Can conservation advance several goals at once, or do we have to choose?

Background

There's a lot of work to do in conservation! Species extinctions are accelerating despite the fact that more area is protected each year. We’re also trying to slow climate change and help people through conservation. So conservationists need to find ways to focus limited resources on the places that matter the most.

How do we know what places are the most important? First, we must be clear about what we are trying to achieve. Is our goal to keep as much ecosystem area intact as possible (and every acre is equal, regardless of what species are there)? To prevent the most species from going extinct, perhaps by working in places with many species and high threat (favoring rainforests over deserts and tundra)? To protect places that people get the most benefit from?

Conservation organizations are increasingly trying to have it all – working towards multiple goals like these at the same time There is relatively little science looking at whether different goals like this are aligned (meaning that pursuing one goal will tend to effectively advance other goals), or conflict (meaning that we can’t have our cake and eat it too – pursuing one goal won’t do much for others).

To start grappling with these ideas, I worked with researchers from the University of Tennessee Knoxville to conduct an analysis in the 48 contiguous United States (where data is plentiful) and looked at a single conservation action: where to protect currently unprotected ecosystems. The results of our work were recently published in the scientific journal Conservation Letters.

Research design

In the study, we used Google Earth Engine to examine every square kilometer of land to identify the unprotected habitat in each one, and five potential benefits of land protection there: 1) area of potential habitat protected, 2) number of species present, 3) number of threatened species present, 4) carbon storage, and 5) recreational use. 

We then looked across the nation for the “best deals” (or high return on investment, also known as ROI) for conservation: where benefits are high, cost of land is low, and the threat of habitat conversion is high (indicating a clear need for conservation to avoid loss of habitat and species).

These data were used to answer two questions. First, what places offer the best deals for each of the five benefits we considered, and thus could be priorities for conservation? Second, how well do the benefits correlate with each other? In other words, will pursuing one benefit typically provide other benefits, or are there trade-offs?

What we found

For the first question on the best places to prioritize conservation work, some results were fairly obvious: recreation benefits were highest near cities; even major tourist destinations like Yellowstone National Park get fewer visitors than some less famous (but more convenient) parks like Fair Park in Dallas. Each benefit had some variation in where the best places were located, but across all five benefits the top ROI scores were generally from the Dakotas down into Texas and Arkansas (see Figures 1 and 2 in the paper). Area and species richness had the most shared best sites, carbon shared a modest amount of best sites with other benefits, and recreation and other benefits had the fewest shared best sites.

On the second question (how each benefit correlates with the others), we found very high correlation in ROI between the four environmental benefits (an r of 0.89-0.99), but more modest correlation in ROI between recreation and all four environmental benefits (r of 0.5-0.52). That means places that score well for one environmental benefit typically score well for the others (and likewise for places that score badly), but it is less common for places to score well on both environmental benefits and recreation.

However, our results change when we adjust our analysis. For example, we focused on existing ecosystems, which means we excluded opportunities for reforestation or other kinds of restoration. Focusing on ecosystems threatened by conversion also really narrowed the places that scored best. When we broadened our analysis to consider all unprotected habitat (regardless of whether or not it is predicted to be converted by 2100), the benefits showed much lower correlation. For example, area and recreational use were positively correlated (r of 0.5) when including threat, but negatively correlated (r of -0.65) when threat is omitted (indicating there is typically a trade-off between the two). The highest correlation when threat was excluded was for area and number of species (r of 0.58, vs. 0.99 including threat). This highlights the importance of starting with a clear strategic vision for a conservation focus: even an analysis like ours looking at trade-offs has some assumptions baked in that can make a big difference!

How to use our results

So how can our results be used? We have three main recommendations. First, organizations can evaluate an existing conservation program focused on a particular region (or across the U.S.), which includes looking at which goals have the best opportunities in that region, and whether they tend to align or conflict. That understanding can clarify what outcomes they’re likely to get in a region if they keep working as they have (we have calculated correlations between each pair of benefits for each terrestrial ecoregion in the U.S.).

Second, organizations could pick new places to work as their programs expand or change, to make sure they’re focused on places with the strongest opportunities to advance the goals they see as top priorities.

Third, our framework can evaluate how national conservation proposals would perform across the five benefits. For example, imagine that an organization focused on recreation wants to suggest where and how the U.S. government should focus their efforts to protect 30% of the U.S. by 2030 (30x30). Since 30x30 is an area target, they might want to recommend an approach where area and recreation are well correlated. Our results show that a focus on expanding existing protected areas would do this better than either protecting other federal lands or protecting places near Indigenous lands.

Hopefully our results and approach will help organizations be more effective at pursuing the goals that matter most to them.

#conservation, #science, #goalsetting, #priorities