Different facets of biodiversity other than species numbers are increasingly appreciated as critical for maintaining the function of ecosystems and their services to humans1, 2. While new international policy and assessment processes such as the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) recognize the importance of an increasingly global, quantitative and comprehensive approach to biodiversity protection, most insights are still focused on a single facet of biodiversity—species3. Here we broaden the focus and provide an evaluation of how much of the world’s species, functional and phylogenetic diversity of birds and mammals is currently protected and the scope for improvement. We show that the large existing gaps in the coverage for each facet of diversity could be remedied by a slight expansion of protected areas: an additional 5% of the land has the potential to more than triple the protected range of species or phylogenetic or functional units. Further, the same areas are often priorities for multiple diversity facets and for both taxa. However, we find that the choice of conservation strategy has a fundamental effect on outcomes. It is more difficult (that is, requires more land) to maximize basic representation of the global biodiversity pool than to maximize local diversity. Overall, species and phylogenetic priorities are more similar to each other than they are to functional priorities, and priorities for the different bird biodiversity facets are more similar than those of mammals. Our work shows that large gains in biodiversity protection are possible, while also highlighting the need to explicitly link desired conservation objectives and biodiversity metrics. We provide a framework and quantitative tools to advance these goals for multi-faceted biodiversity conservation.
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Extended data figures and tables
Extended Data Figures
- Extended Data Figure 1: Which method is best for protecting diversity and how does the threshold for protection change the outcomes? Spatial conservation algorithms versus selecting the most diverse areas (diversity hotspots) for protection. (202 KB)
a–c, Bird (a, c) and mammal (b) diversity. Bars show how much of each metric is currently protected (grey) compared to how much could be protected with a 5% expansion in protected areas (colours) and the total possible (white). Protected areas are expanded by selecting the most diverse 5% of cells (Expand-Diversity) or spatial prioritizations that use the conservation principles of irreplaceability and complementarity. Priorities are shown for the maximizing global diversity (Expand-Global) and maximizing local diversity (Expand-Local) approaches. For the metrics that require a cell threshold, c shows how much diversity is protected for birds in each scenario if a more stringent threshold of three cells protected (instead of the single-cell threshold used in a, b) is used. Species/phylogenetic/functional branches that occur in less than three cells are considered protected if all of their distribution is protected (for example, they occur in two cells and both are protected). Increasing the cell-based threshold substantially decreases the amount of diversity currently considered protected (77% of species protected for 1-cell versus 60% for 3-cell), but the rate of diversity increase with protected area expansion is steeper, meaning that this difference is partly made up for in a 5% expansion (90% of species could end up protected at the 3-cell threshold).
- Extended Data Figure 2: The outcome of protected area expansion for species, phylogenetic and functional prioritizations for different sets of bird and mammal species. (118 KB)
The percentage of the total range occurrences protected (that is, the average spatial range of species that is protected) are shown for each species set: all bird or mammal species; species with the greatest evolutionary distinctiveness (top 10%); the most functionally distinct species (top 10%); the rarest species (top 10% most rare); species that are evolutionarily distinct and rare; and functionally distinct and rare species. Outcomes with the maximizing local diversity objective are shown in a for the full species sets, and maximizing global diversity for rare species in b.
- Extended Data Figure 3: Priorities for expanding protected areas to benefit the bird versus mammal phylogenetic and functional trees of life. (434 KB)
a–l, Phylogenetic (a–f) and functional (g–l) trees of life are presented separately. a, d, g, j, Biodiversity gain is measured with per cent phylogenetic diversity (a, d) or per cent functional diversity (g, j) protected in at least one cell for the maximize global diversity objective, and per cent of the spatial range of occurrences protected (that is, the spatial representation of the functional or phylogenetic tree of life) for the maximize local diversity objective. Solid lines are gains from the actual layout of protected areas, and dotted lines indicate the hypothetical case that both the new and existing protected area network were designed for this objective. b, e, h, k, Graphs of the spatial match in priorities for birds versus mammals with protected area expansion scenarios. c, f, i, l, Maps showing the priority areas for each group (bird priority only, mammal priority only, birds and mammals priority) for a 5% expansion scenario.
- Extended Data Figure 4: Uncertainty in species and phylogenetic priorities. (337 KB)
a–d, Maximize global diversity (a, c) and maximise local diversity (b, d) strategies and their effect on different priorities for birds and mammals (across 100 phylogenies and 100 species replicates each). Graphs show the diversity that could be added into protection with an increase in land area protected for species (grey lines) and phylogenetic prioritizations (blue lines). ‘% Global PD Protected’ is the sum of phylogenetic branches (weighted by branch length) protected in at least one cell, and ‘% SD Prot’ is the number of species protected in at least one cell (both metrics expressed as a percentage of total possible diversity). Rare diversity is also considered. The ‘%Range Rare Species’ is the average spatial distribution that is protected for the rarest species (the rarest 10%) and the ‘% Range Rare Phylo’ is the average spatial distribution of the rarest phylogenetic branches (rarest 10%) that are protected (weighted by the branch length). For the local objective (b), the tree of life is represented spatially as the per cent of the spatial range of the phylogeny that is protected ‘% Range Phylo Protected’ and species are represented as the average per cent of the spatial range of species ‘% Range Species Protected’ that are protected. Maps (c, d) show the similarities and differences in the top priorities for species and phylogenetic diversity for birds and mammals separately. The top priority is defined as cells that were consistently in the top 5% priority for protected area expansion across all species or phylogenetic runs.
- Extended Data Figure 5: Uncertainty in species and functional priorities for birds and mammals for the maximize global diversity strategy. (435 KB)
a, Graphs show the diversity that could be added into protection with an increase in land in protection for species (grey lines) and functional prioritizations with all traits considered (dark blue lines). Light blue lines represent trait dendrograms constructed without one trait (activity time, diet, foraging height and body mass). The ‘% Global FD Protected’ is the sum of functional branches (weighted by branch length) protected in at least one cell, and ‘% Global SD Protected’ is the number of species protected in at least one cell (both metrics expressed as a % of total possible diversity). FD, functional diversity; SD, species diversity. Rare diversity is also considered. The ‘% Range Rare Species Prot.’ shows the average spatial distribution that is protected for the rarest species (the rarest 10%) and the ‘% Range Rare Funct. Prot.’ is the average spatial distribution of the rarest functional branches (rarest 10%) that are protected (weighted by the branch length). Maps show how priorities change (or remain the same) when all traits are used (b) and when body mass is removed from consideration (c). Note that trait sensitivity to choice of traits was much lower with the local objective than for the global objective, and that spatial priorities are nearly identical. Additional results and/or graphs are available from the authors upon request.
- Extended Data Figure 6: Uncertainty in definition of protected areas. (455 KB)
a–c, Uncertainty in definitions for birds from all IUCN categories with a 17% area threshold (a) and IUCN categories I–IV with a 10% (b) and 50% (c) threshold. Protected area thresholds are defined as those that have at least x% of the cell area in defined IUCN categories. Graphs show the diversity that could be added into protection with an extra 5% of the land area for species (blue) or phylogenies (green) and for ‘maximize local diversity’ or ‘maximize global diversity’ objectives. ‘% Global Diversity Protected’ is the sum of species or phylogenetic branches (weighted by branch length) protected in at least one cell (both metrics expressed as a percentage of total possible diversity). Rare diversity graphs show the average spatial distribution that is protected for the rarest 10% of species or the average spatial distribution of the rarest 10% of phylogenetic branches that are protected (weighted by the branch length). The ‘% Range Protected’ is the average per cent of the spatial range of species or phylogenetic branches (weighted by the branch length) that is protected. Maps show the top priorities (that is, the top 5%) for bird species, phylogenetic diversity, and the match between the two.
- Extended Data Figure 7: Maps of weighted endemism (species, phylogenetic, and functional) for birds and mammals and comparisons between rankings produced by selecting grid cells with the highest endemism values for each biodiversity facet. (262 KB)
a, b, Weighted endemism maps for birds (a) and mammals (b) show the raw values of species weighted endemism, phylogenetic endemism and functional endemism. Maps of ranked endemism are calculated by selecting the top 5% of grid cells that have the highest weighted endemism values for each facet and that are not already protected. Colours indicate whether the grid cell is in the top 5% for one, two or all facets. For additional maps see https://mol.org/patterns/facets.
Extended Data Tables
- Extended Data Table 1: How expanding protected areas by 5% could increase protected area coverage for the 20 most evolutionary and functionally distinct, rarest (<20 total occurrences), and least protected bird and mammal species (<1% of their range meeting the threshold protected area coverage) (368 KB)