Pan-tropical study reveals huge variation in effectiveness of protected areas

Protected areas such as national parks and World Heritage sites are probably our best bet for conserving nature in the long term.  They're not the only game in town but they're certainly the cornerstone of global conservation efforts.

Are protected areas protecting nature?

Given this, we really need to know how well protected areas are functioning. 

Are they doing what they're supposed to be doing -- acting as 'Arks' for biodiversity and natural ecological processes -- as well as harboring indigenous peoples, supporting ecotourism, and providing environmental benefits such as clean water, carbon storage, and flood mitigation? 

This is a very big and important question.  A particularly impressive study has recently been published by Ben Spracklen and colleagues.  Their goal: to compare the effectiveness of moist-forest reserves across the tropics and subtropics in halting deforestation.

Stopping deforestation, of course, is one of the main things we want our protected areas to do.  And in many places it's a tall order because tropical regions are often under assault from a range of threatening processes. 

In the last few decades one of the most striking patterns across the tropics has been large-scale deforestation, with many tropical reserves rapidly being isolated from their surrounding forests -- effectively becoming habitat fragments. 

And that's a scary proposition because we all know that fragmentation causes a great many problems for tropical biodiversity and ecosystems.

Key findings

In this context the Spracken et al. study is particularly important.  The authors assessed deforestation both inside and immediately outside nearly 3,400 protected areas within 56 nations, contrasting the situations in 2000 and 2012.  Some of their key conclusions:

1.  Most protected areas are under pressure.  Overall, 73 percent have extensive deforestation occurring just outside of the reserve.

2.  There is great variation in protected-area effectiveness, both among different continents and different nations.

3.  Protected areas are generally doing better in more-affluent nations (with higher per-capita GDP) than they are in poorer countries.

4.  Reserves also tend to suffer in nations that have dense rural populations, although this trend was weaker than the 'wealth' effect.

5.  At a continental scale, protected areas are faring the worst in Asia, with intermediate success in the New World and African tropics.  Reserves in Australasia (Australia and New Guinea) are faring the best overall.

6.  At regional scales, Southeast Asia, West Africa, and Central America have the poorest protected-area performance.

7.  Despite strong differences among continents and regions, there's still a lot of variation at the national level.  For example, within Asia, protected areas are faring better in Thailand and Laos than they are elsewhere in the region.  And in Central America, reserves in Costa Rica and Belize are doing better than those in other countries. 

For protected areas, green is good, whereas orange and red are bad (from Spracklen et al. 2015, PLoS One).

8.  Not surprisingly, countries with large and relatively remote frontiers, such as those in the Amazon and Congo Basin, tend to have relatively low forest loss within their protected areas.

9.  Happily, there was little evidence that protected areas are simply displacing deforestation -- pushing it elsewhere outside of their boundaries.  That's good news, because it suggests that protected areas help to reduce deforestation rates.

10.  Protected areas with steeper slopes or higher elevations than their surroundings experience less degradation than do those that have less-challenging topography.

11.  Finally, reserves that have a lot of deforestation happening around them also tend to have more deforestation inside them. 

Somewhat surprisingly, the authors did not discuss this latter point in their paper, but when asked about it they verified that this indeed was the case.  This is consistent with a central finding from the 2012 study of tropical forest reserves in Nature led by ALERT director Bill Laurance.  The key point: we can't ignore what's happening outside protected areas because those same effects tend to 'leak inside', with serious impacts on biodiversity.

Take-home messages

All in all, the Spracklen et al. paper is one of the most important studies ever published on protected areas.  Sweeping in scope, it's arguably a scientific tour de force with profound implications.

It's telling us that, in general, our protected areas are working -- to a degree.  They're slowing or halting deforestation, and they're not simply displacing it someplace else.

But there's still huge room for improvement. 

Protected areas in many nations -- especially in Southeast Asia, West Africa, and Central America -- just aren't doing enough. 

We need to battle to safeguard the protected areas in these places, because they sustain some of the biologically richest -- and most imperiled -- real estate on the planet.