Conservation and regeneration practice questions.

A conservation agency can protect the same total area of savannah in four different layouts. Which layout is generally expected to conserve the most species?

• Four separate small reserves, each with a long narrow shape
• Four separate small reserves with no links between them
• One large compact reserve linked by a wildlife corridor
• One large reserve with a long, deeply indented boundary

Answer: One large compact reserve linked by a wildlife corridor

Reserve design favours large, compact, connected areas: a compact shape minimises the edge-to-interior ratio and corridors restore the gene flow that isolation removes. Splitting the same area into small fragments recreates the very problem that protection is meant to solve.

Which action falls under CITES rather than under the Convention on Biological Diversity?

• Sharing the benefits of genetic resources with the source country
• Exporting the shell of a listed sea turtle for sale abroad
• Drawing up a national biodiversity strategy and action plan
• Designating a coastal lagoon as a wetland of international importance

Answer: Exporting the shell of a listed sea turtle for sale abroad

CITES (1973) regulates cross-border trade in listed species, while the Convention on Biological Diversity (Rio, 1992) is an umbrella treaty on conserving and sustainably using biodiversity within states. The lagoon designation belongs to Ramsar (1971).

The last 30 individuals of a forest bird are taken into a breeding centre because their habitat is being logged. This programme is best classified as

• ex-situ conservation, because the birds are kept outside the wild
• in-situ conservation, because the species stays in its own country
• habitat restoration, because the logged forest will be replanted later
• rewilding, because captive birds may eventually be released

Answer: ex-situ conservation, because the birds are kept outside the wild

The in-situ / ex-situ distinction rests on whether the organisms remain in their natural habitat, not on national borders or on future intentions. Ex-situ work buys time for a species but does not conserve the ecosystem processes it depends on.

Grey wolves were returned to Yellowstone National Park in 1995, and ecologists have since linked the change to greater regeneration of willow and aspen along streams. The proposed mechanism is that

• wolves fertilised the streamside soil with the remains of kills
• wolves fed on willow and aspen shoots less than elk did
• wolves increased the elk population, which then spread more tree seeds
• wolves reduced and moved elk herds, easing browsing pressure

Answer: wolves reduced and moved elk herds, easing browsing pressure

Returning a top predator can trigger a trophic cascade: the change works down the food chain through the density and behaviour of the herbivore, not through direct action on the plants. Note that ecologists still debate how much of the recovery the wolves alone explain.

Two reserves holding the same woodland species are separated by ten kilometres of arable farmland. Conservationists plant a continuous strip of woodland joining them. The main expected benefit is that

• the total protected area is increased by the strip that was planted
• individuals can move between the reserves, restoring gene flow
• the edge-to-area ratio of each reserve is reduced
• the strip provides a permanent supply of timber

Answer: individuals can move between the reserves, restoring gene flow

A corridor treats isolation rather than area: it lets individuals disperse, which keeps the two populations genetically one and allows a patch to be recolonised after a local loss. The corridor also adds edge, so it is not primarily an area gain.

A conservation charity builds its fundraising around one large, appealing mammal, although several inconspicuous species in the same forest are more threatened. That mammal is being used as

• an indicator species
• a keystone species
• a flagship species
• a pioneer species

Answer: a flagship species

A flagship species is chosen for its effect on people rather than its ecological role: it raises money and political support that then protects the habitat and everything in it. It need not be a keystone species, and it is a fair criticism that the approach directs funding by charisma.