| 1. |
- Pangala, Sunitha R., et al.
(författare)
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Large emissions from floodplain trees close the Amazon methane budget
- 2017
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Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 552:7684, s. 230-
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Tidskriftsartikel (refereegranskat)abstract
- Wetlands are the largest global source of atmospheric methane (CH4)(1), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain(2,3), the largest natural geographic source of CH4 in the tropics, consistently underestimate the atmospheric burden of CH4 determined via remote sensing and inversion modelling(4,5), pointing to a major gap in our understanding of the contribution of these ecosystems to CH4 emissions. Here we report CH4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests(6) and tropical peat swamp forests(7), representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (delta C-13) of -66.2 +/- 6.4 per mil, consistent with a soil biogenic origin. We estimate that floodplain trees emit 15.1 +/- 1.8 to 21.2 +/- 2.5 teragrams of CH4 a year, in addition to the 20.5 +/- 5.3 teragrams a year emitted regionally from other sources. Furthermore, we provide a topdown regional estimate of CH4 emissions of 42.7 +/- 5.6 teragrams of CH4 a year for the Amazon basin, based on regular vertical lower-troposphere CH4 profiles covering the period 2010-2013. We find close agreement between our top-down and combined bottom-up estimates, indicating that large CH4 emissions from trees adapted to permanent or seasonal inundation can account for the emission source that is required to close the Amazon CH4 budget. Our findings demonstrate the importance of tree stem surfaces in mediating approximately half of all wetland CH4 emissions in the Amazon floodplain, a region that represents up to one-third of the global wetland CH4 source when trees are combined with other emission sources.
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| 2. |
- Zune-da-Silva, Felipe, et al.
(författare)
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Edge Influence over Functional Tree Traits in an Atlantic Forest Remnant : [Influência das bordas sobre características funcionais das árvores em um remanescente de mata atlântica]
- 2022
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Ingår i: Revista Árvore. - : Universidade Federal de Vicosa. - 0100-6762 .- 1806-9088. ; 46
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Tidskriftsartikel (refereegranskat)abstract
- Habitat fragmentation is one of the leading causes of edge genesis and its effects. Functional tree traits such as wood density, height, and diameter are essential variables from which it is possible to infer several ecological processes. This study assessed the variability of the functional traits of trees over two habitats (edge and interior) of a forest remnant The hypothesis tested were i) the functional traits would have lower values at the edges than the interior, and ii) environmental variables would influence such differences. This study was carried out in the largest Atlantic Forest remnant within Serra da Tiririca State Park, Brazil, by establishing ten plots (50 x 20 m) among different habitats. Within each plot, wood samples were taken from all trees with a diameter of >= 10 cm. It was recorded the altitude, distance from the plots to the edge, and fire records as possible explanatory variables (environmental variables). Wood density was obtained using the immersion method. To verify differences in functional traits by habitat, the Wilcoxon test was applied. Additionally, the influence of explanatory variables on functional traits through generalized linear models was evaluated. One hundred eighty-five trees were recorded at the edges and 218 trees at the interior of the remnant. Wood density and tree height were significantly lower in the edges than in the interior. Furthermore, the best models indicated significant relationships between wood density and habitats, as well as diameter and distance to the edge. This study was effective in raising suitable variables to predict edge effects.
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| 3. |
- Zune-da-Silva, Felipe, et al.
(författare)
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Influence of fire on edge vegetation in an Atlantic Forest remnant in Brazil
- 2022
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Ingår i: Scientia Forestalis/Forest Sciences. - : IPEF-INST PESQUISAS ESTUDOS FLORESTAIS. - 1413-9324 .- 2318-1222. ; 50
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Tidskriftsartikel (refereegranskat)abstract
- Fires and habitat fragmentation are responsible for devastating large ecosystems around the biosphere. The increasing use of remote sensing allows fire patterns to be identified and plays an essential role in preventing fires. In this context, this study aimed to describe the variation in evidence of fire between the edge and the interior of an Atlantic Forest remnant in southeastern Brazil and infer its effects on vegetation. Fire records were acquired between 2010 and 2020 from the Instituto Nacional de Pesquisas Espaciais database and United States Geological Survey satellite images. For each scene, the images were processed and the normalized difference vegetation index (NDVI) was calculated. To assess the variation, records were classified and compared according to the year, month, hours, and habitat type (edge and interior). To verify the influence of fires on vegetation, simple linear regressions were performed based on the fire risk due to the NDVI-year-habitat interaction. The data included 748 fire records, with the highest occurrences from April to August, and 51% of the fires occurred between 15h and 20h, indicating periods with more intense solar radiation. The relationship between fire risk and NDVI-year-habitat was significant (F = 30.35; R-2 = 0.26; p < 0.0001), and the edges were more vulnerable to fire risk. This study shows that in an Atlantic Forest remnant, areas with lower vegetation indices, such as edges, are more vulnerable to fire than areas with dense forest vegetation.
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