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Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5° grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC) observations from 30 northern peatland sites, with the maximum rate of carboxylation (Vcmax) being optimized at each site. Regarding short-term day-to-day variations, the model performance was good for gross primary production (GPP) (r2 Combining double low line 0.76; Nash-Sutcliffe modeling efficiency, MEF Combining double low line 0.76) and ecosystem respiration (ER, r2 Combining double low line 0.78, MEF Combining double low line 0.75), with lesser accuracy for latent heat fluxes (LE, r2 Combining double low line 0.42, MEF Combining double low line 0.14) and and net ecosystem CO2 exchange (NEE, r2 Combining double low line 0.38, MEF Combining double low line 0.26). Seasonal variations in GPP, ER, NEE, and energy fluxes on monthly scales showed moderate to high r2 values (0.57-0.86). For spatial across-site gradients of annual mean GPP, ER, NEE, and LE, r2 values of 0.93, 0.89, 0.27, and 0.71 were achieved, respectively. Water table (WT) variation was not well predicted (r2

Significant climate risks are associated with a positive carbon-temperature feedback in northern latitude carbon-rich ecosystems, making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on simultaneous and quasi-continuous ecosystem observations of CO2 and CH4 fluxes. Experimental areas are located both in natural and in managed wetlands and cover a wide range of climatic regions, ecosystem types, and management practices. Based on direct observations we predict that sustained CH4 emissions in natural ecosystems are in the long term (i.e., several centuries) typically offset by CO2 uptake, although with large spatiotemporal variability. Using a space-for-time analogy across ecological and climatic gradients, we represent the chronosequence from natural to managed conditions to quantify the "cost" of CH4 emissions for the benefit of net carbon sequestration. With a sustained pulse-response radiative forcing model, we found a significant increase in atmospheric forcing due to land management, in particular for wetland converted to cropland. Our results quantify the role of human activities on the climate footprint of northern wetlands and call for development of active mitigation strategies for managed wetlands and new guidelines of the Intergovernmental Panel on Climate Change (IPCC) accounting for both sustained CH4 emissions and cumulative CO2 exchange.

Short Rotation Forestry (SRF) is the practice of cultivating fast-growing tree species mainly for the production of biomass. In Ireland, SRF rotation lengths are less than 20 years. SRF forest cover is expected to increase in response to the increasing demand for fibre products and renewable energy targets set by the European Union. Although Irish policy supports the establishment of SRF, prior research identified Irish forest industry concerns over the market opportunities for SRF, which may limit its establishment. A SRF market was successfully established in Oregon, U.S., mainly based on hybrid poplar (Populus spp.). A survey was carried out there and its results were supplemented by US-based literature. The objective was to benchmark conditions that facilitated market development in Oregon with current conditions in Ireland, to identify and describe gaps and opportunities that hat could be applicable to growers and potential users of SRF in Ireland. The key success factors in growing and marketing SRF in Oregon were large-scale plantations, local supply chains, consistency of supply, FSC certification and the targeting of high-value products. Small-scale plantations and low-value product systems were unsuccessful in Oregon. However, liquid biofuels and payment for ecosystem services are new opportunities currently in development. These options could also be applied in Ireland to motivate SRF development and improve the sustainability of these plantations. [ABSTRACT FROM AUTHOR]

Highlights: [•] The peatland in the current investigation behaved as a net sink for direct CO2 NEE. [•] Key met variables (and their interaction) to describe CO2 exchange were determined. [•] WTL found to influence long-term CO2 exchange for both day and night. [•] Models to describe day and night CO2 exchange developed for weekly and annual time-scales. [•] Indirect and direct contribution to the variation of CO2 exchange quantified. [Copyright &y& Elsevier]

This article examines the possibility of exploiting ground reflectance in the near-infrared (NIR) for monitoring grassland phytomass on a temporal basis. Three new spectral vegetation indices (infrared slope index, ISI; normalized infrared difference index, NIDI; and normalized difference structural index, NDSI), which are based on the reflectance values in the H25 (863–881 nm) and the H18 (745–751 nm) Chris Proba (mode 5) bands, are proposed. Ground measurements of hyperspectral reflectance and phytomass were made at six grassland sites in the Italian and Austrian mountains using a hand-held spectroradiometer. At full canopy cover, strong saturation was observed for many traditional vegetation indices (normalized difference vegetation index (NDVI), modified simple ratio (MSR), enhanced vegetation index (EVI), enhanced vegetation index 2 (EVI 2), renormalized difference vegetation index (RDVI), wide dynamic range vegetation index (WDRVI)). Conversely, ISI and NDSI were linearly related to grassland phytomass with negligible inter-annual variability. The relationships between both ISI and NDSI and phytomass were however site specific. The WinSail model indicated that this was mostly due to grassland species composition and background reflectance. Further studies are needed to confirm the usefulness of these indices (e.g. using multispectral specific sensors) for monitoring vegetation structural biophysical variables in other ecosystem types and to test these relationships with aircraft and satellite sensors data. For grassland ecosystems, we conclude that ISI and NDSI hold great promise for non-destructively monitoring the temporal variability of grassland phytomass. [ABSTRACT FROM AUTHOR]

Although northern peatlands cover only 3% of the land surface, their thick peat deposits contain an estimated one-third of the world's soil organic carbon (SOC). Under a changing climate the potential of peatlands to continue sequestering carbon is unknown. This paper presents an analysis of 6 years of total carbon balance of an almost intact Atlantic blanket bog in Glencar, County Kerry, Ireland. The three components of the measured carbon balance were: the land-atmosphere fluxes of carbon dioxide (CO) and methane (CH) and the flux of dissolved organic carbon (DOC) exported in a stream draining the peatland. The 6 years C balance was computed from 6 years (2003-2008) of measurements of meteorological and eddy-covariance CO fluxes, periodic chamber measurements of CH fluxes over 3.5 years, and 2 years of continuous DOC flux measurements. Over the 6 years, the mean annual carbon was −29.7±30.6 (±1 SD) g C m yr with its components as follows: carbon in CO was a sink of −47.8±30.0 g C m yr; carbon in CH was a source of 4.1±0.5 g C m yr and the carbon exported as stream DOC was a source of 14.0±1.6 g C m yr. For 2 out of the 6 years, the site was a source of carbon with the sum of CH and DOC flux exceeding the carbon sequestered as CO. The average C balance for the 6 years corresponds to an average annual growth rate of the peatland surface of 1.3 mm yr. [ABSTRACT FROM AUTHOR]

Abstract: Northern peatlands contain an estimated 1/3 of the world''s soil carbon pool. This large carbon pool is of concern due to its uncertain future in a changing climate. Blanket bogs are peatlands that occur in temperate maritime regions where precipitation is much greater than evapotranspiration. We describe five years (1 October 2002 to 30 September 2007) of eddy-covariance (EC) carbon dioxide (CO2) flux measurements in an Atlantic blanket bog in Ireland. The measured net ecosystem CO2 exchange (NEE) was partitioned into its components of ecosystem respiration (ER) and gross ecosystem production (GEP). The inter-annual variation of the CO2 fluxes was investigated using correlation coefficient analyses with measured hydro-meteorological parameters. The annual NEE was negative for all five years (thus the peatland was a sink of CO2), ranging between −16.5±5.1 and −96.5±23.2gC-CO2 m−2 (average of −54.9±15.6gC-CO2 m−2). During the study period, NEE was negative for the same five months in each year (May–September). NEE showed the highest CO2 uptake (due to the highest GEP) in the summer with intermediate rather than extreme meteorological conditions, thus with low vapour pressure deficit, intermediate soil water content, air temperature and light radiation, which might be partly explained by the role of the bryophyte community. Under climate change predictions of higher temperature, the inter-annual variation analysis suggests that ER might increase in winter. Furthermore, the predicted lower precipitation and higher temperature in the summer are expected to lead to lower GEP. The resulting increase in NEE (thus lower CO2 uptake) will be partly compensated by a higher GEP in warmer winters and in dryer autumns. Moreover, the CO2 uptake will benefit by a longer growing season, while wetter conditions will likely lower the ecosystem respiration in the spring. The length of the growing season was found to be driven by warmer winter and September soil temperatures. [Copyright &y& Elsevier]