Global Forest Change 2000–2019
Data Download
Results from time-series analysis of Landsat images in characterizing global forest extent and change from 2000 through 2019. For additional information about these results, please see the associated journal article (Hansen et al., Science 2013).
Web-based visualizations of these results are also available at our main site:
Please use that URL when linking to this dataset.
We anticipate releasing updated versions of this dataset. To keep up to date with the latest updates, and to help us better understand how these data are used, please register as a user. Thanks!
User Notes for Version 1.7 Update
This update of gross forest cover loss includes new 2019 loss-year and multispectral imagery layers. Relative to the version 1.0 product our method has been modified in numerous ways, and the new update should be seen as part of a transition to a future version 2.0 that is more consistent over the entire 2000-onward period. Key changes include:
These changes lead to a different and improved detection of global forest loss. However, the years preceding 2011 have not yet been reprocessed in this manner, and users will notice inconsistencies as a result. It must also be noted that a full validation of the results incorporating Landsat 8 has not been undertaken. Such an analysis may reveal a more sensitive ability to detect and map forest disturbance with Landsat 8 data. If this is the case then there will be a more fundamental limitation to the consistency of the mapped interannual loss before and after the inclusion of Landsat 8 data, and a validation of Landsat 8-incorporated loss detection is planned. The integrated use of version 1.0 2000–2012 data and updated version 1.7 2011–2019 data should be performed with caution.
Some examples of improved change detection in the 2011–2019 update include the following:
These are examples of dynamics that may be differentially mapped over the 2001-2019 period in Version 1.7. A version 2.0 reprocessing of the 2000-onward record is planned, but no delivery date is yet confirmed.
The original version 1.0 data is also still available for download here.
License and Attribution
This work is licensed under a Creative Commons Attribution 4.0 International License. You are free to copy and redistribute the material in any medium or format, and to transform and build upon the material for any purpose, even commercially. You must give appropriate credit, provide a link to the license, and indicate if changes were made.
Use the following credit when these data are displayed:
Use the following credit when these data are cited:
Hansen, M. C., P. V. Potapov, R. Moore, M. Hancher, S. A. Turubanova, A. Tyukavina, D. Thau, S. V. Stehman, S. J. Goetz, T. R. Loveland, A. Kommareddy, A. Egorov, L. Chini, C. O. Justice, and J. R. G. Townshend. 2013. “High-Resolution Global Maps of 21st-Century Forest Cover Change.” Science 342 (15 November): 850–53. Data available on-line from: http://earthenginepartners.appspot.com/science-2013-global-forest.
Dataset Details
This global dataset is divided into 10×10 degree tiles, consisting of seven files per tile. All files contain unsigned 8-bit values and have a spatial resolution of 1 arc-second per pixel, or approximately 30 meters per pixel at the equator.
Tree canopy cover for year 2000 ( treecover2000 ) Tree cover in the year 2000, defined as canopy closure for all vegetation taller than 5m in height. Encoded as a percentage per output grid cell, in the range 0–100. Global forest cover gain 2000–2012 ( gain ) Forest gain during the period 2000–2012, defined as the inverse of loss, or a non-forest to forest change entirely within the study period. Encoded as either 1 (gain) or 0 (no gain). Year of gross forest cover loss event ( lossyear ) Forest loss during the period 2000–2019, defined as a stand-replacement disturbance, or a change from a forest to non-forest state. Encoded as either 0 (no loss) or else a value in the range 1–17, representing loss detected primarily in the year 2001–2019, respectively. Data mask ( datamask ) Three values representing areas of no data (0), mapped land surface (1), and permanent water bodies (2). Circa year 2000 Landsat 7 cloud-free image composite ( first ) Reference multispectral imagery from the first available year, typically 2000. If no cloud-free observations were available for year 2000, imagery was taken from the closest year with cloud-free data, within the range 1999–2012. Circa year 2019 Landsat cloud-free image composite ( last ) Reference multispectral imagery from the last available year, typically 2019. If no cloud-free observations were available for year 2019, imagery was taken from the closest year with cloud-free data, within the range 2010–2015.
Reference composite imagery are median observations from a set of quality assessed growing season observations in four spectral bands, specifically Landsat bands 3, 4, 5, and 7. Normalized top-of-atmosphere (TOA) reflectance values (ρ) have been scaled to an 8-bit data range using a scale factor (g):
The g factor was chosen independently for each band to preserve the band-specific dynamic range, as shown in the following table:
| Landsat Band | g |
|---|---|
| Band 3 (red) | 508 |
| Band 4 (NIR) | 254 |
| Band 5 (SWIR) | 363 |
| Band 7 (SWIR) | 423 |
Download Instructions
To download individual 10×10 degree granules, click on a region on the map below and then click on the URLs underneath it.
Global Forest Change 2000–2020
Data Download
Results from time-series analysis of Landsat images in characterizing global forest extent and change from 2000 through 2020. For additional information about these results, please see the associated journal article (Hansen et al., Science 2013).
Web-based visualizations of these results are also available at our main site:
Please use that URL when linking to this dataset.
We anticipate releasing updated versions of this dataset. To keep up to date with the latest updates, and to help us better understand how these data are used, please register as a user. Thanks!
Usage Notes
The Global Land Analysis and Discovery (GLAD) laboratory at the University of Maryland, in partnership with Global Forest Watch (GFW), provides annually updated global-scale forest loss data, derived using Landsat time-series imagery. These data, available here, are a relative indicator of spatiotemporal trends in forest loss dynamics globally. However, inconsistencies exist due to the following factors:
While the resulting map data are a largely viable relative indicator of trends, care must be taken when comparing change across any interval. Applying a temporal filter, for example a 3-year moving average, is often useful in discerning trends. However, definitive area estimation should not be made using pixels counts from the forest loss layers.
The Intergovernmental Panel on Climate Change (IPCC) provides guidance on reporting areal extent and change of land cover and land use, requiring the use of estimators that neither over or underestimate dynamics to the degree possible, and that have known uncertainties. The maps provided by GLAD do not have these properties. However, the maps can be leveraged to facilitate appropriate probability-based statistical methods in deriving statistically valid areas of forest extent and change. Specifically, the maps may be used as a stratifier in targeting forest extent and/or change by a probability sample. The team at GLAD has demonstrated such approaches using the GLAD forest loss data in sample-based area estimation (Tyukavina et al., ERL, 2018, Turubanova et al., ERL, 2019, and Potapov et al., RSE, 2019, among others).
User Notes for Version 1.8 Update
This update of gross forest cover loss includes new 2020 loss-year and multispectral imagery layers. Relative to the version 1.0 product our method has been modified in numerous ways, and the new update should be seen as part of a transition to a future version 2.0 that is more consistent over the entire 2000-onward period. Key changes include:
These changes lead to a different and improved detection of global forest loss. However, the years preceding 2011 have not yet been reprocessed in this manner, and users will notice inconsistencies as a result. It must also be noted that a full validation of the results incorporating Landsat 8 has not been undertaken. Such an analysis may reveal a more sensitive ability to detect and map forest disturbance with Landsat 8 data. If this is the case then there will be a more fundamental limitation to the consistency of the mapped interannual loss before and after the inclusion of Landsat 8 data, and a validation of Landsat 8-incorporated loss detection is planned. The integrated use of version 1.0 2000–2012 data and updated version 1.8 2011–2020 data should be performed with caution.
Some examples of improved change detection in the 2011–2020 update include the following:
These are examples of dynamics that may be differentially mapped over the 2001-2020 period in Version 1.8. A version 2.0 reprocessing of the 2000-onward record is planned, but no delivery date is yet confirmed.
The original version 1.0 data is also still available for download here.
License and Attribution
This work is licensed under a Creative Commons Attribution 4.0 International License. You are free to copy and redistribute the material in any medium or format, and to transform and build upon the material for any purpose, even commercially. You must give appropriate credit, provide a link to the license, and indicate if changes were made.
Use the following credit when these data are displayed:
Use the following credit when these data are cited:
Hansen, M. C., P. V. Potapov, R. Moore, M. Hancher, S. A. Turubanova, A. Tyukavina, D. Thau, S. V. Stehman, S. J. Goetz, T. R. Loveland, A. Kommareddy, A. Egorov, L. Chini, C. O. Justice, and J. R. G. Townshend. 2013. “High-Resolution Global Maps of 21st-Century Forest Cover Change.” Science 342 (15 November): 850–53. Data available on-line from: http://earthenginepartners.appspot.com/science-2013-global-forest.
Dataset Details
This global dataset is divided into 10×10 degree tiles, consisting of seven files per tile. All files contain unsigned 8-bit values and have a spatial resolution of 1 arc-second per pixel, or approximately 30 meters per pixel at the equator.
Tree canopy cover for year 2000 ( treecover2000 ) Tree cover in the year 2000, defined as canopy closure for all vegetation taller than 5m in height. Encoded as a percentage per output grid cell, in the range 0–100. Global forest cover gain 2000–2012 ( gain ) Forest gain during the period 2000–2012, defined as the inverse of loss, or a non-forest to forest change entirely within the study period. Encoded as either 1 (gain) or 0 (no gain). Year of gross forest cover loss event ( lossyear ) Forest loss during the period 2000–2020, defined as a stand-replacement disturbance, or a change from a forest to non-forest state. Encoded as either 0 (no loss) or else a value in the range 1–20, representing loss detected primarily in the year 2001–2020, respectively. Data mask ( datamask ) Three values representing areas of no data (0), mapped land surface (1), and permanent water bodies (2). Circa year 2000 Landsat 7 cloud-free image composite ( first ) Reference multispectral imagery from the first available year, typically 2000. If no cloud-free observations were available for year 2000, imagery was taken from the closest year with cloud-free data, within the range 1999–2012. Circa year 2020 Landsat cloud-free image composite ( last ) Reference multispectral imagery from the last available year, typically 2020. If no cloud-free observations were available for year 2020, imagery was taken from the closest year with cloud-free data.
Reference composite imagery are median observations from a set of quality assessed growing season observations in four spectral bands, specifically Landsat bands 3, 4, 5, and 7. Normalized top-of-atmosphere (TOA) reflectance values (ρ) have been scaled to an 8-bit data range using a scale factor (g):
The g factor was chosen independently for each band to preserve the band-specific dynamic range, as shown in the following table:
| Landsat Band | g |
|---|---|
| Band 3 (red) | 508 |
| Band 4 (NIR) | 254 |
| Band 5 (SWIR) | 363 |
| Band 7 (SWIR) | 423 |
Download Instructions
To download individual 10×10 degree granules, click on a region on the map below and then click on the URLs underneath it.
Форумы GIS-Lab.info
Геоинформационные системы (ГИС) и Дистанционное зондирование Земли
Каким образом создана карта Global Forest Change
Каким образом создана карта Global Forest Change
Сообщение nick777 » 12 фев 2014, 17:54
Re: Каким образом создана карта Global Forest Change
Сообщение nadiopt » 12 фев 2014, 17:57
Re: Каким образом создана карта Global Forest Change
Сообщение dime1 » 12 фев 2014, 18:28
Там сложный алгоритм, который раскрыт не будет (хотя для L8 и местечковый вариант модели был бы полезен). Вычисляли в параллельном процессинге на мощностях Google.
[ Сообщение с мобильного устройства ]
Re: Каким образом создана карта Global Forest Change
Сообщение nick777 » 12 фев 2014, 19:01
Re: Каким образом создана карта Global Forest Change
Сообщение nick777 » 12 фев 2014, 19:01
Re: Каким образом создана карта Global Forest Change
Сообщение nadiopt » 12 фев 2014, 19:09
Re: Каким образом создана карта Global Forest Change
Сообщение dime1 » 12 фев 2014, 19:14
Re: Каким образом создана карта Global Forest Change
Сообщение gimran » 12 фев 2014, 19:23
Re: Каким образом создана карта Global Forest Change
Сообщение manisha » 21 фев 2014, 16:56
dime1 писал(а): Там сложный алгоритм, который раскрыт не будет (хотя для L8 и местечковый вариант модели был бы полезен). Вычисляли в параллельном процессинге на мощностях Google.
[ Сообщение с мобильного устройства ]
Насколько я знаю, ихние алгоритмы используют и для аналогичных продуктов по росту городов.
