Research ArticleAPPLIED ECOLOGY

A third of the tropical African flora is potentially threatened with extinction

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Science Advances  20 Nov 2019:
Vol. 5, no. 11, eaax9444
DOI: 10.1126/sciadv.aax9444
  • Fig. 1 Correspondence between categories of the PACA and the IUCN categories.

    PACA categories: LT, PT, PNT, LR, PR, and LNT. IUCN categories: EX, extinct; EW, extinct in the wild; CR; EN; VU; NT; and LC.

  • Fig. 2 Spatial distribution of threatened plant species across tropical Africa.

    Proportion of species preliminarily assessed as (A) LT or PT following criterion A; (B) LT or PT following criterion B; and (C) LT or PT following both criteria A and B. Values are based on adaptive resolution sampling unit (SU) (for explanation, see text).

  • Fig. 3 Spatial distribution of rare plant species across tropical Africa.

    Proportion of species preliminarily assessed as LR/PR following Criterion B. Values are based on adaptive resolution SU (for explanation, see text).

  • Table 1 Number of threatened and nonthreatened plant species for tropical Africa.

    Total number and proportion of 22,036 vascular plant species assessed as LT/PT and LNT under our Preliminary Automated Conservation Assessments approach. LR/PR categories include species that meet three subcriteria of IUCN Criterion B [Extent of Occurrence (EOO), Area of Occupancy (AOO), and number of locations] but for which known subpopulations are apparently not exposed to a decline of habitat quality due to land cover conversion.

    PACA threat
    category
    Criterion ACriterion BBoth Criteria
    LT/PT5,023 (22.8%)4,879 (22.1%)6,990 (31.7%)
    LT2,652 (12%)2,803 (12.7%)3,823 (17.3%)
    PT2,371 (10.8%)2,076 (9.4%)3,167 (14.4%)
    PNT17,013 (77.2%)17,157 (77.9%)15,046 (68.3%)
    LR7,304 (33.1%)7,304 (33.2%)
    PR1,154 (5.3%)1,154 (5.2%)
    LNT8,699 (39.5%)6,588 (29.9%)
  • Table 2 Number of threatened species per country and ecoregion.

    Top 10 countries and ecoregions with the highest proportion of LT/PT species assessed under both Criteria A and B, under Criterion B, and under Criterion A. LT/PT (see Fig. 1).

    CountryArea (km2)Number of recordsNumber of speciesLT/PT species
    under Criteria A
    and B
    LT/PT species
    under Criterion A
    LT/PT species
    under Criterion B
    Sierra Leone71,5764,4451,32553.450.813.0
    Gambia10,2751359750.548.58.2
    Ethiopia1,127,09624,8823,81050.244.326.4
    Liberia95,25215,8482,22948.946.411.9
    Senegal196,6091,86778147.644.79.1
    Ivory Coast320,93435,9153,42143.539.711.0
    Guinea243,9409,3452,18942.939.510.5
    Ghana238,55911,1412,58041.639.07.7
    Benin116,10520,4862,37134.330.96.5
    Uganda241,4745,9411,94834.030.310.0
    Ecoregions
    Ethiopian montane
    moorlands
    25,049.11,13581476.574.330.2
    Inner Niger Delta
    flooded savanna
    45,868.11379767.064.914.4
    Ethiopian montane
    grasslands and
    woodlands
    244,349.011,3904,20059.756.920.9
    Ethiopian montane
    forests
    247,734.36,8412,88553.349.116.8
    Sahelian Acacia
    savanna
    3,042,451.42,82098652.950.112.0
    Guinean mangroves23,418.91,5981,15951.650.54.6
    Western Guinean
    lowland forests
    204,226.325,4972,75848.345.114.4
    Mandara Plateau
    mosaic
    7,478.583448447.344.89.3
    Ethiopian xeric
    grasslands and
    shrublands
    151,868.745226543.436.614.3
    Guinean montane
    forests
    30,923.59,3833,53742.839.29.1
  • Table 3 Comparing PACA versus full IUCN assessments.

    Confusion matrices comparing the published full IUCN assessments published after 2001 (columns) and preliminary automated conservation assessments for 2009 species (rows). The matrix above includes Rare categories (LR and PR) within Threatened categories while the matrix below does not.

    EX/CR/ENVUNT/LC
    Including Rare species into threat categories
    LT/LR505180329
    PT/PR69107239
    LNT25103452
    Excluding Rare species from threat categories
    LT12153136
    PT3254189
    PNT446283695
  • Table 4 Number of threated species for four habit types.

    Total number and proportion (in %) of species per habit assessed as LT/PT using PACA under Criterion A, Criterion B, and both Criteria A and B. LT species encompass EN and CR IUCN categories, and PT species encompass the VU IUCN category.

    Threat categoryTree: Total (proportion)Shrub: Total (proportion)Herb: Total (proportion)Liana: Total (proportion)
    LT/PT
    Criterion A658 (18.8%)865 (17.7%)2818 (27.6%)442 (25.6%)
    Criterion B596 (17%)945 (19.4%)2666 (26%)341 (19.8%)
    Criteria A and B959 (27.4%)1305 (26.7%)3761 (36.8%)605 (35.1%)
    PNT
    Criterion A2843 (81.2%)4025 (82.3%)7414 (72.5%)1281 (74.3%)
    Criterion B1886 (53.9%)1910 (39.1%)3623 (35.4%)973 (56.5%)
    Criteria A and B2542 (72.6%)3585 (73.4%)6471 (63.3%)1118 (64.8%)

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/11/eaax9444/DC1

    Fig. S1. Total number of species assessed as Likely/Potentially Threatened following criterion A, B, and both A and B.

    Fig. S2. Total number of species preliminarily assessed as LR/PR following the Criterion B.

    Fig. S3. Summary statistics for full conservation assessments of plant species published on the IUCN Red List portal (version 2018-2, www.iucnredlist.org).

    Fig. S4. Proportion of species preliminarily assessed as Likely/Potentially Threatened following Criterion A and Criterion B for four habit types.

    Table S1. Proportion (in %) of LT/PT species assessed under Criteria A, B, and both A and B for all countries within our study area (tropical Africa).

    Table S2. Number of LT/PT species assessed under Criteria A, B, and both A and B for all countries within our study area (tropical Africa).

    Table S3. Proportions of likely/potentially threatened species assessed under Criteria A, B, and both A and B across ecoregions.

    Table S4. Number of likely/potentially threatened species assessed under both Criteria A and B and total number of species for four different habits for each ecoregion.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Total number of species assessed as Likely/Potentially Threatened following criterion A, B, and both A and B.
    • Fig. S2. Total number of species preliminarily assessed as LR/PR following the Criterion B.
    • Fig. S3. Summary statistics for full conservation assessments of plant species published on the IUCN Red List portal (version 2018-2, www.iucnredlist.org).
    • Fig. S4. Proportion of species preliminarily assessed as Likely/Potentially Threatened following Criterion A and Criterion B for four habit types.
    • Table S1. Proportion (in %) of LT/PT species assessed under Criteria A, B, and both A and B for all countries within our study area (tropical Africa).
    • Table S2. Number of LT/PT species assessed under Criteria A, B, and both A and B for all countries within our study area (tropical Africa).
    • Table S3. Proportions of likely/potentially threatened species assessed under Criteria A, B, and both A and B across ecoregions.
    • Table S4. Number of likely/potentially threatened species assessed under both Criteria A and B and total number of species for four different habits for each ecoregion.

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