16.14: There are multiple effective strategies for preserving biodiversity.

In a survey asking which animal they would like to be, men and women gave very different answers. Among men, the top answer was eagle, followed by tiger, lion, and dolphin. As their first choice, women chose cat, followed by butterfly, swan, and swallow. It’s just a silly survey, but the differences in male and female selections parallel the fact that people have very different preferences when it comes to preserving biodiversity. One person may view as unthinkable the loss of a particular species or habitat, while another may view other species or habitats as much more valuable.

Most approaches to conservation biology, as we’ve seen, have focused on the preservation of individual species. Increasingly, however, conservation biology is shifting toward the preservation of important habitats, focusing on conserving communities and ecosystems. This habitat-conserving approach also leads to the preservation of individual species, but it has the added benefit of preserving, at the same time, many different species within a habitat, including many that have not yet been identified, particularly microbes and fungi.

One example of an effort aimed at the preservation of important habitat is the World Wildlife Fund’s “Global 200,” an identification of all of the most biologically distinct habitats on earth. The identification of these habitats, which include terrestrial, freshwater, and marine habitats, is part of an innovative strategy, often called landscape conservation, that is geared toward conserving not just species but habitats and ecological processes (e.g., large-scale migrations and predator-prey interactions). In an age of scarce conservation resources and limited time, this approach prioritizes the conservation of biologically unique habitats on earth.

The habitat conservation approach is not new. The very first attempts at conservation in the United States were the creation of Yellowstone Park in 1872 and Yosemite in 1890, both large-scale efforts geared not simply toward the preservation of one or a few species but rather toward the preservation of the “wilderness.” In the time since then, significant efforts have been made to establish national parks, wilderness areas, and recreation areas (FIGURE 16-35).

As conservation biologists have started to better understand population dynamics and biogeography, the design of natural preserves has evolved. Modern preserve design focuses not simply on maximizing the variety of habitats and biodiversity preserved but on using several design features that maximize the efficiency of the preserves (FIGURE 16-36).

• Larger, rather than smaller, preserves (including a preference for a single, undivided preserve over several smaller preserves)
• Circular, rather than linear, preserves to reduce the negative effects at the preserve edges
• Corridors—even just relatively narrow strips of land—that connect larger natural preserves, allow gene flow, and reduce inbreeding among distinct populations in the different preserves
• Buffer zones (which permit limited amounts of human activity) around core areas (which contain the habitat to be conserved)

As conservation plans aimed at preserving habitats increase, efforts focusing on individual species still continue to be effective. Several strategies targeting individual species for conservation have been particularly successful at preserving large amounts of biodiversity beyond that single species.

1. Flagship species. Some species, because they are particularly charismatic, distinctive, vulnerable, or otherwise appealing, can engender significant public support. Examples include the giant panda of China, the golden lion tamarin of Brazil’s coastal forest, the mountain gorilla of Central Africa, the orangutan of Southeast Asia, the leatherback sea turtle, the Indian tiger, and the African elephant. Preservation of these species, given their habitat needs, can serve to preserve many other species as well.

2. Keystone species. As we saw in Chapter 15, keystone species have a disproportionate effect on the biodiversity of a community. Their removal can lead to massive changes in the composition of species in an ecosystem, often causing huge loss of biodiversity. Examples include kelp, California mussels, grizzly bears, beavers, and sea stars.

3. Indicator species. These are species whose presence within an ecosystem indicates the presence or well-being of a large range of other species. For example, the presence or absence of lichens is an indicator of air quality, because they are sensitive to sulfur dioxide, a component of industrial fumes. When lichens disappear from trees, it is usually an indicator of increased pollution, which endangers the entire ecosystem. Conversely, when lichens are present and healthy, they indicate that the ecosystem is healthy.

4. Umbrella species. These include wide-ranging species with such large needs for habitat and other resources that their preservation ends up protecting the numerous other species within that same habitat, without having to identify these other species as conservation targets. Umbrella species tend to be large, wide-ranging vertebrates.

For the most critically endangered species and degraded habitats, all hope is not necessarily lost. Captive breeding programs and habitat restoration have had some success in bringing back biodiversity from the brink of extinction. Zoos and botanical gardens have taken the lead in many of these efforts. In the 1980s, for example, when the population size of the California condor had dropped to 22 individuals, due to poaching, lead poisoning, and habitat loss, all of the birds were caught and taken to zoos, where a captive breeding program began. With the success of these breeding programs, by 2011 the population had reached 400, including close to 200 birds in the wild and the remainder in zoos. Breeding programs are not a complete conservation solution on their own, however. It is essential that the species’ habitats are not destroyed or altered if the species are to flourish again under natural conditions.

Restoration ecology, which uses the principles of ecology to restore degraded habitats to their natural state, has also been an important tool of conservation biologists. Wetlands that have been degraded by dredging and development, in particular, have benefited. Reintroduction of the native plant species and restoration of water and stream flow patterns can be instrumental in restoring these habitats.

Taken together, the strategies used by conservation biologists represent an important step toward reducing the adverse effects of one hugely successful (from a population growth perspective) species—humans—on other species. Although we are far from living with minimal disturbance of the environment in which we live, continued conservation efforts offer our best hope for a sustainable future.