Why national parks and nature reserves don’t always safeguard ecosystems as expected

Setting aside land for nature is one of the main global strategies to conserve biodiversity. From national parks to local reserves, these areas are designed to give wildlife the space it needs to thrive. But my latest research with colleagues shows that these protected areas don’t always work in the way we expect.

They can help increase the number of species and provide habitats for large predators. But they don’t necessarily preserve the complex web of interactions that keeps ecosystems functioning. Our study found that the effectiveness of protected areas varies widely across Europe. This has mixed effects on the ecological relationships that sustain life.

Protected areas are central to international conservation policy. In 2022, governments at the UN biodiversity conference (Cop15) agreed to the Kunming-Montreal Global Biodiversity Framework. The framework aims to protect 30% of the world’s land and sea by 2030. The ambition is to halt biodiversity loss and safeguard the services that healthy ecosystems provide.

But while the number of protected areas continues to grow, there is still debate about how well they work. Most studies measure biodiversity success by counting species or tracking population trends. These are important, but they miss a crucial part of how ecosystems operate: the network of ecological interactions. Interactions between species such as predator-prey relationships connect species together in ecosystems and are crucial for their persistence.

Read more: World's protected natural areas too small and isolated to benefit wildlife – new study

We wanted to find out how effective protected areas are at maintaining these networks. Understanding this is central to ensuring that conservation measures protect not only individual species, but the relationships between them that support ecosystem stability and resilience.

We analysed 376,556 records of bird sightings gathered by citizen scientists from online databases. These records covered 509 bird species distributed across 45 protected networks stretching from the Mediterranean to Scandinavia.

By combining these observations with information on which species eats what, we built food webs, which are diagrams that map predator-prey interactions, for both protected and non-protected environments. We then compared the structure of these food webs to assess how well protection helped maintain their integrity.

We found that protected areas can have positive effects on the structure of food webs, but not always. In general, protected sites supported more bird species, particularly those in the middle of the food chain, and we also found larger predators within those areas. For example, less pristine or smaller habitats may only have a sparrowhawk. Whereas more diverse habitats may have a golden or a Bonelli’s eagle. That’s often a sign of a healthier ecosystem.

But for other important features, such as how many interactions each species has or how long the food chains are, the results were far less consistent. Some protected areas showed positive effects, while others showed neutral or even negative ones.

When protection doesn’t mean balance

This means that what works for conserving species does not necessarily work for conserving the ecological interactions between them. Preserving these relationships is crucial because they underpin ecosystem stability.

If predators decline or disappear altogether, their prey can grow, unchecked. This may disrupt the balance of an entire ecosystem. One striking example comes from the Aleutian Islands off Alaska, where the loss of sea otters led to an explosion in sea urchins and the near collapse of kelp forests.

The same principles apply across terrestrial ecosystems. The loss of pollinators, for instance, can have dramatic consequences for both wild plants and crops, threatening food security as well as biodiversity. These examples show why it’s not enough to conserve species in isolation. The connections between species also need protection.

Our study found that how well a protected area works depends a lot on where it is located and how it is managed. We found that factors such as remoteness, habitat diversity, human pressure and the amount of surrounding agricultural land were all linked to how well food webs were preserved.

Protected areas established under the EU Birds Directive, which specifically focuses on maintaining bird populations and habitats, showed the strongest positive effects. This suggests that having a clear conservation goal and strong management practices makes a real difference.

Protected areas that are more diverse in habitat types also tend to support richer ecological networks. This demonstrates the importance of maintaining habitat integrity. In comparison, areas with a lot of human activity or patchy habitats often find it harder to maintain the balance of species and interactions that make ecosystems thrive.

Rethinking how we measure conservation

Our study highlights the complexity of conservation action. Simply protecting land is not enough. To be truly effective, conservation must consider not only how many species live within an area, but also how those species interact.

These interactions are essentially the ecological glue of the natural world. They are what allow ecosystems to persist and perform vital functions such as pollination, pest control and nutrient cycling. Ignoring them risks overlooking early warning signs of ecosystem collapse.

Read more: Protecting Brazil and Indonesia's tropical forests requires political will, law enforcement and public pressure

To secure a sustainable future, conservation policies must go beyond species counts and focus on safeguarding the intricate networks that keep life in balance.

If we focus on how nature functions, not just which species live there, we can make sure protected areas really keep our ecosystems healthy.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Miguel Lurgi, Swansea University

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Miguel Lurgi does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.