Listen and read 4: Ecology - Thấm Tâm Vy

Nội dung text: Listen and read 4: Ecology - Thấm Tâm Vy

1. LISTEN AND READ 04 In July 2016 he and his colleagues identified 20 marulas in every zone and used a hammer and a soil corer to remove from each of them a circular section of bark 5cm in ECOLOGY diameter. Having inflicted this damage, they monitored the wounds over the course of A tale of elephants, ants, trees and fire shows how complex nature is the following two years, to see what would happen. Ecological links are not always predictable To their surprise, they discovered that the wounds of trees in fire zones recovered far better than those of trees that had seen no fires at all. Wounded trees in the annual burn ECOLOGY IS A complicated thing. Given the facts that elephant damage often kills zone regrew 98% of their lost bark during the two years of the study. Those living in the trees and bush fires often kill trees it would be reasonable to deduce that a combination biennial burn zone regrew 92% of it. But those in the zone where fires were suppressed of the two would make things worse. Counter-intuitively, though, as research just regrew only 72%. published in Biotropica, by Benjamin Wigley of Nelson Mandela University in South The researchers also found something else when they were measuring the trees’ Africa shows, if a tree has already been damaged, fire can actually help to make things wounds: ants. Ten of the 20 trees in the fire-suppression zone developed ant colonies in better. their wounds. The ants in question were a species that is known to damage trees and is One common way in which elephants harm trees is by stripping them of their bark. Dr presumed to impair tissue healing. By contrast, only five trees in the biennial burn zone Wigley, who did indeed start from the obvious assumption, set off to find out how much and three in the annual zone developed ants’ nests in their wounds. worse bush fires would make the effects of this barkstripping. To this end he set up a It looks, therefore, as if bush fires are cauterising trees’ wounds by killing ants that study in the Kruger National Park, a reserve on South Africa’s border with might otherwise infest them. Though such fires are surely harmful to healthy trees, it Mozambique. seems, in an example of two negatives making a positive, as if they are actually helpful [The Economist, August 10, 2019] Since 1954, the Kruger has been the site of experiments in which plots of land have to sick ones.  been burned at intervals, to discern the effects of fire on savannah ecology. Dr Wigley tapped into these experiments by looking at trees in three different zones. In one of Notes. these the vegetation was burned every year. In the second it was burned every other - tap into: = mention; discuss: bàn đến year. The third zone, by contrast, was actively shielded from fire. - cauterise: làm cho chai cứng To keep things consistent, he looked at the fate of a single tree species, the marula (pictured), in all three zones. He picked marulas because they are particular victims of elephant activity. Their fruit are delicious, and prized by elephants and people alike. But elephants also seem to enjoy eating their bark. TQT LISTEN AND READ 04
2. ELEPHANT IN THE ROOM That’s why Zambia wants its elephants moved to the slightly less restrictive Appendix The ban on trading ivory is unfair but necessary II, which would allow some trade in, for example, hunting trophies. Four other southern Easing it would bring an increase in poaching African countries (Botswana, Namibia, South Africa and Zimbabwe), whose elephants were moved to Appendix II 20 years ago, want to be allowed to trade in their products, NEARLY 6,000 species of animals and about 30,000 species of plants are listed in the which, despite the change in status, they have mostly been prohibited from doing. various appendices of the Convention on International Trade in Endangered Species To understand why these reasonable-sounding proposals should be rejected, consider (CITES) to protect them against over-exploitation. But as CITES convenes its three- what has happened to elephant numbers since CITES most recently authorised some yearly decision-making conference in Geneva this month, one animal, as so often in the legal trade, when Botswana, Namibia and South Africa were allowed in 2007 to sell a past, will attract much of the attention: the African elephant. fixed amount of ivory to Japan, as a one-off. Elephant numbers started falling again. A survey conducted in 2014-15 estimated that elephant numbers had fallen by 30% across 18 countries since 2007; another estimated a decline of over 100,000 elephants, a fifth of the total number, between 2006 and 2015. Increased poaching was at least partly to blame. These numbers suggest that the existence of even a small legal market increases the incentive for poaching. It allows black-marketeers to pass off illegal ivory as the legal variety, and it sustains demand. The biggest market is in China. Last year the government banned domestic sales of ivory, but its customs officials seize a lot of smuggled products—notably from Japan, which CITES licensed as a market in 2007. For the poachers, ivory is fungible. If it is hard to secure in Zambia or Botswana, another country’s elephants will be in the gun-sights. Congo, Mozambique and, especially, Tanzania, have seen sharp declines. Unfair though it is, countries with better-run conservation programmes are, in effect, paying for the failings of those with feeble institutions. In the long run, technology can help make trade compatible with conservation. In better-resourced national parks, drones are used to make it easier for rangers to spot poachers. DNA testing of ivory shipments can establish where they came from, and thus The elephant is in many ways CITES’s mascot. It was rescued in 1989 from what whether they are legal. As prices fall and countries get richer, both technologies are seemed inevitable extinction after half the population had been wiped out by poaching likely to spread. in just a decade. That year elephants were included in CITES’s Appendix I, under which The objection to trade in products of endangered species is not moral, it is pragmatic. virtually all international trade in their products is banned. The slaughter slowed. This When the world is confident that it will boost elephant numbers rather than wipe them month’s meeting will consider competing proposals about how absolute the ban should out, the ivory trade should be encouraged. Regrettably, that point has not yet come. And be, since in some countries elephant populations have recovered. Countries seeking a until it does, the best hope for the elephant—and even more endangered species, such as modest relaxation have a strong case to make. But it is not strong enough. The ban must rhinos—lies not in easing the ban on trading their products, but in enforcing it better.  stay. [The Economist, August 10, 2019] Understandably, countries that have done a good job protecting their elephants feel this is unfair. They point out that they have devoted huge resources to the elephant, through Notes. the costs of law enforcement alone. And the real burden of all this is borne by poor local - as a one-off: việc chỉ xảy ra một lần people who are in competition with wildlife for resources, and sometimes in conflict - drone: máy bay không người lái with it—elephants can be destructive. People and governments, so the argument goes, need to have an economic stake in the elephants’ survival. The ivory trade would give them one. TQT LISTEN AND READ 04