Protected Areas and the Conservation of Biodiversity

A Need for Generalities:

Protected areas (national parks, biological reserves, etc) have been the traditional method of implementing species protection.  Building off this historical precedent, the global protected area network has grown rapidly in the past 20 years.  Before creating more protected areas, however, we should first understand whether protected areas do what we want them to.  The main problem with understand how protected areas function is the overwhelming scale of geography at which the global protected area network occurs.  Additionally, every protected area is designated for a different purpose.  Thus, many scientists have been able to independently assess the effectiveness of individual protected areas, but drawing generalities across the global network has proven difficult.  This lack of generality may indicate the difficulty in drawing global conclusions, but it is certainly not indicative of the importance of a general understanding.  Extinctions are a global phenomenon, and a global understanding of protected areas is necessary in order to effectively implement adequate species protection.  

The World Database on Protected Areas shows that ~13% (excluding Antarctica) of the earth's land surface falls under some sort of protected status. However, the distribution of those areas is skewed away from strict nature reserves and limited use national parks (IUCN Ia, Ib, II). For an interesting breakdown of the WDPA dataset, see Chape et al, 2005. These figures have led to speculation that, although the protected area network has grown rapidly, its effectiveness at preventing species extinctions may be limited.  I have implemented two studies to address this lack of generality, which I describe below.

Are protected areas protected?:

 In an attempt to gain a general understanding of how well protected areas are protected, colleagues and I used global datasets to quantify remaining natural vegetation in and around protected areas in four tropical moist forests. We also estimated the fragmentation of the forests and how much area lies within a given distance inside the protected area boundaries. The Amazon and Congo are “wilderness forests”, the two largest remaining tracts of tropical moist forest, while the Atlantic Coast and West Africa Forests are biodiversity “hotspots”. These are regions with high numbers of endemic species (>1000 endemic plants) and high levels of habitat loss (<30% of natural habitats remaining.)

We surveyed tropical moist forests because they contain the large majority of terrestrial species and their conversion to open pastures, crops, and other human-dominated ecosystems is clear in remotely sensed images.

Quantifying deforestation, fragmentation, and the size of remnant habitats is a coarse approach to an issue as complicated as determining whether protected areas protect species. It overlooks many threats and ignores the fact that some protected areas are not established for that purpose. Nonetheless, with tropical moist forests being destroyed at a rate between 1 – 2 million km2 per decade — and even more forest damaged by shifted cultivation, fires, and selective harvesting — assessing the role of protected areas in containing continuous forest cover is a necessary, if not sufficient, component to understanding how the protected area network fits into a broader conservation strategy.

Collaborators:
Scott Loarie
Stuart Pimm

Geographic Representativeness:

Understanding how each country’s protected area network represents conditions within that country is vital if we are to fairly and efficiently assess conservation efforts on a global scale.  It is often conjectured that protected areas are created on otherwise undesirable lands.  This has been shown to be true for the Western United States, but is it a global phenomenon?

There are two main questions.  First, is it a globally generalized trend that countries protect undesirable landscapes?  This is often claimed, with scant supporting evidence.  The absence of an answer leads to uniformed discussions on the global protected area network.  To investigate this, colleagues and I are analyzing elevation, slope, and agricultural suitability.  Are protected areas, on average, at higher elevations and on steeper slopes and agriculturally unsuitable lands?  If so, this would indicate that protected area networks offer less conservation impact than desired.  If not, then the conservation community can feel more secure in the distribution of the global protected area network.  

Second, how equitably is each country’s protected area network distributed across available landscape diversity? If the network is not distributed evenly, what is it skewed towards (ex: unproductive agricultural lands)?  An equitably distributed protected area network is necessary for several reasons.  Most importantly, it is necessary in the face of ecological and climactic uncertainty.  By “putting all the eggs in one basket”, a country faces the risk of losing the protective value of its network during natural disasters, climate change, animal migrations, etc.  By proportioning the network over the entire range of abiotic and biotic holdings, each country ensures that it will be able to withstand ecological stochasticity, as best as possible.  Unlike plants and animals, protected areas cannot shift with changing climates.  Thus, the protected area network must, in a pre-existing way, be well-prepared to offer refuge for shifting species.

Collaborators:
Scott Loarie
Dean Urban