Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights
Site index and stand age are important variables in forestry. Site index describes the growing potential at a given location, expressed as the height that trees can attain at a given age under favorable growing conditions. It is traditionally used to classify forests in terms of future timber yield...
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| Language: | English |
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MDPI AG
2023-08-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/17/4195 |
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| author | Ivan Huuva Jörgen Wallerman Johan E. S. Fransson Henrik J. Persson |
| author_facet | Ivan Huuva Jörgen Wallerman Johan E. S. Fransson Henrik J. Persson |
| author_sort | Ivan Huuva |
| collection | DOAJ |
| description | Site index and stand age are important variables in forestry. Site index describes the growing potential at a given location, expressed as the height that trees can attain at a given age under favorable growing conditions. It is traditionally used to classify forests in terms of future timber yield potential. Stand age is used for the planning of management activities such as thinning and harvest. SI has previously been predicted using remote sensing, but usually relying on either very short time series or repeated ALS acquisitions. In this study, site index and forest stand age were predicted from time series of interferometric TanDEM-X data spanning seven growth seasons in a hemi-boreal forest in Remningstorp, a test site located in southern Sweden. The goal of the study was to see how satellite-based radar time series could be used to estimate site index and stand age. Compared to previous studies, we used a longer time series and applied a penetration depth correction to the phase heights, thereby avoiding the need for calibration using ancillary field or ALS data. The time series consisted of 30 TanDEM-X strip map scenes acquired between 2011 and 2018. Established height development curves were fitted to the time series of TanDEM-X-based top heights. This enabled simultaneous estimation of both age and site index on 91 field plots with a 10 m radius. The RMSE of predicted SI and age were 6.9 m and 38 years for untreated plots when both SI and age were predicted. When predicting SI and the age was known, the RMSE of the predicted SI was 4.0 m. No significant prediction bias was observed for untreated plots, while underestimation of SI and overestimation of age increased with the intensity of treatment. |
| first_indexed | 2024-03-10T23:14:37Z |
| format | Article |
| id | doaj.art-b09a85d54b8d4108a866314c335cd4f0 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T23:14:37Z |
| publishDate | 2023-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-b09a85d54b8d4108a866314c335cd4f02023-11-19T08:45:46ZengMDPI AGRemote Sensing2072-42922023-08-011517419510.3390/rs15174195Prediction of Site Index and Age Using Time Series of TanDEM-X Phase HeightsIvan Huuva0Jörgen Wallerman1Johan E. S. Fransson2Henrik J. Persson3Department of Forest Resource Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, SE-901 83 Umeå, SwedenDepartment of Forest Resource Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, SE-901 83 Umeå, SwedenDepartment of Forestry and Wood Technology, Linnaeus University, Georg Lückligs väg 1, SE-351 95 Växjö, SwedenDepartment of Forest Resource Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, SE-901 83 Umeå, SwedenSite index and stand age are important variables in forestry. Site index describes the growing potential at a given location, expressed as the height that trees can attain at a given age under favorable growing conditions. It is traditionally used to classify forests in terms of future timber yield potential. Stand age is used for the planning of management activities such as thinning and harvest. SI has previously been predicted using remote sensing, but usually relying on either very short time series or repeated ALS acquisitions. In this study, site index and forest stand age were predicted from time series of interferometric TanDEM-X data spanning seven growth seasons in a hemi-boreal forest in Remningstorp, a test site located in southern Sweden. The goal of the study was to see how satellite-based radar time series could be used to estimate site index and stand age. Compared to previous studies, we used a longer time series and applied a penetration depth correction to the phase heights, thereby avoiding the need for calibration using ancillary field or ALS data. The time series consisted of 30 TanDEM-X strip map scenes acquired between 2011 and 2018. Established height development curves were fitted to the time series of TanDEM-X-based top heights. This enabled simultaneous estimation of both age and site index on 91 field plots with a 10 m radius. The RMSE of predicted SI and age were 6.9 m and 38 years for untreated plots when both SI and age were predicted. When predicting SI and the age was known, the RMSE of the predicted SI was 4.0 m. No significant prediction bias was observed for untreated plots, while underestimation of SI and overestimation of age increased with the intensity of treatment.https://www.mdpi.com/2072-4292/15/17/4195site indextime seriesInSARheight development curvesgrowth measurementforestry |
| spellingShingle | Ivan Huuva Jörgen Wallerman Johan E. S. Fransson Henrik J. Persson Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights Remote Sensing site index time series InSAR height development curves growth measurement forestry |
| title | Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights |
| title_full | Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights |
| title_fullStr | Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights |
| title_full_unstemmed | Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights |
| title_short | Prediction of Site Index and Age Using Time Series of TanDEM-X Phase Heights |
| title_sort | prediction of site index and age using time series of tandem x phase heights |
| topic | site index time series InSAR height development curves growth measurement forestry |
| url | https://www.mdpi.com/2072-4292/15/17/4195 |
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