Cover image: as trees spread across the valley, the rugged landscape of Ennerdale in the English Lake District is slowly regaining a softer, more naturalistic character. © Tony Simpkins
Welcome to the twelfth, and final, instalment of 100 Key Concepts. Last time we saw that humans have caused many problems in the natural world. Here we’ll be looking at the kinds of conservation measures we can take to redress the balances we’ve upset, and undo the damage of decades or centuries of exploitation.
93 PROTECTED AREAS
Some of the world’s most beautiful landscapes occur in protected areas, zones of habitat (on land or underwater) which are legally protected from human exploitation. Often, this means they’re safe from being developed, used for agriculture, or their organisms harvested for human use. Protected areas are bastions of wilderness in an increasingly exploited landscape, and as the human world expands, they become ever more important. Some, like Yellowstone National Park in the USA or the Serengeti of Tanzania, are protected for their rich natural history. Others, like Australia’s Uluru, are protected because of their immense cultural and historical value. Protected areas can be oases for rare or threatened species, helping them to avoid extinction when pressures rise elsewhere. In northeast Borneo, the Danum Valley Conservation Area protects one of the largest areas of intact lowland rainforest on the island. While the surrounding forests have been converted into a patchwork of palm oil plantations and logging concessions, the Danum Valley has remained almost untouched by humans for thousands of years, and is protected for its conservation and research value. Species rare elsewhere, such as orangutans, clouded leopards, and the Critically Endangered Bornean rhinoceros, all have strongholds within the valley, offering hope for these species’ recoveries in the future.
94 HABITAT MANAGEMENT
While protected areas can help stop good-quality habitat from deteriorating, much of the planet’s natural systems have already been impacted by humans. Sometimes, this impact has been serious, threatening the species the live there, and these habitats are ripe for restoration and management. Habitat management is often carried out to improve the conditions for a target species, which can help rare species to recover and resits other threats to their survival. In northwest England, areas of grassland overlying alkaline limestone are an increasingly rare habitat. For hundreds of years, these grasslands were kept open by the grazing of sheep and cattle, but as livestock farming has dwindled away in this part of the world, many grasslands have gone unmanaged. Trees have encroached upon the open areas, thick canopies making conditions too shady for most grassland plants to bear, and the species which rely on them have suffered as a result. One such species is the high brown fritillary, the UK’s rarest butterfly, which has undergone a 96% decline in the past 45 years. The fritillary needs stands of bracken to survive, where it lays its eggs on violet plants. The dead leaves of last year’s bracken, almost black, trap a lot of heat from the early spring sunshine, raising the temperature around the violets by up to ten degrees Celsius. Without this specific microenvironment, conditions are too cold for the fritillary’s caterpillars to develop. In the butterfly’s last strongholds in the area, a combination of cattle grazing and manual cutting-back of the bracken keeps the habitat balanced, retaining the mix of open areas and light shade the fritillary needs to make a recovery.
95 PREDATOR CONTROL
Historically, humans have gotten along poorly with other large predators. They eat our livestock, and occasionally our friends and family, and as a result they have been extirpated from many parts of the world. Unfortunately, this causes another problem, as the species that were controlled by their presence are suddenly allowed to run rampant. In these situations, predator control – though removal or culling – might be needed to help rare prey species. Across much of the UK’s uplands, predators like foxes and crows are becoming a serious problem for some of our rarer breeding birds, like curlews, dotterels, and black grouse. Across much of northern Europe, these small predators are kept to low numbers by the presence of larger predators – lynx, wolves, bears, and eagles. But these species have been absent from the UK for centuries, so it falls on humans to do their job, at significant cost.
96 CAPTIVE BREEDING
Sometimes, actions taken to protect a species in its natural environment – in situ conservation – just aren’t enough. In these cases, ex situ conservation is needed to ensure a species’ survival, by removing individuals from the dangerous environment. Captive breeding is one of the most common methods of ex situ conservation, where organisms are bred in captivity to preserve their population while the wild one is threatened. It acts as a safety net, so if the wild populations are lost, the species still persists. The Guam kingfisher, native to the island of Guam in the west Pacific, was extirpated from its native range in the 1980s following the introduction of the bird-eating brown tree snake from Australia. Fortunately, some birds were rescued from the wild before the species went extinct, and around 200 birds currently live in zoos in Guam, and at the Smithsonian’s National Zoo in America. As scientists discover more about how the kingfishers live, they’re having more success with getting them to breed. There’s potential that the kingfishers could be introduced to snake-free islands near Guam, like Rota and Tinian, until suitable habitat is restored on the birds’ original home island.
97 GENE BANKING
Captive breeding isn’t always possible. Sometimes, it’s difficult to keep organisms in captivity. Maybe they don’t reproduce well when they’re cooped up. Perhaps, like trees, there are incredibly long gaps between one generation and the next. In these gases, it might be better to invest in gene banking. This involves preserving genetic material from rare or important species for long periods of time, often cryogenically, by keeping it frozen at very low temperatures. This can help species to survive while conditions in their natural range are improved, without expending a lot of resources caring for active organisms. On the Arctic island of Svalbard, buried beneath a sandstone mountain and a permanent layer of ice, is a labyrinth of tunnels holding the Svalbard Global Seed Vault. The vault contains hundreds of millions of seeds from a vast range of plant species, primarily crops which are important to human culture and survival. The vault’s naturally cold surroundings reduce the cost of keeping the seeds frozen, extending their shelf life to decades or centuries, and its location beneath a mountain protects it from any natural or manmade disasters that might threaten its contents. The genes preserved in the vault could be used to bolster the genetic diversity of crops in the future, giving them the capacity to survive threats like diseases.
When a species has vanished from its natural range, but survives in captivity, it is classed as Extinct in the Wild. Once the threats that pushed it to extinction in the first place have been dealt with, reintroduction is a logical next step: captive-bred individuals are reintroduced to their native range. This ensures that populations persist in the areas where they’re meant to be, maintaining these areas’ natural heritage. In 1972, the Arabian oryx, theorised to be one origin of the unicorn myth, went extinct across its natural range in the deserts of the Middle East due to hunting. The first reintroduction occurred in Oman in 1980, and the population successfully re-established itself. As of today, some 850 individuals are found in the wild across the Arabian Peninsula, split between two populations in Saudi Arabia, one each in Israel and the United Arab Emirates, and the original population in Oman. Thanks to the success of its reintroduction, the Arabian oryx has been downlisted from Extinct in the Wild to Vulnerable, significantly reducing its chances of extinction.
Reintroduction is just one step, returning a single species back to the wild. On a larger scale, dealing with multiple species and habitats, this is often referred to as rewilding, the process of returning an environment to a more ‘natural’ state, such as replanting farmland with trees to create new woodland. This can help expand and connect areas of threatened habitat, and reduce the need for human management by reintroducing species that do the job for free – like wolves controlling fox populations, taking pressure off breeding birds. Much of Ennerdale, a valley in the English Lake District, has been rewilded through a ‘hands-off’ approach from the landowners. By allowing the environment to take its own course, shaped by natural processes, unexpected outcomes have emerged. Arctic char, a salmon-like fish trapped in the area after the last ice age ended, have experienced a population increase as water quality in the River Liza has improved. Woodlands are spreading across the valley, covering the rugged landscape in a soft blanket of trees, and raising the possibility of species reintroductions. Pine martens, a rare tree-living predator related to weasels, may find the new forests inhabitable. The forests might also be a good reintroduction site for Eurasian lynx, western Europe’s largest cat species, extinct in Britain for 800 years.
100 THE VALUE OF NATURE
Just by existing, nature does a lot for us, and it does it for free. These services would rack up a bill of tens of trillions of dollars per year just from supporting humanity, never mind the huge range of other life and ecosystems on the planet. Nutrient cycling, feeding carbon, nitrogen, phosphorus, and magnesium back into the system, ensures that ecosystems stay rich and don’t wither away. Pollination, provided by insects, birds, and bats, helps plants to reproduce, and animals also spread their seeds to new locations. Many species provide us with food, raw materials, and medicine. Wasps control pest insects in our crop fields; peat bogs suck up water, reducing flooding and locking away greenhouse gases; reedbeds purify water. Nature provides us with recreational experiences, psychological therapy, forms the bedrock of cultural traditions, and helps us to learn about ourselves. Nature links us to the past, present, and future. Nature makes us human. When we preserve nature, we preserve ourselves.
So that’s the end of 100 Key Concepts. I hope you’ve enjoyed finding out more about ecology and conservation; let me know what you’d like to hear more about next!