Shifting environmental controls on CH4 fluxes in a sub-boreal peatland

We monitored CO2 and CH4 fluxes using eddy covariance from 19 May to 27 September 2011 in a poor fen located in northern Michigan. The objectives of this paper are to: (1) quantify the flux of CH4 from a sub-boreal peatland, and (2) determine which abiotic and biotic factors were the most correlated to the flux of CH4 over the measurement period. Net daily CH4 fluxes increased from 70 mg CH4 m−2 d−1 to 220 mg CH4 m−2 d−1 from mid May to mid July. After July, CH4 losses steadily declined to approximately 50 mg CH4 m−2 d−1 in late September. During the study period, the peatland lost 17.4 g CH4 m−2. Both abiotic and biotic variables were correlated with CH4 fluxes. When the different variables were analyzed together, the preferred model included mean daily soil temperature at 20 cm, daily net ecosystem exchange (NEE) and the interaction between mean daily soil temperature at 20 cm and NEE (R2 = 0.47, p value \u3c 0.001). The interaction was important because the relationship between daily NEE and mean daily soil temperature with CH4 flux changed when NEE was negative (CO2 uptake from the atmosphere) or positive (CO2 losses to the atmosphere). On days when daily NEE was negative, 25% of the CH4 flux could be explained by correlations with NEE, however on days when daily NEE was positive, there was no correlation between daily NEE and the CH4 flux. In contrast, daily mean soil temperature at 20 cm was poorly correlated to changes in CH4 when NEE was negative (17%), but the correlation increased to 34% when NEE was positive. The interaction between daily NEE and mean daily soil temperature at 20 cm indicates shifting environmental controls on the CH4 flux throughout the growing season

Biogeochemical research priorities for sustainable biofuel and bioenergy feedstock production in the Americas.

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 interrelated 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.Fil: Gollany, Hero T. USDA. Agricultural Research Service. Columbia Plateau Conservation Research Center; Estados UnidosFil: Titus, Brian D. Pacific Forestry Centre. Canadian Forest Service. Natural Resources Canada; CanadáFil: Scott, Andrew USDA Forest Service. Agricultural Research Center. Southern Research Station; Estados UnicosFil: Asbjornsen, Heidi. University of New Hampshire. Institute for Earth, Oceans and Space. Department of Natural Resources and the Environment and the Earth Systems Research Center; Estados UnidosFil: Resh, Sigrid C. Michigan Technological University. School of Forest Resources and Environmental Science; Estados UnidosFil: Chimner, Rodney Allen. Michigan Technological University. School of Forest Resources and Environmental Science; Estados UnidosFil: Kaczmarek, Donald J. Oregon Department of Forestry; Estados UnidosFil: Leite, Luiz F. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA); BrasilFil: Ferreira, Ana C. Climate Change Adaptation Consultant; BrasilFil: Rod, Kenton A. Washington State University. School of the Environment; Estados UnidosFil: Hilbert, Jorge Antonio. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Ingeniería Rural; ArgentinaFil: Galdos, Marcelo. Brazilian Center for Research in Energy and Materials (CNPEM). Brazilian Bioethanol Science and Technology Laboratory (CTBE); BrasilFil: Cisz, Michelle E. Michigan Technological University. School of Forest Resources and Environmental Science; Estados Unido

Congo Basin peatlands: threats and conservation priorities

The recent publication of the first spatially explicit map of peatlands in the Cuvette Centrale, central Congo Basin, reveals it to be the most extensive tropical peatland complex, at ca. 145,500 km2. With an estimated 30.6 Pg of carbon stored in these peatlands, there are now questions about whether these carbon stocks are under threat and, if so, what can be done to protect them. Here, we analyse the potential threats to Congo Basin peat carbon stocks and identify knowledge gaps in relation to these threats, and to how the peatland systems might respond. Climate change emerges as a particularly pressing concern, given its potential to destabilise carbon stocks across the whole area. Socio-economic developments are increasing across central Africa and, whilst much of the peatland area is protected on paper by some form of conservation designation, the potential exists for hydrocarbon exploration, logging, plantations and other forms of disturbance to significantly damage the peatland ecosystems. The low level of human intervention at present suggests that the opportunity still exists to protect the peatlands in a largely intact state, possibly drawing on climate change mitigation funding, which can be used not only to protect the peat carbon pool but also to improve the livelihoods of people living in and around these peatlands

Variation in carbon and nitrogen concentrations among peatland categories at the global scale

Publisher Copyright: © 2022 This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.Peatlands account for 15 to 30% of the world's soil carbon (C) stock and are important controls over global nitrogen (N) cycles. However, C and N concentrations are known to vary among peatlands contributing to the uncertainty of global C inventories, but there are few global studies that relate peatland classification to peat chemistry. We analyzed 436 peat cores sampled in 24 countries across six continents and measured C, N, and organic matter (OM) content at three depths down to 70 cm. Sites were distinguished between northern (387) and tropical (49) peatlands and assigned to one of six distinct broadly recognized peatland categories that vary primarily along a pH gradient. Peat C and N concentrations, OM content, and C:N ratios differed significantly among peatland categories, but few differences in chemistry with depth were found within each category. Across all peatlands C and N concentrations in the 10-20 cm layer, were 440 ± 85.1 g kg-1 and 13.9 ± 7.4 g kg-1, with an average C:N ratio of 30.1 ± 20.8. Among peatland categories, median C concentrations were highest in bogs, poor fens and tropical swamps (446-532 g kg-1) and lowest in intermediate and extremely rich fens (375-414 g kg-1). The C:OM ratio in peat was similar across most peatland categories, except in deeper samples from ombrotrophic tropical peat swamps that were higher than other peatlands categories. Peat N concentrations and C:N ratios varied approximately two-fold among peatland categories and N concentrations tended to be higher (and C:N lower) in intermediate fens compared with other peatland types. This study reports on a unique data set and demonstrates that differences in peat C and OM concentrations among broadly classified peatland categories are predictable, which can aid future studies that use land cover assessments to refine global peatland C and N stocks.Peer reviewe

Artificial microtopography and herbivory protection facilitates wetland tree (Thuja occidentalis L.) survival and growth in created wetlands

© 2015, Springer Science+Business Media Dordrecht. 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

Characterizing northern white-cedar communities in harvested and unharvested lowland forests of Michigan, USA

Understanding the complexity of forest community dynamics is essential in forest management planning and stewardship, yet lowland northern white-cedar (Thuja occidentalis L.) are often managed as homogenous communities. Through this study, we defined lowland white-cedar forest community types in unharvested and harvested forest stands within the State of Michigan and examined community type associations with ecological variables. Data collected in unharvested stands revealed three white-cedar community subtypes: (1) cedar-deciduous, (2) cedar-conifer, and (3) cedar-shrub. These unharvested subtypes were dominated by white-cedar, yet characterized by different soils, hydrology, geochemical gradients, and associated tree species. In harvested stands, six community types were identified: (1) aspen-fir, (2) winterberry-willow, (3) balsam fir, (4) cedar-red maple, (5) cedar-black spruce, and (6) alder-tamarack. These harvested community types were located along ecological gradients, including soil type (organic or mineral) and soil water pH. Using community types in unharvested and harvested stands, and associated ecological gradients, potential pathways of compositional transition were theorized. Findings suggest that cedar community subtype affects the likelihood of cedar regeneration and dictates the alternative species replacing cedar after harvest. These findings and potential pathways are useful to forestry practitioners, as they highlight potential changes in tree species dominance following harvest across a range of lowland white-cedar community types, allowing refinement of silvicultural prescriptions to ensure desired outcomes

Shifting environmental controls on CH₄ fluxes in a sub-boreal peatland

We monitored CO₂ and CH₄ fluxes using eddy covariance from 19 May to 27 September 2011 in a poor fen located in northern Michigan. The objectives of this paper are to: (1) quantify the flux of CH₄ from a sub-boreal peatland, and (2) determine which abiotic and biotic factors were the most correlated to the flux of CH₄ over the measurement period. Net daily CH₄ fluxes increased from 70 mg CH₄ m⁻² d⁻¹ to 220 mg CH₄ m⁻² d⁻¹ from mid May to mid July. After July, CH₄ losses steadily declined to approximately 50 mg CH₄ m⁻² d⁻¹ in late September. During the study period, the peatland lost 17.4 g CH₄ m⁻². Both abiotic and biotic variables were correlated with CH₄ fluxes. When the different variables were analyzed together, the preferred model included mean daily soil temperature at 20 cm, daily net ecosystem exchange (NEE) and the interaction between mean daily soil temperature at 20 cm and NEE (<i>R</i>² = 0.47, <i>p</i> value < 0.001). The interaction was important because the relationship between daily NEE and mean daily soil temperature with CH₄ flux changed when NEE was negative (CO₂ uptake from the atmosphere) or positive (CO₂ losses to the atmosphere). On days when daily NEE was negative, 25% of the CH₄ flux could be explained by correlations with NEE, however on days when daily NEE was positive, there was no correlation between daily NEE and the CH₄ flux. In contrast, daily mean soil temperature at 20 cm was poorly correlated to changes in CH₄ when NEE was negative (17%), but the correlation increased to 34% when NEE was positive. The interaction between daily NEE and mean daily soil temperature at 20 cm indicates shifting environmental controls on the CH₄ flux throughout the growing season