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| 2. |
- ter Steege, Hans, et al.
(författare)
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Mapping density, diversity and species-richness of the Amazon tree flora
- 2023
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Ingår i: COMMUNICATIONS BIOLOGY. - 2399-3642. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution. A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.
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| 3. |
- Magnusson, Sofia E., et al.
(författare)
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Mast cell chymase contributes to the antibody response and the severity of autoimmune arthritis
- 2009
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 23:3, s. 875-882
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells are implicated in rheumatoid arthritis, but the mechanism by which they contribute to disease progression is not clarified. Here we investigated whether mouse mast cell protease-4 (mMCP-4), a chymase present in the mast cell secretory granule, contributes to experimental arthritis. Two models of arthritis were investigated in mMCP-4(+/+) and mMCP-4(-/-) DBA/1 mice: collagen-induced arthritis (CIA) was induced by immunization with collagen II (CII) in Freund's complete adjuvant, and a passive model of arthritis was induced by administration of anti-CII antibodies. The clinical scores were significantly reduced in the mMCP-4(-/-) animals as compared to mMCP-4(+/+) controls in both arthritis models. In CIA, the number of affected paws was lower in the CII-immunized mMCP-4(-/-) mice, with less cartilage destruction, pannus formation, and mononuclear cell and mast cell influx in the mMCP-4(-/-) joints. Interestingly, the lower clinical scores in the CII-immunized mMCP-4(-/-) mice coincided with lower serum levels of immunoglobulin G anti-CII antibodies. Our findings identify a pathogenic role of mMCP-4 in autoimmune arthritis.
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| 6. |
- Eriksson, Leif, 1970, et al.
(författare)
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Stem volume estimation for boreal forest using ALOS PALSAR
- 2007
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Ingår i: 5th International Symposium on Retrieval of Bio- and Geophysical Parameters from SAR Data for Land Applications, Bari, Italy, September 25-28, 2007, ESA, Istituto di Studi sui Sistemi Intelligenti per l´Automazione. ; , s. CD-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An evaluation of ALOS PALSAR data for standwise forest stem volume estimation has been performed at a Swedish test site. The site is dominated by coniferous tree species. SAR data from three operational PALSAR modes, including single, dual and quad polarization, have been analyzed. In total, images from 18 different dates were included. Altogether, 56 forest stands with stem volume in the range of 45-650 m3 ha-1 (average 325 m3 ha-1) were analyzed by relating backscatter intensity to field data. The estimation accuracy of stem volume at stand level was calculated in terms of root mean square error (RMSE). For the best case investigated an RMSE of 30% was obtained for one of the single polarization images acquired in the winter season. In this case no saturation was observed for high stem volumes. The corresponding RMSEs for the dual and quad polarization images were between 62%, and 81%. The better results for single polarization might be explained by particularly favourable weather conditions at image acquisition. An extended evaluation will be performed to verify the cause.
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| 7. |
- Fransson, J.E.S., et al.
(författare)
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Detection of clear-cuts using ALOS PALSAR satellite images
- 2008
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Ingår i: Proceedings of the European Conference on Synthetic Aperture Radar, EUSAR. - 2197-4403. ; 1-4
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Konferensbidrag (refereegranskat)abstract
- The objective of this study is to make a first evaluation of the possibilities to detect forest clear-cuts using high-resolution ALOS PALSAR FBD (Fine Beam Dual polarization) satellite images. New operational applications for mapping of changes in forest cover are of interest for government authorities in Sweden and in other countries with similar needs. The study was conducted in southern Sweden and included seven old coniferous stands located on flat terrain. Three of the stands were clear-felled and the remaining stands were left untreated for reference. Altogether, six PALSAR FBD images (look angle 34.3°, HH- and HV-polarization) acquired during the summer and fall seasons were analyzed. The difference in backscattering coefficient between the reference and the clear-felled stands was on average 2.4 dB and 2.9 dB for the HH- and HV-polarization, respectively. When comparing the backscattering coefficient before and after clear-felling the drop was found to be 1.7 dB and 2.3 dB for the HH- and HV-polarization, respectively.
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| 8. |
- Magnusson, Mattias, et al.
(författare)
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Airborne low-frequency synthetic aperture radar and optical satellite data as complementary data sources for forest stem volume estimation
- 2010
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 25, s. 89-99
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Tidskriftsartikel (refereegranskat)abstract
- Forest stem volume estimation using a combination of airborne CARABAS-II low-frequency synthetic aperture radar (SAR) and multispectral optical Landsat ETM+ satellite data was evaluated and compared with aerial photo-interpretation. The study was performed in coniferous-dominated hemi-boreal forests at a test site located in southern Sweden. The stem volume for the stands included in the analysis was in the range of 15-585 m(3) ha(-1) (average 266 m(3) ha(-1)) and the average size of the stands was 3.5 ha. Regression analysis was used to develop stem volume models. The accuracy in terms of root mean square error (RMSE) was found to be 18.5% (of the average stem volume) for CARABAS-II, 24.8% for Landsat ETM+, and 14.3% for the combination. CARABAS-II gave the best results for high stem volumes, and Landsat ETM+ was more accurate for lower stem volumes. Hence, the two data sources supplement each other providing in combination better results over the whole range of stem volumes. Using conventional aerial photo-interpretation in panchromatic photographs for stem volume estimation the RMSE was found to be 23.7% (21.1% after correction for systematic errors). In conclusion, the method of combining airborne low-frequency SAR and optical satellite data for stem volume estimation gave an accuracy that was significantly better than aerial photo-interpretation and comparable with airborne laser scanning.
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| 9. |
- Magnusson, M., et al.
(författare)
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Estimation of forest stem volume using ALOS PALSAR satellite images
- 2007
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Ingår i: IEEE Geoscience and Remote Sensing Symposium (IGARSS 2007), Barcelona, Spain, July 23-27, 2007. ; DOI: 10.1109/IGARSS.2007.4423813, s. 4343-4346
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A first evaluation of ALOS PALSAR data for forest stem volume estimation has been performed at a coniferous dominated test site in Sweden. In total, 7 Fine Beam Single polarization (FBS, look angle 34.3°, HH-polarization) and 7 Polarimetric (PLR, look angle 21.5°, HH-, HV-, VH-, and VV-polarization) SAR images were used. In total, 56 forest stands with stem volume in the range of 45-650 m3 ha-1 (average 325 m3 ha-1) were analyzed by relating backscatter intensity to field data. The estimation accuracy of stem volume at stand level was calculated in terms of root mean square error (RMSE). For the best case investigated an RMSE of 30% was obtained using one of the FBS images acquired in the winter season. The corre-sponding RMSEs for the PLR images with HH-, HV-, VH-, and VV-polarization were 65%, 65%, 62%, and 81%, respectively. The better results for FBS compared to PLR mode could be explained by particularly favorable weather conditions at image acquisition, or by the higher ground resolution in the FBS images, which makes small stands less sensitive to errors in geo-coding.
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| 10. |
- Eriksson, Leif, 1970, et al.
(författare)
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ALOS PALSAR calibration and validation activities in Sweden
- 2008
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Ingår i: Proceedings of The First Joint PI Symposium of ALOS Data Nodes for ALOS Science Program in Kyoto, Kyoto, Japan, 19 - 23 November, 2007. - 1349-113X. - 9784906653041 ; JAXA-SP-07-012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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