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A small imbalance in plant productivity and decomposition accounts for the carbon (C) accumulation capacity of peatlands. As climate changes, the continuity of peatland net C storage relies on rising primary production to offset increasing ecosystem respiration (ER) along with the persistence of older C in waterlogged peat. A lowering in the water table position in peatlands often increases decomposition rates, but concurrent plant community shifts can interactively alter ER and plant productivity responses. The combined effects of water table variation and plant communities on older peat C loss are unknown. We used a full-factorial 1-m

Páramo peatlands are a regional reservoir of biodiversity and ecosystem services, accumulating large amounts of carbon and buffering water flows. Despite their importance, they have a long history of use and impacts including drainage for agriculture and grazing, and water withdrawal for human uses. Here we present a preliminary assessment of the conservation status of páramo peatlands in Ecuador and, using a case study, discuss peatland restoration as a tool for mitigation and adaptation to the impacts of current climate change. Through a simple index assessing the cumulative presence of signs of human activities on 163 peatland sites, we found that the level of impact was higher for peatlands located in the Western branch of the cordillera, whereas current human population density, precipitation, and elevation were not significant predictors of the levels of impact. Also, starting in 2017, we implemented a pilot restoration initiative on a 21-ha peatland which had been drained and converted into pasture for at least 150 years. The restoration consisted of two ditch blocking techniques implemented to stop fast-moving water and promote the rewetting of the peatland. During the next 3 years, water table increased from 27 ± 3 cm below the soil surface to 7 ± 1 cm by 2021, while wetland plant communities are colonizing and closing the pools in the blocked ditches. Re-wetting of the peatland has led to an increase in the abundance of native species. This case study suggests that restoration initiatives are an efficient and cost-effective approach to a better management of páramo peatlands, with high potential as a tool for mitigation and adaptation to climate change.

Many tropical mountain peatlands in the Andes are formed by cushion plants. These unique cushion plant peatlands are intensively utilized for grazing and are also influenced by climate change, both of which alter hydrologic conditions. Little is known about the natural hydroperiods and greenhouse gas fluxes of these peatlands or the consequences of hydrologic alteration for these fluxes. Therefore, our objectives were to assess how carbon dioxide (CO2) and methane (CH4) fluxes varied across a hydrological gradient caused by ditching and evaluate how short-term carbon cycling responds after rewetting from ditch blocking in a tropical mountain peatland. The study was carried out in Huascaran National Park, Peru using static chamber methods. Comparing reference to highly drained conditions, mid-day net ecosystem exchange (NEE) was higher (1.07 ± 0.06 vs. 0.76 ± 0.11 g CO2 m−2 h−1), and the light compensation point for CO2 uptake was lower. Gas fluxes were relatively stable in the rewetted and reference treatments, with small positive responses of NEE to rising water tables. CH4 emissions averaged 2.76 ± 1.06 mg CH4 m−2 day−1, with negative fluxes at water tables >10 cm below the soil surface, and positive fluxes at higher water levels. Our results indicate that undrained peatlands appear to be carbon sinks, highly drained peatlands were likely carbon sources, and rewetting of moderately drained peatlands increased NEE and the ability to store carbon to undrained reference conditions. Ditching of peatlands will likely increase their susceptibility to negative climate change impacts, and hydrologic restoration could moderate these impacts.

Peatlands store one-third of Earth's soil carbon, the stability of which is uncertain due to climate change-driven shifts in hydrology and vegetation, and consequent impacts on microbial communities that mediate decomposition. Peatland carbon cycling varies over steep physicochemical gradients characterizing vertical peat profiles. However, it is unclear how drought-mediated changes in plant functional groups (PFGs) and water table (WT) levels affect microbial communities at different depths. We combined a multiyear mesocosm experiment with community sequencing across a 70-cm depth gradient, to test the hypotheses that vascular PFGs (Ericaceae vs. sedges) and WT (high vs. low) structure peatland microbial communities in depth-dependent ways. Several key results emerged. (i) Both fungal and prokaryote (bacteria and archaea) community structure shifted with WT and PFG manipulation, but fungi were much more sensitive to PFG whereas prokaryotes were much more sensitive to WT. (ii) PFG effects were largely driven by Ericaceae, although sedge effects were evident in specific cases (e.g., methanotrophs). (iii) Treatment effects varied with depth: the influence of PFG was strongest in shallow peat (0-10, 10-20 cm), whereas WT effects were strongest at the surface and middle depths (0-10, 30-40 cm), and all treatment effects waned in the deepest peat (60-70 cm). Our results underline the depth-dependent and taxon-specific ways that plant communities and hydrologic variability shape peatland microbial communities, pointing to the importance of understanding how these factors integrate across soil profiles when examining peatland responses to climate change.

Globally important carbon (C) stores in northern peatlands are vulnerable to oxidation in a changing climate. A growing body of literature draws attention to the importance of dissolved organic matter (DOM) in governing anaerobic metabolism in organic soil, but exactly how the reduction‐oxidation (redox) activities of DOM, and particularly the phenolic fraction, are likely to change in an altered climate remain unclear. We used large mesocosms in the PEATcosm experiment to assess changes in peatland DOM and redox potential in response to experimental manipulations of water table (WT) position and plant functional groups (PFGs). WT position and PFGs interacted in their effects on redox potential and quantity and quality of DOM. Phenolics were generally of higher molecular weight and more oxidized with sedges in lowered WTs. Altered DOM character included changes in dissolved nitrogen (N), with higher N: [phenolics] with higher E4:E6 (absorbance ratio λ = 465:665) DOM in the lowered WT and sedge PFG treatments. Conversely, biomolecular assignments to amino‐sugars were largely absent from low‐WT treatments. Low WT resulted in the creation of unique N compounds, which were more condensed (lower H:C), that changed with depth and PFG. The accumulation of oxidized compounds with low WT and in sedge rhizospheres could be very important pools of electron acceptors beneath the WT, and their mechanisms of formation are discussed. This work suggests the effects of changes in vegetation communities can be as great as WT position in directly and interactively mediating peat redox environment and the redox‐activity of DOM.

Arbuscular mycorrhizal (AM) fungi are hypothesized to assist growth of northern white-cedar in acid peatlands, yet there is little direct evidence that they can provide sufficient resources, especially nitrogen (N), from unfertilized peat soils. Our objective was to determine mycorrhizal efficacy to support cedar growth and nutrient supply as part of a low-impact approach for ecological restoration of cedar in peatlands. We tested the effectiveness of AM inoculation in a greenhouse experiment in factorial combination with fertilization and liming. We also determined AM colonization rate in the different treatment combinations. We found that AM inoculation in the absence of fertilization significantly increased all growth parameters, phosphorus (P) concentrations, and N, P, and copper (Cu) content of the seedlings, and decreased N:P ratios. Fertilizer alone had a similar impact on plant growth and nutrient acquisition when compared to un-fertilized AM inoculation treatments. Liming alone was ineffective at increasing cedar growth and nutrient uptake. There were many interactions of AM inoculation with liming and fertilization. Specifically, the positive effect of AM inoculation on many growth and nutrition metrics was strongly reduced in the presence of fertilization, whereas the P benefit of mycorrhizas appeared to increase under liming. We conclude that addition of AM inoculation alone improved cedar growth and P acquisition, reducing the need for fertilizer and lime in peatlands. However, seedling N limitation might be a problem in strongly N-deficient peat soils.

Wetlands (called bofedales in the Andes of Peru) are abundant and important components of many mountain ecosystems across the globe. They provide many benefits including water storage, high quality habitat, pasture, nutrient sinks and transformations, and carbon storage. The remote and rugged setting of mountain wetlands creates challenges for mapping, typically leading to misclassification and underestimates of wetland extent. We used multi-date, multi-sensor radar and optical imagery (Landsat TM/PALSAR/RADARSAT-1/SRTM DEM-TPI) combined with ground truthing for mapping wetlands in Huascaran National Park, Peru. We mapped bofedales into major wetland types: 1) cushion plant peatlands, 2) cushion plant wet meadows, and 3) graminoid wet meadows with an overall accuracy of 92%. A fourth wetland type was found (graminoid peatlands) but was too rare to map accurately, thus it was combined with cushion peatland to form a single peatland class. Total wetland area mapped in the National Park is 38,444 ha, which is 11% of the park area. Peatlands were the most abundant wetland type occupying 6.3% of the park, followed by graminoid wet meadows (3.5%) and cushion wet meadows (1.3%). These maps will serve as the foundation for improved management, including restoration, and estimates of landscape carbon stocks.

Soil and the inherent biogeochemical processes in wetlands contrast starkly with those in upland forests and rangelands. The differences stem from extended periods of anoxia, or the lack of oxygen in the soil, that characterize wetland soils; in contrast, upland soils are nearly always oxic. As a result, wetland soil biogeochemistry is characterized by anaerobic processes, and wetland vegetation exhibits specific adaptations to grow under these conditions. However, many wetlands may also have periods during the year where the soils are unsaturated and aerated. This fluctuation between aerated and nonaerated soil conditions, along with the specialized vegetation, gives rise to a wide variety of highly valued ecosystem services.

The carbon sink potential of peatlands depends on the balance of carbon uptake by plants and microbial decomposition. The rates of both these processes will increase with warming but it remains unclear which will dominate the global peatland response. Here we examine the global relationship between peatland carbon accumulation rates during the last millennium and planetary-scale climate space. A positive relationship is found between carbon accumulation and cumulative photosynthetically active radiation during the growing season for mid- to high-latitude peatlands in both hemispheres. However, this relationship reverses at lower latitudes, suggesting that carbon accumulation is lower under the warmest climate regimes. Projections under Representative Concentration Pathway (RCP)2.6 and RCP8.5 scenarios indicate that the present-day global sink will increase slightly until around AD 2100 but decline thereafter. Peatlands will remain a carbon sink in the future, but their response to warming switches from a negative to a positive climate feedback (decreased carbon sink with warming) at the end of the twenty-first century.

Ditching is a common practice to dewater wetlands, including peatlands, and ditch blocking is a common method for restoring wetlands because substrate is often unavailable for filling the ditches. However, filling has many advantages compared to blocking ditches. Our goal was to test whether ditches could be filled in a Colorado sloping fen (Chattanooga Fen) using bales created from shredded aspen (Populus tremuloides) tree‐fiber. We monitored water table levels before and after we filled two ditches (combined length of approximately 165 m × 3 m wide) as well as an undisturbed reference portion of Chattanooga fen. The reference site had stable water tables that rarely dropped more than 20 cm below the soil surface. The ditches had been dewatering large areas of the fen for at least 100 years. Filling the ditches with fiber bales resulted in a water table increase between 2 and 22 cm in an area up to 150 m below the ditch. Native sedges now cover the area where we filled the ditches, with no erosion or compression/settling of the ground observed and no water backing up behind the filled ditches. Filling the ditches with shredded fiber bales is a good option for restoration in wilderness areas, or areas lacking peat or mineral soil fill because it is a natural material that is easily transported and placed in the ditches.

Indonesia and Peru harbor some of the largest lowland tropical peatland areas. Indonesian peatlands are subject to much greater anthropogenic activity than Peru’s, including drainage, logging, agricultural conversion, and burning, resulting in high greenhouse gas and particulate emissions. To derive insights from the Indonesian experience, we explored patterns of impact in the two countries, and compared their predisposing factors. Impacts differ greatly among Indonesian regions and the Peruvian Amazon in the following order: Sumatra > Kalimantan > Papua > Peru. All impacts, except fire, are positively related to population density. Factors enhancing Indonesian peatlands’ susceptibility to disturbance include peat doming that facilitates drainage, coastal location, high local population, road access, government policies permitting peatland use, lack of enforcement of protections, and dry seasons that favor extensive burning. The main factors that could reduce peatland degradation in Peru compared with Indonesia are geographic isolation from coastal population centers, more compact peatland geomorphology, lower population and road density, more peatlands in protected areas, different land tenure policies, and different climatic drivers of fire; whereas factors that could enhance peatland degradation include oil and gas development, road expansion in peatland areas, and an absence of government policies explicitly protecting peatlands. We conclude that current peatland integrity in Peru arises from a confluence of factors that has slowed development, with no absolute barriers protecting Peruvian peatlands from a similar fate to Indonesia’s. If the goal is to maintain the integrity of Peruvian peatlands, government policies recognizing unique peatland functions and sensitivities will be necessary.

Peatlands play a critical role in terrestrial carbon (C) storage, containing an estimated 30% of global soil C, despite occupying only 3% of global land area. Historic management of peatlands has led to widespread degradation and loss of important ecosystem services, including C sequestration. Legacy drainage features in the peatlands of northern Minnesota, USA were studied to assess the volume of peat and the amount of C lost in the ~100 years since drainage. Using high-resolution Light Detection and Ranging (LiDAR) data, we measured elevation changes adjacent to legacy ditches to model pre-ditch surface elevations, which were used to calculate peat volume loss. We established relationships between volume loss and site characteristics from existing geographic information systems datasets and used those relationships to scale volume loss to all mapped peatland ditches in northern Minnesota (USA). We estimated that 0.165 ± 0.009 km3 of peat have been lost along almost 4000 km of peatland ditches. Peat loss upslope of ditches was significantly less than downslope (P < 0.001). Mean width of the entire ditch-effect zone was 333 ± 8.32 m. Using our volume loss estimates, literature estimates of oxidation, and mean bulk density and peat C% values from Minnesota peatlands, we calculate a total historic loss 3.847 ± 0.364 Tg C. Assuming a constant oxidation rate during the 100 years since drainage, euic and dysic peatlands within the ditch effect zone have lost 0.26 ± 0.08 and 0.40 ± 0.13 Mg C ha-1 yr-1, respectively, comparable to IPCC estimates. Our spatially-explicit peat loss estimates could be incorporated into decision support tools to inform management decisions regarding peatland C and other ecosystem services.

The paramo ecoregion of Ecuador contains extensive peatlands that are known to contain carbon (C) dense soils capable of long-term C storage. Although high-altitude mountain peatlands are typically small when compared to low altitude peatlands, they are abundant across the Andean landscape and are likely a key component in regional C cycling. Since efforts to quantify peatland distribution and C stocks across the tropical Andes have been limited due to the difficulty in sampling remote areas with very deep peat, there is a large knowledge gap in our quantification of the current C pools in the Andean mountains, which limits our ability to predict and monitor change from high rates of land use and climate change. In this paper we tested if ground penetrating radar (GPR), combined with manual coring and C analysis could be used for estimating C stocks in peatlands of the Ecuadorian paramo. Our results indicated that GPR was successful in quantifying peat depths and carbon stocks. Detection of volcanic horizons like tephra layers allowed further refinement of variability of C stocks within the peat column, while providing information on the lateral extent of tephras at high (cm scale) resolution that may prove very useful for the correlation of time-stratigraphic markers between sediments in alpine peatlands. In conclusion, this paper provides a methodological basis for quantifying C stocks in high altitude peatlands and to infer changes in the physical properties of soils that could be used as proxies for C content or paleoclimate reconstructions.

Globally, peatlands store a large quantity of soil carbon that can be subsequently modified by hydrologic alterations from land-use change and climate change. However, there are many uncertainties in predicting how carbon cycling and greenhouse gas emissions are altered by long-term changes in hydrology. Therefore, the goal of this study was to quantify how multi-decadal manipulations of water table (WT) levels affected carbon cycling (plant production and net ecosystem exchange from three eddy covariance towers) in a peatland complex modified by levee construction, which created a wetter area up-gradient of the levee (mean WT was 12.1 cm below the surface), a dry area below the levee (36.8 cm), and an adjacent reference site not affected by the levee (21.6 cm). We found that mean total plant production was greatest in the reference site (311.9 g C m−2 y−1), followed by the dry site (290.5 g C m−2 y−1), and lowest in the wet site (227.1 g C m−2 y−1). Net ecosystem exchange during the growing season was negative for all sites (sink), with the wet site having the greatest sink and the dry site having the lowest sink. Ecosystem respiration increased and CH4 emissions decreased with a decreasing WT level. This research demonstrates that human alteration of peatland WT levels can have long-term (>50 years) consequences on peatland carbon cycling.

Peatland restoration in North America (NA) was initiated approximately 25 years ago on peat-extracted bogs. Recent advances in peatland restoration in NA have expanded the original concepts and methodology. Restoration efforts in NA now include restoring peatlands from many diverse types of disturbances (e.g. roads, agriculture, grazing, erosion, forestry, and petrol industry infrastructure impacts) and occur in a greater array of peatland types (e.g. fens and swamps). Because fens are groundwater and surface flow driven, techniques to restore the hydrology of fens are generally more complicated than bogs. Restoring a greater variety of peatland types on a large-scale basis (>10 ha) commands new techniques for reestablishing a broader array of plants other than Sphagnum spp., including non-Sphagnum mosses, sedges, nonericaceous shrubs, and trees. The rationale for restoring peatlands has expanded to include legal requirements, wetland mitigation and banking, climate mitigation, water quality, and as part of responsible ecosystem management for industry or society. In the past 25 years, peatland restoration in NA has evolved from (1) trial and error to a more empirically based scientific approach, (2) small site-specific experiments to landscape-scale restoration (e.g. hydrological connectivity, ecological fragmentation), and (3) individual stakeholder (academic) to multiple stakeholders across jurisdictional boundaries (private, local, and regional governmental agencies, NGOs, and so on). However, many research gaps still exist that must be addressed to enhance our ability to restore peatlands successfully.

The paramo is a high altitude tropical Andean ecosystem that contains peatlands with thick horizons of carbon (C) dense soils. Soil C data are sparse for most of the paramo, especially in peatlands, which limits our ability to provide accurate regional and country wide estimates of C storage. Therefore, the objective of our research was to quantify belowground C stocks and accumulation rates in paramo peatland soils in two regions of northeastern Ecuador. Peatland soil cores were collected from Antisana Ecological Reserve and Cayambe-Coca National Park. We measured soil C densities and 14C dates to estimate soil accumulation rates. The mean peatland soil depth across both regions was 3.8 m and contained an estimated mean C storage of 1282 Mg ha−1. Peatlands older than 3000 cal. year BP had a mean long-term C accumulation rate of 26 g m−2 year−1, with peatlands younger than 500 cal. year BP displaying mean recent rates of C accumulation of 134 g m−2 year−1. These peatlands also receive large inputs of mineral material, predominantly from volcanic deposition, that has created many interbedded non-peat mineral soil horizons that contained 48 % of the soil C. Because of large C stocks in Ecuadorian mountain peatlands and the potential disturbance from land use and climate change, additional studies are need to provide essential baseline assessments and estimates of C storage in the Andes.

Tropical peatlands are a major, but understudied, biophysical feedback factor on the atmospheric greenhouse effect. The largest expanses of tropical peatlands are located in lowland areas of Southeast Asia and the Amazon basin. The Loreto Region of Amazonian Peru contains ~63,000 km2 of peatlands. However, little is known about the biogeochemistry of these peatlands, and in particular, the cycling of carbon dioxide (CO2) and methane (CH4), and their responses to hydrometeorological forcings. To address these knowledge gaps, we established an eddy covariance (EC) flux tower in a natural palm (Mauritia flexuosa L.f.) swamp peatland near Iquitos, Peru. Here, we report ecosystem-scale CO2 and CH4 flux observations for this Amazonian palm swamp peatland over a two-year period in relation to hydrometeorological forcings. Seasonal and short-term variations in hydrometeorological forcing had a strong effect on CO2 and CH4 fluxes. High air temperature and vapor pressure deficit (VPD) exerted an important limitation on photosynthesis during the dry season, while latent heat flux appeared to be insensitive to these climate drivers. Evidence from light-response analyses and flux partitioning support that photosynthetic activity was downregulated during dry conditions, while ecosystem respiration (RE) was either inhibited or enhanced depending on water table position. The cumulative net ecosystem CO2 exchange indicated that the peatland was a significant CO2 sink ranging from −465 (−279 to −651) g C m−2 y−1 in 2018 to −462 (−277 to −647) g C m−2 y−1 in 2019. The forest was a CH4 source of 22 (20 to 24) g C m−2 y−1, similar in magnitude to other tropical peatlands and larger than boreal and arctic peatlands. Thus, the annual carbon budget of this Amazonian palm swamp peatland appears to be a major carbon sink under current hydrometeorological conditions.

Vernal pools are isolated ephemeral bodies of water that are often overlooked on the landscape. Despite their temporary nature, these pools are important to forest communities, providing critical breeding habitat for amphibians and an important food and water source for other taxonomic groups including birds, bats, and other terrestrial vertebrates. Sparse information about vernal pools in the upper Midwest, including Pictured Rocks National Lakeshore (PIRO), inhibits conservation. We sampled soil, vegetation, and amphibians in 21 vernal pools in PIRO during spring 2010 to provide quantitative and qualitative evaluation of vernal pool abiotic and biotic characteristics within PIRO to help managers determine which pools to prioritize for conservation. Average vernal pool size sampled was 0.124 ha. Soils had an average of 13.5% carbon and 0.7% nitrogen. Vegetation was diverse within the vernal pools, with 115 vascular plants identified. Five species of amphibians were encountered during our surveys...

Northern white-cedar (Thuja occidentalis L.) wetlands are highly valuable both commercially and as wildlife habitat. However, northern white-cedar forested wetlands are declining in area from forestry activities and development, with mitigation efforts often failing to reproduce these ecosystems. For this reason, the goal of this project was to determine the feasibility of creating a northern white-cedar forested wetland as a wetland mitigation option. Microtopography has been shown to be important for northern white-cedar establishment and recruitment, so a series of hummocks and flat areas were created and planted with northern white-cedar seedlings in two created wetlands in northern Michigan, USA. We examined the influence of microtopography and exposure to deer browse on white-cedar survivorship and height growth, 2 and 5 years after establishment. Hummock microtopography increased both tree survival and height growth. Percent survival after 5 years in protected fenced areas was 75 % on hummocks, while percent survival was only 15 % in protected fenced flat areas. Height growth rates were also greater on fenced hummocks, averaging 30 cm per year, compared to an average of 8 cm per year on fenced flat areas. Protection from browsing also improved white-cedar survival and height growth. Fenced white-cedar had 15–20 % greater survival compared to unfenced white-cedar and had 25–100 % greater growth rates. Our results indicate that incorporating microtopography and protection from browsing into future restoration or regeneration projects involving northern white-cedar should be considered as a viable option where high or variable water tables are expected.

Tropical peatlands store a significant portion of the global soil carbon (C) pool. However, tropical mountain peatlands contain extensive peat soils that have yet to be mapped or included in global C estimates. This lack of data hinders our ability to inform policy and apply sustainable management practices to these peatlands that are experiencing unprecedented high rates of land use and land cover change. Rapid large scale mapping activities are urgently needed to quantify tropical wetland extent and rate of degradation. We tested a combination of multi-date, multi-sensor radar and optical imagery (Landsat TM/PALSAR/RADARSAT-1/TPI image stack) for detecting peatlands in a 2715 km2 area in the high elevation mountains of the Ecuadorian paramo. The map was combined with an extensive soil coring data set to produce the first estimate of regional peatland soil C storage in the paramo. Our map displayed a high coverage of peatlands (614 km2) containing an estimated 128.2 ± 9.1 Tg of peatland belowground soil C within the mapping area. Scaling-up to the country level, paramo peatlands likely represent less than 1% of the total land area of Ecuador but could contain ~23% of the above and belowground vegetation C stocks in Ecuadorian forests. These mapping approaches provide an essential methodological improvement applicable to mountain peatlands across the globe, facilitating mapping efforts in support of effective policy and sustainable management, including national and global C accounting and C management efforts. This article is protected by copyright. All rights reserved.

Wet meadows are important ecosystems for forage production and as carbon reservoirs in semi-arid areas. In Patagonia, Argentina, large areas of wet meadows have been classified as overgrazed by livestock. The objective of this study was to determine whether long-term overgrazing has affected carbon (C) storage in plant and soil pools in wet and mesic meadows. The study occurred in Northern Patagonia, in three study sites located along a precipitation gradient. Our results indicate that long-term overgrazing reduced, on average, 35 % of the total ecosystem C pool. There was significantly lower aboveground and belowground plant production in heavily grazed compared to lightly grazed sites, 419 ± 262 – 128 ± 110 g m2 year−1 and 3796 ± 2622 – 1702 ± 1012 g m2 year−1, respectively. Soil C concentrations were also less in heavily grazed sites (184 ± 98 – 105 ± 58 g kg−1 at 1 m depth, respectively). The response of meadows to long-term heavy grazing also appears to be influenced by different levels of precipitation, with sites in drier areas being apparently more susceptible to overgrazing. Our results indicate that new management and restoration practices are needed to stop and reverse meadow deterioration in degraded meadows of Northern Patagonia. Fil: Enriquez, Andrea Soledad. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Chimner, Rodney A.. Michigan Technological University; Estados Unidos Fil: Cremona, Victoria. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Bordenave; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Diehl, Paula. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bonvissuto, Griselda Luz. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Bordenave; Argentina

Our objective was to assess the impacts of water table position and plant functional type on peat structure, plant community composition and aboveground plant production. We initiated a full factorial experiment with 2 water table (WT) treatments (high and low) and 3 plant functional groups (PFG: sedge, Ericaceae, sedge and Ericaceae- unmanipulated) in twenty-four 1 m3 intact peatland mesocosms. We measured vegetation cover, aboveground plant production, and peat subsidence to analyze interactive PFG and WT effects. Sphagnum rubellum cover increased under high WT, while Polytrichum cover increased with low WT and in sedge only PFGs. Sphagnum production was greatest with high WT, while vascular plant production was greater in low WT treatments. There was an interactive WT x PFG effect on Ericaceae production. Lowered WT resulted in significant peat surface change and increased subsidence. There were significant PFG and WT effects on net peat accumulation, with the lowest rates of accumulation, high and low WT, in sedge only PFGs. The shift in water balance leading to lowered water table position predicted with changing climate could impact plant community composition and production, and would likely result in the subsidence of peat.

Wet meadows are seasonally saturated wetlands that can develop in arid and semi-arid areas. In the semi-arid region of North Patagonia, Argentina wet meadows are islands of high net primary productivity surrounded by low productivity steppe vegetation. Because of this, Patagonian wet meadows have been heavily grazed by livestock for more than a century. It has been shown that overgrazed wet meadows have lower soil carbon, however, little is known about how overgrazing impacts N dynamics. To this end, we measured ammonium (NH4+), nitrate (NO3−), and total nitrogen (Nt) in paired wet meadows that varied in long-term grazing intensity (heavy vs. light). Results indicate that heavily grazed sites had on average 43% less Nt and 57% less NH4+ than lightly grazed sites. Soil NH4+ concentrations were always significantly greater than NO3− concentrations, being the later often below detection levels. In addition, NH4+ concentrations were correlated with soil moisture in lightly grazed sites, but not in heavily grazed sites. These findings indicate that implementation of better management practices are currently needed to promote more sustainable grazing in semi-arid wet meadows of North Patagonia.

Many international protocols (e.g., REDD+) are developing inventories of ecosystem carbon stocks and fluxes at country and regional scales, which can include peatlands. As the only nationally implemented field inventory and re- measurement of forest soils in the US, the USDA Forest ServiceForestInventoryandAnalysisProgram(FIA)samples the top 20 cm of organic soils, but there is a large unsampled fraction of soil carbon stored in America' sp eatland forests. Improved methods could allow the FIA program to more comprehensivelyestimatesoilcarbonstocksandstockchange in forested peatlands. We evaluated six rapid peat sampling methods in northern peatlands: 1) general probing of peat thickness, 2) general probing of peat thickness by general vegetation type, 3) partial profile coring #1, 0-20 cm, 4) partial profile coring #2, 25-75 cm, 5) partial profile coring #3, 50-100 cm, 6) intermittent profile coring and compared them to 7) measurements derived from whole profile sam- pling. We also tested our methods against an independent database of 85 peat cores collected from Manitoba, Canada. Overall,wefoundthatthe0-20cmpartialprofilecoremethod was the least accurate method and should not be used (64-67 % accurate). The remaining rapid peat sampling methods all provided accuracies >85 % compared to whole profile sampling. In conclusion, we found that there are sev- eral good options for rapidly sampling peat C stocks that if incorporated, could greatly increase our estimates of carbon stored in peat.

Following a prolonged drought, more than 7,250 ha of a large fen complex in Michigan’s Upper Peninsula burned in late summer of 2007. As part of fire-fighting efforts, over 48 km of bulldozed firebreaks were made in and around the peatland. In 2008, the State of Michigan restored over 32 km of firebreak in upland areas, but 14.5 km through the fen proper remained as open-water ditches. In the fall of 2009, we restored 2 km of ditch by replacing spoils with an excavator. In addition to ditch filling, we conducted experimental plantings of 18 species of vascular plants and 6 mosses to test the effectiveness of seeding, moss diaspore application and mulching. Surveys during the first and second summers found excellent regrowth of vegetation both within the treatment plots and the controls. Contrary to most published results, the unmulched plots had the greatest vegetative cover and richness of plant species, followed by the mulched plots and the unplanted controls. By 2011, mean vegetative cover on the treatment plots had exceeded the undisturbed ones. Our results indicate that filling is an excellent method of ditch restoration in fens and that seeding increases both plant cover and species richness. Conversely, the addition of moss diaspores and mulch were apparently unnecessary in this case, as moss cover in treatment and control plots was similar along the length of the ditch, likely because of the perennially high water table and the presence of living diaspores in the replaced spoils.

Dissolved organic carbon (DOC) production, consumption, and quality displayed differences after long-term (~55 years) hydrological alterations in a poor fen peatland in northern Michigan. The construction of an earthen levee resulted in areas of a raised and lowered water table (WT) relative to an unaltered intermediate WT site. The lowered WT site had greater peat aeration and larger seasonal vertical WT fluctuations that likely elevated peat decomposition and subsidence with subsequent increases in bulk density, vertical hydraulic gradient, decreased hydraulic conductivity (Ksat), and a greater pore water residence time relative to the unaltered site. The raised WT site displayed a decreased Ksat combined with seasonal upwelling events that contributed to a longer residence time in comparison to the unaltered site. These differences are potentially contributing to elevated DOC concentrations at the lowered and raised WT site relative to the unaltered site. Additionally, spectrophotometric indices and chemical constituent assays indicated that the lowered site DOC was more aromatic and contained elevated concentrations of phenolics compared to the intermediate site. The raised site DOC was less aromatic, less humified, and also had a greater phenolic content than the intermediate site. Furthermore, an incubation experiment showed that DOC in the raised site contained the greatest labile carbon source. Based on our results, long-term WT alterations will likely impose significant effects on DOC dynamics in these peatlands; however, WT position alone was not a good predictor of DOC concentrations, though impoundment appears to produce a more labile DOC whereas drainage increases DOC aromaticity.

Although much is known about the physiological capabilities of reed canarygrass (RCG) and the consequences of invasion, less is known about the roles that wetland type and surrounding disturbances play in facilitating the spread of RCG in predominantly forested landscapes. Therefore, the goals of our study were to test if (1) certain wetland types in the Northern Great Lakes region were more susceptible to RCG invasion, (2) certain disturbances facilitated RCG, and (3) the level of road development and the presence or absence of a ditch bordering each observed road influences the frequency of adjacent RCG populations. We randomly selected 28 wetlands within the Keweenaw Bay Indian Community reservation in the Upper Peninsula of Michigan. At each wetland, we collected plant community and environmental data and catalogued disturbances. In all, 287 plant species were identified. Cluster analysis revealed 16 distinct vegetation communities, which were distributed among three broader wetland community types: (1) nonforested graminoid, (2) Sphagnum peatlands, and (3) forested wetlands. Occurrence of RCG was most common in the nonforested graminoid communities and was also positively correlated to disturbance. The most frequent disturbances were roads, off-road vehicle trails, and logging activity. Additionally, paved and graded roads, and roads with ditches, were more likely to have RCG alongside them than unpaved dirt roads. Our data suggest that RCG occurrence is controlled by interactions between wetland types and disturbance.

Studies conducted across northern Europe and North America have shown increases in dissolved organic carbon (DOC) in aquatic systems in recent decades. While there is little consensus as to the exact mechanisms for the increases in DOC, hypotheses converge on such climate change factors as warming, increased precipitation variability, and changes in atmospheric deposition. In this study, we tested the effects of warming on peat porewater composition by actively warming a peatland with infrared lamps mounted 1.24 m above the peat surface for 3 years. Mean growing season peat temperatures in the warmed plots (n = 5) were 1.9 ± 0.4 °C warmer than the control plots at 5 cm depth (t statistic = 5.03, p = 0.007). Mean porewater DOC concentrations measured throughout the growing season were 15 % higher in the warmed plots (73.4 ± 3.2 mg L−1) than in the control plots (63.7 ± 2.1 mg L−1) at 25 cm (t = 4.69, p

Recently, it has been found that several species of oaks (e.g. Q. douglasii) are phreatophytes, or predominately use groundwater. The objectives of our study were to determine if riparian bur oak (Quercus macrocarpa) also used groundwater. This study took place in Homestead National Monument (Homestead, NM), Nebraska, where bur oak grow within the historical floodplain of Cub Creek with groundwater six to seven meters below the surface. Plant and soil samples for isotopic analysis were collected from three sites during 2008 and 2009. Water table depth was measured continuously, and river stage and precipitation were monitored daily by Homestead NM staff. We analyzed river water, groundwater, twig xylem water, and soil water for natural abundance of oxygen isotopes (which can be used as a natural tracer to identify different sources of water). A three-pool mixing model indicated that bur oak were using from 70% to 88% groundwater, 10% to 12% deep soil water, and a maximum of only 8% from shallow ...

Rapid expansion in biomass production for biofuels and bioenergy in the Americas is increasing demand on the ecosystem resources required to sustain soil and site productivity. We review the current state of knowledge and highlight gaps in research on biogeochemical processes and ecosystem sustainability related to biomass production. Biomass production systems incrementally remove greater quantities of organic matter, which in turn affects soil organic matter and associated carbon and nutrient storage (and hence long-term soil productivity) and off-site impacts. While these consequences have been extensively studied for some crops and sites, the ongoing and impending impacts of biomass removal require management strategies for ensuring that soil properties and functions are sustained for all combinations of crops, soils, sites, climates, and management systems, and that impacts of biomass management (including off-site impacts) are environmentally acceptable. In a changing global environment, knowledge of cumulative impacts will also become increasingly important. Long-term experiments are essential for key crops, soils, and management systems because short-term results do not necessarily reflect long-term impacts, although improved modeling capability may help to predict these impacts. Identification and validation of soil sustainability indicators for both site prescriptions and spatial applications would better inform commercial and policy decisions. In an increasingly inter-related but constrained global context, researchers should engage across inter-disciplinary, inter-agency, and international lines to better ensure the long-term soil productivity across a range of scales, from site to landscape.

Drained peatlands are a global concern due to alterations of the water and carbon cycle, loss of habitat, and increased fire frequency. However, methods for restoring drained sloping peatlands are limited and poorly tested. Therefore, we measured water table dynamics, CO2 fluxes, and soil properties at four sloping fens that were restored (1–20 years post-restoration) with the installation of small check dams in ditches that had drained the sites for a century. Restoration had a positive effect on water tables, increasing from approximately 45 cm below the surface to approximately 15 cm below the surface during the summers. Restoration also benefited CO2 fluxes, as the mean net ecosystem exchange was greatest in the restored areas (−2.19 g CO2 m−2 hour-1) compared to the unrestored drained areas (−1.28 g CO2 m−2 hour−1), while in reference areas it was −1.74 g CO2 m−2 hour−1. Drainage also caused significant changes to the peat soil including: 25% reduction in soil organic matter (lost between 1.4 to 3.6 kg/m2), increased bulk density, decreased porosity, and reduced saturated hydraulic conductivity. Restoration did not affect these parameters, even 20 years after restoration. This study suggests that although natural water table levels have been reestablished and the process of carbon sequestration improved, the physical properties of the most disturbed, near surface peat soils do not mimic reference conditions 20 years post-restoration.

Northern peatland water table position is tightly coupled to carbon (C) cycling dynamics and is predicted to change from shifts in temperature and precipitation patterns associated with global climate change. However, it is uncertain how long-term water table alterations will alter C dynamics in northern peatlands because most studies have focused on short-term water table manipulations. The goal of our study was to quantify the effect of long-term water table changes (~80 years) on gaseous C fluxes in a peatland in the Upper Peninsula of Michigan. Chamber methods were utilized to measure ecosystem respiration (ER), gross primary production (GPP), net ecosystem exchange (NEE), and methane (CH4) fluxes in a peatland experiencing levee induced long-term water table drawdown and impoundment in relation to an unaltered site. Inundation raised water table levels by approximately ~10 cm and resulted in a decrease in ER and GPP, but an increase of CH4 emissions. Conversely, the drained sites, with water table levels ~15 cm lower, resulted in a significant increase in ER and GPP, but a decrease in CH4 emissions. However, NEE was not significantly different between the water table treatments. In summary, our data indicates that long-term water table drawdown and inundation was still altering peatland gaseous C fluxes, even after 80 years. In addition, many of the patterns we found were of similar magnitude to those measured in short-term studies, which indicates that short-term studies might be useful for predicting the direction and magnitude of future C changes in peatlands.

A large wetland drainage project was initiated in 1912 near the town of Seney, Michigan, U.S.A. This project included the construction of a series of ditches through a large peatland to drain the land for agricultural use. The largest of these ditches was the 35 km long Walsh Ditch. Much of the drained wetland affected by the Walsh Ditch is now managed by the U.S. Fish and Wildlife Service as part of Seney National Wildlife Refuge. Between 2002–2003, nine large earthen ditch plugs were installed along a 4.5 km section of the ditch in an attempt to restore the hydrological and ecological integrity of the approximately 1400 ha of wetlands and streams. This study explores the effects that the ditch plugs had on the hydrology and vegetation structure of the adjacent landscape 8y later. Plot level measurements (707 m2 plots) of hydrology and vegetation, combined with an analysis of land cover change using aerial imagery, indicated that the ditch plugs had been successful in altering the hydrology and ...

Open top chambers (OTCs) and infrared (IR) lamps have been widely used for experimentally warming ecosystems, especially in high latitude and alpine regions. The efficacy of OTCs and IR lamps is variable, yet there has not been a direct, experimentally controlled comparison of these warming methods. We, therefore, implemented a factorial study in a northern Michigan peatland to test how warming and microtopography interacted to affect micrometeorological parameters and CO2 and CH4 flux rates. IR lamps significantly warmed the soil (5 cm depth; P < 0.05) by 1.4 and 1.9°C in 2009 and 2010, respectively, with the majority of warming occurring during nighttime hours. OTCs did not provide any long-term warming increase compared to control plots, which is contrary to OTC studies at high latitudes. By investigating diurnal heating patterns and micrometeorological variables, we determined that OTCs were not achieving strong daytime heating peaks and were often cooler than controls during nighttime hours. Temperate day-length, cloudy and humid conditions, and latent heat loss were factors that may have inhibited OTC warming. Warming treatments created mixed effects on gas flux components. Within drier, hummock plots, IR lamps significantly increased gross ecosystem production (GEP) but not ecosystem respiration (ER), whereas OTCs had no effect on GEP or ER in hummocks. In wetter, lawn plots, warming treatments had no effect on CO2 flux or CH4 flux. We show here that IR lamps are more effective than OTCs for studying how temperate peatlands may respond to increased temperatures.

Water-limited grasslands may be exceedingly vulnerable to changes in the timing or amount of precipitation which may result in shifts in the magnitudes and patterns of carbon cycling. Shifts in CO2 exchange may lead to alterations in carbon sequestration or net losses and could accentuate the rising CO2 concentrations in the atmosphere or ameliorate the increases. The objective of our project was to quantify how changes in winter, summer, and combined winter and summer precipitation may alter rates of ecosystem C cycling in the mixed-grass prairie of the United States. Three replicated 50 m snow fences were installed to increase winter snow while summer precipitation was manipulated by either increasing (C50%) or decreasing (� 50%) precipitation amounts. Measurements of net ecosystem exchange (NEE), gross ecosystem photosynthesis (GEP), and ecosystem respiration (ER) and plant biomass were conducted throughout the snow-free period. Deeper snow in winter increased summer ER by an average of 27%, GEP by 45%, NEE by 90% and plant biomass by 50% compared to ambient snow conditions. Average plant biomass increased 44% with the addition of summer rain and decreased by 18% where rainfall was excluded under ambient snow conditions. Average NEE was also lower where rain was excluded. Our findings indicate that seasonality changes of precipitation may be important in regulating the future extent of C sequestration and C cycling in one of the most extensive, intact grasslands of North America. Copyright  2010 John Wiley & Sons, Ltd.

Summary • Although global change is known to influence plant invasion, little is known about interactions between altered precipitation and invasion. In the North American mixedgrass prairie, invasive species are often abundant in wet and nitrogen (N)-rich areas, suggesting that predicted changes in precipitation and N deposition could exacerbate invasion.  Here, this possibility was tested by seeding six invasive species into experimental plots of mixedgrass prairie treated with a factorial combination of increased snow, summer irrigation, and N addition.  Without added snow, seeded invasive species were rarely observed. Snow addition increased average above-ground biomass of Centaurea diffusa from 0.026 to 66 g m −2 , of Gypsophila paniculata from 0.1 to 7.3 g m −2 , and of Linaria dalmatica from 5 to 101 g m −2 . Given added snow, summer irrigation increased the density of G. paniculata, and N addition increased the density and biomass of L. dalmatica. Plant density responses mirrored those of plant biomass, indicating that increases in biomass resulted, in part, from increases in recruitment. In contrast to seeded invasive species, resident species did not respond to snow addition.  These results suggest that increases in snowfall or variability of snowfall may exacerbate forb invasion in the mixedgrass prairie.

High arctic wetlands hold large stores of soil carbon (C). The fate of these C stores in a changing climate is uncertain, as rising air temperatures may differentially affect photosynthesis and ecosystem respiration (ER). In this study, open-top warming chambers were used to increase air and soil temperatures in contrasting microtopographic positions of a high arctic fen in NW Greenland. CO2 exchange between the ecosystem and the atmosphere was measured on 28 dates over a 3-year period. Measurements of the normalized difference vegetation index, leaf and stem growth, leaf-level gas exchange, leaf nitrogen, leaf δ13C, and fine root production were made to investigate the mechanisms and consequences of observed changes in CO2 exchange. Gross ecosystem photosynthesis (GEP) increased with chamber warming in hollows, which are characterized by standing water, and in hummocks, which extend above the water table. ER, however, increased only in hummocks, such that net ecosystem exchange (NEE) increased in hollows, but did not change in hummocks with chamber warming. Complementary measurements of plant growth revealed that increases in GEP corresponded with increases in C allocation to aboveground biomass in hummocks and belowground biomass in hollows. Our results and those of several recent studies clearly demonstrate that effects of climate change on the C balance of northern wetlands will depend upon microtopography which, in turn, may be sensitive to climate change.

In Hawai'i, mangrove trees are introduced species that can rapidly colonize many nearshore environments. Mangroves have been introduced on O'ahu, and Rhizophora mangle in particular has created numerous problems that have led to several mangrove removals and increased interest in long-term management of mangroves. The objective of this project was to quantify current locations of mangroves and their historical rate of expansion on O'ahu. We used the Geographic Information System (GIS) to map mangroves from digitized air photographs from six time periods: 1951–1953, 1963–1965, 1978, 1982, 1991, and 2001. We found that mangroves are still expanding at a rapid rate on O'ahu 80 yr after their introduction. Mangroves have colonized many different landforms, including tidal flats, riverbanks, fishponds, canals, protected reefs, embayments, lagoons, and other protected areas. Currently, mangroves are widely distributed and occur on all coasts except the dry leeward coast and occupy a total of 147 ha. Roughly 70% (102 ha) of all mangroves occur in Pearl Harbor.