Large-Scale Biomass Classification in Boreal Forests With TanDEM-X Data

Caicoya, Astor Toraño; Kugler, Florian; Hajnsek, Irena; Papathanassiou, Konstantinos

doi:10.1109/tgrs.2016.2575542

Cited by 44 publications

(15 citation statements)

References 31 publications

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“…where h V represents the PolInSAR vegetation height. An additional model used in the literature was based on a power law for the height [60,61,63] yielding the next model as…”

Section: Statistical Models For Forest Aboveground Biomass Estimationmentioning

confidence: 99%

Aboveground Forest Biomass Estimation Combining L- and P-Band SAR Acquisitions

Schlund

Davidson

2018

Remote Sensing

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While considerable research has focused on using either L-band or P-band SAR (Synthetic Aperture Radar) on their own for forest biomass retrieval, the use of the two bands simultaneously to improve forest biomass retrieval remains less explored. In this paper, we make use of L- and P-band airborne SAR and in situ data measured in the field together with laser scanning data acquired over one hemi-boreal (Remningstorp) and one boreal (Krycklan) forest study area in Sweden. We fit statistical models to different combinations of topographic-corrected SAR backscatter and forest heights estimated from PolInSAR for the biomass estimation, and evaluate retrieval performance in terms of R2 and using 10-fold cross-validation. The study shows that specific combinations of radar observables from L- and P-band lead to biomass predictions that are more accurate in comparison with single-band retrievals. The correlations and accuracies between the combinations of SAR features and aboveground biomass are consistent across the two study areas, whereas the retrieval performance varied for individual bands. P-band-based retrievals were more accurate than L-band for the hemi-boreal Remningstorp site and less accurate than L-band for the boreal Krycklan site. The aboveground biomass levels as well as the ground topography differ between the two sites. The results suggest that P-band is more sensitive to higher biomass and L-band to lower biomass forests. The forest height from PolInSAR improved the results at L-band in the higher biomass substantially, whereas no improvement was observed at P-band in both study areas. These results are relevant in the context of combining information over boreal forests from future low-frequency SAR missions such as the European Space Agency (ESA) BIOMASS mission, which will operate at P-band, and future L-band missions planned by several space agencies.

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“…where h V represents the PolInSAR vegetation height. An additional model used in the literature was based on a power law for the height [60,61,63] yielding the next model as…”

Section: Statistical Models For Forest Aboveground Biomass Estimationmentioning

confidence: 99%

Aboveground Forest Biomass Estimation Combining L- and P-Band SAR Acquisitions

Schlund

Davidson

2018

Remote Sensing

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“…The forest structure is influenced by growth, mortality, and degradation as well as management conditions. X-band data in the form of bistatic TanDEM-X observations have recently been considered as possible to use for stem volume or AGB estimation in boreal forests [3][4][5][6][7][8][9][10][11][12] as well as tropical forests [13][14][15][16][17][18]. In particular, in the case of boreal forest, high accuracy estimates of AGB have been obtained.…”

Section: Introductionmentioning

confidence: 99%

On the Sensitivity of TanDEM-X-Observations to Boreal Forest Structure

2019

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The structure of forests is important to observe for understanding coupling to global dynamics of ecosystems, biodiversity, and management aspects. In this paper, the sensitivity of X-band to boreal forest stem volume and to vertical and horizontal structure in the form of forest height and horizontal vegetation density is studied using TanDEM-X satellite observations from two study sites in Sweden: Remningstorp and Krycklan. The forest was analyzed with the Interferometric Water Cloud Model (IWCM), without the use of local data for model training, and compared with measurements by Airborne Lidar Scanning (ALS). On one hand, a large number of stands were studied, and in addition, plots with different types of changes between 2010 and 2014 were also studied. It is shown that the TanDEM-X phase height is, under certain conditions, equal to the product of the ALS quantities for height and density. Therefore, the sensitivity of phase height to relative changes in height and density is the same. For stands with a phase height >5 m we obtained an root-mean-square error, RMSE, of 8% and 10% for tree height in Remningstorp and Krycklan, respectively, and for vegetation density an RMSE of 13% for both. Furthermore, we obtained an RMSE of 17% for estimation of above ground biomass at stand level in Remningstorp and in Krycklan. The forest changes estimated with TanDEM-X/IWCM and ALS are small for all plots except clear cuts but show similar trends. Plots without forest management changes show a mean estimated height growth of 2.7% with TanDEM-X/IWCM versus 2.1% with ALS and a biomass growth of 4.3% versus 4.2% per year. The agreement between the estimates from TanDEM-X/IWCM and ALS is in general good, except for stands with low phase height.

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“…Interferometric synthetic aperture radar (InSAR) remote sensing systems offer an opportunity to determine three-dimensional properties of forest stands, such as forest height and aboveground biomass, AGB, of importance for inventory and monitoring purposes. The bistatic TanDEM-X system has been shown to be able to determine boreal forest properties with very high accuracy [3][4][5][6][7][8][9][10][11][12][13][14], primarily based on information from the interferometric phase height. The latter depends on tree height, as well as forest density, and is therefore also closely related to stem volume and AGB.…”

Section: Introductionmentioning

confidence: 99%

Biomass Growth from Multi-Temporal TanDEM-X Interferometric Synthetic Aperture Radar Observations of a Boreal Forest Site

2018

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Forest growth estimation is important in forest research and forest management, but complex to analyze in diverse forest stands. Twelve summertime TanDEM-X acquisitions from the boreal test site, Krycklan, in Sweden, with a known digital terrain model, DTM, have been used to study phase height and aboveground biomass change over 3.2 years based on the Interferometric Water Cloud Model, IWCM. The maximum phase height rate was determined to 0.29 m/yr, while the mean phase height rate was 0.16 m/yr. The corresponding maximum growth rate of the aboveground dry biomass, AGB, was 4.0 Mg/ha/yr with a mean rate of 1.9 Mg/ha/yr for 27 stands, varying from 23 to 183 Mg/ha. The highest relative AGB growth was found for young stands and high growth rates up to an age of 150 years. Growth rate differences relative a simplified model assuming AGB to be proportional to the phase height were studied, and the possibility to avoid a DTM was discussed. Effects of tree species, thinning, and clear cutting were evaluated. Verifications using in situ data from 2008 and a different in situ dataset combined with airborne laser scanning data from 2015 have been discussed. It was concluded that the use of multi-temporal TanDEM-X interferometric synthetic aperture radar observations with AGB estimates of each individual observation can be an important method to derive growth rates in boreal forests.

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Large-Scale Biomass Classification in Boreal Forests With TanDEM-X Data

Cited by 44 publications

References 31 publications

Aboveground Forest Biomass Estimation Combining L- and P-Band SAR Acquisitions

Aboveground Forest Biomass Estimation Combining L- and P-Band SAR Acquisitions

On the Sensitivity of TanDEM-X-Observations to Boreal Forest Structure

Biomass Growth from Multi-Temporal TanDEM-X Interferometric Synthetic Aperture Radar Observations of a Boreal Forest Site

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