How Much Is Enough?

Have you ever really thought about how big an elephant is? Or a black rhino? Or how about all the room a cheetah needs to roam? It’s a pretty considerable amount of space. So the question becomes, how much space does an elephant, or a black rhino, or a cheetah need to survive and thrive? How much space would an entire population need? Well, a new study published through the Public Library of Science tries to answer the ever important question of how big and how connected protected areas need to be to maximize the effects of conservation efforts for a wide variety of African megafauna living in the Maputaland-Pondoland-Albany biodiversity hotspot, ranging in size from elephants and rhinos to wild dogs and cheetahs.

Researchers considered six different possible scenarios, each with a different level of compartmentalization and interconnectedness within and between already protected areas. The first of these options represented the current status quo, with the maximum number of small, separate areas. The second removed all internal fences between adjacent protected areas, creating a series of larger protected areas. Each of the other four then altered how corridors were set up between the protected lands, which in turn would affect how well populations could deal with localized population decline.

The group used a combination of two statistical methods, population viability analysis (a fairly standard conservation method for establishing how likely it is that a given population will survive or go locally extinct) and decision-analysis (which allowed them to examine the effects of individual conservation efforts and external threats, while also looking at species-specific benefits or detriments). What they found was that the models with the largest area and greatest level of connectivity between them would ensure the greatest probability of survival (although the plan with the most protected corridors, which would also cost the most, was not different in effect from the cheaper version with less protected avenues between parks).

They found this by examining how each of the six species they were considering (all of which are listed as endangered or threatened by international, national, and local policies) would be affected by individual components of their environment, such as disease or human encroachment, and comparing that to their average population growth. They then took into consideration how mobile each smaller group of individuals could be, and how these subpopulations could interact, with members of each flowing between them within and between protected areas.

Regular interactions between these groups of interconnected subpopulations, called metapopulations, are necessary for endangered and threatened species to deal with local population loss. Imagine that a disease swept through and killed all but three leopards within one of these subpopulations. If the protected area is too small or too segmented by fences, then this group will most likely disappear over time, as no new individuals can join their ranks, and the population is too small to restore its own numbers. However, if the area is connected to a broader network of subpopulations within the park, or even between parks, then this group could recover by absorbing individuals from other populations or even being absorbed themselves.

This process of consolidating and connecting lands is not a simple and easy option though. It would require collaboration between local communities, government agencies, and private landowners, all working together towards condensing land ownership and management. People tend to get testy about these types of plans, when they suddenly don’t technically control land they own. That being said, as the authors point out, by pooling lands, the varying landholders would also greatly reduce costs of managing the lands. At the same time, there are a number of conservation groups offering financial benefits for consolidating land ownership like this, which could lead to increased ecotourism and a subsequent boost to the local economy. The South African government also offers tax cuts and other incentives for engaging in cooperative conservation efforts. All in all, losing direct control would most certainly offer a wide range of fiscal benefits that its fairly tough to argue with.

So the answer to the ever-looming question of how much land do we need is that we need quite a bit. But luckily, we just so happen to have quite a bit of land, and a whole host of reasons to use it to help protect some of our most endangered and most beloved wildlife. Because, as we are all well aware, elephants are most definitely worth it.

Original article: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0071788

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