Tropical Peat Swamp Research Articles

Evaluating ex situ rates of carbon dioxide flux from northern Borneo peat swamp soils

Abstract This study quantified CO2 emissions from tropical peat swamp soils in Brunei Darussalam. At each site, soil was collected from areas of intact and degraded peat and CO2 flux, and total organic content were measured ex situ. Soil organic content (~20–99%) was not significantly different between intact and degraded forest samples. CO2 flux was higher for intact forest samples than degraded forest samples (~1.0 vs. ~0.6 μmol CO2 m−2 s−1, respectively) but did not differ among forest locations. From our laboratory experiments, we estimated a potential emissions of ~10–20 t CO2 ha−1 y−1 which is in the lower range of values reported for other tropical peat swamps. However, our results are likely affected by unmeasured variation in root respiration and the lability of resident carbon. Overall, these findings provide experimental evidence to support that clearance of tropical peat swamp forests can increase CO2 emissions due to faster rates of decomposition.

A three-dimensional (3D) printing approach to fabricate an isolation chip for high throughput in situ cultivation of environmental microbes.

The full plethora of environmental bacteria is often poorly represented in vitro as the majority remain difficult, if not impossible, to culture under standard laboratory settings. These bacteria often require native conditions for the formation of cell masses that collectively have higher chances of survival. With that, a 3D-printed version of the isolation chip (iChip) was used to cultivate bacteria from a tropical peat swamp in situ prior to growth and maintenance in vitro. Briefly, plates made from either acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), or epoxy resin were tested in terms of their usability and durability under acidic conditions similar to those of peat matter. The epoxy resin plates were then found to be most optimal for the sampling conditions. Peat soil samples were collected from the base of a Koompassia malaccensis tree and reconstituted in molten 10% (wt/vol) tryptone soy agar (TSA) prior to inoculation. The iChips were subsequently assembled and buried in the site of origin. As a comparison, bacteria from the same soil sample were cultivated directly on TSA and incubated at 28 °C for two weeks. Thereafter, agar plugs from the iChip were transferred to TSA plates to allow microcolonies within each plug to grow. Each pure isolate from both cultivation approaches that grew was then pooled and extracted for total DNA prior to 16S rRNA gene amplification and sequencing via Illumina MiSeq. Taxonomic abundance comparison revealed that the bacterial taxa at the level of order were significantly different between the two approaches, particularly in the orders, Burkholderiales, Xanthomonodales, Enterobacteriales, and Actinomycetales (differences of 12.0, 7.1, 8.0, and 4.2%, respectively). This indicated that the 3D-printed iChips present a possible low-cost tool for the isolation of bacterial genera that may not be able to grow on media directly in vitro.

The Potency of Cratoxylum arborescens Blume (Geronggang) and Combrecarpus rotundatus Dans (Tumih) as Natural Regeneration in Degraded Tropical Peat Swamp Forest

The massive forest fire disasters have left an enormous area of ​​degraded peatland. This study aims to analyze the performance of two species, namely C. arborescens and C. rotundatus, as the natural regeneration post forest fires. This research was conducted in 5 different locations that experienced severe fires in 2006. We made a total of 25 plots for each location to measure biodiversity at four growth levels. We analyzed the data with vegetation analysis formulas from Magurran. The results show that at the tree growth level, C. rotundatus can withstand the fires in 2006 and is currently still growing in more significant numbers than C. arborescens. At the pole, sapling, and seedling growth levels, these species perform well as natural regeneration species with many individuals, but C. arborescens is a bit more dominant. Both species are suitable for natural regeneration after fires in degraded peat swamp forests based on survived and existing individuals. On the other hand, both species could not improve the vegetation diversity in the whole ecosystem. These two species can be the option for natural regeneration if there a limited budget and the degraded areas are in a very remote location.

Assessing Impact of Multiple Fires on a Tropical Peat Swamp Forest Using High and Very High-Resolution Satellite Images

Tropical peat swamp forests, found mainly in Southeast Asia, have been threatened by recurring El Niño fires. Repeated burnings form a complex and heterogeneous landscape comprising a mosaic of burned patches of different fire frequencies, requiring fine-scale assessment to understand their impact. We examined the impact of the El Niño fires of 1998 and 2003 on a tropical peat swamp forest in northern Borneo, with the combined use of high and very high-resolution satellite images. Object-based and pixel-based classifications were compared to classify a QuickBird image. Burned patches of different fire frequencies were derived based on unsupervised classification of the principal components of multitemporal Normalized Difference Water Index (NDWI) data. The results show that the object-based classification was more accurate than the pixel-based classification for generating a detailed land cover map. Fire frequency had a severe impact on the number of burned patches and the residual forest cover. Larger patch area retained more residual forest cover for the burned patches. Forest structure of burned-twice patches was more severely altered compared to burned-once patches. Two burned-once patches had a relatively promising recovery potential by natural regeneration due to higher residual forest cover, a vast number of large trees, and aboveground biomass. Except for the largest patch, rehabilitation seemed inevitable for burned-twice patches. This approach can be applied to assess the impact of multiple fires on other forest types for better post-fire forest management.

Land Cover and Land Use Change Decreases Net Ecosystem Production in Tropical Peatlands of West Kalimantan, Indonesia

Deforested and converted tropical peat swamp forests are susceptible to fires and are a major source of greenhouse gas (GHG) emissions. However, information on the influence of land-use change (LUC) on the carbon dynamics in these disturbed peat forests is limited. This study aimed to quantify soil respiration (heterotrophic and autotrophic), net primary production (NPP), and net ecosystem production (NEP) in peat swamp forests, partially logged forests, early seral grasslands (deforested peat), and smallholder-oil palm estates (converted peat). Peat swamp forests (PSF) showed similar soil respiration with logged forests (LPSF) and oil palm (OP) estates (37.7 Mg CO2 ha−1 yr−1, 40.7 Mg CO2 ha−1 yr−1, and 38.7 Mg CO2 ha−1 yr−1, respectively), but higher than early seral (ES) grassland sites (30.7 Mg CO2 ha−1 yr−1). NPP of intact peat forests (13.2 Mg C ha−1 yr−1) was significantly greater than LPSF (11.1 Mg C ha−1 yr−1), ES (10.8 Mg C ha−1 yr−1), and OP (3.7 Mg C ha−1 yr−1). Peat swamp forests and seral grasslands were net carbon sinks (10.8 Mg CO2 ha−1 yr−1 and 9.1 CO2 ha−1 yr−1, respectively). In contrast, logged forests and oil palm estates were net carbon sources; they had negative mean Net Ecosystem Production (NEP) values (−0.1 Mg CO2 ha−1 yr−1 and −25.1 Mg CO2 ha−1 yr−1, respectively). The shift from carbon sinks to sources associated with land-use change was principally due to a decreased Net Primary Production (NPP) rather than increased soil respiration. Conservation of the remaining peat swamp forests and rehabilitation of deforested peatlands are crucial in GHG emission reduction programs.

The Covid-19 pandemic impact on indigenous people livelihoods in the peat swamp forest ecosystem in Central Kalimantan Indonesia

Global tropical peat swamp forest ecosystems mostly are found in Indonesia. However, these unique yet fragile ecosystems are subject to deforestation and degradation due to forest fires and land conversion. Peat swamp forests are well known for their ecosystem services related to global climate mitigation because they store carbon inside and are very vulnerable to forest fires. Another direct function is providing various needs for the indigenous people livelihoods who live close to and in the areas. This study was conducted qualitatively to assess the forest utilization and the impact of the COVID-19 pandemic on the livelihoods of indigenous people. The study results show that the Dayak Ngaju Communities utilize the forest for timber, non-timbers, medicinal plants, foods, and religious culture. There is no significant impact of COVID-19 on forest product collection activities, but the pandemic impacts the marketing and sales of forest products. The marketing of fish and other non-timber forest products has been negatively affected due to decreased demand and limited transportation. On the contrary, the use, need, and demand for medicinal plants for the traditional medicine of COVID-19 is increasing significantly and improving local livelihoods.

Influence of fire and drainage on evapotranspiration in a degraded peat swamp forest in Central Kalimantan, Indonesia

Tropical peat swamp forests (PSFs) play a significant role in the exchange of water between land and the atmosphere. However, fire and drainage have been expanding in PSFs in recent decades. Although there is concern on the influence of fire and drainage on water circulation, their influence on evapotranspiration (ET) is insufficiently understood. Furthermore, repeated fire occurrences and their corresponding influence on the ET by recurrent burning and smoldering is unexplored. To elucidate these influences, we examined long-term variation of ET in a degraded peat swamp forest in Central Kalimantan, Indonesia that was affected by drainage and repeated fire. The continuous observation of energy fluxes was conducted for approximately 13 years between 2004 and 2016 by using the eddy covariance technique. The site burned in 2009 and 2014, and was drained in 2014. Monthly ET and net radiation (Rn) fluctuated in synchrony and thus they decreased considerably under fire-induced dense haze during the El Niño drought. Troughs of ET, groundwater level (GWL) and Rn and crests of vapor pressure deficit (VPD) coincided in their time-series variations. In the case of ET > precipitation (P), ET decreased when the GWL was deeper than −0.5 m. Half-hourly ET had a strong positive correlation with Rn (R = 0.89, p < 0.01), and partial positive relationship with VPD when VPD < 20 hPa and with GWL when GWL < -0.5 m. ET had no correlation with the Enhanced Vegetation Index (EVI), which represents above ground biomass for the entire observation period. Alternately, the results of path analysis showed that some environmental factors controlled ET differently depending on environmental conditions. Generally, VPD negatively affected ET due to stomatal regulation functions under dry atmospheric conditions. However, the effect was negligible during the water-logged periods. This is because atmospheric dryness facilitated evaporation from exposed water on the ground surface, which canceled out the negative effect of transpiration due to stomatal closure. After drainage by canal excavation, fluctuation of GWL did not significantly influence ET, although ET decreased. This may be due to the hydrophobic dried peat soil, which prevents rainwater infiltration, disconnection of capillary force, or disabled root water uptake as GWL excessively deepened. Fire potentially decreased ET due to decreased transpiration by burning of vegetation. However, the decreasing effect was cancelled by increased evaporation from the waterlogged ground surface during the subsequent La Niña event. Drainage undoubtedly deepened the GWL, and ET severely decreased in cases with extremely deep GWL.

Temporal patterns control carbon balance in forest and agricultural tropical peatlands in North Selangor, Malaysia

Tropical peat swamp forests can sequester significant amount of carbon (C). However, there is dearth of understanding on the tropical soils’ C stocks and emissions because of the changes in peatland use, land use policies, and micro-climate. The objective of this study was to determine the C stocks and fluxes of two peat swamp forests and a peatland under mixed cropping in Selangor, Malaysia. Standard procedures were used to determine aboveground biomass, belowground biomass, selected peat soil physical, chemical, and biological properties, and environmental variables that are related to peat soil respirations. The mean C stocks for the peat swamp forest and mixed cropping sites were 1788.79 Mg C ha-1 and 1023.57 Mg C ha-1, respectively. The carbon dioxide emission rates of peat swamp forest and mixed cropping sites ranged from 7.20 to 73.13 tCO2 ha-1 year-1 and 26.50 to 43.43 tCO2 ha-1 year-1, respectively. These emissions are related to seasonal changes because the relative humidity, soil temperature, and ground water of the experimental sites had significant effects on soil respiration. Unlike the mixed cropping sites, the fluxes of the peat swamp forest were significantly higher in the dry season compared with the wet season. These findings suggest that peat soil respiration is controlled by relative humidity, temperature, and the changes in ground water table. Continued monitoring and conservation efforts to preserve stored C in peatlands are essential.

Identification of Bird species in Wetlands around Siran Lake, Muara Kaman, Central Mahakam, East Kalimantan

The avifauna of tropical peat swamp forests in East Kalimantan has not been well documented because of the smallest peat area compared to central Kalimantan. The surveys were conducted using various methods in the Muara Siran peat swamp forests and surrounding areas of Lake Siran (heath forest and riparian) in East Kalimantan, Indonesia. These findings were recorded on a list of 80 bird species as well as in numerous noteworthy records. Wetlands are an essential habitat for many threatened and near-threatened bird species. We also discovered Gallinula tenebrosa in Siran Lake, a species that has not been seen in over a century. However, it has a wide distribution globally, including in Australia and the United States. In the peat swamp forest, we recorded Cymbirrhinchus macrurus and Ichtyophaga humilis, rare and widely distributed. We also found Dicrurus hottentotus and Dicrurus remifer, some species of Ferruginous Babbler, Trichastoma bicolor, and the White-necked Babbler, Stachyris leucotis. The Hook-billed bulbul Setornis criniger and the Sooty capped Babbler Malacopteron affinae are found in riparian forests. There are six species of woodpecker. Dryocopus javensis, Great Slaty Woodpecker, Mulleripicus pulverulentus, Meyglyptes tukki, Picus puniceus, and Sasia abnormis. Cuckoo-shrike Coracina striata and Pitta sordia were also discovered. Wetlands (peat swamp forest, heath forest, and riparian areas) should be better protected due to their importance to many species, particularly from destruction and loss of habitat caused by forest fires.

Keanekaragaman Jenis Herpetofauna (Ordo Squamata) di Kawasan Hutan Rawa Gambut Tropis Mangsang-Kepayang, Sumatera Selatan

Herpetofauna is a group of fauna consisting of amphibians and reptiles. The Squamata Order is one of the Reptiles that has the highest number of species. The Mangsang-Kepayang tropical peat swamp forest area of South Sumatra kepayang is one of the key biodiversity on the island of Sumatra. The diversity of herpetofauna can be used as a parameter of the balance and quality of the area where it lives. The problem raised in this study is how is the diversity of herpetofauna species (order Squamata) in the area of the tropical peat swamp forest of Mangsang-Kepayang, South Sumatra? Based on the problems that arise, then this study aims at the diversity of herpetofauna species (order Squamata) in the area of tropical peat swamp forest in Mangsang-Kepayang, South Sumatra. Sampling along the Boyong-Code River from upstream to downstream uses a combination of several methods, namely VES (Visual Encounter Survey), Time Search, and Road Cruising. The results obtained are 7 species of members of the Suborder Lacertilia (lizards) and 2 species of members of the Suborder Serpentes (snakes). Based on these results it can be seen that the area of Mangsang-Kepayang tropical peat swamp forest in South Sumatra is a suitable habitat for Squamata Order members.

The environmental implications of upper Paleozoic plant-fossil assemblages with mixtures of wetland and drought-tolerant taxa in tropical Pangea

We evaluate the influences of elevation and climate on the spatio-temporal distribution of wetland and dryland biomes during the Pennsylvanian and early Permian in tropical Pangea. The longstanding “upland model” places drought-tolerant vegetation in elevated habitats, where slope and drainage created moisture-limited substrates under a humid climate that simultaneously promoted peat accumulation in contemporaneous lowlands. Upland plants were periodically transported to, and buried in, lowlands. Rare preservation of dryland vegetation thus reflects its general absence in basins, and taphonomic vagaries of long-distance transport. The alternative “climate model” proposes that drought-tolerant plants dominated tropical habitats when climate was seasonally dry, with wetland vegetation reduced to scattered refugia. Environmental changes attending glacial-interglacial cycles caused alternating wetter-drier conditions, and the relative abundance of wetland versus dryland biomes in basinal lowlands thus varied with climatic oscillations. The paucity of drought-tolerant plants reflects a preservational megabias against habitats with seasonal moisture deficits.The environmental signal of “mixed” plant-fossil assemblages, comprising taxa characteristic of both wetland and dryland biomes, may help resolve these debates. We review key Pennsylvanian and lower Permian mixed assemblages from tropical Euramerican Pangea, and interpret their original habitats and climatic contexts based on multidisciplinary lines of evidence, including sedimentology, taphonomy, physiology, and paleoecology. Evaluations also consider patterns of vegetational distribution and taphonomy in modern tropical environments. We suggest that even a cursory view of current tropical plant distribution exposes flaws in the upland model. Where tropical climate is sufficiently humid to support peat swamps, slopes and elevated habitats do not host drought-tolerant vegetation, but are occupied by plants similar to those in lowland settings. This occurs because equable, high precipitation strongly dampens water-table variation across entire landscapes. Furthermore, taphonomic studies indicate that most plant-fossil assemblages record vegetation living near the burial site. Fossil floras thus reflect environmental conditions near their growth site, excluding an upland origin for most occurrences of drought-tolerant taxa. Conversely, the climate model is consistent with modern tropical vegetational distribution and soundly explains late Paleozoic floristic patterns. When Pangean tropical lowlands experienced seasonally dry conditions, plants tolerant of moisture deficits dominated most habitats, whereas wetland vegetation was restricted to wetter sites with greater preservation potential. This occurred because topographic variations are magnified under seasonal precipitation regimes, creating a complex habitat mosaic with wetland patches in a landscape subject to seasonal drought. Accordingly, we propose that a macrofloral assemblage with even rare drought-tolerant taxa indicates seasonality in the broader landscape.At larger spatio-temporal scales, disagreement also persists about whether tectonic uplift or long-term climatic drying was the primary driver of changes in late Paleozoic floristic patterns and areal extent of tropical peat swamps. We argue that tectonic activity alone cannot explain the drastic reduction in peat swamps or coincident changes in dominance-diversity of wetland vegetation. Rates of plant dispersal and evolution far outpace that of mountain building, and peat-forming wetlands persisted in elevated habitats well into the Late Pennsylvanian. Therefore, progressive late Paleozoic aridification was the most probable driver of changing floral patterns and the distribution of wetland and dryland biomes in tropical Pangea.

Assessing the carbon dioxide balance of a degraded tropical peat swamp forest following multiple fire events of different intensities

Tropical peat swamp forest is a unique ecosystem rich in carbon and water, accumulating a huge amount of carbon as peat. However, the huge carbon pool has been threatened by oxidative peat decomposition and fire loss mainly because of deforestation and drainage. Fire causes acute carbon dioxide (CO2) emissions through the combustion of biomass and peat. Also, fire should change the CO2 balance of postfire ecosystems. Although it is crucial to quantify CO2 balance even after a fire event to understand the total fire impact, information based on field measurement is lacking. Thus, we had measured eddy CO2 flux above a repeatedly burned degraded peat forest for about 13 years since 2004. The site was a stable CO2 source of 147−290 g C m−2 yr−1 for five years after a stand-replacing fire in 2002. Unexpectedly, a moderate-severity fire in 2009 changed the site to a CO2 sink of about −600 g C m−2 yr−1. The drastic change would have been caused by a large decrease in the decomposition of plant debris, which had accumulated since the 2002 fire but was burned by the 2009 fire. In contrast, gross primary production (GPP) remained about the same even though vegetation was damaged, mainly because year-round wet conditions caused by a La Niña event promoted the regrowth of hygrophilous herbaceous plants and were favorable to their GPP. The site also had a low-severity fire and was drained in 2014 but did not return to a CO2 source. However, the net ecosystem CO2 uptake after the 2009 fire was insufficient to recover a large amount of fire CO2 emission. If CO2 emissions from four fires in 1999, 2002, 2009 and 2014 are counted, the site is expected to owe an outstanding CO2 debt of 25 kg C m−2.

Linking prokaryotic community composition to carbon biogeochemical cycling across a tropical peat dome in Sarawak, Malaysia

Tropical peat swamp forest is a global store of carbon in a water-saturated, anoxic and acidic environment. This ecosystem holds diverse prokaryotic communities that play a major role in nutrient cycling. A study was conducted in which a total of 24 peat soil samples were collected in three forest types in a tropical peat dome in Sarawak, Malaysia namely, Mixed Peat Swamp (MPS), Alan Batu (ABt), and Alan Bunga (ABg) forests to profile the soil prokaryotic communities through meta 16S amplicon analysis using Illumina Miseq. Results showed these ecosystems were dominated by anaerobes and fermenters such as Acidobacteria, Proteobacteria, Actinobacteria and Firmicutes that cover 80–90% of the total prokaryotic abundance. Overall, the microbial community composition was different amongst forest types and depths. Additionally, this study highlighted the prokaryotic communities’ composition in MPS was driven by higher humification level and lower pH whereas in ABt and ABg, the less acidic condition and higher organic matter content were the main factors. It was also observed that prokaryotic diversity and abundance were higher in the more oligotrophic ABt and ABg forest despite the constantly waterlogged condition. In MPS, the methanotroph Methylovirgula ligni was found to be the major species in this forest type that utilize methane (CH4), which could potentially be the contributing factor to the low CH4 gas emissions. Aquitalea magnusonii and Paraburkholderia oxyphila, which can degrade aromatic compounds, were the major species in ABt and ABg forests respectively. This information can be advantageous for future study in understanding the underlying mechanisms of environmental-driven alterations in soil microbial communities and its potential implications on biogeochemical processes in relation to peatland management.

Short- and long-term carbon emissions from oil palm plantations converted from logged tropical peat swamp forest.

Need for regional economic development and global demand for agro-industrial commodities have resulted in large-scale conversion of forested landscapes to industrial agriculture across South East Asia. However, net emissions of CO2 from tropical peatland conversions may be significant and remain poorly quantified, resulting in controversy around the magnitude of carbon release following conversion. Here we present long-term, whole ecosystem monitoring of carbon exchange from two oil palm plantations on converted tropical peat swamp forest. Our sites compare a newly converted oil palm plantation (OPnew) to a mature oil palm plantation (OPmature) and combine them in the context of existing emission factors. Mean annual net emission (NEE) of CO2 measured at OPnew during the conversion period (137.8MgCO2 ha-1 year-1 ) was an order of magnitude lower during the measurement period at OPmature (17.5MgCO2 ha-1 year-1 ). However, mean water table depth (WTD) was shallower (0.26m) than a typical drainage target of 0.6m suggesting our emissions may be a conservative estimate for mature plantations, mean WTD at OPnew was more typical at 0.54m. Reductions in net emissions were primarily driven by increasing biomass accumulation into highly productive palms. Further analysis suggested annual peat carbon losses of 24.9MgCO2 -Cha-1 year-1 over the first 6years, lower than previous estimates for this early period from subsidence studies, losses reduced to 12.8MgCO2 -Cha-1 year-1 in the later, mature phase. Despite reductions in NEE and carbon loss over time, the system remained a large net source of carbon to the atmosphere after 12years with the remaining 8years of a typical plantation's rotation unlikely to recoup losses. These results emphasize the need for effective protection of tropical peatlands globally and strengthening of legislative enforcement where moratoria on peatland conversion already exist.

Influence of disturbances and environmental changes on albedo in tropical peat ecosystems

Tropical peat swamp forests have been experiencing drastic disturbances, such as deforestation, drainage, and fire. We examined how such disturbances influence albedo, which regulates radiative energy exchange between the terrestrial surface and the atmosphere. We conducted continuous field observations at three sites: undrained forest (UF), drained forest (DF), and drained burned ex-forest (DB), in Central Kalimantan, Indonesia, for over 13 years.Observed albedo was strongly influenced by haze caused by fire because the haze layer covering the canopy has a relatively high reflectance. Under severe haze conditions in October 2015, apparent albedo increased to 0.156, 0.162, and 0.183 at the UF, DF, and DB sites respectively. Mean monthly albedos excluding fire periods were 0.094 ± 0.005, 0.092 ± 0.006, and 0.099 ± 0.017 (mean ± 1 standard deviation) at the UF, DF, and DB sites respectively. Seasonal fluctuation in albedo at the DB site, where ferns were dominant, was greater than at the UF and DF sites.Albedo at the DF site was significantly lower than that at the UF site from February to August (p < 0.05). At the forest sites the albedo increased as groundwater level decreased. Albedo was higher under high vapor pressure deficit at all sites. At the DB site albedo decreased when the soil surface was water-saturated and patched with puddles, potentially due to the low albedo of open water. The albedo at the DB site was lower than that at the forest sites at the beginning of the observation period. Subsequently, the albedo increased and exceeded those at the UF and DF sites immediately after fire damage in 2009. This could be explained by the expansion of bright-colored ferns and sedges over dark-colored peat soil. According to our results, haze, groundwater level, and vegetation cover significantly influence albedo in tropical peat swamp forests.

The early benefits of agroforestry as the solution of social conflict and peat land degradation in Kampar - Riau, Indonesia

Agroforestry has been mentioned has good potency to be selected as one of the tools to overcome the problem of degraded tropical peat swamp forest (TPSF) which was associated with social conflict. Here, we evaluated the early benefits of agroforestry for some aspects which has relationship with the attempt to overcome social conflict and peatland degradation*. We established the experimental plot of agroforestry in the conflict area at forest area with special purpose (KHDTK) in Kepau Jaya Village, Kampar District, Riau Province. We planted three native tree species of TPSF, namely were Balangeran(Shorea balangeran), Geronggang(Cratoxylum arborescens)and Gelam(Melaleuca cajuputi subsp. cumingiana.In this plot, between rows of tree plantation the local farmer cultivated their crop. At 11 months after plantation; the ranges of survival rate, height and collar diameter increment of all tree native species were 56.2% - 72.44%, 97.4 m/year – 163.0 m/year and 2.04 cm/year – 3.2 cm/year, respectively. Furthermore, from the yields of the three types of seasonal crops (melon, chilli and luffa), the average income which was gathered by farmers was of 6,000,000 IDR. We also observed that during this agroforestry activity, the intensity of forest disturbance by the local community around KHDTK was relatively reduced. It is important to manage and increase those diverse benefits in further years.

Assessment of yeasts in tropical peat swamp forests in Thailand

Despite the abundance of yeasts in peatland, only a few studies on peatland yeasts have been reported and, further, most of those studies were carried out in boreal regions. In response, this study assesses yeast communities in tropical peat swamp forests (PSFs). Peat soils or soils from a primary or natural PSF were collected in Thailand at Khanthuli PSF (PKT), while those from secondary or disturbed PSFs were collected from Khanthuli (SKT) and Khuankreng PSFs (SKK). Clone libraries of each sample were separately constructed using PCR products of the D1/D2 domains of the large subunit ribosomal DNA. Most of the yeast operational taxonomic units (OTUs) detected in Khanthuli PSF, both PKT and SKT, belonged to the phylum Ascomycota. Meanwhile, most of the yeast OTUs in SKK belonged to Basidiomycota. Each PSF area exhibited a specific yeast community. Only a few OTUs were shared between the different areas. The dominant yeast species in PKT and SKT was Galactomyces candidus, whereas in SKK, it was Solicoccozyma keelungensis. Saccharomyces cerevisiae was the only common species in each area. In addition, many more potential new yeast taxa are still undiscovered in the peatlands. The canonical correspondence analysis (CCA) showed that the abundance of G. candidus was related to sites with higher nitrogen concentrations and higher pH, while the abundance of So. Keelungensis was related to a combination of pH and electrical conductivity rather than total potassium contents. These results suggest that yeast communities in primary and secondary PSFs were different, which may be due to both biotic and abiotic factors.

Land-Use Changes and the Effects of Oil Palm Expansion on a Peatland in Southern Thailand

Tropical peatlands are one of the largest reservoirs of terrestrial organic carbon. However, present-day tropical peat swamp forests are under threat by anthropogenic disturbances and have already been widely degraded. Anthropogenic pressures on peatland ecosystems have resulted in ecological and biogeochemical changes and the release of carbon to the atmosphere. In Southeast Asia, the conversion of peatlands to oil palm plantations has accelerated significantly during the last 2 decades. This research analyzed direct and indirect land-use changes (DLUC and ILUC) that have been associated with oil palm expansion and anthropogenic impacts in the Princess Sirindhorn Wildlife Sanctuary (PSWS), Narathiwat, southern Thailand. Our analysis is based on land-use and land-cover data of the Land Development of Thailand from two different periods: 2000–2009 and 2009–2016. For the purpose of comparison, the data were reclassified into 12 types of land use: oil palm, para rubber, paddy field, abandoned paddy field, orchard, other agriculture lands, wetlands and peatlands, mangrove, evergreen forest, water area, build-up area, and unused area. In addition, the area of net change due to DLUC and ILUC was calculated, and carbon stock changes were estimated from above- and below-ground biomass and soil organic carbon. The results show that the total oil palm plantation area has increased from 0.04% in 2000 to 6.84% in 2016, because of a Thai government policy promoting the use of biodiesel and increasing capacity of palm oil production in 2005. Paddy field, evergreen forest, wetlands, and peatlands were the main areas being replaced. The clearance of natural forest greatly increased in the period of 2000–2009. The ILUC indicates that the expansion of oil palm plantations invades other croplands (paddy field, para rubber, and orchard). The results demonstrate that the conversion of natural landscapes (evergreen forest, mangrove, wetlands, and peatlands) to oil palm plantations at Princess Sirindhorn Wildlife Sanctuary area had a negative effect, with carbon stock changes of 4 million Mg C during 2000–2016 (0.25 million Mg C/year). Given the significance of carbon stock changes arising from land-use changes, this research highlights the need for sustainable land-use management and long-term monitoring.

Chitinophaga extrema sp. nov., isolated from subsurface soil and leaf litter in a tropical peat swamp forest

A Gram-negative, filamentous aerobic bacterium designated as strain Mgbs1T was isolated on 12 April 2017 from the subsurface soil and leaf litter substrate at the base of a Koompassia malaccensis tree in a tropical peat swamp forest in the northern regions of the state of Selangor, Malaysia (3° 39' 04.7' N 101° 17' 43.7'' E). Phylogenetic analyses based on the full 16S rRNA sequence revealed that strain Mgbs1T belongs to the genus Chitinophaga with the greatest sequence similarity to Chitinophaga terrae KP01T (97.65 %), Chitinophaga jiangningensis DSM27406T (97.58 %), and Chitinophaga dinghuensis DHOC24T (97.17 %). The major fatty acids of strain Mgbs1T (>10 %) are iso-C15 : 0, C16 : 1 ω5c and iso-C17 : 0 3-OH while the predominant respiratory quinone is menaquinone-7. Strain Mgbs1T has a complete genome size of 8.03 Mb, with a G+C content of 48.5 mol%. The DNA-DNA hybridization (DDH) score between strain Mgbs1T and C. jiangningensis DSM27406T was 15.9 %, while in silico DDH values of strain Mgbs1T against C. dinghuensis DHOC24T and C. terrae KP01T were 20.0 and 19.10% respectively. Concurrently, Average Nucleotide Identity (ANI) scores between strain Mgbs1T against all three reference strains are 73.2 %. Based on the phenotypic, chemotaxonomic, and phylogenetic consensus, strain Mgbs1T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga extrema sp. nov. is proposed (=DSM 108835T=JCM 33276T).

Dissolved organic carbon and physicochemical variables of peat water in tropical peat swamp forests

Degradation of peatlands in Indonesia has been caused by fires, drainage, and deforestation of peat swamp forests. Fires release carbon dioxide (CO2) intensively but occasionally, whereas drainage enhances CO2 emission from the soil and dissolves organic carbon (DOC) leaching through peat water flow. DOC was affected not only by peat degradation but also by the physicochemical variables of peat water. A study on DOC and physicochemical variables of peat water to investigate the effects of drainage and fires has been conducted in three tropical peat swamp forests of Central Kalimantan. They were a relatively intact peat swamp forest with little drainage (UF), a drained peat swamp forest (DF), and a drained, burnt peat swamp forest (DB). The DOC concentration was analyzed using a total organic carbon (TOC) analyzer, while physicochemical variables, including electrical conductivity (EC), pH, and inorganic nitrogen were measured using EC meter, pH meter, and ion analyzer, respectively. Research results showed that the highest DOC concentration was measured in DF, whereas the lowest DOC concentration was in DB. DOC was resulted from peat decomposition due to low pH, low C/N, and high EC conditions. These results indicate that DOC leaching through peat water flow may occur by drainage rather than fires.