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PEATMAP: Refining estimates of global peatland distribution based on a meta-analysis
Abstract
Peatlands play important ecological, economic and cultural roles in human well-being. Although considered sensitive to climate change and anthropogenic pressures, the spatial extent of peatlands is poorly constrained. We report the development of an improved global peatland map, PEATMAP, based on a meta-analysis of geospatial information collated from a variety of sources at global, regional and national levels. We estimate total global peatland area to be 4.23 million km 2 , approximately 2.84% of the world land area. Our results suggest that previous global peatland inventories are likely to underestimate peat extent in the tropics, and to overestimate it in parts of mid-and high-latitudes of the Northern Hemisphere. Global wetland and soil datasets are poorly suited to estimating peatland distribution. For instance, tropical peatland extents are overestimated by Global Lakes and Wetlands Database – Level 3 (GLWD-3) due to the lack of ground-truthing data; and underestimated by the use of histosols to represent peatlands in the Harmonized World Soil Database (HWSD) v1.2, as large areas of swamp forest peat in the humid tropics are omitted. PEATMAP and its underlying data are freely available as a potentially useful tool for scientists and policy makers with interests in peatlands or wetlands. PEATMAP's data format and file structure are intended to allow it to be readily updated when previously undocumented peatlands are found and mapped, and when regional or national land cover maps are updated and refined.
... Over the past decades, a number of studies have assessed the extent and distribution of peatlands (e.g. Lehner & Döll, 2004;FAO, 2012;Xu et al., 2018). A short overview of PSF based on different studies can be found in Table 2.1. ...
... A short overview of PSF based on different studies can be found in Table 2.1. In a recent study, Xu et al. (2018) reports that world's peatlands cover around 2.84% (423 Mha) of the global terrestrial area, where Asia represents 38.4%, North American contains 31.6%, and the others including Africa 4.4%, Australasia and Oceania 1.6%, Europe 12.5% and South America 11.5% ...
... 1 Estimates of global peatland areas from a variety of studies (Source:Xu et al., 2018) ...
Peat swamp forest (PSF) is an ecosystem of global significance. It sequesters and stores atmospheric carbon, regulate hydrological system, provide habitat for many endemic wildlife, and deliver livelihoods support to thousands of local people. Despite these values, during the last several decades PSF have been subject to extensive deforestation and degradation globally. A significant portion (7%) of the Malaysia’s total land mass is PSF that are traditionally managed with the state governance system. However, depletion of this PSF has been continued due to various anthropological causes including intensive logging, drainage, fire, conversion to agriculture, oil pam, settlement, industry etc. Continued depletion of PSF with the centralized governance system (in other ways, here, state forest management, SFM system), and the success of community-based forest management (CBFM) approach in many countries of the world motivated several South-East Asian (SEA) countries to impart changes in their governance system from traditional centralized/state governance approach to CBFM approach. Recently, in Malaysia, specifically State Government of Selangor introduced CBFM approach in the governance of depleted PSF at Raja Musa Forest Reserve (RMFR) in collaboration with Global Environment Centre (GEC, a national non-government organisation). However, the success and/or failure of the newly applied CBFM approach in terms of PSF restoration and community development has not been fully explored yet. The aim of this research was to understand the effectiveness of community participation toward restoration and sustainable conservation of degraded PSF of RMFR in Peninsular Malaysia, with the following objectives: (i) ascertain characteristics of peat, peatland and peat swamp forest, and activities involve in PSF restoration through literature review, (ii) examine the formation and functions of social capital, and the level of community participation in PSF restoration, (iii) analyse the impacts of institutional setting and governance on sustainable conservation and community-based PSF restoration, (iv) assess ecological outcomes of community-based PSF restoration programme, and (v) examine the effect of management regimes of the PSF on local peoples’ socio-economic and environmental benefits. To attain these objectives, the study deployed a pluralistic research approach of social research and ecological (e. g. vegetation survey) study. For social research, both qualitative and quantitative data were collected through a stakeholders’ workshop (with the presence of 49 participants from federal and state Forestry Department, other government agencies, NGOs, local government, academics, local community leaders), four focus group discussions, five key informant interviews and 200 household interviews in four adjacent villages of RMFR. In addition, secondary data was collected from official documents of GEC local office. Building on the concepts and theoretical framework of social capital and level of participation, this research found that some social capital has been developed through forming three local organizations viz. Friends of North Selangor Peat Swamp Forest (FNSPSF), Junior Peatland Forest Ranger (JPFR) and Peatland Forest Ranger (PFR), and integrating another existing organization (Homestay agro-tourism Sungai Sireh) in the restoration programme. In addition, some structural social capital (bonding, bridging and linking) among local community, other similar organizations, NGOs and SSFD have also been developed. But trust (cognitive social capital) among local community, and GEC and SSFD was in question and economic development activities were also very minimal, which demotivated local community and thus showed low level of their participation in the restoration programme. I concluded to reform the organizational structure of local community-based organizations (CBO) by forming two site specific CBOs on local environment namely Forest Conservation and Recreation Village (FCRV), and Forest Restoration Village (FRV), in addition to the current FNSPSF for improving local involvement in the PSF restoration and community development programme. Based on Institutional Analysis and Development framework and concepts of forest property rights (specifically de facto rights), empirical qualitative and quantitative research was carried out on the effectiveness of the local community participation on PSF governance at RMFR; and the impacts of CBFM approach on the de facto rights. I found that CBFM regime had a significant impact on the reduction of exercising de facto rights, which might be related to improved monitoring and enforcement. Further, I identified seven major categories of actors who are actively involved in the PSF restoration programme; however, two actors such as GEC and SSFD play the key role in all governance functions and interact with most of the actors. FNSPSF (key local CBO), have very insignificant role and limited interaction with other actors in the current governance structure. The actors’ participation was enabled by a number of regional, national and local level strategy, policy, and agreements. Although the emergence of the current CBFM showed its effectiveness in the PSF restoration programme; however, limited participation of local community (in particular FNSPSF) in PSF governance posed the major threat to the sustainability of this multi-stakeholder PSF restoration programme. I recommended to put FNSPSF at the centre of the collaborative organizational structure with policy, capacity building and funding support to improve the efficacy and to sustain this newly emergent multi-stakeholder PSF governance. The study on the ecological outcomes of the community-based restoration programme was assessed by collecting data through focus group discussions and key informant interviews (for data on restoration approach), official documents (for data on plantation establishment, water table monitoring and fire incidences) and vegetation survey (for data on planted tree growth and natural regeneration data). Results revealed that PSF rewetting (e.g. improvement of water table) can be achieved with canal blocking and clay dyke construction; further, fire incidences can be reduced through improving water table, providing training on fire drill, creating awareness, and involving local community in forest vigilance. However, annual rate of plantation (about 30 hectares (ha) per year) was found low compared to the total targeted plantation area (1,000 ha). The composition of planted species is limited to only Euodia redlevi with some few other species e.g. Shorea leprosula, Myristica lowiana and M. pruinosa. The average survival rate is 65% with a MAI (mean annual increment) of diameter and height of E. redlevi decreased from younger plantations (3-year) toward older (5-, 7-year). Sixteen regenerating species was identified with an average of 17,798 seedlings ha-1. Natural regeneration was dominated by E. redlevi and only 10.6% of the regeneration could survived to the young tree stage. I recommend to expedite the plantation with diverse potential native species and giving emphasis on post-plantation maintenance. The perceived environmental and socio-economic benefits derived from the community-based restoration programme and local community’s willingness to participate revealed through four focus group discussions, five key-informant interviews and 200 household interviews. I found that CBFM approach has helped to improve some societal and economic benefits including introduction of nature-based recreation, increased income from eco-tourism and community nursery establishment, and nature education and research, and declined PSF conversion to other land uses. On the other hand, perceived environmental benefits including water storage and supply for irrigation, biodiversity and habitat conservation, carbon sequestration capacity of the community-based PSF restoration programme and the material benefits from timber and non-timber forest products (NTFP) supply has not showed any significant improvement yet. This study provides a number of recommendations which highlights institutional such as local level CBOs and multi-stakeholder governance structure, and legal reform, and capacity building of the local community through training and fund streaming to strengthen the community-based PSF governance in Malaysia. In addition, recommendations regarding ecological restoration points out to continue the canal blocking activities with proper maintenance and community patrolling, expedite the annual tree planting rate, increase the number of planted species, and enrichment plantation with diverse species in the planted and assisted natural regeneration forests. I highlight the potential of this study to influence policy space in Malaysia and other SEA countries, as they have similar socio-economic conditions, PSF degradation contexts, and community-based restoration possibilities.
... Peatlands in various regions of the world have been drained by man, leading to radical changes in organic soil-forming process [9,[20][21][22][23][24][25][26]. The lack of land and the hunger after the Second World War significantly intensified these transformations [8]. ...
... Drainage of organic soils may also occur in natural conditions, due to both climate change (warming and drought periods) and changes in hydrology, e.g., deepening of the river bed as a result of deep-seated erosion. Such episodes of the natural desiccation of peatlands occurred many times in the Holocene and are recorded in the stratigraphy of peat deposits [16,25]. Degradation of organic soils caused by their drainage carries a high risk to the environment and agricultural management. ...
... Organic soils are productive, and fertile, but when drained, their water retention and filtration are disturbed, the carbon can no longer be stored (and is released), and plant and animal habitats are lost. Drained organic soils have reduced water storage capacity, and organic matter mineralization releases greenhouse gases into the atmosphere, as well as nutrients to groundwaters [2,9,12,21,[25][26][27][28][29]. Degraded organic soils have limited agricultural usefulness, and are exposed to wind erosion and fires (which are difficult to extinguish). ...
Organic soils that had been drained in order to obtain fertile agricultural land underwent changes leading to the formation of mursh (also known as moorsh). The mursh-forming process is a generic soil process that occurs in drained (artificially or naturally) organic soils, and leads to the changes in soil morphology, soil physical properties (including water retention capability), physicochemical properties, and chemical and biological properties. The aim of the paper is to present scientific knowledge on mursh soils, especially those that are not available to the wider audience. We firstly reviewed scientific literature on the mursh (moorsh) forming process of drained organic soils used for agriculture. We described the specific character of organic soils, differences between mursh and peat, the origin of the mursh-forming process, and the classification of organic soils (Histosols). Additionally, we described the changes in organic matter, such as the loss of soil carbon, increase of availability of plant nutrients, and leaching of biogens to groundwater. We revealed that the mineral matter in organic soils can be an indicator for distinguishing various types of murshes. We have highlighted the current gaps in the research that need to be filled in. The mursh-forming process is inherently related to the mineralization of soil organic matter and leads to a reduction of organic carbon in soil. Mursh has many unfavorable properties with regards to agriculture and environmental management. These properties are mainly related to decreased water storage capacity, which significantly limits the hydrological function of organic soils. The use of drained organic soils is a trade-off between environmental quality and agricultural production.
... The formation of this thick organic soil layer requires wet and low-oxygen conditions that prevent dead plant litter from being fully decomposed (Finlayson and Milton, 2018). Around 85 % of global peatlands C storage is in northern high-latitude regions (415 ± 150 Pg C) (Nichols and Peteet, 2019;Turunen et al., 2002) where low temperature and relatively high precipitation create favorable conditions for peat accumulation (Xu et al., 2018;Hugelius et al., 2020). ...
... For a given grid cell where wetland abundance is n % (n is an integer), λ thres is the TWI value of the nth largest TWI values among 100 bins. The spatially explicit wetland fraction (n %) during 1940-1990 is consistent with the wetland fraction in 1990 in the Holocene simulation, which is the average value of three peatland maps covering the pan-Arctic region (Xu et al., 2018;Hugelius et al., 2020;Melton et al., 2022). The shallowest WTD in each grid cell is ...
... As for the PET calibration, spatially explicit k c−pft values are also calibrated by PEST (v17.2 for Linux). The wetland abundance at the end of the Holocene simulation (i.e., reference dataset) (Xu et al., 2018;Hugelius et al., 2020;Melton et al., 2022) and the wetland abundance interpolated by TOPMODEL from calibrated WTD (average of 1940-1990) are shown in Fig. 2. Notably, the extent of pan-Arctic peatlands is used as an approximation of pan-Arctic wetlands because the northern peatland extent is estimated to be 2.9-3.3 Mkm 2 , with an average of 3.05 Mkm 2 (Xu et al., 2018;Hugelius et al., 2020;Melton et al., 2022), while the northern wetland extent is estimated to be 3.2 Mkm 2 (Olefeldt et al., 2021), indicating that northern wetlands are dominated by northern peatlands. ...
Northern peatlands have been a large C sink during the Holocene, but whether they will keep being a C sink under future climate change is uncertain. This study simulates the responses of northern peatlands to future climate until 2300 with a Peatland version Terrestrial Ecosystem Model (PTEM). The simulations are driven with two sets of CMIP5 climate data (IPSL-CM5A-LR and bcc-csm1-1) under three warming scenarios (RCPs 2.6, 4.5 and 8.5). Peatland area expansion, shrinkage, and C accumulation and decomposition are modeled. In the 21st century, northern peatlands are projected to be a C source of 1.2–13.3 Pg C under all climate scenarios except for RCP 2.6 of bcc-csm1-1 (a sink of 0.8 Pg C). During 2100–2300, northern peatlands under all scenarios are a C source under IPSL-CM5A-LR scenarios, being larger sources than bcc-csm1-1 scenarios (5.9–118.3 vs. 0.7–87.6 Pg C). C sources are attributed to (1) the peatland water table depth (WTD) becoming deeper and permafrost thaw increasing decomposition rate; (2) net primary production (NPP) not increasing much as climate warms because peat drying suppresses net N mineralization; and (3) as WTD deepens, peatlands switching from moss–herbaceous dominated to moss–woody dominated, while woody plants require more N for productivity. Under IPSL-CM5A-LR scenarios, northern peatlands remain as a C sink until the pan-Arctic annual temperature reaches −2.6 to −2.89 ∘C, while this threshold is −2.09 to −2.35 ∘C under bcc-csm1-1 scenarios. This study predicts a northern peatland sink-to-source shift in around 2050, earlier than previous estimates of after 2100, and emphasizes the vulnerability of northern peatlands to climate change.
... Peatlands cover only~3% of global land area (Xu et al., 2018), but the carbon they store is equivalent to around twice that of global forests (Pan et al., 2011). Peatlands have accumulated~600 Gt of carbon during the Holocene, primarily at mid-to high-latitudes in the Northern Hemisphere (Yu et al., 2010). ...
... Symbols with a white fill indicate that no charcoal was present throughout a record. Grey shading denotes peatland areas sourced from PEATMAP(Xu et al., 2018). ...
Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale relies heavily on individual site-based reconstructions. For the first time, we synthesise peatland macrocharcoal records from across North America, Europe, and Patagonia to reveal regional variation in peatland burning during the Holocene. We used an existing database of proximal sedimentary charcoal to represent regional burning trends in the wider landscape for each region. Long-term trends in peatland burning appear to be largely climate driven, with human activities likely having an increasing influence in the late Holocene. Warmer conditions during the Holocene Thermal Maximum (∼9–6 cal. ka BP) were associated with greater peatland burning in North America's Atlantic coast, southern Scandinavia and the Baltics, and Patagonia. Since the Little Ice Age, peatland burning has declined across North America and in some areas of Europe. This decline is mirrored by a decrease in wider landscape burning in some, but not all sub-regions, linked to fire-suppression policies, and landscape fragmentation caused by agricultural expansion. Peatlands demonstrate lower susceptibility to burning than the wider landscape in several instances, probably because of autogenic processes that maintain high levels of near-surface wetness even during drought. Nonetheless, widespread drying and degradation of peatlands, particularly in Europe, has likely increased their vulnerability to burning in recent centuries. Consequently, peatland restoration efforts are important to mitigate the risk of peatland fire under a changing climate. Finally, we make recommendations for future research to improve our understanding of the controls on peatland fires.
... Peatlands have been recognized as globally important carbon sinks over a long period resulting in a net global climate cooling effect during the Holocene [1]. The world's peat swamp forest area is around 44 Mha or 11% of the world's forest area [2] and 2.84% of the world's land area [3], containing around 500 -700 Gt of carbon [4] equivalent to 32 to 46% (1,500 Gt) of soil carbon [5]. Intact peatlands have poor drainage, permanent inundation, and poor oxygen conditions, so organic matter is not fully decomposed and forms peat [6,7]. ...
... Peatlands are widely used for various purposes, namely for agricultural activities, forestry, fuel production, industry and other purposes so the demand for peat resources has dramatically increased significantly [6]. Focusing on Indonesia, which is a country that has the fourth largest area of peat swamp forest in the world after Russia, Canada, and the USA [3,13] stated that approximately 95% of Indonesia's peatlands have been opened and drained both for use as large-scale company plantations and small-scale community agriculture. This condition was exacerbated by the severe fires in 2015 as a result of El Nino causing huge losses, both material and health, and inevitably caused problems with neighboring countries (Malaysia, Singapore) [14]. ...
Tropical peatlands are one of the largest carbon-storing ecosystems in the world. Draining tropical peatland causes environmental damage including greenhouse gas emissions. Drained peat is highly susceptible to fires that increase carbon emissions into the air. Rewetting is one way to solve the problem because, to achieve a zero or negative carbon balance, the water level should be close to or above the surface to maintain the water saturation of peat. The government of Indonesia has thoughtfully restored the peatland by implementing the 3R approach (rewetting, revegetation, and revitalizing local livelihood). After rewetting, paludiculture (wetland cultivation) is a promising land-use option for peatland. Through paludiculture, the peatland ecosystem will be improved which has already undergone drainage and will re-encourage carbon accumulative in peatland. This paper aims to determine the potential of paludiculture to support climate change adaptation including presenting challenges and opportunities in its implementation. Paludiculture has been shown to reduce greenhouse gas emissions by keeping peat moist. Besides having an ecological function, paludiculture also functions economically because it can be an alternative source of livelihood for people living around peat.
... The variable PET for each site is retrieved from the Global Aridity Index dataset 35,36 . The variable PSF for each site is retrieved from a global peatland map 37 . ...
... We used a global peatland map based on a meta-analysis of geospatial information from a variety of sources 37 . The global peatland distribution was derived by combining peatland-specific datasets at the global, regional and national level and the distribution of histosols derived from Harmonized World Soil Database v1.2, which resulted in a fine spatial coverage of PSF. ...
The ecosystem carbon turnover time—an emergent ecosystem property that partly determines the feedback between the terrestrial carbon cycle and climate—is strongly controlled by temperature. However, it remains uncertain to what extent hydrometeorological conditions may influence the apparent temperature sensitivity of τ, defined as the factor by which the carbon turnover time increases with a 10 °C rise in temperature (Q10). Here, we investigate the responses of the ecosystem carbon turnover to temperature and hydrometeorological factors using an ensemble of observation-based global datasets and a global compilation of in situ measurements. We find that temperature and hydrometeorology are almost equally important in shaping the spatial pattern of ecosystem carbon turnover, explaining 60 and 40% of the global variability, respectively. Accounting for hydrometeorological effects puts a strong constraint on Q10 values with a substantial reduction in magnitude and uncertainties, leading Q10 to converge to 1.6 ± 0.1 globally. These findings suggest that hydrometeorological conditions modulate the apparent temperature sensitivity of terrestrial carbon turnover times, confounding the role of temperature in quantifying the response of the carbon cycle to climate change.
... Peatlands cover an estimated 4.4 M km 2 of the Earth's surface, from southern America (Patagonia) peatlands (⁓0.04 M km 2 ) to tropical (⁓0.37 M km 2 ) and northern (subarctic/boreal, and temperate) peatlands (⁓4 M km 2 ) (Yu et al., 2010). While occupying <3 % of the global land surface, they account for about one-third of the terrestrial store of soil organic carbon and provide significant freshwater resources (Xu et al., 2018a;Xu et al., 2018b). Moreover, peatland ecosystems are important for nature conservation since they are home to fragile flora and fauna species (Bonn et al., 2016;Hannigan and Kelly-Quinn, 2012;Renou-Wilson, 2018;Renou-Wilson et al., 2011). ...
Despite peatlands' important feedbacks on the climate and global biogeochemical cycles, predicting their dynamics involves many uncertainties and an overwhelming variety of available models. This paper reviews the most widely used process-based models for simulating peatlands' dynamics, i.e., the exchanges of energy and mass (water, carbon, and nitrogen). 'Peatlands' here refers to mires, fens, bogs, and peat swamps both intact and degraded. Using a systematic search (involving 4900 articles), 45 models were selected that appeared at least twice in the literature. The models were classified into four categories: terrestrial ecosystem models (biogeochemical and global dynamic vegetation models, n = 21), hydrological models (n = 14), land surface models (n = 7), and eco-hydrological models (n = 3), 18 of which featured "peatland-specific" modules. By analysing their corresponding publications (n = 231), we identified their proven applicability domains (hydrology and carbon cycles dominated) for different peatland types and climate zones (northern bogs and fens dominated). The studies range in scale from small plots to global, and from single events to millennia. Following a FOSS (Free Open-Source Software) and FAIR (Findable, Accessible, Interoperable, Reusable) assessment, the number of models was reduced to 12. Then, we conducted a technical review of the approaches and associated challenges, as well as the basic aspects of each model, e.g., spatiotemporal resolution, input/output data format and modularity. Our review streamlines the process of model selection and highlights: (i) standardization and coordination are required for both data exchange and model calibration/validation to facilitate intercomparison studies; and (ii) there are overlaps in the models' scopes and approaches, making it imperative to fully optimize the strengths of existing models rather than creating redundant ones. In this regard, we provide a futuristic outlook for a 'peatland community modelling platform' and suggest an international peatland modelling intercomparison project.
... Surface flow wetlands are favored due to their lower construction and maintenance costs compared to subsurface flow systems (Halverson, 2004;Lee et al., 2009). Peatlands are naturally abundant and a prevalent land type in boreal and temperate regions (Xu et al., 2018;Lappalainen, 1996). Their use as semi-natural or natural treatment wetlands for the purification of various types of wastewater (e.g., municipal and mining) is a common practice in Finland (Ronkanen and Kløve, 2005;Kujala et al., 2019), Canada (Dubuc et al., 1986;Nichols and Higgins, 2000;Hayward et al., 2014), Estonia (Öövel et al., 2005;Maddison et al., 2009) as well as in Norway (Søvik et al., 2006) and USA (Kadlec, 2009). ...
In wastewater treatment, wetlands are regarded as cost-efficient and sustainable purification systems. Currently,
different types of wetland are used for year-round treatment of municipal wastewater (the polishing step after the
secondary or tertiary units) in cold climate regions. However, there is a lack of understanding regarding the
effect of freezing cold conditions on pollutant removal processes, in particular regarding those linked to nitrogen
cycling. This study evaluated the effect of cold winter conditions on contaminant removal, with a focus on ni-
trogen transformation and removal in a pond-type surface flow wetland with reed (Reed-SF) and a peat-based
horizontal subsurface flow (Peat-HSSF) wetland. Year-round full-scale wetland monitoring was complemented
with pilot-scale laboratory experiments, which allowed to follow the cold-climate induced effects on contaminant
removal and nitrogen processes, along with other water quality, environmental, and microbial parameters.
Overall, it was observed that the effect of cold climate conditions on nitrogen removal was dependent on the
wetland type in combination with the quality of the inflow water. When treating ammonium (NH4) rich
wastewater, removal of total nitrogen (Ntot), as well as NH4, was higher in the Peat-HSSF than in the Reed-SF
wetland. Under frozen conditions, NH4 removal decreased slightly but remained positive in the pilot Peat-
HSSF, whereas it declined and even turned into leaching in the pilot Reed-SF wetland. Conditions encoun-
tered in the Peat-HSSF wetlands (high abundances of active nitrifying bacteria, high levels of dissolved oxygen
(DO) and redox potential) supported nitrification, which continued under cold conditions. Whereas in the Reed-
SF, a low abundance of active nitrifying bacteria was found, especially in the water column under frozen con-
ditions. DO here was low and decreased in cold conditions with ice cover.
... We calculated the accumulated carbon stock of the standing area of recovering forest in 2018 and produced a map, aggregated to 0.1° grid square of the 2018 carbon stock. Here we also show the regions identified as peatland 67,68 , to highlight where there may be further soil carbon benefits. We also applied a similar approach to Chazdon et al. 5 and modelled the potential carbon stock at the end of 2030 if all the 2018 standing forest remained standing and were protected until the year 2030. ...
The globally important carbon sink of intact, old-growth tropical humid forests is declining because of climate change, deforestation and degradation from fire and logging1–3. Recovering tropical secondary and degraded forests now cover about 10% of the tropical forest area⁴, but how much carbon they accumulate remains uncertain. Here we quantify the aboveground carbon (AGC) sink of recovering forests across three main continuous tropical humid regions: the Amazon, Borneo and Central Africa5,6. On the basis of satellite data products4,7, our analysis encompasses the heterogeneous spatial and temporal patterns of growth in degraded and secondary forests, influenced by key environmental and anthropogenic drivers. In the first 20 years of recovery, regrowth rates in Borneo were up to 45% and 58% higher than in Central Africa and the Amazon, respectively. This is due to variables such as temperature, water deficit and disturbance regimes. We find that regrowing degraded and secondary forests accumulated 107 Tg C year⁻¹ (90–130 Tg C year⁻¹) between 1984 and 2018, counterbalancing 26% (21–34%) of carbon emissions from humid tropical forest loss during the same period. Protecting old-growth forests is therefore a priority. Furthermore, we estimate that conserving recovering degraded and secondary forests can have a feasible future carbon sink potential of 53 Tg C year⁻¹ (44–62 Tg C year⁻¹) across the main tropical regions studied.
... Global evidence has been synthesized on the effectiveness of conservation actions in peatlands in cool-climate regions (Rowland et al., 2021;Taylor et al., 2018). It is unclear how relevant the broader evidence base is to inform management of alpine peatlands given their location (Xu et al., 2018) and that threats to them differ from other peatlands (primary threats are wildfires and introduced herbivores, rather than agriculture and forestry). ...
Experts can provide valuable information to fill knowledge gaps in published research on management effectiveness, particularly for threatened ecosystems, for which there is often limited evidence and the need for prompt intervention to ensure their persistence. One such ecosystem, alpine peatlands, is threatened by climate change and other pressures, provides vital ecosystem services, and supports unique biodiversity. In a workshop, we gathered and synthesized into an accessible format information from experts on interventions used, threat context, and intervention effectiveness for Australian alpine peatlands and used this knowledge to evaluate local relevance of the global literature for this threatened ecosystem. Experts identified 15 interventions used to conserve Australian peatlands, most of which enhanced or restored peatland condition and effectively addressed diverse threats. Experts' perspectives and global studies were aligned strongly, suggesting that research on peatland management may be broadly relevant across contexts, despite the distinct characteristics of Australian systems. Our workshop-based expert elicitation approach provided insights into current management practices unavailable in the literature. This article is protected by copyright. All rights reserved.
... Tropical peat swamp forests (TPSF) are wetland forest ecosystems globally valued for carbon storage, centres of species endemism, floral and faunal diversity, and regional for water cycling, livelihoods for local communities, public health and cultural landscapes (Harrison, Ottay, et al., 2020;Harrison, Wijedasa, et al., 2020;Page et al., 2011;Posa et al., 2011). Globally tropical peatlands cover 185 to 470 million km 2 , equivalent to ~3% of the global land surface area, with large expanses of TPSF found across Southeast Asia, South America and equatorial Africa (Dargie et al., 2017;Gumbricht et al., 2017;Xu et al., 2018). However, TPSF have experienced rapid degradation in recent decades through timber logging, land conversion for agricultural purposes, associated drainage and fire, with particularly widespread loss and degradation of TPSF across Southeast Asia (Harrison, Ottay, et al., 2020;Miettinen et al., 2016;Page et al., 2009). ...
... Overall, terrestrial ecosystems mitigate ≈30 % of anthropogenic CO 2 emissions (3,4). The predominant terrestrial carbon sink -peatlands -store 100% more carbon than all forests while covering less than 3% of the globe (5)(6)(7)(8). Sphagnum mosses dominate peatlands (9) and are responsible for most C sequestration in the form of recalcitrant peat (10). They harbor diverse communities of single-celled (i.e., bacteria, archaea, protists) and multi-celled (i.e., fungi, metazoa) organisms that influence C cycling directly (11,12), through respiration of ≈100 Pg · C · yr − 1 in soils alone (13,14), and indirectly, by supplying nitrogen needed for Sphagnum moss growth (15)(16)(17), converting methane into CO 2 necessary for photosynthesis (18)(19)(20), providing stress tolerance to the host mosses (21,22), and assisting in host-pathogen defense (23). ...
Microbes play a major role in the global carbon cycle that fuels climate change. But how microbes may in turn respond to climate change remains poorly understood. Here, we collect data from a long-term whole-ecosystem warming experiment at a boreal peatland to address how temperature and carbon dioxide jointly influence protist communities: i.e., abundant and diverse, but poorly understood, microbial Eukaryotes. Protists influence ecosystem function directly through photosynthesis and respiration, and indirectly through predation on decomposers (bacteria, archaea, and fungi). Using a combination of high-throughput fluid imaging and 18S amplicon sequencing, we report climate-induced, community-wide shifts in protist community functional composition (e.g., size, shape, and metabolism) that could alter the overall function of peatland ecosystems. We also show that these responses to warming and elevated carbon dioxide are the result of taxonomic turnover. Surprisingly, our results clearly show strong interactive effects between temperature and carbon dioxide, such that the effects of warming on functional composition are generally reversed by elevated carbon dioxide. These findings show how the interactive effects of warming and rising carbon dioxide could alter the structure and function of peatland microbial food webs: a fragile ecosystem that stores 25% of terrestrial carbon and is increasingly threatened by human exploitation.
... Minerotrophic peatlands are groundwater fed, with water influx dependent on catchment characteristics; whereas ombrotrophic peatlands (bogs) are rain-fed and dependent on the balance between precipitation and evaporative and fluvial losses to sustain high water tables. Peatlands occur across a wide geographical range that spans the temperate, boreal and subarctic climate zones, as well as in the tropics if the appropriate climate conditions along with waterlogging are found (Xu et al. 2018). ...
Globally, major efforts are being made to restore peatlands to maximise their resilience to anthropogenic climate change, which puts continuous pressure on peatland ecosystems and modifies the geography of the environmental envelope that underpins peatland functioning. A probable effect of climate change is reduction in the waterlogged conditions that are key to peatland formation and continued accumulation of carbon (C) in peat. C sequestration in peatlands arises from a delicate imbalance between primary production and decomposition, and microbial processes are potentially pivotal in regulating feedbacks between environmental change and the peatland C cycle. Increased soil temperature, caused by climate warming or disturbance of the natural vegetation cover and drainage, may result in reductions of long-term C storage via changes in microbial community composition and metabolic rates. Moreover, changes in water table depth alter the redox state and hence have broad consequences for microbial functions, including effects on fungal and bacterial communities especially methanogens and methanotrophs. This article is a perspective review of the effects of climate change and ecosystem restoration on peatland microbial communities and the implications for C sequestration and climate regulation. It is authored by peatland scientists, microbial ecologists, land managers and non-governmental organisations who were attendees at a series of three workshops held at The University of Manchester (UK) in 2019-2020. Our review suggests that the increase in methane flux sometimes observed when water tables are restored is predicated on the availability of labile carbon from vegetation and the absence of alternative terminal electron acceptors. Peatland microbial communities respond relatively rapidly to shifts in vegetation induced by climate change and subsequent changes in the quantity and quality of below-ground C substrate inputs. Other consequences of climate change that affect peatland microbial communities and C cycling include alterations in snow cover and permafrost thaw. In the face of rapid climate change, restoration of a resilient microbiome is essential to sustaining the climate regulation functions of peatland systems. Technological developments enabling faster characterisation of microbial communities and functions support progress towards this goal, which will require a strongly interdisciplinary approach.
... Pristine wetland ecosystems play a critical role in the carbon cycle by acting as a natural sink for CO2 and are the largest reservoir of carbon (C). Occupying 3% of the land surface, wetland ecosystems store more carbon than any other terrestrial ecosystems, including forests [2][3][4]. One of the most waterlogged regions of the world is the West Siberian Lowland (WSL), where wetland ecosystems cover 592,440 km 2 and store more than 3% (70 PgC) of the total carbon of terrestrial ecosystems [5][6][7]. ...
The Mukhrino field station has participated in the national project on the inventory of carbon fluxes and pools in the terrestrial ecosystems of Russia since 2022. The development of a network of measurements of CO2 fluxes and phytomass covered six types of bog ecosystems typical to Western Siberia. The gross ecosystem exchange (GEE) of the field-layer vegetation (medians for the period from the end of May to the end of July, mgC m −2 h −1 ; see errors in Results section) decreased in series: Sphagnum bog with sparse low pine trees ("Open bog"), ridges in ridge-hollow patterned bogs ("Ridge"), pine-dwarf shrub-Sphagnum bog ("Tall ryam"), hollows in patterned bogs ("S.hollow", "E.hollow") and pine-dwarf shrub-Sphagnum bog ("Ryam"): −220, −200, −125, −120, −109 and −86, respectively. Ecosystem respiration (Reco) here was 106, 106, 182, 55, 97 and 136. The aboveground and belowground phytomass of mosses in this series varied between 368 ± 106-472 ± 184 and 2484 ± 517-6041 ± 2079 g/m 2 , respectively: the aboveground phytomass of vascular plants and plant litter-15 ± 7-128 ± 95 and 10 ± 6-128 ± 43, respectively. According to the results of mathematical modeling, the best proxy for GEE, in addition to photosynthetically active radiation and soil surface temperature, was the aboveground phytomass of vascular plants (PhV), and for Reco-PhV and the mass of the plant litter of vascular plants.
... Northern peatlands in temperate, boreal, and Arctic regions cover 3.7 ± 0.5 million km 2 , and store 415 ± 150 Pg of C (Hugelius et al., 2020). Globally, the majority of peatlands are found in the boreal biome (Joosten and Clarke, 2002), where 15% of the land cover is peatland (Xu et al., 2018). ...
DigiBog is a numerical model that simulates peat accumulation in temperate peatlands. Here, we modify DigiBog for boreal peatlands (DigiBog_Boreal) by accounting for snow cover, short growing seasons and groundwater exchanges between the peat and the aquifer. DigiBog_Boreal is then used to replicate ~6500 years of peat accumulation at two high boreal latitude peatlands in Quebec, Canada. DigiBog_Boreal was driven with a weather generator and climate models, while peat cores from the sites were used to develop initial conditions and calibrate DigiBog_Boreal. Our results demonstrate that DigiBog_Boreal can replicate well peat thickness and age-depth profiles but cannot produce long-term fluctuations in water-table depths. Here, a possible explanation for DigiBog_Boreal's underperformance is the stability in the climatic drivers and less likely the new model developments. The results also indicate that peat decomposition and accumulation in DigiBog_Boreal are sensitive to water stored on the peat surface.
... We summarized losses by river basins with the basin outlines from the ISLSCP river network 76 . Peatland-rich regions were delineated by applying a 20% area threshold to the PEATMAP product 69 , gridded at 0.5° resolution. Global and regional peatland losses were estimated by assuming that the share of peatland versus other wetland loss is in proportion to their present share of coverage in each grid cell. ...
Wetlands have long been drained for human use, thereby strongly affecting greenhouse gas fluxes, flood control, nutrient cycling and biodiversity1,2. Nevertheless, the global extent of natural wetland loss remains remarkably uncertain³. Here, we reconstruct the spatial distribution and timing of wetland loss through conversion to seven human land uses between 1700 and 2020, by combining national and subnational records of drainage and conversion with land-use maps and simulated wetland extents. We estimate that 3.4 million km² (confidence interval 2.9–3.8) of inland wetlands have been lost since 1700, primarily for conversion to croplands. This net loss of 21% (confidence interval 16–23%) of global wetland area is lower than that suggested previously by extrapolations of data disproportionately from high-loss regions. Wetland loss has been concentrated in Europe, the United States and China, and rapidly expanded during the mid-twentieth century. Our reconstruction elucidates the timing and land-use drivers of global wetland losses, providing an improved historical baseline to guide assessment of wetland loss impact on Earth system processes, conservation planning to protect remaining wetlands and prioritization of sites for wetland restoration⁴.
... Moreover, while there have been global mapping initiatives such as the global wetland map developed by the Center for International Forestry Research (https://www2.cifor.org/global-wetlands/, accessed on 31 January 2023), the global map of saltmarshes [10], or the global map of peatlands [11], there is a gap with respect to long-term monitoring efforts. ...
Wetlands, which provide multiple functions and ecosystem services, have decreased and been degraded worldwide for several decades due to human activities and climate change. Managers and scientists need tools to characterize and monitor wetland areas, structure, and functions in the long term and at regional and global scales and assess the effects of planning policies on their conservation status. The Landsat earth observation program has collected satellite images since 1972, which makes it the longest global earth observation record with respect to remote sensing. In this review, we describe how Landsat data have been used for long-term (≥20 years) wetland monitoring. A total of 351 articles were analyzed based on 5 topics and 22 attributes that address long-term wetland monitoring and Landsat data analysis issues. Results showed that (1) the open access Landsat archive successfully highlights changes in wetland areas, structure, and functions worldwide; (2) recent progress in artificial intelligence (AI) and machine learning opens new prospects for analyzing the Landsat archive; (3) most unexplored wetlands can be investigated using the Landsat archive; (4) new cloud-computing tools enable dense Landsat times-series to be processed over large areas. We recommend that future studies focus on changes in wetland functions using AI methods along with cloud computing. This review did not include reports and articles that do not mention the use of Landsat imagery.
... Significant changes are to be expected in boreal regions, as they are some of the fastest warming places on Earth (Kokkonen et al., 2019). Boreal zones are also where most of the peatlands are occurring (Xu et al., 2018). A phenomenon called evotranspiration, 2 caused by climate change is converting the boreal peatlands to suitable places for trees to enter. ...
Trees are “rooted”. Nevertheless, long-term scientific observations have proved that trees do migrate through landscapes and regions, very slowly and over decades to survive the impacts of climate change which advances faster than they do. The Wandering Tree project by artist Agnes Meyer-Brandis observes tree migration in different ecosystems, in Finland at Siikaneva peatland. The project creates narratives and raises questions of the effects of climate change on the ecosystems considered “naturally” unchangeable. This visual essay illustrates yet undiscovered stories of a tree. What happens in the peatland when we are not there? What stories will entangle with the new path of the pine?
... The United Nations Framework Convention on Climate Change (UNFCCC) highlighted peatlands as a priority via the introduction of the Wetlands Drainage and Rewetting (WDR) activity under Article 3.4 of the Kyoto Protocol (UNFCCC, 2011). Peatlands account for 5 -30 % of soil C stock (Minasny et al., 2019;UNEP, 2022) while covering only ~ 3 % of the earths land surface (Xu et al., 2018). Drained/degraded peatlands, used for industrial extraction, forestry, or agriculture (pasture), are responsible for emissions which are affecting the global C balance (Evans et al., 2021;Qiu et al., 2020;UNEP, 2022). ...
Peatlands are important sites of ecosystem services, particularly as soil carbon stores, and are recognised in many international climate strategies. However, drained peatlands, which have been modified for industrial extraction or agriculture, are responsible for carbon emission. Peatland restoration aims to return these degraded sites to a natural state. Multiple means of remotely monitoring the success of peat restoration are available, ranging from space-based satellite measurements (optical and radar) to airborne geophysical measurements (electro-magnetic and radiometric). This paper integrates multi-band, spatially coincident, remotely sensed data into a single framework, resulting in a comprehensive interpretation of intra-peatland variation of key restoration indicators. It uses a semi-automatic, data driven approach with unsupervised neural network machine learning clustering. A Multi-Cluster Average Standard Deviation metric is introduced which can determine the appropriate number of clusters for any dataset. The method was applied to a site in Ireland, representative of degraded peatlands, where optical satellite and airborne radiometric geophysical measurements were combined. The method was successful at determining the appropriate number of clusters for single and combined datasets, and the resulting cluster signatures provided visually compelling representations of the intra-peatland variation. This resulted in a comprehensive interpretation of intra-peatland variation of several key peatland restoration indicators, namely surface vegetation levels and soil moisture to ~ 60 cm of the peat surface. The study provides a framework for high spatial and temporal resolution monitoring of peatland restoration using future drone-based platforms.
... Peatlands play an important role as a global carbon (C) sink (Clymo, 1984). Peatlands only cover approximately 3% of global land surface but contain around 25% of terrestrially stored C (Xu et al., 2018;Yu et al., 2010). Peatlands also play a role in numerous ecological processes that can influence downstream habitats, including water filtration, erosion control, and flood prevention (Shuttleworth et al., 2019;Vitt, 2006). ...
... We used FluxCom ensemble carbon flux products based on MODIS remote sensing (RS; 0.5° spatial resolution) and based on MODIS plus meteorological data (RS + METEO; 0.5° spatial resolution) (Jung et al., 2020). Statistically upscaled CH 4 estimates from Peltola et al. (2019) were provided using three different wetland maps, including the static global wetland map PEATMAP (Xu et al., 2018), the dynamic wetland map based on DYPTOP (Dynamical Peatland Model Based on TOPMODEL; Stocker et al., 2014), and the Global Lakes and Wetlands Database (GLWD; Lehner & Döll, 2004). ...
Arctic-boreal landscapes are experiencing profound warming, along with changes in ecosystem moisture status and disturbance from fire. This region is of global importance in terms of carbon feedbacks to climate, yet the sign (sink or source) and magnitude of the Arctic-boreal carbon budget within recent years remains highly uncertain. Here, we provide new estimates of recent (2003-2015) vegetation gross primary productivity (GPP), ecosystem respiration (Reco ), net ecosystem CO2 exchange (NEE; Reco - GPP), and terrestrial methane (CH4 ) emissions for the Arctic-boreal zone using a satellite data-driven process-model for northern ecosystems (TCFM-Arctic), calibrated and evaluated using measurements from >60 tower eddy covariance (EC) sites. We used TCFM-Arctic to obtain daily 1-km2 flux estimates and annual carbon budgets for the pan-Arctic-boreal region. Across the domain, the model indicated an overall average NEE sink of -850 Tg CO2 -C year-1 . Eurasian boreal zones, especially those in Siberia, contributed to a majority of the net sink. In contrast, the tundra biome was relatively carbon neutral (ranging from small sink to source). Regional CH4 emissions from tundra and boreal wetlands (not accounting for aquatic CH4 ) were estimated at 35 Tg CH4 -C year-1 . Accounting for additional emissions from open water aquatic bodies and from fire, using available estimates from the literature, reduced the total regional NEE sink by 21% and shifted many far northern tundra landscapes, and some boreal forests, to a net carbon source. This assessment, based on in situ observations and models, improves our understanding of the high-latitude carbon status and also indicates a continued need for integrated site-to-regional assessments to monitor the vulnerability of these ecosystems to climate change.
... To minimize environmental harm, we used several environmental-based constraints to exclude development in (1) 56 , and (5) locations where inundation would displace more than 50,000 people 57 . We also considered various economic constraints associated with construction in areas with complex geology and seismic hazards. ...
The benefits of developing the world’s hydropower potential are intensely debated when considering the need to avoid or minimize environmental impacts. However, estimates of global unused profitable hydropower potential with strict environmental constraints have rarely been reported. In this study we performed a global assessment of the unused profitable hydropower potential by developing a unified framework that identifies a subset of hydropower station locations with reduced environmental impacts on the network of 2.89 million rivers worldwide. We found that the global unused profitable hydropower potential is 5.27 PWh yr−1, two-thirds of which is distributed across the Himalayas. Africa’s unused profitable hydropower is 0.60 PWh yr−1, four times larger than its developed hydropower. By contrast, Europe’s hydropower potential is extremely exploited. The estimates, derived from a consistent and transparent framework, are useful for formulating national hydropower development strategies. The development of hydropower offers a renewable energy source that can help reduce society’s dependence on fossil fuels. A global assessment of the unused profitable hydropower potential can be performed by incorporating strict constraints to identify hydropower station locations with reduced environmental and societal impacts.
... Tropical peatlands are one of the essential water-logged global sinks of atmospheric carbon dioxide (CO2) and have accumulated at least 100 Gt carbon (Dommain et al. 2011;Xu et al. 2018). The Indonesian archipelago, especially Papua, Sumatra, and Kalimantan, is a large island rich in soil carbon since around 21 Mha of tropical peatland is distributed in these areas. ...
Astiani D, Widiastuti T, Ekamawanti HA, Ekyastuti W, Roslinda E, Mujiman. 2022. The partial contribution of CO2-emission losses from subsidence in small-holder oil palm plantation on a tropical peatland in West Kalimantan, Indonesia. Biodiversitas 23: 6539-6545. Carbon storage in tropical peat ecosystems over thousands of years, especially within peat soil, is in huge quantity. Degradation of peat ecosystems is generally caused by human factors, whether intentional or not, damaging the carbon storage function of tropical peatlands, where forest clearing, drainage development, and burning of land converted to agriculture and plantations result in significant greenhouse gas emissions. Tropical peat in the Kubu Raya District of West Kalimantan, which has a relatively large area of peat, has been degraded as a cause of uncontrolled drainage and land fires caused by a lack of management after its forest cover was lost. The main impact is an increase in peat CO2 emissions due to changes in land use, especially lowering groundwater levels. Subsequently, the subsidence process also occurs after land clearing. This study aims to obtain the proportion of carbon biomass loss due to the CO2 emission process from reducing the peat layer due to subsidence. Data collection was executed for two years, where CO2 emission was monitored bi-weekly, and the subsidence was measured bi-monthly. The results demonstrate groundwater levels dictate the peat CO2 emission and subsidence. Lowering GWL 30 to -85 cm increases CO2 by more than three times, approximately. The rate of peat subsidence shows similar trends to the emission. The proportion of peat biomass loss on CO2 emission was between 58.9 to 73.5%, except for GWL ~5 cm, where the proportion was the highest at 82%. The results of this study are beneficial in explaining the part of the subsidence that impacts the sources of CO2 emissions from the small-holder oil palm and GWL management on peatlands.
... Peatland is widely distributed in northern Eurasia and North America, as well as other countries worldwide, covering an area of 423 million hectares (Xu et al, 2018), which represents 2.8% of the Earth's total land surface area. ...
In this study, a series of consolidated, undrained triaxial compression tests were conducted to investigate peat shear behaviour on samples from 1.65 m depth when subjected to different stress levels from 10.4 kPa to 40.5 kPa. At the consolidation stage, the triaxial test specifically investigated the peat isotropic compressibility at low stress levels, showing an agreement with oedometer test data available in literature. The subsequent triaxial shearing stage results show most of the test data failed to reach the tension cut-off line (q/p’ = 3), which indicated that the deviator stress may represent more of an interparticle connection than the tension of fibres and woods in peaty soils. For peat, the membrane correction effect on peat shear resistance is strain dependent; generally, small within 10% shear strain, but becomes significant above 10% shear strain. A critical state line for peat was determined based on the maximum curvature approach, where the Mohr-Coulomb model has difficulty in determining the friction angle for peat. Of the data recorded for the peat, 78% fell within the range of 30 to 60 degrees, increasing to 90.4% when ignoring points lower than 10 kPa; the previous test data for very low stress level (less than 10kPa) might not be sufficiently reliable due to limitations of conventional triaxial testing apparatus, specimen preparation and etc. In addition, organic content also plays an important role on the peat shear behaviour. In general, when the organic content exceeds 75%, the deviator stress behaves like organic soils, otherwise, the peat behaves more like a mineral soil. In peat samples with organic content higher than 75%, the direct shear box test gives higher estimates of shear strength than the triaxial shear test, but not necessarily accurate — the mechanism of direct shear acts only at the centre of a specimen, while triaxial shear can shear throughout the specimens.
... Peat deposits play a crucial role in global climate through carbon sequestration despite covering an area of only 3% of Earth's land area (Gallego-Sala et al., 2018;Xu et al., 2018;Yu, 2012). Therefore, peat deposits are thought to be responsible for cooling at times during the Holocene (Frolking et al., 2006;IPCC Climate Change, 2013;Loisel et al., 2021). ...
... Introduction The world's peatlands are estimated at 397-423 million ha or equivalent to 3% of the land area; some of the most extensive peatlands are in Canada, the Soviet Union, the USA, and Indonesia [1]. Peatlands are in the world's spotlight as the largest absorbent and store of terrestrial carbon and regulators of water absorption up to 90% of their volume [2]. However, most of the world's peatlands, particularly in southeast Asia, are degraded and converted to oil palm plantations and industrial plantations [3]. ...
As large tracts of degraded peatlands are caused by conversion and fires, peat restoration is carried out to restore peat ecosystems to their natural condition and support the socioeconomics of communities around peatlands that are affected because they depend on the resources provided by peatlands as livelihoods. This study aims to see the implementation of peat restoration in the Rewetting, Revegetation, and Revitalization (3R) approach in Jambi Province. The research focuses on the economic revitalization of people’s livelihoods. This research method is exploratory qualitative, while data collection is through interviews, observations, documentation, and literature: data analysis techniques, data reduction, data presentation, and conclusion drawing. The results of research on the implementation of peat restoration in Jambi Province have been carried out since 2018; the implementation of the 3R has not been optimal, which is still far from the target set. In particular, assistance for the economic revitalization of people’s livelihoods lacks help, so the program’s sustainability is stopped halfway. In addition, the collaboration and coordination of the Regional Peat Restoration Team (TRGD) agencies did not go well.
... Peatlands cover around 2%-3% of the Earth continental surface (Xu et al., 2018) and, owing to sequestration/release of CO 2 , play a crucial role in the regulation of global climate (Gallego-Sala et al., 2018;Loisel et al., 2014;Yu, 2012). At the same time, peatlands are excellent repositories of past and recent environmental changes (De Vleeschouwer et al., 2010a;Shotyk, 1988). ...
The subalpine, atmospherically fed Śnieżka peatland, located in the Polish part of the Sudetes, is one of the nominated candidates for the GSSP of the Anthropocene. Data from two profiles, Sn1 (2012) and Sn0 (2020), from this site are critical for distinguishing the proposed epoch, while an additional core Sn2 is presented to support main evidence. The Sn0 archive contains a wide array of critical markers such as plutonium (Pu), radiocarbon (F ¹⁴ C), fly ash particles, Hg and stable C and N isotopes which are consistent with the previously well documented ²¹⁰ Pb/ ¹⁴ C dated Sn1 profile, which provides a high-resolution and comprehensive database of trace elements and rare earth elements (REE), Pb isotopes, Pu, Cs, pollen and testate amoebae. The 1952 worldwide appearance of Pu, owing to its global synchronicity and repeatability between the cores, is proposed here as a primary marker of the Anthropocene, supported by the prominent upturn of selected chemostratigraphic and biostratigraphic indicators as well as the appearance of technofossils and artificial radionuclides.
... Peatland is a soil type covering only 3% of the land area [1,2]. Peatlands in the world are estimated to cover 423-436 million hectares [3,4], of which 3.1% or 13.43 million hectares of the world's peatlands are located in Indonesia [5]. Peatlands in Indonesia is mainly found in three major islands, namely Sumatra (5.8-7.2 million ha), Kalimantan (4.5-5.6 million ha) and Papua (3-8 million ha) [2,6,7,8]. ...
Tropical peatlands in Indonesia are severely degraded due to unsustainable logging, conversion to plantations, poor drainage, and repeated fires. Traditional communities in Central Kalimantan used to build “beje” ponds for fishing and paludikulur farming system (agrosilvo fishery) in deep peatlands area that are frequently flooded. However, hardly reached spot in peat swamp makes areas suitable for beje difficult to find. This study aims to map the location suitable for beje using Normalized Difference Water Index (NDWI) from Landsat 8 OLI imagery. Canopy results from the NDWI were used as a reference for field investigations at nine sites from each NDWI class. The classification test results show that NDWI is able to distinguish dry and wet areas in tropical peatlands, with a manufacturer accuracy of 83.3% and user accuracy of 84.9%. As a result, the area suitable for beje ponds development is ±9,616 ha, or 6.2% of the total area studied.
... We restricted this species' modeled distribution to 10 km inland from the coastline (Natural Earth, 2021). For the other two habitat-specific species, Gonystylus bancanus and Myristica malabarica, we restricted modeled distribution to 10 km into the matrix surrounding peatlands (Xu et al., 2018). We refer to the resulting SDMs as validated SDMs. ...
Tree diversity in Asia’s tropical and subtropical forests is central to nature-based solutions. Species vulnerability to multiple threats, which affect provision of ecosystem services, is poorly understood. We conducted a region-wide, spatially explicit assessment of the vulnerability of 63 socioeconomically important tree species to overexploitation, fire, overgrazing, habitat conversion, and climate change. Trees were selected for assessment from national priority lists, and selections were validated by an expert network representing 20 countries. We used Maxent suitability modeling to predict species distribution ranges, freely accessible spatial data sets to map threat exposures, and functional traits to estimate threat sensitivities. Species-specific vulnerability maps were created as the product of exposure maps and sensitivity estimates. Based on vulnerability to current threats and climate change, we identified priority areas for conservation and restoration. Overall, 74% of the
most important areas for conservation of these trees fell outside protected areas, and all species were severely threatened across an average of 47% of their native ranges. The most imminent threats were overexploitation and habitat conversion; populations were severely threatened by these factors in an average of 24% and 16% of their ranges, respectively. Our model predicted limited overall climate change impacts, although some study species were likely to lose over 15% of their habitat by 2050 due to climate change. We pinpointed specific natural areas in Borneo rain forests as hotspots for in situ conservation of forest genetic resources, more than 82% of which fell outside designated protected areas. We also identified degraded areas in Western Ghats, Indochina dry forests, and Sumatran rain forests as hotspots for restoration, where planting or assisted natural regeneration will help conserve these species, and croplands in southern India and Thailand as potentially important agroforestry options. Our results highlight the need for regionally coordinated action for effective conservation and restoration.
... According to Xu et al., a significant portion of the earth's natural peat land is located in Asia (38.1%) and North America (31.6%), mainly in Canada and Alaska. Regarding percentages, Europe accounts for 12.5%, South America for 11.5%, Africa for 4.4%, and Australasia and Oceania for 1.6% [1]. Bangladesh is a South Asian country with a high population density, low-lying, and primarily riverine terrain with a coastline that extends 580 km along the island's northern part in the Bay of Bengal. ...
This research investigates the characteristics of organic soil from southwest Bangladesh and the influence of sand columns on the void ratio (V0), consolidation coefficient (CC), and volume compressibility (CV) of stabilized soil. On the laboratory scale, cylindrical columns of varying diameters were extruded through organic soil samples and stabilized with 3%, 5%, 8%, 10%, and 23% sand in various geometries. After evaluating the engineering parameters, a series of 1-D consolidation experiments were performed to assess the effect of the sand column on stabilized soil samples. According to the Unified Soil Classification System (USCS), the organic soil used in this research is defined as organic silt (OH). According to the findings, the organic soil has a liquid limit of 118% and its particles pass through a 0.075 mm sieve. By incorporating sand columns, rapid consolidation was obtained, and the sample containing 77% organic soil and 23% sand exhibited the best consistent compressibility features. The effects of column number and geometry on the compressibility behavior of organic soil samples were also examined. The results for the 77% organic soil and 23% sand in a single column and the 82% organic soil and 8% sand in a double column are nearly identical. This study reveals that stabilization with sand columns may significantly enhance the physical and consolidation behavior of organic soil in southwest Bangladesh.
... "Calcareous fen"). In addition, overlaying the global peatland map (Xu et al., 2018) on the worldwide carbonate bedrock distribution map (Goldscheider et al., 2020) reveals that high peatland densities occur in carbonate areas, especially in the northern hemisphere such as UK, Siberia or western China. ...
Continental hydrosystems and in particular peatlands play an important role in the carbon cycle of the Critical Zone (CZ). Peatlands are important sinks for organic carbon and have therefore been extensively studied. However, peatlands are not only important for the fate of organic carbon, but they also affect the cycle of Dissolved Inorganic Carbon (DIC) of the peatland and the surrounding watershed. The fate of DIC is particularly complex in peatlands in limestone-dominated regions, because bicarbonate concentrations in surface and groundwater are high and the interaction between peatlands and surrounding hydrosystems are facilitated by the presence of highly permeable karst aquifers. In the present paper we study the origin and the fractionation of DIC in a peatland located on top of a karst aquifer. The study is based on hydrochemical and isotopic (δ¹³CDIC) data from samples recovered during 2 campaigns (low flow, high flow) at various depths within the Forbonnet peatland (Jura Mountains, eastern France), at the peatland outlet and at adjacent karst springs representing the underlying aquifer. In order to evaluate secondary fractionation processes, the measured δ¹³CDIC compositions were compared to modeled values considering the origin of DIC and potentially associated fractionation and speciation processes. The main results are: (1) DIC is lost at the bog surface by CO2 outgassing. (2) The δ¹³CDIC compositions of deep catotelm pore waters from the bog were much heavier than the modeled values. We relate this discrepancy to methanogenesis and show that this process is favored by reduced conditions at pH ~ 6 and a HCO3⁻ content of ~1 mmol/L, most probably due to punctual groundwater inflows at the base of the bog. Finally, contrasted δ¹³CDIC compositions between the bog and the fen of the peatland reveal an additional ecohydrological control on DIC speciation.
... The rise in atmospheric temperature has an imperative role in determining soil carbon dynamics and vice versa (Zhao et al., 2017;Hartley et al., 2021). Since more carbon is stored as soil organic carbon than the sum of carbon in atmosphere and terrestrial vegetation which accounts for ∼40% of terrestrial carbon (Jackson et al., 2017), soil carbon governs the global carbon cycle that influences the undergoing rapid human-driven climate change (Xu et al., 2018;Harris et al., 2021). However, other studies have shown that mean annual temperature have a positive effect on soil carbon accumulation in forests by increasing photosynthesis and thus litterfall and root death (Rodeghiero and Cescatti, 2005;Dusenge et al., 2019;Wang and Huang, 2020). ...
Forests have the largest terrestrial nutrient pools. The loss of soil carbon and nitrogen in forests under ongoing climate warming is subject to severe environmental degradation. To mitigate the negative effects of global warming on soil carbon and nitrogen in forest, it is important to obtain a better understanding of how elevated temperature and altered precipitation variability impact soil nutrient dynamics. To explore such interactions, we coupled an eco-hydrological model (Multi-Layer Canopy model, MLCan) with a biogeochemical model and applied the combined model to Pinus densiflora forest in Gwangneung Experimental Forest, South Korea, from 2004 to 2020. Our results showed that there was a time lag of 4 years to trigger soil organic carbon losses under the elevated temperature of +1.11°C during 2014–2020 compared to 2010–2013. A temperature rise over a prolonged period increased microbial biomass and activity, stimulating soil organic carbon decomposition. The combination of soil nitrate accumulation and exceptional but expected delay in heavy precipitation seasons of 2 months led to nitrate leaching four times higher than the average at 1 m depth in 2010. Reduced evapotranspiration and heavy precipitation during early fall caused intense subsurface water flux, resulting in a great increase in the risk of nitrate leaching. Our results highlight that the impacts of global warming on soil carbon decompositions has a time lag of 4 years and changes in precipitation characteristics will lead to excessive nitrate loss in P. densiflora forests under climate change.
... Peatlands are spread almost all over the world, with an estimated 4,232,369 km 2 or about 2.84% of the world's land area (Xu et al., 2018). Peatland areas are found in Indonesia, reaching 14,905,575 ha on the islands of Kalimantan and Sumatra and the island of Irian. ...
Many factors destroy peat ecosystems, including land fires. The cause of the fire was motivated by economic aspects, namely land clearing for agricultural, plantation, and residential activities. Desa Peduli Gambut Program has main activities: strengthening local knowledge and village community preparedness in dealing with peat fire disasters and non-burning land management. The process requires the participation of farmers as an essential determining factor to ensure the success and sustainability of a program. This study analyzes farmer participation in the DPG program in Teluk Pekedai District. The descriptive quantitative method is supported by qualitative data using Sherry Arnstein's (1969) participation level analysis. The analysis results show that farmer participation in the DPG program in Teluk Pekedai District is at the therapy level. The low level of community participation in a program occurs because the level of government domination in deciding program plans is the cause of problems in program implementation. Farmer participation can increase by the role of the DPG chairperson, the role of the village facilitator, the village government and local government, and all elements of the community (community leaders).
... Peatland ecosystems are regarded as highly important by both ecologists and climate scientists due to their essential role in the regulation of the local and regional water balance and their high capacity for carbon storage [1]. Recent studies indicate that tropical peatlands cover 23-30% of the total peatland area in the world, i.e., 90 to 170 Mha [2][3][4], which is much greater than the previous estimates of 36-44 Mha [5][6][7]. This substantial increase in the tropical peatland area is related to new discoveries of large peatlands in remote ...
Paleoecological reconstructions of hydrological regimes in tropical peatlands during the Holocene are important for the estimation of their responses to changing environments. However, the application of some widely used proxies, such as testate amoebae, is hampered by poor knowledge of their morphology and ecological preferences in the region. The aim of this study is to describe the morphospecies composition of sub-fossil testate amoebae in deposits of a tropical peatland in Central Sumatra (Indonesia) during the Holocene and reconstruct the hydrological regime using morphospecies- and functional-trait-based approaches. In total, 48 testate amoeba morphospecies were observed. Based on morphospecies composition, we distinguished three main periods of peatland development (13,400–8000, 8000–2000, 2000 cal yr BP–present). The application of the morphospecies-based transfer function provided a more reliable reconstruction of the water regime in comparison to the functional trait-based one. The weak performance of the latter might be related to the poor preservation of shells and the greater variation in the functional traits in sub-fossil communities as compared to the training set and linear modeling approach. These results call for future studies on the functional and morphospecies composition of testate amoebae in a wider range of tropical peatlands to improve the quality of hydrological reconstructions.
Peatland environments are the Earth’s largest terrestrial carbon store and have the potential to act as carbon sinks. However, the development of windfarms on peatlands is affecting their morphology, hydrology, ground-level climate conditions, carbon functions and vegetation, and long-term consequences still need to be assessed. Blanket bogs are a rare type of ombrotrophic peatland that are typical of oceanic areas with high precipitation and low temperatures. Their distribution has been mapped across Europe, where they are mainly located on hill summits where wind energy potential is higher, making them attractive sites for windfarm developments. The promotion of renewable energy is currently a priority given the environmental and economic drive to increase low-carbon energy production. Establishing windfarms on peatland in pursuit of greener energy, therefore, risks compromising and undermining the green-energy transition. Despite this, the extent of windfarm infrastructures on blanket bogs have not yet been reported at the European scale. This research reports the extent of windfarm infrastructures on recognised blanket bogs, with a geographical focus on Europe, where blanket bogs have been mapped systematically. Under the EU Habitats Directive (92/43/EEC), there are 36 European regions NUTS level 2 with recognised blanket bogs. Of these, 12 have windfarm developments, including 644 wind turbines, 253.4 km of vehicular access tracks and an affected area of 207.6 ha, mainly in Ireland and Scotland where the extent of blanket bogs is also higher. However, despite Spain having under 0.2% of Europe’s recognised blanket bogs area, this was the most affected country. In Scotland, a comparison of the recognised blanket bogs under the Habitats Directive (92/43/EEC) with blanket bogs recorded in national inventories indicates that the extent of windfarm developments was higher, with 1,063 wind turbines and 634.5 km of vehicular access tracks. Our results highlight the extent of windfarm developments on blanket bog habitat, both in areas where peatlands are broadly distributed across the landscape, and also in areas where this recognised habitat is particularly rare. There is a pressing need to assess the long-term impacts of windfarms on peatlands to ensure that efforts to meet energy targets result only in carbon sequestration, and do not jeopardise ecosystem services. Blanket bogs represent a particularly vulnerable habitat, the study of which should be prioritised updating national and international inventories to protect and restore this habitat.
Peatlands are some of the largest carbon reservoirs in terrestrial ecosystems and play a key role in the global carbon cycle. Understanding peatland development, carbon accumulation processes, and the peatland response to varying forcing factors over different temporal and spatial scales helps reveal the underlying processes and general patterns of these ecosystems. To assess the role of climate and local conditions in peatland development, the basal samples from 23 peat cores and three well dated long peat cores were used to explore peatland initiation, lateral expansion, and carbon accumulation rate in the Baijianghe peatland located in the Changbai Mountains, Northeast China. Our results reveal that the Baijianghe peatland was initiated from forest conditions at 7.9 cal. kyr BP and then expanded laterally by paludification. The rapid expansion between 5 and 4 cal. kyr BP likely resulted from high precipitation and gentle topography. The mean carbon accumulation rates of the three long peat cores were 36.3, 39.1 and 48.4 g C m−2 yr−1, respectively, which are higher than rates from the northern peatlands. Both climate and local conditions have exerted an important influence on carbon accumulation rates in the Baijianghe peatland since the middle Holocene. The carbon accumulation patterns between 5 and 1.5 cal. kyr BP were probably linked to local conditions rather than climatic settings, including topography, hydrological conditions, and plant composition. The consistently decreasing carbon accumulation rate values at all locations within the BJH peatland over the last 1.5 cal. kyr BP suggests that climate is the primary control. This study highlights the varying primary controls on the process of peatland development and reveals the important role of local conditions in carbon accumulation.
1. Northern peatlands are inaccessible wetlands that serve important ecosystem services to humans, including climate regulation by storing and sequestering carbon. Unmanned aerial vehicles or drones are ideal to map vegetation and associated functions in these ecosystems, but standardized methods to optimize efficiency (highest accuracy with lowest processing time) are lacking. 2. We collected high-resolution drone imagery at three different altitudes (20 m, 60 m, and 120 m) of two Irish peatlands contrasting in pattern complexity and evaluated to what extent classification accuracy of vegetation patterns (microforms and plant functional types) changed using different flight altitudes, minimum segment size and training/testing sample size. We also analysed the processing time of all classifications to find the most efficient combination of parameters. 3. Classification accuracy was consistently high (>90 %) and estimated areas of both patterns were uniform among all flight altitudes, independent of pattern complexity. Minimum segment size and training/testing sample size were also important parameters affecting the efficiency of classifications. Total processing time from imagery capture to final map was 19–22 times faster with drone imagery at 120 m altitude than at 20 m, and seven times faster than at 60 m. 4. Our findings suggest that flying at the maximum legal altitude of 120 m is the most efficient approach for landscape-scale mapping of vegetation in peatlands or other ecosystems with similar short vegetation structure. We conclude that flying higher is always more efficient as long as the pixel size of drone imagery remains under the pixel size of the pattern under investigation.
Torfowiska zajmują ok. 3% powierzchni lądów, a magazynują aż ok. 25% zawartego w glebie węgla. Są więc ekosystemami szczególnej uwagi ze względu na ich udział w globalnym cyklu węglowym. Torfowiska o niezaburzonych stosunkach wodnych akumulują węgiel w torfie co działa ochładzająco na atmosferę w skali globalnej w dłuższym okresie (poprzez wychwytywanie CO2 z powietrza, który jest gazem cieplarnianym). Zupełnie odwrotnie dzieje się, gdy dochodzi do obniżenia poziomu wód gruntowych, wtedy torfowiska stają się emiterami netto CO2. Z drugiej jednak strony utrzymujący się długo zbyt wysoki poziom wody przyczynia się do wzmożonej emisji metanu (CH4), również gazu cieplarnianego. Ważne jest zrozumienie mechanizmów funkcjonowania torfowisk w warunkach gwałtownie zmieniającego się klimatu. W tym celu stosuje się wiele perspektyw, zarówno w odniesieniu do skali przestrzennej, jak i czasowej analiz, począwszy od analiz paleoekologicznych aż po badania eksperymentalne. Integracja tych wszystkich perspektyw powinna stać się priorytetowym działaniem w celu określenia punktów zwrotnych i trajektorii zmian dla torfowisk.
Peatlands are globally important long‐term sinks of atmospheric carbon dioxide (CO2). However, there is concern that climate change‐mediated drying will reduce gross primary productivity (GPP) and increase ecosystem respiration (ER) making peatlands vulnerable to a weaker carbon sink function and potential net carbon loss. While large and deep peatlands are usually resilient to moderate summer drying, CO2 exchange in shallow Boreal Shield peatlands is likely more sensitive to drying given the reduced groundwater connectivity and water storage potential. To better understand the carbon cycling responses of Boreal Shield peatlands to meteorological conditions, we examined ecohydrological controls on CO2 fluxes using the eddy covariance technique at a shallow peatland during the summer season for 5 years, from 2016–2020. We found lower GPP in dry summer years. Mean summer water table depth (WTD) was found to be significantly correlated with summer total net ecosystem CO2 exchange (R² = 0.78; p value = 0.046) and GPP (R² = 0.83; p value = 0.03), where wet summers with a WT close to the peat surface sequestered more than twice the amount of CO2 than dry summers. Our findings suggest that shallow Boreal Shield peatland GPP may be sensitive to climate‐mediated drying as they may switch to a net CO2 source in the summer season when WTDs exceed a critical ecohydrological threshold for a prolonged period of time.
A sub-surface forest fire is a kind of fire that spreads slowly with no flames and lower temperatures, and threatens the ecosystem and human life. The moisture content of humus is considered to be an important factor in determining fire occurrence and sustaining. The humus of the Larix gmelinii in the Daxing’an Mountains was selected for the experiment, the limit moisture content condition of sub-surface forest fires was determined by an experiment simulating smoldering, and the prediction model of the probability of sub-surface forest fire occurrence was established. The results will be of great significance for the prevention, monitoring, and fighting of sub-surface forest fires in the boreal forest. The results showed that when the moisture content of humus in the upper layer was low, the smoldering process could be self-sustaining at 20%. For deeper layers of a depth of 18 cm, this increased to 30% moisture content of the humus and was the critical depth for sub-surface fires. The moisture content of 40% was a limit to burning where smoldering can only last for a short duration and is then extinguished. When the moisture content of the humus was 20%, the smoldering temperature was higher and the rate of spread was faster, with smoldering being maintained for longer periods at 30% moisture content. The regression prediction model of the highest temperature and vertical rate of spread in a column of humus was correlated to moisture content and depth, and the model significance was good at p < 0.01. Based on moisture content and depth, the occurrence probability prediction model of sub-surface fires has a good correlation (R2 = 0.93) and high prediction accuracy (AUC = 0.995). The effect of moisture content (Or = 4.008) on the occurrence probability of sub-surface fires is higher than that of depth (Or = 2.948). The results point out that it is necessary to prevent and monitor the occurrence of sub-surface fires when the humus moisture content is less than 40%. In order to reduce the risk of sub-surface fires, the monitoring time of the fire field should be extended after the fire is extinguished due to the slow-burning process of the sub-surface fire. Increasing the moisture content of the humus is an important method to reduce the probability and restrain the spread of sub-surface fires.
Climate warming is leading to permafrost thaw in northern peatlands, and current predictions suggest that thawing will drive greater surface wetness and an increase in methane emissions. Hydrology largely drives peatland vegetation composition, which is a key element in peatland functioning and thus in carbon dynamics. These processes are expected to change. Peatland carbon accumulation is determined by the balance between plant production and peat decomposition. But both processes are expected to accelerate in northern peatlands due to warming, leading to uncertainty in future peatland carbon budgets. Here, we compile a dataset of vegetation changes and apparent carbon accumulation data reconstructed from 33 peat cores collected from 16 sub‐arctic peatlands in Fennoscandia and European Russia. The data cover the past two millennia that has undergone prominent changes in climate and a notable increase in annual temperatures towards present times. We show a pattern where European sub‐Arctic peatland microhabitats have undergone a habitat change where currently drier habitats dominated by Sphagnum mosses replaced wetter sedge‐dominated vegetation and these new habitats have remained relatively stable over the recent decades. Our results suggest an alternative future pathway where sub‐arctic peatlands may at least partly sustain dry vegetation and enhance the carbon sink capacity of northern peatlands.
Peatlands are limno-terrestrial habitats that support rich microscopic algae, whereas algal distribution is poorly known in peaty environments. This study aims to explore diatom diversity patterns and underlying driving forces in Sphagnum peatlands of central and northeastern China. A total of 200 diatom species were observed in 138 living Sphagnum samples collected from 8 peatlands in northeastern and central China, suggesting that diatoms are more prevalent in these limno-terrestrial environments than generally considered. The Simpson index was negatively correlated with dissolved organic carbon (DOC) in central China, while it was negatively correlated with water table depth (WTD) in northeastern China. Distance–decay rate of diatom community similarity was faster in central China than in northeastern China, probably due to strong dispersal limitation in these enclosed montane peatlands of central China. For diatom composition in the two regions, the pure effect of environmental variables explained more variance than that of regional climate or spatial factors, suggesting that niche-based processes primarily determined diatom composition in these peatlands. Our results highlight the importance of WTD and DOC in constraining diatom diversity patterns in Sphagnum peatlands.
To understand the variability of methane (CH4) fluxes between a temperate mid-altitude Sphagnum-dominated peatland and the atmosphere, we monitored simultaneously eddy covariance, hydrometeorological and physical parameters between April 2019 and December 2021. The site was a CH4 source for the atmosphere, with a cumulative emission of 23.9 ± 0.6 g C m⁻² year⁻¹. At the interannual scale, deeper water table during vegetation growth periods resulted in lower CH4 fluxes (FCH4), and reciprocally. Furthermore, the seasonal temperature variation in the anaerobic peat layer was a good predictor for FCH4. However, while the lowest temperatures occurred between December and February, the lowest FCH4 were observed between March and May, with around 30% of negative FCH4. Indeed, the fastest increase in temperature of the aerobic layer likely stimulated methanotrophy at the expense of methanogenesis. Negative FCH4, systematically observed at midday, were concurrent with high photon flux densities, latent heat fluxes and net negative ecosystem CO2 exchanges, suggesting the control of photosynthesis over CH4 oxidation. Moreover, our results highlighted marked diurnal cycles with FCH4 maximal at night and minimal at midday for all seasons. This diurnal cyclicity is in opposition to what is typically known for peatlands dominated by vascular plants. Physical parameters, such as soil surface temperature and sensible heat fluxes, likely contribute to this diurnal FCH4 cyclicity and require further investigation. Our study thus demonstrates that diurnal variations in FCH4 must be considered before upscaling to seasonal or annual cycles, along with the effect of vegetation on CH4 transfer and oxidation processes.
Northern peatlands play a disproportionally large role in the global carbon balance due to the massive amount of carbon stored in peat and ongoing sequestration. Vegetation composition and structure are recognised indicators for carbon sequestration and storage potential in these ecosystems, but decadal dynamics and roles of autogenic succession, climate, and land-use herein remain poorly understood.
We assessed vegetation changes in the least disturbed centre of twelve Irish peatland reserves sampled across a gradient in temperature and precipitation between 1978(1983)–2021, combining re-classified traditional high-resolution vegetation maps with recent very high-resolution drone imagery. Specifically, we tested whether microform proportions of open water, wet hollow, moist lawn, and dry hummock had changed and explored to what extent changes were related to climate and land-use drivers.
Results revealed that the studied peatlands underwent an overall unidirectional surface drying trend, with dry hummocks expanding at the expense of open water and wet hollow, while moist lawns remained approximately equal in proportions. The degree of change varied between the studied peatlands, with western blanket bogs and unrestored raised bogs experiencing more surface drying than mountain blanket bogs and raised bogs under hydrological restoration. While our results indicated climate and/or land-use as drivers of surface drying, our sample size was too small to make definitive conclusions about their exact role.
The overall change from wet to dry surface conditions between 1978 and 2021 occurred at a much faster rate than hitherto reported for these slow-changing ecosystems. This raises concern for the future resilience of peatlands to changes in climate and land-use, as well as their potential impact on the peatland carbon balance.
Wetlands are important providers of ecosystem services and key regulators of climate change. They positively contribute to global warming through their greenhouse gas emissions, and negatively through the accumulation of organic material in histosols, particularly in peatlands. Our understanding of wetlands' services is currently constrained by limited knowledge on their distribution, extent, volume, inter-annual flood variability, and disturbance levels. We present an expert system approach to estimate wetland and peatland areas, depths and volumes, which relies on three biophysical indices related to wetland and peat formation: 1. Long-term water supply exceeding atmospheric water demand; 2. Annually or seasonally water-logged soils; 3. A geomorphological position where water is supplied and retained. Tropical and subtropical wetlands estimates reach 4.7 million km(2) . In line with current understanding, the American continent is the major contributor (45%) and Brazil, with its Amazonian inter-fluvial region, contains the largest tropical wetland area (800,720 km(2) ). Our model suggests, however, unprecedented extents and volumes of peatland in the tropics (1.7 million km(2) and 7,268 (6,076-7,368) km(3) ), which more than three-fold current estimates. Unlike current understanding, our estimates suggest that South America and not Asia contributes the most to tropical peatland area and volume (ca. 44% for both) partly related to some yet unaccounted extended deep deposits but mainly to extended but shallow peat in the Amazon Basin. Brazil leads the peatland area and volume contribution. Asia hosts 38% of both tropical peat area and volume with Indonesia as the main regional contributor and still the holder of the deepest and most extended peat areas in the tropics. Africa hosts more peat than previously reported but climatic and topographic contexts leave it as the least peat forming continent. Our results suggest large biases in our current understanding of the distribution, area, and volumes of tropical peat and their continental contributions. This article is protected by copyright. All rights reserved.
www.cambridge.org/9781107619708
Peatlands provide globally important ecosystem services through climate and water regulation or biodiversity conservation. While covering only 3% of the earth's surface, degrading peatlands are responsible for nearly a quarter of carbon emissions from the land use sector. Bringing together world-class experts from science, policy and practice to highlight and debate the importance of peatlands from an ecological, social and economic perspective, this book focuses on how peatland restoration can foster climate change mitigation. Featuring a range of global case studies, opportunities for reclamation and sustainable management are illustrated throughout against the challenges faced by conservation biologists. Written for a global audience of environmental scientists, practitioners and policy makers, as well as graduate students from natural and social sciences, this interdisciplinary book provides vital pointers towards managing peatland conservation in a changing environment.
In headwater peatlands, saturation-excess overland flow is a dominant source of river discharge. Human modifications to headwater peatlands result in vegetation cover change but there is a lack of understanding about how the spatial distribution of such change impacts flood peaks. A fully distributed version of TOPMODEL with an overland flow velocity module was used to simulate flood response for three upland peat basins. Bare peat strips adjacent to channels resulted in a higher and faster flow peak; for a 20 mm h-1 rainfall event, with bare riparian zones covering 10% of the basin area, peaks were increased, compared to the current hydrograph, by 12.8%, 1.8%, and 19.6% in the three basins. High density Sphagnum ground cover over the same riparian zones reduced flow peaks (e.g., by 10.1%, 1.8%, and 13.4% for the 20 mm h-1 event) compared to the current hydrograph. With similar total areas of land-cover change, the size of randomly located patches of changed cover had no effect on peak flow for patch sizes up to 40,000 m2. However, cover changes on gentle slope areas generally resulted in a larger change in peak flow when compared with the same changes on steeper slopes. Considering all results for the same proportion of catchment area that undergoes change, land-cover change along narrow riparian buffer strips had the highest impact on river flow. Thus, the protection and revegetation of damaged riparian areas in upland peat catchments may be highly beneficial for flood management.
Soils are subject to varying degrees of direct or indirect human disturbance, constituting a major global change driver. Factoring out natural from direct and indirect human influence is not always straightforward, but some human activities have clear impacts. These include land use change, land management, and land degradation (erosion, compaction, sealing and salinization). The intensity of land use also exerts a great impact on soils, and soils are also subject to indirect impacts arising from human activity, such as acid deposition (sulphur and nitrogen) and heavy metal pollution. In this critical review, we report the state-of-the-art understanding of these global change pressures on soils, identify knowledge gaps and research challenges, and highlight actions and policies to minimise adverse environmental impacts arising from these global change drivers. Soils are central to considerations of what constitutes sustainable intensification. Therefore, ensuring that vulnerable and high environmental value soils are considered when protecting important habitats and ecosystems, will help to reduce the pressure on land from global change drivers. To ensure that soils are protected as part of wider environmental efforts, a global soil resilience programme should be considered, to monitor, recover or sustain soil fertility and function, and to enhance the ecosystem services provided by soils. Soils cannot, and should not, be considered in isolation of the ecosystems that they underpin and vice versa. The role of soils in supporting ecosystems and natural capital needs greater recognition. The lasting legacy of the International Year of Soils in 2015 should be to put soils at the centre of policy supporting environmental protection and sustainable development. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Climate change has the capacity to alter physical and biological ecosystem processes, jeopardizing the survival of associated species. This is a particular concern in cool, wet northern peatlands that could experience warmer, drier conditions. Here we show that climate, ecosystem processes and food chains combine to influence the population performance of species in British blanket bogs. Our peatland process model accurately predicts water-table depth, which predicts abundance of craneflies (keystone invertebrates), which in turn predicts observed abundances and population persistence of three ecosystem-specialist bird species that feed on craneflies during the breeding season. Climate change projections suggest that falling water tables could cause 56–81% declines in cranefly abundance and, hence, 15–51% reductions in the abundances of these birds by 2051–2080. We conclude that physical (precipitation, temperature and topography), biophysical (evapotranspiration and desiccation of invertebrates) and ecological (food chains) processes combine to determine the distributions and survival of ecosystem-specialist predators.
The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget and thus atmospheric carbon concentrations. We review current estimates of SOC stocks and mass (stock * area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent and coherent global data sets of SOC, giving a total mass of 2476 Pg when using the original values for bulk density. Adjusting the HWSD's bulk density (BD) of soil high in organic carbon results in a mass of 1230 Pg, and additionally setting the BD of Histosols to 0.1 g cm-3 (typical of peat soils), results in a mass of 1062 Pg. The uncertainty in BD of Histosols alone introduces a range of -56 to +180 Pg C into the estimate of global SOC mass in the top 1 m, larger than estimates of global soil respiration. We report the spatial distribution of SOC stocks per 0.5 arcminutes; the areal masses of SOC; and the quantiles of SOC stocks by continents, wetland types, and permafrost types. Depending on the definition of "wetland", wetland soils contain between 82 and 158 Pg SOC. With more detailed estimates for permafrost from the Northern Circumpolar Soil Carbon Database (496 Pg SOC) and tropical peatland carbon incorporated, global soils contain 1325 Pg SOC in the upper 1 m, including 421 Pg in tropical soils, whereof 40 Pg occurs in tropical wetlands. Global SOC amounts to just under 3000 Pg when estimates for deeper soil layers are included. Variability in estimates is due to variation in definitions of soil units, differences in soil property databases, scarcity of information about soil carbon at depths > 1 m in peatlands, and variation in definitions of "peatland".
Open access, available from http://www.soil-journal.net/1/351/2015/soil-1-351-2015.html
Our limited knowledge of the size of the carbon pool and exchange fluxes in forested lowland tropical peatlands represents a major gap in our understanding of the global carbon cycle. Peat deposits in several regions (e.g. the Congo Basin, much of Amazonia) are only just beginning to be mapped and characterised. Here we consider the extent to which methodological improvements and improved coordination between researchers could help to fill this gap. We review the literature on measurement of the key parameters required to calculate carbon pools and fluxes, including peatland area, peat bulk density, carbon concentration, above-ground carbon stocks, litter inputs to the peat, gaseous carbon exchange, and waterborne carbon fluxes. We identify areas where further research and better coordination are particularly needed in order to reduce the uncertainties in estimates of tropical peatland carbon pools and fluxes, thereby facilitating better-informed management of these exceptionally carbon-rich ecosystems.
It has been frequently stated, but without provision of supporting evidence, that the world has lost 50% of its
wetlands (or 50% since 1900 AD). This review of 189 reports of change in wetland area finds that the reported long-term loss of natural wetlands averages between 54–57% but loss may have been as high as 87% since 1700 AD. There has been a much (3.7 times) faster rate of wetland loss during the 20th and early 21st centuries, with a loss of 64–71% of wetlands since 1900 AD. Losses have been larger and faster for inland than coastal natural wetlands. Although the rate of wetland loss in Europe has slowed, and in North America has remained low since the 1980s, the rate has remained high in Asia, where large-scale and rapid conversion of coastal and inland natural wetlands is continuing. It is unclear whether the investment by national governments in the Ramsar Convention on Wetlands has influenced these rates of loss. There is a need to improve the knowledge of change in wetland areas worldwide, particularly for Africa, the Neotropics and
Oceania, and to improve the consistency of data on change in wetland areas in published papers and reports.
Tropical peat swamp forest is a unique ecosystem that is most extensive in Southeast Asia, where it is under enormous threat from logging, fire, and land conversion. Recent research has shown this ecosystem's significance as a global carbon store, but its value for biodiversity remains poorly understood. We review the current status and biological knowledge of tropical peat swamp forests, as well as the impacts of human disturbances. We demonstrate that these forests have distinct floral compositions, provide habitat for a considerable proportion of the region's fauna, and are important for the conservation of threatened taxa, particularly specialized freshwater fishes. However, we estimate that only 36% of the historical peat swamp forest area remains, with only 9% currently in designated protected areas. Given that peat swamp forests are more vulnerable to synergies between human disturbances than other forest ecosystems, their protection and restoration are conservation priorities that require urgent action.
Since the launch of the first land-observation satellite (Landsat-1) in 1972, land-cover mapping has accumulated a wide range of knowledge in the peer-reviewed literature. However, this knowledge has never been comprehensively analysed for new discoveries. Here, we developed the first spatialized database of scientific literature in English about land-cover mapping. Using this database, we tried to identify the spatial temporal patterns and spatial hotspots of land-cover mapping research around the world. Among other findings, we observed (1) a significant mismatch between hotspot areas of land-cover mapping and areas that are either hard to map or rich in biodiversity; (2) mapping frequency is positively related to economic conditions; (3) there is no obvious temporal trend showing improvement in mapping accuracy; (4) images with more spectral bands or a combination of data types resulted in increased mapping accuracies; (5) accuracy differences due to algorithm differences are not as large as those due to various types of data used; and (6) the complexity of a classification system decreases its mapping accuracy. We recommend that one way to improve our understanding of the challenges, advances, and applications of previous land-cover mapping is for journals to require area-based information at the time of manuscript submission. In addition, building a standard protocol for systematic assessment of land-cover mapping efforts at the global scale through international collaboration is badly needed.
Global land cover types in 2001 and 2010 were mapped at 250 m resolution with multiple year time series Moderate Resolution Imaging Spectrometer (MODIS) data. The map for each single year was produced not only from data of that particular year but also from data acquired in the preceding and subsequent years as temporal context. Slope data and geographical coordinates of pixels were also used. The classification system was derived from the finer resolution observation and monitoring of global land cover (FROM-GLC) project. Samples were based on the 2010 FROM-GLC project and samples for other years were obtained by excluding those changed from 2010. A random forest classifier was used to obtain original class labels and to estimate class probabilities for 2000–2002, and 2009–2011. The overall accuracies estimated from cross validation of samples are 74.93% for 2001 and 75.17% for 2010. The classification results were further improved through post processing. A spatial-temporal consistency model, Maximum a Posteriori Markov Random Fields (MAP-MRF), was first applied to improve land cover classification for each 3 consecutive years. The MRF outputs for 2001 and 2010 were then processed with a rule-based label adjustment method with MOD44B, slope and composited EVI series as auxiliary data. The label adjustment process relabeled the over-classified forests, water bodies and barren lands to alternative classes with maximum probabilities.
Carbon stored in soils worldwide exceeds the amount of carbon stored in phytomass and the atmosphere. Despite the large quantity of carbon stored as soil organic carbon (SOC), consensus is lacking on the size of global SOC stocks, their spatial distribution, and the carbon emissions from soils due to changes in land use and land cover. This article summarizes published estimates of global SOC stocks through time and provides an overview of the likely impacts of management options on SOC stocks. We then discuss the implications of existing knowledge of SOC stocks, their geographical distribution and the emissions due to management regimes on policy decisions, and the need for better soil carbon science to mitigate losses and enhance soil carbon stocks.
Peatlands contain a large belowground carbon (C) stock in the biosphere, and their dynamics have important implications for the global carbon cycle. However, there are still large uncertainties in C stock estimates and poor understanding of C dynamics across timescales. Here I review different approaches and associated uncertainties of C stock estimates in the literature, and on the basis of the literature review my best estimate of C stocks and uncertainty is 500 ± 100 (approximate range) gigatons of C (Gt C) in northern peatlands. The greatest source of uncertainty for all the approaches is the lack or insufficient representation of data, including depth, bulk density and carbon accumulation data, especially from the world's large peatlands. Several ways to improve estimates of peat carbon stocks are also discussed in this paper, including the estimates of C stocks by regions and further utilizations of widely available basal peat ages.
Changes in peatland carbon stocks over time, estimated using Sphagnum (peat moss) spore data and down-core peat accumulation records, show different patterns during the Holocene, and I argue that spore-based approach underestimates the abundance of peatlands in their early histories. Considering long-term peat decomposition using peat accumulation data allows estimates of net carbon sequestration rates by peatlands, or net (ecosystem) carbon balance (NECB), which indicates more than half of peat carbon (> 270 Gt C) was sequestrated before 7000 yr ago during the Holocene. Contemporary carbon flux studies at 5 peatland sites show much larger NECB during the last decade (32 ± 7.8 (S.E.) g C m<sup>−2</sup> yr<sup>–1</sup>) than during the last 7000 yr (∼ 11 g C m<sup>−2</sup> yr<sup>–1</sup>), as modeled from peat records across northern peatlands. This discrepancy highlights the urgent need for carbon accumulation data and process understanding, especially at decadal and centennial timescales, that would bridge current knowledge gaps and facilitate comparisons of NECB across all timescales.
A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observation system requires transformational advances from the existing sparse, exploratory framework towards a dense, robust, and sustained system in all components: anthropogenic emissions, the atmosphere, the ocean, and the terrestrial biosphere. The paper is addressed to scientists, policymakers, and funding agencies who need to have a global picture of the current state of the (diverse) carbon observations. We identify the current state of carbon observations, and the needs and notional requirements for a global integrated carbon observation system that can be built in the next decade. A key conclusion is the substantial expansion of the ground-based observation networks required to reach the high spatial resolution for CO2 and CH4 fluxes, and for carbon stocks for addressing policy-relevant objectives, and attributing flux changes to underlying processes in each region. In order to establish flux and stock diagnostics over areas such as the southern oceans, tropical forests, and the Arctic, in situ observations will have to be complemented with remote-sensing measurements. Remote sensing offers the advantage of dense spatial coverage and frequent revisit. A key challenge is to bring remote-sensing measurements to a level of long-term consistency and accuracy so that they can be efficiently combined in models to reduce uncertainties, in synergy with ground-based data. Bringing tight observational constraints on fossil fuel and land use change emissions will be the biggest challenge for deployment of a policy-relevant integrated carbon observation system. This will require in situ and remotely sensed data at much higher resolution and density than currently achieved for natural fluxes, although over a small land area (cities, industrial sites, power plants), as well as the inclusion of fossil fuel CO2 proxy measurements such as radiocarbon in CO2 and carbon-fuel combustion tracers. Additionally, a policy-relevant carbon monitoring system should also provide mechanisms for reconciling regional top-down (atmosphere-based) and bottom-up (surface-based) flux estimates across the range of spatial and temporal scales relevant to mitigation policies. In addition, uncertainties for each observation data-stream should be assessed. The success of the system will rely on long-term commitments to monitoring, on improved international collaboration to fill gaps in the current observations, on sustained efforts to improve access to the different data streams and make databases interoperable, and on the calibration of each component of the system to agreed-upon international scales.
Peatlands occupy a relatively small fraction of the Earth’s land area, but they are a globally important carbon store because of their high carbon density. Undisturbed peatlands are currently a weak carbon sink (~0.1 Pg C y–1), a moderate source of methane (CH4; ~0.03 Pg CH4 y–1), and a very weak source of nitrous oxide (N2O; ~0.00002 Pg N2O–N y–1). Anthropogenic disturbance, primarily agriculture and forestry drainage (10%–20% of global peatlands), results in net CO2 emissions, reduced CH4 emissions, and increased N2O emissions. This likely changes the global peatland greenhouse gas balance to a C source (~0.1 Pg C y–1), a 10% smaller CH4 source, and a larger (but still small) N2O source (~0.0004 Pg N2O–N y–1). There is no strong evidence that peatlands significantly contributed to 20th century changes in the atmospheric burden of CO2, CH4, or N2O; will this picture change in the 21st century? A review of experimental and observational studies of peatland dynamics indicates that the main global change impacts on peatlands that may have significant climate impacts are (1) drainage, especially in the tropics; (2) widespread permafrost thaw; and (3) increased fire intensity and frequency as a result of drier climatic conditions and (or) drainage. Quantitative estimates of global change impacts are limited by the sparse field data (particularly in the tropics), the large variability present in existing data, uncertainties in the future trajectory of peatland use, interactive effects of individual impacts, and the unprecedented rates of climate change expected in the 21st century.
This paper on reports the production of a 1 km spatial resolution land cover classification using data for 1992-1993 from the Advanced Very High Resolution Radiometer (AVHRR). This map will be included as an at-launch product of the Moderate Resolution Imaging Spectroradiometer (MODIS) to serve as an input for several algorithms requiring knowledge of land cover type. The methodology was derived from a similar effort to create a product at 8 km spatial resolution, where high resolution data sets were interpreted in order to derive a coarse-resolution training data set. A set of 37 294 x 1 km pixels was used within a hierarchical tree structure to classify the AVHRR data into 12 classes. The approach taken involved a hierarchy of pair-wise class trees where a logic based on vegetation form was applied until all classes were depicted. Multitemporal AVHRR metrics were used to predict class memberships. Minimum annual red reflectance, peak annual Normalized Difference Vegetation Index (NDVI), and minimum channel three brightness temperature were among the most used metrics. Depictions of forests and woodlands, and areas of mechanized agriculture are in general agreement with other sources of information, while classes such as low biomass agriculture and high-latitude broadleaf forest are not. Comparisons of the final product with regional digital land cover maps derived from high-resolution remotely sensed data reveal general agreement, except for apparently poor depictions of temperate pastures within areas of agriculture. Distinguishing between forest and non-forest was achieved with agreements ranging from 81 to 92% for these regional subsets. The agreements for all classes varied from an average of 65% when viewing all pixels to an average of 82% when viewing only those 1 km pixels consisting of greater than 90% one class within the high-resolution data sets.
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Oil palm supplies >30% of world vegetable oil production1. Plantation expansion is occurring throughout the tropics, predominantly in Indonesia, where forests with heterogeneous carbon stocks undergo high conversion rates2, 3, 4. Quantifying oil palm’s contribution to global carbon budgets therefore requires refined spatio-temporal assessments of land cover converted to plantations5, 6. Here, we report oil palm development across Kalimantan (538,346 km2) from 1990 to 2010, and project expansion to 2020 within government-allocated leases. Using Landsat satellite analyses to discern multiple land covers, coupled with above- and below-ground carbon accounting, we develop the first high-resolution carbon flux estimates from Kalimantan plantations. From 1990 to 2010, 90% of lands converted to oil palm were forested (47% intact, 22% logged, 21% agroforests). By 2010, 87% of total oil palm area (31,640 km2) occurred on mineral soils, and these plantations contributed 61–73% of 1990–2010 net oil palm emissions (0.020–0.024 GtC yr−1). Although oil palm expanded 278% from 2000 to 2010, 79% of allocated leases remained undeveloped. By 2020, full lease development would convert 93,844 km2 (~ 90% forested lands, including 41% intact forests). Oil palm would then occupy 34% of lowlands outside protected areas. Plantation expansion in Kalimantan alone is projected to contribute 18–22% (0.12–0.15 GtC yr−1) of Indonesia’s 2020 CO2-equivalent emissions. Allocated oil palm leases represent a critical yet undocumented source of deforestation and carbon emissions.
Conversion of tropical peatlands to agriculture leads to a release of
carbon from previously stable, long-term storage, resulting in land
subsidence that can be a surrogate measure of CO2 emissions
to the atmosphere. We present an analysis of recent large-scale
subsidence monitoring studies in Acacia and oil palm plantations on
peatland in SE Asia, and compare the findings with previous studies.
Subsidence in the first 5 yr after drainage was found to be 142 cm, of
which 75 cm occurred in the first year. After 5 yr, the subsidence rate
in both plantation types, at average water table depths of 0.7 m,
remained constant at around 5 cm yr-1. The results confirm
that primary consolidation contributed substantially to total subsidence
only in the first year after drainage, that secondary consolidation was
negligible, and that the amount of compaction was also much reduced
within 5 yr. Over 5 yr after drainage, 75 % of cumulative subsidence was
caused by peat oxidation, and after 18 yr this was 92 %. The average
rate of carbon loss over the first 5 yr was 178 t CO2eq
ha-1 yr-1, which reduced to 73 t CO2eq
ha-1 yr-1 over subsequent years, potentially
resulting in an average loss of 100 t CO2eq ha-1
yr-1 over 25 yr. Part of the observed range in subsidence and
carbon loss values is explained by differences in water table depth, but
vegetation cover and other factors such as addition of fertilizers also
influence peat oxidation. A relationship with groundwater table depth
shows that subsidence and carbon loss are still considerable even at the
highest water levels theoretically possible in plantations. This implies
that improved plantation water management will reduce these impacts by
20 % at most, relative to current conditions, and that high rates of
carbon loss and land subsidence are inevitable consequences of
conversion of forested tropical peatlands to other land uses.
Peatlands store vast amounts of organic carbon, amounting to approximately 455 Pg. Carbon builds up in these water-saturated environments owing to the presence of phenolic compounds-which inhibit microbial activity and therefore prevent the breakdown of organic matter. Anoxic conditions limit the activity of phenol oxidase, the enzyme responsible for the breakdown of phenolic compounds. Droughts introduce oxygen into these systems, and the frequency of these events is rising. Here, we combine in vitro manipulations, mesocosm experiments and field observations to examine the impact of drought on peatland carbon loss. We show that drought stimulates bacterial growth and phenol oxidase activity, resulting in a reduction in the concentration of phenolic compounds in peat. This further stimulates microbial growth, causing the breakdown of organic matter and the release of carbon dioxide in a biogeochemical cascade. We further show that re-wetting the peat accelerates carbon losses to the atmosphere and receiving waters, owing to drought-induced increases in nutrient and labile carbon levels, which raise pH and stimulate anaerobic decomposition. We suggest that severe drought, and subsequent re-wetting, could destabilize peatland carbon stocks; understanding this process could aid understanding of interactions between peatlands and other environmental trends, and lead to the development of strategies for increasing carbon stocks.
Our estimates indicate that about 30% of the seven million square kilometers that make up the Amazon basin comply with international
criteria for wetland definition. Most countries sharing the Amazon basin have signed the Ramsar Convention on Wetlands of
International Importance but still lack complete wetland inventories, classification systems, and management plans. Amazonian
wetlands vary considerably with respect to hydrology, water and soil fertility, vegetation cover, diversity of plant and animal
species, and primary and secondary productivity. They also play important roles in the hydrology and biogeochemical cycles
of the basin. Here, we propose a classification system for large Amazonian wetland types based on climatic, hydrological,
hydrochemical, and botanical parameters. The classification scheme divides natural wetlands into one group with rather stable
water levels and another with oscillating water levels. These groups are subdivided into 14 major wetland types. The types
are characterized and their distributions and extents are mapped.
KeywordsAmazon basin–Higher vegetation–Hydrology–Water types
Peatlands provide globally important ecosystem services through climate and water regulation or biodiversity conservation. While covering only 3% of the earth's surface, degrading peatlands are responsible for nearly a quarter of carbon emissions from the land use sector. Bringing together world-class experts from science, policy and practice to highlight and debate the importance of peatlands from an ecological, social and economic perspective, this book focuses on how peatland restoration can foster climate change mitigation. Featuring a range of global case studies, opportunities for reclamation and sustainable management are illustrated throughout against the challenges faced by conservation biologists. Written for a global audience of environmental scientists, practitioners and policy makers, as well as graduate students from natural and social sciences, this interdisciplinary book provides vital pointers towards managing peatland conservation in a changing environment.
Information related to land cover is immensely important to global change science. In the past decade, data sources and methodologies for creating global land cover maps from remote sensing have evolved rapidly. Here we describe the datasets and algorithms used to create the Collection 5 MODIS Global Land Cover Type product, which is substantially changed relative to Collection 4. In addition to using updated input data, the algorithm and ancillary datasets used to produce the product have been refined. Most importantly, the Collection 5 product is generated at 500-m spatial resolution, providing a four-fold increase in spatial resolution relative to the previous version. In addition, many components of the classification algorithm have been changed. The training site database has been revised, land surface temperature is now included as an input feature, and ancillary datasets used in post-processing of ensemble decision tree results have been updated. Further, methods used to correct classifier results for bias imposed by training data properties have been refined, techniques used to fuse ancillary data based on spatially varying prior probabilities have been revised, and a variety of methods have been developed to address limitations of the algorithm for the urban, wetland, and deciduous needleleaf classes. Finally, techniques used to stabilize classification results across years have been developed and implemented to reduce year-to-year variation in land cover labels not associated with land cover change. Results from a cross-validation analysis indicate that the overall accuracy of the product is about 75% correctly classified, but that the range in class-specific accuracies is large. Comparison of Collection 5 maps with Collection 4 results show substantial differences arising from increased spatial resolution and changes in the input data and classification algorithm.
