The effects of burning and grazing on soil carbon dynamics in managed Peruvian tropical montane grasslands

The authors wish to thank the Manu National Park forest rangers for allowing us to use their facilities and the field technicians for their assistance. We also thank the Amazon Basin Conservation Association for institutional support. This material is based upon work supported by the UK Natural Environment Council under joint grant references NE/H006583, NE/H007849 and NE/H006753. This publication is a contribution from the Scottish Alliance for Geoscience, Environment and Society (http://www.sages.ac.uk). Imma Oliveras was supported with a NERC grant NE/G006385/1.Peer reviewedPublisher PD

Seasonal variability in methane and nitrous oxide fluxes from tropical peatlands in the western Amazon basin

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An incubation study of GHG flux responses to a changing water table linked to biochemical parameters across a peatland restoration chronosequence

Large areas of northern peatlands have been drained and afforested with conifers in the 20th century. This has led to changes in the hydrology of the peatlands, the quality and quantity of organic matter inputs and soil microbial communities, which are all likely to impact on greenhouse gas (GHG) fluxes. Considerable areas of these forest plantations are undergoing restoration, and our aim was to assess whether contrasting compositions of peat, in conjunction with hydrological changes in a controlled lab experiment, impact on GHG fluxes. We incubated vegetation free cores (at 8 °C) from a near-natural bog, restoration sites felled in 1998, 2006, 2012 and a current forest plantation at (a) low water tables, (b) high tables or (c) water tables that were changed from low to high. Results show that peat quality and nutrient availability in the pore water have been altered by the forest plantations, which resulted in dissimilar carbon dioxide (CO2) fluxes between the sites under the same temperature and water table conditions. Higher CO2 fluxes were found in the peat cores from the forest plantations than from sites that have undergone restoration and from the near-natural bog. However, there were few differences in methane (CH4) fluxes from the different sites, indicating that on its own (i.e., in the absence of biotic interactions under field conditions) the effects of forestry on CH4 flux are limited

Methane Emissions from a Grassland-Wetland Complex in the Southern Peruvian Andes

Wet organic-rich mineral and peat soils in the tropical Andes represent a potentially significant, but little studied, source of methane to the atmosphere. Here we report the results of field and laboratory measurements of soil-atmosphere methane exchange and associated environmental variables from freely draining upland and inundation prone wetland soils in a humid puna ecosystem in the Southeastern Andes of Peru. Between seasons and across the landscape soil-atmosphere exchange varied between uptake and emission. Notable hotspots of methane emission, peaking during the wet season, were observed from both upland and wetland soils with particularly strong emissions from moss-accumulating topographic lows. This variability was best explained by the influence of oxygen concentration on methane production in superficial soil horizons

An assessment of oil palm plantation aboveground biomass stocks on tropical peat using destructive and non-destructive methods

Acknowledgements The authors would like to thank the Director-General of the Malaysian Palm Oil Board for permission to publish these results. This study was carried out as part of a wider tropical peat research collaboration between MPOB, University of Exeter and University of Aberdeen and we would like to thank the MPOB staff and the Sarawak Oil Palm Berhard for help and support during the project. Specifically, from the Sarawak Oil Palm Berhard we would like to thank: Mr. Paul (group CEO), Mr. Chua Kian Hong (group plantation manager), Mr. Phang Seng Nam (regional plantation controller) and Mr. Sammy (Sabaju plantation manager) for being kind enough to allow this research to be carried out within their plantation and for the provision of logistical support. From MPOB we would like to thank the dedicated field technicians, Steward Saging and Ham Jonathon for their invaluable support.Peer reviewedPublisher PD

Carbon Emissions From Oil Palm Plantations on Peat Soil

This project was funded by the Natural Environmental Research Council, UK (grant code: 1368637) and the Malaysian Palm Oil Board (grant code: R010913000).Peer reviewedPublisher PD

Net soil carbon balance in afforested peatlands and separating autotrophic and heterotrophic soil CO2 effluxes

Peatlands are a significant global carbon (C) store, which can be compromised by drainage and afforestation. Quantifying the rate of C loss from peat soils under forestry is challenging, as soil CO2 efflux includes both CO2 produced from heterotrophic peat decomposition and CO2 produced by tree roots and associated fungal networks (autotrophic respiration). We experimentally terminated autotrophic below-ground respiration in replicated forest plots by cutting through all living tree roots (trenching) and measured soil surface CO2 flux, litter input, litter decay rate, and soil temperature and moisture over 2 years. Decomposition of cut roots was measured and CO2 fluxes were corrected for this, which resulted in a large change in the fraction heterotrophic : autotrophic flux, suggesting that even 2 years after trenching decaying root biomass makes significant contributions to the CO2 flux. Annual peat decomposition (heterotrophic CO2 flux) was 115 ± 16 g C m−2 yr−1, representing ca. 40 % of total soil respiration. Decomposition of needle litter is accelerated in the presence of an active rhizosphere, indicating a priming effect by labile C inputs from roots. This suggests that our estimates of peat mineralization in our trenched plots are conservative and underestimate overall rates of peat C loss. Considering also input of litter from trees, our results indicate that the soils in these 30-year-old drained and afforested peatlands are a net sink for C, since substantially more C enters the soil organic matter than is decomposed heterotrophically. This study does not account for fluvial C fluxes, which represent a small flux compared to the CO2 soil efflux; further, root litter and exudate deposition could be a significant C source that is only partially sampled by our approach, adding to these plantations being a potential carbon sink. However, the C balance for these soils should be taken over the lifespan of the trees, in order to determine if the soils under these drained and afforested peatlands are a sustained sink of C or become a net source over longer periods of forestry

Effects of water management and cultivar on carbon dynamics, plant productivity and biomass allocation in European rice systems

We thank the researchers at CREA-Centro di ricerca cerealicoltura e colture industriali, Vercelli, for allowing us to use their facilities, and the technical staff for their assistance. This research was conducted in the framework of the FACCE-JPI project GreenRice (Sustainable and environmental friendly rice cultivation systems in Europe) and was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) BB/M018415/1.Peer reviewedPublisher PD

Complex controls on nitrous oxide flux across a large elevation gradient in the tropical Peruvian Andes

Acknowledgements The authors would like to acknowledge the agencies that funded this research; the UK Natural Environment Research Council (NERC; joint grant references NE/H006583, NE/H007849 and NE/H006753). Patrick Meir was supported by an Australian Research Council Fellowship (FT110100457). Javie Eduardo Silva Espejo, Walter Huaraca Huasco and the ABIDA NGO provided critical fieldwork and logistical support. Angus Calder (University of St.Andrews) and Vicky Munro (University of Aberdeen) provided invaluable laboratory support. Thanks to Adrian Tejedor from the Amazon Conservation Association, who provided assistance with site access and site selection at Hacienda Villa Carmen. This publication is a contribution from the Scottish Alliance for Geoscience, Environment and Society (http://www.sages.ac.uk).Peer reviewedPublisher PD

Evaluating the Classical Versus an Emerging Conceptual Model of Peatland Methane Dynamics

We appreciate discussions with M. Firestone and S. Blazewicz. We received assistance in the field and lab from K. Smetak, H. Dang, and A. McDowell. This research was funded by grants to W.L.S. from the U.S. National Science Foundation (ATM-0842385 and DEB-0543558) and the California Department of Fish and Wildlife (CDFW) and California Department of Water Resources (DWR) contract 4600011240. The data used are listed in the references, tables, supporting information, and the Illinois Digital Environment for Access to Learning and Scholarship (IDEALS) repository at https://www.ideals.illinois.edu/.Peer reviewedPublisher PD