central Kalimantan, Indonesia, with improved peatland management

Hawaii yellow‐eyed grass (Xyris complanata: Xyridaceae) inhabits infertile, acidic peat soil in the rainy tropical zone in Southeast Asia. This monocot plant produces a large number of dormant seeds in order to make a large deposit to seed bank in the soil. Under laboratory conditions, surface‐sterilized X. complanata seeds are rarely able to germinate on sterilized peat moss bed; they require inoculation with either seed epiphytic or soil fungi to facilitate active seed germination. In the present study, three different genera of seed epiphytic fungi were isolated, and two common fungal genera, Fusarium sp. (strain R‐1) and Penicillium sp. (strain Y‐1), were found to promote seed germination of X. complanata. In sterile peat moss beds, the germination‐stimulating fungi also showed growth‐promoting effects on X. complanata seedlings. These results suggest that the seed germination‐promoting fungi likely function as genuine partners for X. complanata in tropical open peat lands.

Life cycle greenhouse gas emissions impacts of the adoption of the EU Directive on biofuels in Spain. Effect of the import of raw materials and land use changes

Coastal mangrove forests provide a broad array of ecosystem services including fisheries production, sediment regulation, wood production and protection from storms and tsunamis. Similarly, peat swamp forests harbour a diverse range of flora and fauna, regulate water regimes and store large amounts of carbon deposited in organic materials below the ground. In Southeast Asia, the conversion rates of mangrove to other land uses, such as shrimp farms and settlements, are among the highest for any forest type. Furthermore, the conversion of peat swamp forests to oil palm and pulp wood plantations and the associated fires have been the main sources of greenhouse gas (GHG) emissions in the region during the past decade. With deforestation accounting for around 17% of global anthropogenic GHG emissions, the upcoming global mechanism known as Reducing Emissions from Deforestation and forest Degradation (REDD+) provides an important climate change mitigation option. This scheme offers economic incentives for conserving forests and associated carbon (C) stores in developing countries. Mangrove and peat swamp ecosystems are well suited to such strategies. However, although their high rates of C assimilation and export (fluxes) are known, their total C storage—the amount that may be emitted upon conversion—has not been well quantified. We measured total ecosystem C storage (above and below ground) in mangrove ecosystems in North Sulawesi, Central Kalimantan and Central Java, Indonesia. We assessed variations in mangrove C-pools along transects running inland from the ocean edge, as well as their vulnerability to sea-level rise and land use. In addition, in Tanjung Puting National Park, Central Kalimantan, we sampled both the total aboveground biomass and the belowground peat horizons to ascertain total ecosystem C-pools. Summary Our measurements show that total carbon storage in mangrove ecosystems is exceptionally high compared with most forest types, with a mean of 968 Mg C ha -1 and range of 863-1073 Mg C ha -1 . These carbon stocks result from a combination of large-stature forest (trees up to ~2 m in diameter) and organic-rich peat soils to a depth of 5 m or more. Aboveground C-stocks vary widely depending on stand composition and history, but belowground pools comprise a large portion of ecosystem C storage in most sites. Although mangrove composition is often stratified with distance from the ocean edge, C storage does not vary consistently along this gradient. Ecosystem C-pools at Tanjung Puting exceed 1000 Mg ha -1 in many of the sampled locations. All sampled stands had a depth to mineral soil of less than 1 m, with a mean peat depth of 45.5 ± 6.8 cm. Mean total C-stock was 894.3 Mg C ha -1 , with a range of 558- 1213 Mg C ha -1 . It should be noted, when considering these estimates of ecosystem pools, that peat depths of tropical peat swamp forests may be as much as 20 m (with an average depth of 3-5 m). Projected rates of sea-level rise (~1 cm yr -1 over the next century) are ~5-10 times higher than typical mangrove sediment accrual rates (1-2 mm yr -1 ), suggesting high susceptibility and a potential positive feedback via loss of C-stocks. Thus, the combination of very high C-stocks, susceptibility to land use activities and numerous ecosystem services makes tropical mangroves ideal candidates for REDD+, particularly if climate change mechanisms can be applied to promoting synergies between adaptation to climate change (e.g. local migration) and mitigation. However, additional studies to better quantify ecosystem C-pools and the potential impact of land cover change and fire are greatly needed in order to make sound policy decisions related to carbon financing through the REDD+ mechanism

Rewetting on agricultural peatlands can offer cost effective greenhouse gas reduction at the national level

Greenhouse gas assessment of soybean production: implications of land use change and different cultivation systems

Much of the peatland in Central Kalimantan is highly degraded because it has been cleared and drained over the last 30–40 years. Degraded peatland is highly susceptible to burning and oxidation and contributes 30–60 % of the annual greenhouse gas emissions of Indonesia. To combat these problems, the Government of Indonesia has made peatland restoration a high priority, with revitalisation of livelihoods being a critical component to help communities transition to rewet peat. We sought to understand this social transition in Tumbang Nusa, one of the villages that has had a high level of intervention through the recent peatland restoration efforts. Over the last five years, several new livelihood initiatives have been deployed in Tumbang Nusa including seven capacity building programs, five government assistance programs and 18 demonstration plots, but many of these initiatives have been unsuccessful, with only a handful of farmers having adopted the outcomes. In effect, the peatland has not been rewet and the community has largely not transitioned to a more sustainable set of livelihoods. To make peatland restoration work it is critical to overcome several barriers so that communities can embrace the restoration process and can drive it autonomously, rather than needing outside input and assistance to maintain momentum. There is also a clear need for a functioning carbon market, such that peatland communities benefit from peat rewetting. Only once the community directly benefits from restoration will it actively participate in ensuring its success.