| 1. |
- Ernfors, Maria, 1973, et al.
(författare)
-
Greenhouse gas dynamics of a well-drained afforested agricultural peatland
- 2020
-
Ingår i: Boreal environment research. - 1239-6095 .- 1797-2469. ; 25, s. 65-77
-
Tidskriftsartikel (refereegranskat)abstract
- About a quarter of the global anthropogenic greenhouse gas emissions are attributable to agriculture, forestry and other land use. Few studies of afforested drained peatlands have measured exchanges of all three major greenhouse gases (GHG) at a given site, leading to uncertainty in estimated GHG budgets. Thus, we measured forest floor exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) at a well-drained afforested peatland in southern Sweden. The CO2 emissions (76 000 kg ha–1 a–1; SE 6 000) were large compared with previous measurements at similar sites, which may have been partly due to a measurement technique that did not underestimate the flux. A net CH4 uptake of 4.4 kg ha–1 a–1 (SE 0.41) and a net N2O emission of 2.7 kg ha–1 a–1 (SE 0.23) were found, which agreed well with published models relating fluxes to stand biomass (CH4 models) or soil C:N ratio (N2O models).
|
|
| 2. |
- Klemedtsson, Leif, 1953, et al.
(författare)
-
Skogaryd – Integration of terrestrial and freshwater greenhouse gas sources and sinks
- 2010
-
Ingår i: 1st COST meeting ‘Belowground carbon in Europeanforest’, Birmensdorf, Switzerland, 26–28 January 2010..
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Forests play an important role in the global carbon (C) cycle, and management as well as climate can cause major effects on the balance of C between the atmosphere and the plant/soil system. With re-gard to our commitments to the Kyoto and post-Kyoto actions on climate change, we need reliable predictions on how this balance is affected by management and climate. In 2006 the Skogaryd Research Forest was established in the southwest of Sweden (58°23’N, 12°09’E). The overall goal is to quantify net greenhouse gas (GHG) fluxes from drained spruce forest, by determining the individual fluxes and pools of C and nitrogen and elucidating their connection to site fertility, drainage status and abiotic parameters and then use the generated data in GHG models, for model validations and ultimately emissions predictions. During 2006-2009 the research has fo-cused on two sites, mineral and organic, dominated by Norway spruce (Picea abies). Both sites are drained fertile soils but with different land-use history that have affected their physical properties. Measurements includes: net ecosystem exchange of CO2, Shoot photosynthesis and respiration at different locations within the canopy, stem respiration, emissions of N2O and CH4 using manual cham-bers, soil respiration with automatic chambers including a trenching experiment where root-, mycelia-, and heterotrophic respiration are separated, fine root production using minirhizotrons, and mycelia production. The organic site also includes a wood ash experiment. From 2010 the research will be expanded to the whole watershed, from the mire system via streams, riparian zones, forests, to lakes and the subsequent exchange between the atmosphere and surface waters. Different terrestrial and limnic ecosystems will be linked holistically, using site specific tech-niques at different scales, from aircraft (km2) to chambers (m2) to create integrated models that can be used to quantify net GHG flux for management strategies.
|
|
| 3. |
- Meyer, Astrid, et al.
(författare)
-
A fertile peatland forest does not constitute a major greenhouse gas sink
- 2013
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10, s. 7739-7758
-
Tidskriftsartikel (refereegranskat)abstract
- Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with high organic matter content. However, the carbon dioxide (CO2) and nitrous oxide (N2O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we etermined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO2 exchange (NEE) were applied, for the year 2008, one direct (eddy covariance) and the other indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.3±3.9 tC ha−1 yr−1 due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was probably in its phase of maximum C assimilation or shortly past it. The N2O fluxes were determined by the closed-chamber technique and amounted to 0.9±0.8 tCeq ha−1 yr−1. According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of −1.2±0.8 t Ceq ha−1 yr−1. This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 0.6±4.5 tCeq ha−1 yr−1. Irrespective of the approach applied, the soil CO2 effluxes counter large amounts of the C sequestration by trees. Due to accumulated uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the rate of C sequestration will likely decrease with forest age, the site will probably become a GHG source once again as the trees do not compensate for the soil C and N losses. Also forests in younger age stages have been shown to have lower C assimilation rates; thus, the overall GHG sink potential of this afforested nutrient-rich organic soil is probably limited to the short period of maximum C assimilation.
|
|
