How Much Land Should Be Protected for Biodiversity?

(June 2006) Biodiversity—the diversity of genes, species, and ecosystems—has long been recognized by scientists and many policymakers as an important global public good.1 And national parks, nature reserves, and other protected areas have been at the forefront of global efforts to conserve biodiversity.2

More than 11 percent of the earth’s territorial area is contained within more than 100,000 protected areas. The protection trend has also been accelerating: More parks and reserves have been established worldwide since 1970 than in all previous periods.3 More than 11 percent of the earth’s territorial area is contained within more than 100,000 protected areas (see table for percentage protected by region.)

Percentage of Surface Area Protected, Selected Regions

Australia/New Zealand
Central America
East Asia
Eastern and Southern Africa
North Africa and Middle East
North America
North Eurasia
South America
South Asia
South East Asia
Western and Central Africa

Source: UNEP-World Conservation Monitoring Centre, World Database on Protected Areas (2006).

While conservation biologists continue to argue that we need to expand the global network of protected areas, pressures from development continue to mount. In the context of expanding industrialization and consumption, persistent poverty, and a growing world population, many observers are asking: “How much protected land is enough?”

One approach that has gained much international currency is the use of numerical or percentage targets for protected areas—say, setting aside 10 percent of a biome (an ecologically distinct terrestrial or marine classification, such as a tundra, boreal forest, or coral reef) for protection. But the targeted approach has its drawbacks: On its own, it doesn’t guarantee protection areas that most need it, nor does it ensure effective management of those areas.

The targeted approach needs scientifically informed guidance to match it to the needs of species and ecosystems, which provide humanity with crucial services (such as pollination, water purification, and climate regulation) as well as the broadest possible library of genetic material for pharmaceutical and agricultural development. In addition, protected areas need better management and financing as well as better ways of garnering the support of surrounding populations, whose cooperation with regulations is essential for the achievement of conservation goals in these areas.

Extinction Rates Accelerating Despite Area-Based Targets of Protection

Delegates at the 1992 Fourth World Congress on National Parks and Protected Areas, a decennial international conference that serves as a global forum for setting the agenda for protected areas worldwide, recommended that “protected areas cover at least 10 percent of each biome by the year 2000.”

In the years since, this target has been generalized to apply to the world as a whole as well as to individual countries, and has become a central component of national and international conservation plans.4 For instance, in recognition of the important roles biodiversity and intact ecosystems play in supporting human well-being, the Millennium Development Goals (MDGs) also include an indicator that encourages countries to track the “ratio of area protected to maintain biological diversity to territorial area.”5

And these targets seem to have worked in terms of expanding the size of protected lands: Approximately 11.58 percent of the earth’s territorial area is now contained within more than 100,000 protected areas.6 As shown in the table, developed regions are not significantly more advanced in designating protected areas than their developing country counterparts.7

But despite having surpassed the 10 percent target, the world remains on the brink of a significant extinction event, with recent extinction rates 100 to 1,000 times greater than rates before the advent of humanity.8 The Millennium Ecosystem Assessment, an international synthesis of scientific information on ecosystem change, asserts that changes in biodiversity due to human activities have been more rapid in the past 50 years than at any time in human history, and that the drivers of change that cause biodiversity loss are either steady or increasing in intensity.9

Area-Based Targets for Protection Attract Politics and Problems

Area-based measures of protection such as the MDG indicator can be important in inspiring political action to support biodiversity conservation. The designation of protected areas can also demonstrate a policy commitment to improve human and ecological well-being.

A highly publicized example is the 2003 announcement of Madgascar’s president Marc Ravalomanana that he would lead an initiative to triple that country’s network of protected areas from 3 percent to just below 10 percent of its territory by 2008. This announcement was heralded by international conservation organizations as a critical step in protecting Madagascar ‘s unique and threatened biodiversity.10 It has also helped to focus international attention and resources on the development of an effective protected-areas network there.

But while the designation of protected areas can be a politically important and meaningful step, area-based targets of this kind provide only a hazy outlook on future conservation prospects. As an indicator, “area” is relatively easy to measure—but without further information on the location, size, and management of the protected area, the potential for achieving global biodiversity conservation goals is unknown.

Problem 1: Rocks and Ice Syndrome

The boundary of a protected area is a political construction and rarely matches up with the ecosystem or biotic boundaries that would be most effective for biodiversity conservation. In the United States and around the world, many protected areas were established for their benefits in terms of scenery and recreation rather than biodiversity conservation, giving rise to what is know as the “rocks and ice syndrome.”11

Conferring protection status to majestic peaks or glaciers may provide beautiful views and opportunities for extreme adventure, but these places are often not the hottest centers of biodiversity. Unfortunately, those lowland areas that contain the richest biodiversity are generally also the areas that are most conducive to agriculture and other human activity deemed essential for social and economic development. Struggles over land use further complicate efforts to establish protected areas.

An area-based protection target of 10 percent of each country, region, or biome ignores the fact that biodiversity is unevenly distributed across the globe. Often, the regions that are in most need of protection are not those with a low percentage of their territory protected, but those with the highest level of endemic species that are also under significant threat. A 2004 study reported in the journal Nature analyzed the locations of threatened species’ habitats vis-à-vis existing protected areas; it found that 20 percent of all threatened species analyzed were “gap species,” with no coverage under the current global network of protected areas.12

Problem 2: Size Matters

The smallness of most individual protected areas is a second weakness in area-based protection targets. Throughout his book Requiem for Nature, Duke University ecologist John Terborgh stresses the importance of preserving areas of undisturbed land that are required for the maintenance of genetically viable populations of top predators. Terborgh highlights three species in Central and South America with large territory requirements for viable populations—the jaguar (750,000 hectares), the harpy eagle (1.5 million hectares), and the giant otter (60 million hectares).13

Very few existing protected areas approach these sizes. Of the more that 100,000 protected areas worldwide, around 2,200 are larger than 100,000 hectares; only 252 are larger than 1 million hectares.14 So while the total area of numerous protected increases, individual reserves are sometimes not large enough to meet the needs of top predators or are not strategically linked to other reserves. The decline of top predators could reverberate through food webs and further threaten ecosystem balance.

Problem 3: Paper Parks

Another problem that plagues protected areas around the world is the “paper parks” phenomenon. In developing countries, limited financial resources are available for national parks departments to manage protected areas. In some cases, protected areas are designated by law, but managers are not hired, boundaries are not demarcated, and management plans do not exist—the park exists only on the paper that designated its legal status.15

Most of the evidence for this phenomenon is anecdotal, and there is some research that indicates the paper park problem is not as serious as some would suggest. Nonetheless, the need for improved financing and management for protected areas is clear.16

Problem 4: Fences and Fines

At the other end of the spectrum from the “paper parks” problem is the dilemma of overly rigid protection regimes. In striving to meet an area-based target, policymakers sometimes establish protected areas that are in direct conflict with the livelihoods of local people. Depending on the management designation of the protected area, communities living near or within a protected area may be denied access to the resources (such as land for agriculture, fuelwood, timber, or game) that often form the basis of their livelihoods.17 Without compensation for lost access to resources and with few viable alternatives, it is not uncommon for local people to violate protected-area regulations.

This dilemma requires thoughtful cost-benefit analysis in selecting management designations for protected areas. It also necessitates the development of innovative financing mechanisms that aim to more equitably distribute the costs associated with the creation of these areas.

Increasingly, conservation organizations and governments are making efforts to incorporate local communities’ economic needs and interests into the design and management of protected areas. And international agreements (such as the Convention on Biological Diversity and the World Parks Congress) explicitly state the importance of involving local communities in planning and ensuring the equal sharing of benefits arising from protected areas.

Refining Measures of Success

The area or number of territories with protection status may be useful as rough measures of political commitment to conservation, but the weaknesses outlined above highlight the need for more refined targets and indicators to chart action and measure progress toward the long-term viability of biodiversity.

An example of innovative planning for effective biodiversity conservation is the Mesoamerican Biological Corridor (MBC), an official initiative signed by leaders of the seven nations in Central America in 1997. The region has approximately 600 protected areas, covering 25 percent of Central America ‘s landmass. However, many of these protected areas suffer from the problems outlined above, and the region’s extensive biodiversity and natural resources continue to face significant threats from population pressure, social inequality, and economic underdevelopment.18

The MBC’s region-wide planning approach works to create and maintain connectivity between existing protected areas that will effectively expand the habitat for the region’s most highly threatened species. Through a painstaking process of scientific analysis and community consultation, the MBC seeks to create “corridors” and multiple-use zones to complement the protected areas network that will, in theory, better meet the needs of species and local communities.

In the end, the absolute size of the global protected areas network may be less important for biodiversity than the location, design, and management of those areas. Creating and managing protected-area networks that will be able to effectively “fill the gaps” will be a challenge in the coming decades, requiring the mobilization of resources, political will, and scientific analysis.

If we are lucky, area-based targets for protection will continue to motivate key decisionmakers to set aside additional territory and resources for protection. But it will be up to the rest of us to demarcate boundaries that optimize well-being for neglected species, ecosystems, and humanity.

Kathleen Mogelgaard is a University of Michigan Population-Environment Fellow at the Population Reference Bureau.


  1. The international consensus on this point is reflected in Article 8 of the 1992 Convention on Biological Diversity, which calls on state parties to “establish a system of protected areas or areas where special measures need to be taken to conserve biological diversity.” See Convention on Biological Diversity, Article 2 (1992), accessed online at, on May 17, 2006.
  2. Richard Primack, Essentials of Conservation Biology (Sunderland, MA: Sinauer Associates, 1993); Gary K. Meffe et al., Principles of Conservation Biology, 2nd edition (Sunderland, MA: Sinauer Associates, 1993); and Andrew Balmford et al., “Economic Reasons for Conserving Wild Nature,” Science 297, no. 5583 (2002): 950.
  3. UNEP-World Conservation Monitoring Centre, World Database on Protected Areas, accessed online at, on May 17, 2006; and Katrina Brandon and Michael Wells, “Planning for People and Parks: Design Dilemmas,” World Development 20, no. 4 (1992): 557-70.
  4. Thomas Brooks et al., “Coverage Provided by the Global Protected Area System: Is it Enough?” BioScience 54, no. 12 (2004): 1081-91; and Ana S.L. Rodrigues et al., “Effectiveness of the Global Protected Areas Network in Representing Species Diversity,” Nature 428, no. 6983 (2004): 650-52.
  5. United Nations Statistics Division, Millennium Development Goal Indicators Database (2000), accessed online at, on May 17, 2006.
  6. UNEP-World Conservation Monitoring Centre, World Database on Protected Areas.
  7. It is worth noting that, while many of the MDG targets focus exclusively on developing regions, the indicators for Target 9 (“Integrate the principles of sustainable development into country policies and programmes and reverse the loss of environmental resources”) require action on the part of developed and developing countries alike.
  8. Stuart L. Pimm et al., “The Future of Biodiversity,” Science 269, no. 5222 (1995): 347-50.
  9. Millennium Ecosystem Assessment, Ecosystems and Human Well-Being: Biodiversity Synthesis (Washington, DC: World Resources Institute, 2005).
  10. Conservation International, “Madagascar to Triple Areas Under Protection,” press release (2003), accessed online at, on May 17, 2006.
  11. John Terborgh, Requiem for Nature (Washington, DC: Island Press, 1999).
  12. Rodrigues et al., “Effectiveness of the Global Protected Areas Network in Representing Species Diversity.”
  13. Terborgh, Requiem for Nature.
  14. World Resources Institute, Earthtrends Data Tables: Protected Areas (2006), accessed online at, on May 17, 2006.
  15. Danielle S. Furlich, “From Peril to Progress,” Nature Conservancy Magazine (September/October 2000).
  16. Aaron G. Bruner, “Effectiveness of Parks in Protecting Biodiversity,” Science 291, no. 5532 (2001): 125-28.
  17. Protected areas include several categories that govern the degree of human activity within them, ranging from “strict nature reserves” to “managed resource protected areas,” which permit varying degrees of “sustainable use” of protected-area resources.
  18. Kenton Miller et al., Defining Common Ground for the Mesoamerican Biological Corridor (Washington, DC: World Resources Institute, 2001).