9 research outputs found
A 1.16 Ma record of carbon accumulation in western European peatland during the Oligocene from the Ballymoney lignite, Northern Ireland
<p>The Oligocene Ballymoney lignite in Northern Ireland is one of the thickest lignites in Europe and provides the potential
for comparing Holocene and pre-Holocene peatland evolution and its response to long-term climate change on time scales much
greater than 10 ka. Samples were collected from 50 m of lignite and analysed for δ<sup>13</sup>C. Spectral analysis of the δ<sup>13</sup>C record reveals that the record contains significant frequencies at 0.21 m<sup>−1</sup> and 1.12 m<sup>−1</sup>. These cycles are interpreted as the <em>c</em>. 100 ka eccentricity and 20 ka precession cycles, respectively. These cycles were then tuned and the duration was determined
as 1.16 Ma with a carbon accumulation rate of 27 g C m<sup>−2</sup> a<sup>−1</sup>. If long-term changes in lignite δ<sup>13</sup>C are related to changes in the δ<sup>13</sup>C of the exogenic carbon reservoir, and if the lignite Chattian age is accepted, then the lignite probably formed between
24.6 and 25.8 Ma. Comparison of the estimated carbon accumulation rate with other Cenozoic peatland carbon accumulation rates
indicates that this rate appears to be insensitive to changes in the concentration of atmospheric CO<sub>2</sub>.
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Diagram depicting sources of scattering from inundated forests (adapted from Kasischke and Bourgeau-Chavez [33]).
Scattering mechanisms in bold represent scattering sources that result in interferometric fringes.</p
Diagram describing structural characteristics of the tropical peat swamp forest that impact scattering signals and associated metrics included in this study (adapted from Kasischke and Bourgeau-Chavez [33]).
Diagram describing structural characteristics of the tropical peat swamp forest that impact scattering signals and associated metrics included in this study (adapted from Kasischke and Bourgeau-Chavez [33]).</p
Photographs illustrating common land cover types and field conditions at north Selangor.
(a) secondary forest, (b) burned peatland with dense grass and shrubs, (c) rice paddy agriculture and (d) oil palm plantation. (Photo credits: MJL).</p
Fig 5 -
Maps presenting processed optical and LiDAR data, describing above-ground biomass structure and peat swamp surface characteristics, including (a) LAI (leaf area index per 20 m2); (b) LiDAR ground point density (ground point number per 10 m2); (c) ROUGH; (d) WD; (e) VDR. All LiDAR-derived datasets are limited to the LiDAR flight line coverage over North Selangor. Base map provided by OpenStreetMap®. OpenStreetMap® is open data, licensed under the Open Data Commons Open Database License (ODbL) by the OpenStreetMap Foundation (OSMF). OpenStreetMap® is made available under the Open Database License: http://opendatacommons.org/licenses/odbl/1.0/. Any rights in individual contents of the database are licensed under the Database Contents License: http://opendatacommons.org/licenses/dbcl/1.0/.</p
PCA visualising the relationship between <i>coherence count</i> (cohcount) values and metrics describing the canopy, trunk and surface layers in the model of the above-ground biomass stand: LAI (canopy openness), ROUGH (canopy roughness), WD (height of forest stand), VDR (ratio of canopy layer to trunk layer) and GPD (exposure of peat swamp forest surface).
Plots represent all 2-dimensional combinations of the first three Principal Components: (a) PC1 and PC2, (b) PC1 and PC3, (c) PC2 and PC3. All three plots show that coherence count is orthogonal to all other variables.</p
Fig 6 -
Sentinel-1 interferograms and coherence maps for North Selangor: a) VV polarisation from 2/7/2017 to 17/7/2017; b) VH polarisation from 2/7/2017 to 17/7/2017; c) VV polarisation from 14/8/2018 to 14/8/2018; d) the VH polarisation from 14/8/2018 to 14/8/2018. Base map provided by OpenStreetMap®. OpenStreetMap® is open data, licensed under the Open Data Commons Open Database License (ODbL) by the OpenStreetMap Foundation (OSMF). OpenStreetMap® is made available under the Open Database License: http://opendatacommons.org/licenses/odbl/1.0/. Any rights in individual contents of the database are licensed under the Database Contents License: http://opendatacommons.org/licenses/dbcl/1.0/.</p
Fig 7 -
(a) Map of coherence counts (cohcount) of interferometric pairs at 20 m resolution between 10/10/2014 and 29/04/2020. The coherence count represents the number of interferometric pairs that are above the coherence threshold of 0.45 (maximum = 1520). (b) Map of land cover for North Selangor. Study of both maps show that coherence counts remained high over forestry within North Selangor relative to other land cover types. Base map provided by OpenStreetMap®. OpenStreetMap® is open data, licensed under the Open Data Commons Open Database License (ODbL) by the OpenStreetMap Foundation (OSMF). OpenStreetMap® is made available under the Open Database License: http://opendatacommons.org/licenses/odbl/1.0/. Any rights in individual contents of the database are licensed under the Database Contents License: http://opendatacommons.org/licenses/dbcl/1.0/.</p
North Selangor reserve boundary and peatland extent located within Selangor, Peninsular Malaysia, SE Asia.
Base map provided by OpenStreetMap®. OpenStreetMap® is open data, licensed under the Open Data Commons Open Database License (ODbL) by the OpenStreetMap Foundation (OSMF). OpenStreetMap® is made available under the Open Database License: http://opendatacommons.org/licenses/odbl/1.0/. Any rights in individual contents of the database are licensed under the Database Contents License: http://opendatacommons.org/licenses/dbcl/1.0/.</p