Spatial distribution of degradation and deforestation of palm swamp peatlands and associated carbon emissions in the Peruvian Amazon.

The vast peat deposits in the Peruvian Amazon are crucial to the global climate. Palm swamp, the most extensive regional peatland ecosystem faces different threats, including deforestation and degradation due to felling of the dominant palm Mauritia flexuosa for fruit harvesting. While these activities convert this natural C sink into a source, the distribution of degradation and deforestation in this ecosystem and related C emissions remain unstudied. We used remote sensing data from Landsat, ALOS-PALSAR, and NASA's GEDI spaceborne LiDAR-derived products to map palm swamp degradation and deforestation within a 28 Mha area of the lowland Peruvian Amazon in 1990-2007 and 2007-2018. We combined this information with a regional peat map, C stock density data and peat emission factors to determine (1) peatland C stocks of peat-forming ecosystems (palm swamp, herbaceous swamp, pole forest), and (2) areas of palm swamp peatland degradation and deforestation and associated C emissions. In the 6.9 ± 0.1 Mha of predicted peat-forming ecosystems within the larger 28 Mha study area, 73% overlaid peat (5.1 ± 0.9 Mha) and stored 3.88 ± 0.12 Pg C. Degradation and deforestation in palm swamp peatlands totaled 535,423 ± 8,419 ha over 1990-2018, with a pronounced dominance for degradation (85%). The degradation rate increased 15% from 15,400 ha y-1 (1990-2007) to 17,650 ha y-1 (2007-2018) and the deforestation rate more than doubled from 1,900 ha y-1 to 4,200 ha y-1. Over 1990-2018, emissions from degradation amounted to 26.3 ± 3.5 Tg C and emissions from deforestation were 12.9 ± 0.5 Tg C. The 2007-2018 emission rate from both biomass and peat loss of 1.9 Tg C yr-1 is four times the average biomass loss rate due to gross deforestation in 2010-2019 reported for the hydromorphic Peruvian Amazon. The magnitude of emissions calls for the country to account for deforestation and degradation of peatlands in national reporting.

Exploring Soil Bacterial Diversity in Relation to Edaphic Physicochemical Properties of High-altitude Wetlands from Argentine Puna.

High Andean wetlands, particularly those known as vegas or bofedales, are essential conservation ecosystems due to their significant contribution to ecosystem services. The soil microbial communities in these ecosystems play a crucial role in fundamental processes such as decomposition and nutrient cycling, sustaining life in the region. However, at present, these microbial communities are poorly understood. In order to contribute to this knowledge, we aimed to characterize and compare the microbial communities from soils of seven Argentine Puna vegas and to analyze their association with soil physicochemical characteristics. Proteobacteria (Gamma and Alphaproteobacteria) was the dominant phylum across all vegas, followed in abundance by Actinobacteriota, Desulfobacterota, and Chloroflexi. Furthermore, the abundance of specific bacterial families and genera varied significantly between the vegas; some of them can be associated with plant growth-promoting bacteria such as Rhodomicrobium in La Quebradita and Quebrada del Diablo, Bacillus in Antofalla and Las Quinuas. Laguna Negra showed no shared ASVs with abundance in genera such as Sphingomonas and Pseudonocardia. The studied vegas also differed in their soil physicochemical properties; however, associations between the composition of microbial communities with the edaphic parameters measured were not found. These results suggest that other environmental factors (e.g., geographic, climatic, and plant communities' characteristics) could determine soil microbial diversity patterns. Further investigations are needed to be focused on understanding the composition and function of microorganisms in the soil associated with specific vegetation types in these high-altitude wetlands, which will provide valuable insights into the ecological dynamics of these ecosystems for conservation strategies.

Mountain wetland soil carbon stocks of Huascarán National Park, Peru.

Although wetlands contain a disproportionately high amount of earth's total soil carbon, many regions are still poorly mapped and with unquantified carbon stocks. The tropical Andes contain a high concentration of wetlands consisting mostly of wet meadows and peatlands, yet their total organic carbon stocks are poorly quantified, as well as the carbon fraction that wet meadows store compared to peatlands. Therefore, our goal was to quantify how soil carbon stocks vary between wet meadows and peatlands for a previously mapped Andean region, Huascarán National Park, Peru. Our secondary goal was to test a rapid peat sampling protocol to facilitate field sampling in remote areas. We sampled soil to calculate carbon stocks of four wetland types: cushion peat, graminoid peat, cushion wet meadow, and graminoid wet meadow. Soil sampling was conducted by using a stratified randomized sampling scheme. Wet meadows were sampled to the mineral boundary using a gouge auger, and we used a combination of full peat cores and a rapid peat sampling procedure to estimate peat carbon stocks. In the lab, soils were processed for bulk density and carbon content, and total carbon stock of each core was calculated. We sampled 63 wet meadows and 42 peatlands. On a per hectare basis, carbon stocks varied strongly between peatlands (avg. 1092 MgC ha-1) and wet meadows (avg. 30 MgC ha-1). Overall, wetlands in Huascarán National Park contain 24.4 Tg of carbon with peatlands storing 97% of the total wetland carbon and wet meadows accounting for 3% of the wetland carbon in the park. In addition, our results show that rapid peat sampling can be an effective method for sampling carbon stocks in peatlands. These data are important for countries developing land use and climate change policies as well as providing a rapid assessment method for wetland carbon stock monitoring programs.

Vegetation structure and aboveground biomass of Páramo peatlands along a high-elevation gradient in the northern Ecuadorian Andes.

The high-elevation peatlands of the páramos of the northern Andes constitute a diverse environment that harbors large numbers of species and several types of plant communities along altitudinal, latitudinal, and environmental gradients. However, little is known about the structure and functioning of these ecosystems, including peatland vegetation types and their relative contribution to the production and accumulation of peat soils. In this paper we characterized the structure of peatland plant communities of the humid páramos of northern Ecuador by describing the distribution of plant growth-forms and their aboveground biomass patterns. Along an elevation gradient of 640 m we sampled vegetation in 16 peatlands and aboveground biomass in four peatlands. Three distinct peatland vegetation types were identified: High elevation Cushion peatlands, dominated by Plantago rigida and Distichia muscoides, Sedge and rush peatlands dominated by Carex spp. and Juncus spp., and Herbaceous and shrubby peatlands, with a more heterogenous and structurally complex vegetation. In terms of aboveground biomass, we found an 8-fold reduction in the higher peatlands compared to the lower sites, suggesting that the steep elevational gradients characteristic of Andean environments might be crucial in structuring the physiognomy and composition of peatland vegetation, either through its effects on temperature and other environmental factors, or through its effects on the age and development of soils. Additional studies are needed to evaluate the potential effects of temperature, hydrology, micro-topography, geological setting, and land-use, which are likely to influence vegetation patters in these peatlands.

The High-Elevation Peatlands of the Northern Andes, Colombia.

Andean peatlands are important carbon reservoirs for countries in the northern Andes and have a unique diversity. Peatland plant diversity is generally related to hydrology and water chemistry, and the response of the vegetation in tropical high-elevation peatlands to changes in elevation, climate, and disturbance is poorly understood. Here, we address the questions of what the main vegetation types of peat-forming vegetation in the northern Andes are, and how the different vegetation types are related to water chemistry and pH. We measured plant diversity in 121 peatlands. We identified a total of 264 species, including 124 bryophytes and 140 vascular plants. We differentiated five main vegetation types: cushion plants, Sphagnum, true mosses, sedges, and grasses. Cushion-dominated peatlands are restricted to elevations above 4000 m. Variation in peatland vegetation is mostly driven be elevation and water chemistry. Encroachment of sedges and Sphagnum sancto-josephense in disturbed sites was associated with a reduction in soil carbon. We conclude that peatland variation is driven first by elevation and climate followed by water chemistry and human disturbances. Sites with higher human disturbances had lower carbon content. Peat-forming vegetation in the northern Andes was unique to each site bringing challenges on how to better conserve them and the ecosystem services they offer.

Assessment of fire resilience in subtropical wetlands using high spatial resolution images.

Resilience is the ability of a system to absorb disturbances, rearrange itself, and adapt in order to maintain its functionality, structure, identity, and feedback. Research involving fire resilience in subtropical wetlands (SW) allows us to understand the dynamics of these ecosystems, measure impacts on fauna and flora, and promote policies for the management and protection. The aim of the present study is to assess the fire resilience of SW. The study was divided into three steps: (i) burned area classification, (ii) vegetation pattern classification, and (iii) temporal analysis of SW fire resilience based on NDVI calculation. Our results show that (a) high resilience potential of emerging plants, which developed green leaves in less than 90 days after the fire; (b) poor recovery of peatlands with underground fire history. Daily coverage of high spatial resolution PlanetScope images has great potential for classification and monitoring of land use in areas where there are rapid changes, such as after a fire event, explosions, and dam ruptures with ore tailings, for example.

Tropical peatlands and their contribution to the global carbon cycle and climate change.

Peatlands are carbon-rich ecosystems that cover 185-423 million hectares (Mha) of the earth's surface. The majority of the world's peatlands are in temperate and boreal zones, whereas tropical ones cover only a total area of 90-170 Mha. However, there are still considerable uncertainties in C stock estimates as well as a lack of information about depth, bulk density and carbon accumulation rates. The incomplete data are notable especially in tropical peatlands located in South America, which are estimated to have the largest area of peatlands in the tropical zone. This paper displays the current state of knowledge surrounding tropical peatlands and their biophysical characteristics, distribution and carbon stock, role in the global climate, the impacts of direct human disturbances on carbon accumulation rates and greenhouse gas (GHG) emissions. Based on the new peat extension and depth data, we estimate that tropical peatlands store 152-288 Gt C, or about half of the global peatland emitted carbon. We discuss the knowledge gaps in research on distribution, depth, C stock and fluxes in these ecosystems which play an important role in the global carbon cycle and risk releasing large quantities of GHGs into the atmosphere (CO2 and CH4 ) when subjected to anthropogenic interferences (e.g., drainage and deforestation). Recent studies show that although climate change has an impact on the carbon fluxes of these ecosystems, the direct anthropogenic disturbance may play a greater role. The future of these systems as carbon sinks will depend on advancing current scientific knowledge and incorporating local understanding to support policies geared toward managing and conserving peatlands in vulnerable regions, such as the Amazon where recent records show increased forest fires and deforestation.

Methane emissions from tree stems in neotropical peatlands.

Neotropical peatlands emit large amounts of methane (CH4 ) from the soil surface, but fluxes from tree stems in these ecosystems are unknown. In this study we investigated CH4 emissions from five tree species in two forest types common to neotropical lowland peatlands in Panama. Methane from tree stems accounted for up to 30% of net ecosystem CH4 emissions. Peak CH4 fluxes were greater during the wet season when the water table was high and temperatures were lower. Emissions were greatest from the hardwood tree Campnosperma panamensis, but most species acted as emitters, with emissions declining exponentially with height along the stem for all species. Overall, species identity, stem diameter, water level, soil temperature and soil CH4 fluxes explained 54% of the variance in stem CH4 emissions from individual trees. On the landscape level, On the landscape level, the high emissions from C. panamensis forests resulted in that they emitted at 340 kg CH4  d-1 during flooded periods despite their substantially lower areal cover. We conclude that emission from tree stems is an important emission pathway for CH4 flux from Neotropical peatlands, and that these emissions vary strongly with season and forest type.

Plant communities control long term carbon accumulation and biogeochemical gradients in a Patagonian bog.

Peat carbon accumulation is controlled by both large scale factors, such as climate and hydrological setting, and small scale factors, such as microtopography and plant community. These small scale factors commonly vary within peatlands and can cause variation in biogeochemical traits and carbon accumulation within the same site. To understand these within-site variations, we investigated long term carbon accumulation, peat decomposition, biogeochemistry of pore water and plant macrofossils along a transect in an ombrotrophic bog in southern Patagonia. An additional question we addressed is how historical deposition of volcanic ash on the peatland has affected its carbon balance. Variability in plant community and water table led to differences in long term peat and carbon accumulation (peat moss > cushion plant), organic matter decomposition (cushion plant > peat moss), and methane production (peat moss > cushion plant). Macrofossil analysis and radiocarbon dating indicated a relationship between plant community and carbon accumulation or decomposition during the historical succession of vegetation in the peatland. C/N ratio and isotopic signatures reflected variability in plant community as litter source, and DOC concentrations were controlled by humification level. Volcanic ash deposition had only limited effect on plant composition, but it was associated with increased decomposition in overlying peat layers. This study highlights the importance of understanding how plant communities develop, as changes in communities could significantly affect the potential of ombrotrophic peatlands as C sink.

Response of testate amoebae to a late Holocene ecosystem shift in an Amazonian peatland.

To date there have only been two studies using testate amoebae as palaeoecological indicators in tropical peatlands. Here we present a new ∼500-year testate amoeba record from San Jorge, a domed peatland in Peruvian Amazonia, which has a well-constrained vegetation history based on pollen analysis. We observe a major shift from Hyalosphenia subflava to Cryptodifflugia oviformis-dominated communities at ∼50 cm depth (c. AD 1760), which suggests a change to drier conditions in the peatland. The application of a statistical transfer function also suggests a deepening of the water table at this time. The transition in the microbial assemblage occurs at a time when pollen and geochemical data indicate drier conditions (reduced influence of river flooding), leading to an ecosystem switch to more ombrotrophic-like conditions in the peatland. Our work illustrates the potential of testate amoebae as important tools in tropical peatland palaeoecology, and the power of multiproxy approaches for understanding the long-term development of tropical peatlands.

An expert system model for mapping tropical wetlands and peatlands reveals South America as the largest contributor.

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, interannual 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; and (3) a geomorphological position where water is supplied and retained. Tropical and subtropical wetlands estimates reach 4.7 million km2 (Mkm2 ). In line with current understanding, the American continent is the major contributor (45%), and Brazil, with its Amazonian interfluvial region, contains the largest tropical wetland area (800,720 km2 ). Our model suggests, however, unprecedented extents and volumes of peatland in the tropics (1.7 Mkm2 and 7,268 (6,076-7,368) km3 ), which more than threefold 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.

Direct and indirect effects of glaciers on aquatic biodiversity in high Andean peatlands.

The rapid melting of glacier cover is one of the most obvious impacts of climate change on alpine ecosystems and biodiversity. Our understanding of the impact of a decrease in glacier runoff on aquatic biodiversity is currently based on the 'glacier-heterogeneity-diversity' paradigm, according to which there is high α-diversity at intermediate levels of glacial influence due to the high degree of environmental heterogeneity caused by glacier water. This α-diversity pattern generates high levels of between-site aquatic community variation (high ß diversity) and increases regional diversity (γ-diversity). There is a rich conceptual background in favor of this paradigm, but empirical data supporting it are scarce. We investigated this paradigm by analyzing the different diversity patterns (α, ß and γ-diversity) of four aquatic groups (zooplankton, macroinvertebrates, algae and macrophytes) living in high-elevation peatlands (>4500 m above sea level). We sampled 200 pools from 20 peatlands along a glacier gradient in the Cordillera Real of Bolivia. We performed structural equation modeling (SEM) to analyze the potential mechanisms underlying the observed diversity patterns. Intermediate levels of glacial influence (15-20% cover) resulted in high heterogeneity, but α-diversity responded to glacial influence only for the zooplankton group (Cladocera). Our SEM analysis did not identify environmental heterogeneity as a significant variable explaining the relationship between glacier and α-diversity. Peatland area had a strong positive effect on heterogeneity and diversity. ß-diversity was significantly associated with glacier gradient, and 12.9% of the total regional diversity (γ-diversity) was restricted to peatlands with a high degree of glacial influence. These species might be lost in a context of glacial retreat. These findings provide new insight into the potential effects of glacial retreat on the aquatic environment and biodiversity in the peatlands of the tropical Andes.

Palaeoecology of testate amoebae in a tropical peatland.

We present the first detailed analysis of subfossil testate amoebae from a tropical peatland. Testate amoebae were analysed in a 4-m peat core from western Amazonia (Peru) and a transfer function developed from the site was applied to reconstruct changes in water table over the past ca. 8,000 years. Testate amoebae were in very low abundance in the core, especially in the lower 125cm, due to a combination of poor preservation and obscuration by other organic matter. A modified preparation method enabled at least 50 testate amoebae to be counted in each core sample. The most abundant taxa preserved include Centropyxis aculeata, Hyalosphenia subflava, Phryganella acropodia and Trigonopyxis arcula. Centropyxis aculeata, an unambiguous wet indicator, is variably present and indicates several phases of near-surface water table. Our work shows that even degraded, low-abundance assemblages of testate amoebae can provide useful information regarding the long-term ecohydrological developmental history of tropical peatlands.

Arcella peruviana sp. nov. (Amoebozoa: Arcellinida, Arcellidae), a new species from a tropical peatland in Amazonia.

There has only been one study on the ecology of testate amoebae from Amazonian peatlands, despite Amazonia being a biodiversity hotspot of global importance. During analysis of litter samples from Aucayacu peatland, western (Peruvian) Amazonia, we discovered a testate amoeba with a distinct morphology unlike any other species reported previously. We describe a new species, Arcella peruviana, based on its distinct morphology, compare it to morphologically similar species and provide information about its ecology. This new species is characterised by a distinct cruciform aperture (diameter ranges between 12 and 17µm) which is slightly invaginated. The test is small (height 43-57µm) and polygonal in cross-section. Our discovery suggests the existence of an unknown diversity of testate amoebae in Amazonia. The absence of the new Arcella species in more intensively-sampled regions supports the view that protists have restricted distributions.