The Species Protection Index

Biodiversity — the variety and abundance of living organisms and the communities they form — is critical to the functioning of healthy ecosystems and to our own survival as humans. But biodiversity is in crisis. Many species are threatened today by habitat loss and degradation, a rapidly changing climate, and other mounting pressures from exploitative human activity. 

Conserving species habitats is one of our most important tools for conserving biodiversity. Protected areas — areas under management guidelines that reduce human impacts — can help secure ecosystem health and the persistence of species who live within the area, if they are wisely planned and managed. However, developing strategic conservation systems is no small task, and too often, protected areas are not established where they are needed most. By having evidence based tools to assess conservation practices we can help make better decisions.

How can we ensure that our conservation actions lead to meaningful species and ecosystem protection?

In order to strategically protect our planet’s incredible biodiversity, we first need to know where species occur throughout the world (see the map below!) and how our conservation efforts can most effectively protect as many species as possible.

Explore the map to see how terrestrial vertebrate species are spread across the world! You can zoom in and out, move around the map, or search for specific locations using the icon in the top left corner.

The Species Protection Index (SPI) measures how well protected areas conserve habitat for species. The SPI reflects how adequately conservation areas in a region represent the region's biodiversity, with a particular emphasis on the region's endemic species. As part of a new generation of data-driven, species-level indicators, the SPI is designed to support biodiversity assessment and conservation decision making. The SPI is a GEO BON (Biodiversity Observation Network) biodiversity indicator used for monitoring and reporting on national progress towards global biodiversity goals and targets. As we will see, the SPI is a flexible tool that can be adapted to provide key information across taxonomic groups, at different geographic scales, and through time.

In order to understand how the SPI is calculated, we must first introduce the concept of a species conservation target. A species conservation target represents some measure of what we think is needed (such as habitat area) for its population to thrive. There is no gold standard for determining how much area a species needs, but we can apply an intuitive rule of thumb: the rarest species with small range sizes generally need the most protection, and the most widespread and common species probably need the least. In practice, many other conservation principles will also influence species persistence through time — such as population size and trends and protected area management effectiveness — but this rule of thumb is a useful proxy for setting area-based conservation targets for species.

To calculate the SPI at the national level, we first need to quantify levels of area-based conservation for species in a country using a related metric called the species protection score.

For a given species, we calculate a Species Protection Score (SPS) by the percentage of its habitat that is currently protected, divided by its area-based conservation target. A species that has met its conservation target will have an SPS of 100; a species halfway to meeting its target will have an SPS of 50. By design, SPS has a maximum value of 100: species that have exceeded their target will not have an SPS higher than 100. For species with ranges that overlap multiple countries, SPS values can be calculated individually for each country, which will reflect how well protected the species is within each country, enabling comparisons between different countries for the same species.

To better understand how a country's SPI is derived from its Species Protection Scores, let's take a look at some examples. Here, we'll start by focusing on a species endemic to Sri Lanka, and then gradually zoom out to some wider-ranging species.

Click the button in the bottom left corner of the maps to open the legend, and move the slider left to right to see how well the protected areas cover the species ranges!

How do these numbers for individual species measure the effectiveness of protected areas within an entire country?

The SPI of a country is simply an average of the Species Protection Scores of all the assessed species within the country (that is, all species relevant to the purpose of the study). For example, if we assumed that our two example species presented above were the only two species in Sri Lanka, we would calculate the current SPI of Sri Lanka by averaging the Species Protection Scores for each species in Sri Lanka: (21 + 100) / 2 = 60.5. Of course, in practice, Sri Lanka has many more species (695 known terrestrial vertebrates, for example), but the approach remains the same, regardless of the number of species.

How should we interpret SPI values?

Like SPS, the SPI ranges from 0–100. An SPI below 100 indicates that a country's network of conserved areas is not yet sufficient to adequately represent its species.

Additionally, we can look at how a country's SPI changes over time, based on when its protected areas were established. Let's take a look again at some example countries!

As mentioned previously, the SPI is not limited to applications at the national level, nor for summaries of full species lists. The SPI can be calculated for any geographic region (e.g., states and provinces, individual protected areas, globally), and for different groups of species, offering further insights into how effectively different groups are collectively safeguarded. The figure shows the global SPI calculated for all terrestrial vertebrates as well as for each vertebrate group (birds, reptiles, etc), which clearly shows us that protection is not equal between species groups.

This versatility enables the SPI to not only offer measurement of the biodiversity outcomes of past conservation decisions, but to also aid future decision-making. In places where objectives seek to extend area-based conservation in support of biodiversity outcomes, the SPI can be integrated into planning processes to compare the performance of different network configurations alongside other common performance metrics, such as ecological connectivity and cost efficiency.

The SPI depends in part on how many species a country has and how well their ranges are protected, but many other facets of geography and human activity influence the degree to which such protection is easily achievable. While Sri Lanka and Mongolia both have stewardship over roughly similar numbers of terrestrial vertebrates (695 vs. 521), and while the SPI suggests that Mongolia is protecting its species more effectively, it is worth noting that Sri Lanka has a population almost seven times larger than Mongolia, in an area approximately 1/24th the size. In which country would you expect biodiversity conservation to carry a heavier burden?

In general, countries with more species will need to invest more resources, money, and land into their protected area network to achieve the same SPI values as countries with less biodiversity. This also means that countries like Sri Lanka, which have higher species richness and many endemic species, can have lower SPI values but still contribute more to global species protection than countries with high SPIs but few species, like Mongolia.

The SPI is a tool to understand how well countries’ protected area networks actually conserve habitat in support of biodiversity. Using this tool, we can:

• prioritize where conservation would be most effective
• identify opportunities to invest in conservation capacity
• hold countries accountable for achieving their biodiversity targets

When we know where species live, we can determine what areas need to be prioritized in future conservation efforts so that as many species' habitats as possible are securely protected. Below is a map that prioritizes areas for conservation based on where terrestrial vertebrates live. All over the world, teams of conservationists are working to turn these priority areas into conservation success stories.

Successful conservation happens when local and indigenous communities are respected and actively involved in project planning and management. Most landscapes on Earth have long histories of traditional human lifestyles interacting harmoniously with the land, and in many cases, these histories have built unique ecosystems that depend on their human inhabitants. Drawing a line in the sand and expelling all people who live in and use that ecosystem in the name of protecting species is at best misguided, at worst intentionally violent.

By respecting dynamic human-nature systems and planning conservation efforts accordingly, we can ensure that ecosystems are protected from exploitative human actions while preserving the sustainable ones. Species are best protected by the people who live and share an ecosystem with them, because ultimately, it is the livelihoods of these local communities that depend the most on species biodiversity.

• Read the Nature article  Include biodiversity representation indicators in area-based conservation targets 
• Read the  SPI factsheet 
• Learn more about where species occur by visiting the  Map of Life 
• Find out about similar research from the  Yale Center for Biodiversity and Global Change 
•  See other GEO BON Global Biodiversity Change Indicators 
• Check out a  global map of national SPI   on the Half-Earth website
•  Learn more about the  E.O. Wilson Biodiversity Foundation’s Half-Earth Project. Their global strategy depends on metrics such as SPI that can provide spatially explicit, high-resolution information about species worldwide.