Research ArticleENVIRONMENTAL STUDIES

Long-term (1990–2019) monitoring of forest cover changes in the humid tropics

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Science Advances  05 Mar 2021:
Vol. 7, no. 10, eabe1603
DOI: 10.1126/sciadv.abe1603
  • Fig. 1 Remaining TMFs.

    Map of TMFs remaining in January 2020.

  • Fig. 2 Illustrations of the transition map.

    Sample patterns of forest cover disturbances (deforestation and degradation) during the period 1990–2019: (A) Remaining mangroves and related changes in Guinea-Bissau (14.9°W, 11.1°N), (B) fires in the Mato Grosso province of Brazil (53.8°W, 13°S), (C) recent deforestation in Colombia (74.4°W, 0.7°N), (D) logging in Mato Grosso (54.5°W, 12°S), (E) deforestation and degradation caused by the railway in Cameroon (13.4°E, 5.8°N), (F) recent selective logging in the Ouésso region of the Republic of Congo (15.7°E, 1.4°N), (G) deforestation for the creation of a dam in Malaysia (113.8°E, 2.4°S), (H) massive deforestation in Cambodia (105.6°E, 12.7°N), and (I) commodities in the Riau province of Indonesia (102°E, 0.4°N). The size of each box is 20 km by 20 km.

  • Fig. 3 Dynamics of annual disturbed areas for the Amazônia Legal region and Indonesia.

    Dynamics of annual disturbed areas from 2001 to 2019 for the Amazônia Legal region of Brazil within the primary forest extent in 2000 from National Institute for Space Research (INPE) and Indonesia using the entire TMF extent (undisturbed and degraded) in 2000 (x axis in years and y axis in million hectares) in comparison with GFC loss and the PRODES data for the Amazônia Legal region of Brazil. Asterisks (*) indicate that the average proportion of disturbance types within total disturbances over the period 2005–2014 is used to distribute the disturbance types for years 2017 to 2019. Defor, deforestation.

  • Fig. 4 Evolution of annual deforestation and degradation at the regional scale.

    Evolution of annual deforestation and degradation (A) over the past 25 years in South America, (B) in continental Southeast Asia, and (C) over the past 15 years in all regions. “Short-term degradation” refers to disturbances that have been observed over less than 1 year, mostly due to selective logging, natural events, and light-impact fires, whereas “long-term degradation” refers mostly to fires that are detected over a period of 1 to 2.5 years.

  • Fig. 5 Hot spots of deforestation and degradation.

    Evolution of total deforested (A) and degraded (B) areas (per box of 1° latitude by 1° longitude size; scale in million hectares) within the labeled time intervals (1990–1999, 2000–2009, and 2010–2019).

  • Table 1 Areas (in million hectares) of undisturbed TMFs for the years 1990, 1995, 2000, 2005, 2010, 2015, and 2020 (on 1 January) by subregion and continent and relative decline (in percentage) over intervals of 30 years (1990–2019) and 10 years (1990–1999, 2000–2009, and 2010–2019).

    The values appearing in italic indicate those derived from an average percentage of invalid pixel observations over the baseline TMF domain (Table 9) higher than 40%.

    Area of undisturbed TMFs on 1 January (Mha)Decline (% of the forest)
    Subregion1990199520002005201020152020[1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa34.634.132.827.423.920.615.655.05.027.135.0
    Central Africa223.1221.5216.1207.2201.1193.7184.717.23.16.98.2
    Southeast
    Africa
    15.715.012.510.18.97.66.459.220.728.627.9
    Central
    America
    34.532.327.424.121.719.616.253.020.820.625.3
    South America670.6655.4628.8600.9583.2568,9548.218.26.27.36.0
    Continental
    Southeast
    Asia
    73.367.257.750.244.439.934.253.321.223.222.9
    Insular
    Southeast
    Asia
    237.9229.5207.8192.9180.8170.5159.133.112.613.012.0
    Continent1990199520002005201020152020[1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    Africa273.4270.6261.4244.7234.0221.9206.724.44.410.511.7
    Latin America705.1687.7656.1625.0604.9588.5564.419.96.97.86.7
    Asia-Oceania311.1296.7265.6243.2225.2210.4193.337.914.615.214.2
    Total1289.61255.01183.11112.91064.01020.8964.425.28.310.19.4
  • Table 2 Areas (in million hectares) of undisturbed and degraded TMFs for the years 1990, 1995, 2000, 2005, 2010, 2015, and 2020 (on 1 January) by subregion and continent and relative decline (in percentage) over intervals of 30 years (1990–2019) and 10 years (1990–1999, 2000–2009, and 2010–2019).

    The values appearing in italic indicate those derived from an average percentage of invalid pixel observations over the baseline TMF domain (Table 11) higher than 40%.

    Area of TMFs (undisturbed and degraded) at the end of the year (Mha)Decline (% of the forest)
    Subregion1990199520002005201020152020[1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa34.634.333.329.827.425.122.136.03.617.819.3
    Central Africa223.1222.3218.6212.7208.9204.4199.910.42.04.44.3
    Southeast
    Africa
    15.715.212.911.010.19.28.545.917.821.815.9
    Central
    America
    34.532.829.026.825.324.022.135.916.012.812.5
    South
    America
    670.6657.7635.5613.7601.0592.4581.613.35.25.43.2
    Continental
    Southeast
    Asia
    73.369.161.355.752.049.246.436.616.315.210.6
    Insular
    Southeast
    Asia
    237.9232.6218.4208.9201.2194.9190.220.08.27.95.5
    Continent1990199520002005201020152020[1990–
    2020]
    [1990–
    2000]
    [2000–
    2010]
    [2010–
    2020]
    Africa273.4271.7264.8253.5246.4238.7230.515.73.17.06.5
    Latin America705.1690.5664.5640.5626.3616.4603.714.45.85.73.6
    Asia-Oceania311.1301.7279.7264.5253.2244.1236.723.910.19.56.5
    Total1289.61263.91209.01158.51125.91099.21070.917.06.26.94.9
  • Table 3 Average annual losses of undisturbed TMF areas (in million hectares) due to deforestation and degradation, from 1990 to 2020 over intervals of 5 years, 30 years (1990–2019), 20 years (2000–2019), and 10 years (1990–1999, 2000–2009, and 2010–2019) by subregion and continent.

    The values appearing in italic indicate those derived from an average percentage of invalid observations (Table 9) higher than 40%.

    Annual loss of undisturbed TMF areas (Mha)
    Subregion[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa0.100.241.080.700.671.010.60.20.90.8
    Central
    Africa
    0.331.071.791.221.491.791.30.71.51.5
    Southeast
    Africa
    0.130.520.470.240.260.240.30.30.40.3
    Central
    America
    0.450.990.660.470.430.670.60.70.60.6
    South
    America
    3.035.335.563.562.854.144.14.24.64.1
    Continental
    Southeast
    Asia
    1.211.901.501.170.891.141.31.61.31.2
    Insular
    Southeast
    Asia
    1.684.322.982.432.072.282.63.02.72.5
    Continent[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2010]
    [2010–
    2020]
    Africa0.561.823.342.152.423.042.21.22.72.6
    Latin
    America
    3.486.326.224.033.274.814.74.95.14.8
    Asia-Oceania2.896.224.483.602.963.423.94.64.03.7
    Total6.9314.3714.049.788.6611.2710.810.611.911.1
  • Table 4 Average annual losses of TMF areas (in million hectares) due to deforestation (with or without prior degradation), from 1990 to 2020 over intervals of 5 years, 30 years (1990–2019), 20 years (2000–2019), and 10 years (1990–1999, 2000–2009, and 2010–2019) by subregion and continent.

    The values appearing in italic indicate those derived from an average percentage of invalid observations (Table 9) higher than 40%.

    Total deforestation on an annual basis by period (Mha)
    Subregion[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa0.060.190.710.480.450.600.40.10.60.5
    Central
    Africa
    0.170.741.180.760.900.910.80.51.00.9
    Southeast
    Africa
    0.100.450.380.180.180.140.20.30.30.2
    Central
    America
    0.340.760.450.290.260.370.40.60.40.3
    South
    America
    2.574.444.352.541.732.163.03.53.41.9
    Continental
    Southeast
    Asia
    0.841.551.130.740.560.540.91.20.90.6
    Insular
    Southeast
    Asia
    1.052.831.911.531.270.941.61.91.71.1
    Continent[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    Africa0.331.382.261.421.541.651.430.861.841.59
    Latin
    America
    2.915.214.802.831.992.533.384.063.822.26
    Asia-Oceania1.894.383.042.271.831.482.483.142.651.65
    Total5.1410.9710.106.525.355.667.298.068.315.51
  • Table 5 Average annual losses of undisturbed TMF areas (in million hectares) due to degradation (followed or not by deforestation), from 1990 to 2020 over intervals of 5 years, 30 years (1990–2019), 20 years (2000–2019), and 10 years (1990–1999, 2000–2009, and 2010–2019) by subregion and continent.

    The values appearing in italic indicate those derived from an average percentage of invalid observations (Table 9) higher than 40%.

    Total degradation on an annual basis by period (Mha)
    Subregion[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa0.080.160.870.500.350.610.40.10.70.5
    Central
    Africa
    0.280.831.400.910.921.240.90.61.21.1
    Southeast
    Africa
    0.090.270.280.140.130.130.20.20.20.1
    Central
    America
    0.290.640.490.340.270.450.40.50.40.4
    South
    America
    1.252.292.611.831.592.542.01.82.22.1
    Continental
    Southeast
    Asia
    0.881.231.030.810.490.780.91.10.90.6
    Insular
    Southeast
    Asia
    1.162.801.981.391.031.651.72.01.71.3
    Continent[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    Africa0.451.262.561.551.401.981.530.862.051.69
    Latin
    America
    1.542.933.102.161.852.992.432.242.632.42
    Asia-Oceania2.044.033.002.211.512.432.543.042.611.97
    Total4.038.238.665.924.777.406.506.137.296.09
  • Table 6 Average annual losses of undisturbed TMF areas (in million hectares) due to direct deforestation (without prior degradation), from 1990 to 2020 over intervals of 5 years, 30 years (1990–2019), 20 years (2000–2019), and 10 years (1990–1999, 2000–2009, and 2010–2019) by subregion and continent.

    The values appearing in italic indicate those derived from an average percentage of invalid observations (Table 9) higher than 40%.

    Annual direct deforestation by period (Mha)
    Subregion[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa0.020.080.210.190.320.400.20.00.20.04
    Central
    Africa
    0.050.240.380.310.570.560.40.10.30.6
    Southeast
    Africa
    0.050.240.190.100.130.100.10.10.10.1
    Central
    America
    0.160.340.170.130.160.220.20.20.20.2
    South
    America
    1.783.052.951.731.261.612.12.42.31.4
    Continental
    Southeast
    Asia
    0.330.660.480.360.410.360.40.50.40.4
    Insular
    Southeast
    Asia
    0.521.531.001.031.040.621.01.01.00.8
    Continent[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    Africa0.110.560.780.601.021.060.690.340.691.04
    Latin
    America
    1.943.393.121.861.421.822.262.662.491.62
    Asia-Oceania0.852.191.481.391.450.991.391.521.441.22
    Total2.906.145.383.863.893.874.344.524.623.88
  • Table 7 Average annual losses of undisturbed TMF areas (in million hectares) due to annual degradation before deforestation, from 1990 to 2020 over intervals of 5 years, 30 years (1990–2019), 20 years (2000–2019), and 10 years (1990–1999, 2000–2009, and 2010–2019) by subregion and continent.

    The values appearing in italic indicate those derived from an average percentage of invalid observations (Table 9) higher than 40%.

    Annual degradation before deforestation by period (Mha)
    Subregion[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa0.040.110.500.280.140.200.20.10.40.2
    Central
    Africa
    0.120.500.790.450.330.350.40.30.60.3
    Southeast
    Africa
    0.060.210.190.080.050.040.10.10.10.0
    Central
    America
    0.180.420.280.160.100.160.20.30.20.1
    South
    America
    0.791.401.400.810.470.550.91.11.10.5
    Continental
    Southeast
    Asia
    0.510.890.650.380.150.180.50.70.50.2
    Insular
    Southeast
    Asia
    0.531.310.910.500.230.310.60.90.70.3
    Continent[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    Africa0.220.821.480.820.520.590.740.521.150.55
    Latin
    America
    0.981.821.680.970.570.711.121.401.33064
    Asia-Oceania1.052.191.560.880.380.491.091.621.220.44
    Total2.244.834.722.661.741.792.953.543.691.63
  • Table 8 Average annual losses of TMF areas (in million hectares) due to deforestation followed by regrowth, from 1990 to 2020 over intervals of 5 years, 30 years (1990–2019), 20 years (2000–2019), and 10 years (1990–1999, 2000–2009, and 2010–2019) by subregion and continent.

    The values appearing in italic indicate those derived from an average percentage of invalid observations (Table 9) higher than 40%.

    Total deforestation followed by regrowth on an annual basis by period (Mha)
    Subregion[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    West Africa0.000.000.010.040.060.030.00.00.00.0
    Central
    Africa
    0.020.040.070.100.130.060.10.00.10.1
    Southeast
    Africa
    0.000.010.020.030.030.010.00.00.00.0
    Central
    America
    0.050.090.070.070.050.020.10.10.10.0
    South
    America
    0.210.400.500.490.370.200.40.30.50.3
    Continental
    Southeast
    Asia
    0.100.200.240.230.140.060.20.20.20.1
    Insular
    Southeast
    Asia
    0.110.330.440.420.300.150.30.20.40.2
    Continent[1990–
    1994]
    [1995–
    1999]
    [2000–
    2004]
    [2005–
    2009]
    [2010–
    2014]
    [2015–
    2019]
    [1990–
    2019]
    [1990–
    1999]
    [2000–
    2009]
    [2010–
    2019]
    Africa0.020.060.100.170.210.100.110.040.130.15
    Latin
    America
    0.260.480.580.560.430.220.420.370.570.32
    Asia-Oceania0.210.530.680.650.440.210.450.370.660.32
    Total0.501.061.361.371.080.530.980.781.370.80
  • Table 9 Average percentage of invalid observations over the baseline TMF domain.

    Average percentage of invalid observations over the baseline TMF domain (A) per year from 1982 to 2020 and (B) over intervals of 5 years (except for the first interval that includes 8 years), by subregion and continent. The values appearing in italic indicate an average percentage of invalid observations higher than 40%.

    A
    Average % of invalid observations (over the total forest domain, per year)
    Subregion19821990199520002005201020152019
    West Africa100.090.884.371.85.90.70.20.0
    Central Africa100.097.787.667.810.23.71.90.0
    Southeast Africa100.092.141.58.41.51.00.50.0
    Central America69.417.05.81.80.70.20.00.0
    South America55.61.70.80.30.10.00.00.0
    Continental
    Southeast
    Asia
    55.249.12.01.00.00.00.00.0
    Insular
    Southeast
    Asia
    34.631.26.51.90.20.10.00.0
    Continent19821990199520002005201020152019
    Africa100.093.571.249.35.91.80.90.0
    Latin America62.59.43.31.00.40.10.00.0
    Asia-Oceania44.940.24.31.40.10.10.00.0
    Total69.147.726.217.32.10.70.30.0
    B
    Average % of invalid observations (over the total forest domain, per year)
    Subregion[1982–1989][1990–1994][1995–1999][2000–2004][2005–2009][2010–2014][2015–2019]
    West Africa98.187.182.540.02.80.40.0
    Central Africa99.494.780.837.26.72.90.4
    Southeast Africa97.980.820.73.91.30.80.1
    Central America50.112.44.31.20.40.10.0
    South America30.51.20.60.20.00.00.0
    Continental
    Southeast
    Asia
    54.514.61.30.40.00.00.0
    Insular
    Southeast
    Asia
    34.316.34.20.80.10.10.0
    Continent[1982–1989][1990–1994][1995–1999][2000–2004][2005–2009][2010–2015][2015–2020]
    Africa99.192.977.635.75.92.40.3
    Latin America31.31.60.80.20.10.00.0
    Asia-Oceania29.512.03.71.30.30.20.0
    Total21.231.923.110.12.30.80.1
  • Table 10 Total areas and proportions of TMF disturbances (deforestation without regrowth, regrowth after deforestation, and forest degradation) and reforestation areas (initially other land cover) over the period 1990–2020 for each subregion and continent (areas in million hectares and proportions in percentages).

    LC, land cover.

    Disturbed areas (Mha)% of total disturbances% of undisturbed forest in 1990
    SubregionDeforestationRegrowthDegradationTotalDeforestationRegrowthDegradationDeforestationRegrowthDegradationTotalReforestation
    (from other LC)
    West Africa11.80.76.519.061.93.734.534.02.018.955.00.4
    Central Africa21.22.115.138.455.25.439.49.50.96.817.21.1
    Southeast Africa6.70.52.19.371.95.722.442.53.413.359.20.2
    Central America10.61.85.918.358.09.732.330.75.117.153.00.7
    South America78.110.933.4122.463.88.927.311.61.65.018.24.0
    Continental
    Southeast
    Asia
    22.04.912.239.156.212.431.430.06.616.753.32.0
    Insular Southeast
    Asia
    38.98.731.178.849.411.139.516.43.713.133.11.6
    ContinentDeforestationRegrowthDegradationTotalDeforestationRegrowthDegradationDeforestationRegrowthDegradationTotalReforestation
    (from other LC)
    Africa39.63.323.866.759.44.935.614.51.28.724.41.6
    Latin America88.712.639.3140.763.19.027.912.61.85.619.94.7
    Asia-Oceania60.913.643.4117.851.711.536.819.64.413.937.93.6
    Total189.229.5106.5325.258.29.132.714.92.38.425.710.0
  • Table 11 Comparison of estimates of annual deforested areas (in million hectares per year) from previous studies and our study, over the tropical belt, over the three continents and Brazil.

    SourceGFC (24)Sample-
    based (32)
    FAO national
    statistics (31)
    PRODES-
    INPE (30)
    This study
    Forest extentWhole TMF
    (undisturbed
    and degraded)
    Primary
    forest from
    INPE
    Natural
    forest*
    All tropical
    forests
    (evergreen and
    deciduous)
    Primary
    forest
    Whole TMFTMF
    excluding
    the tree
    plantations
    Primary
    forest from
    INPE
    Pantropical
    region
    2001–20104.677.247.72
    2001–20124.806.5 ± 0.77.196.44
    2001–20155.076.666.95
    2001–20195.796.66
    Africa2001–20120.731.21 ± 0.41.601.57
    2001–20191.281.64
    Latin America2001–20122.193.7 ± 0.53.253.19
    2001–20192.412.93
    Asia-Oceania2001–20121.891.6 ± 0.42.341.67
    2001–20192.102.09
    Brazil2001–20101.611.351.652.551.57
    2001–20121.541.262.1 ± 0.31.472.322.271.42
    2010–20191.641.340.671.631.04
    2001–20191.641.351.192.101.31

    *Evergreen and deciduous, excluding manage forests (e.g., tree plantations).

    Supplementary Materials

    • Supplementary Materials

      Long-term (1990–2019) monitoring of forest cover changes in the humid tropics

      C. Vancutsem, F. Achard, J.-F. Pekel, G. Vieilledent, S. Carboni, D. Simonetti, J. Gallego, L. E. O. C. Aragão, R. Nasi

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