IELTS Academic Reading Practice Test 429

Beneath the small town of Wieliczka, a dozen or so kilometres south-east of Kraków in southern Poland, lies one of the oldest salt mines in Europe. Visitors who descend into it enter a labyrinth of corridors, stairways and chambers excavated over seven centuries, and the site now attracts more than a million tourists a year. Yet the mine is not merely a monument. For hundreds of years it supplied much of Poland with salt, and the wealth it generated helped to pay for the churches and colleges of the country's historic capital.

The salt itself is far older than the mine. Roughly fourteen million years ago, a shallow arm of the sea stretched across this part of central Europe. The climate was warm, and as the water evaporated it left behind thick beds of sodium chloride mixed with other minerals. Later sediments buried the salt, and when the Carpathian mountains began to rise the deposits were squeezed, folded and pushed upwards into steep, contorted seams. Groundwater dissolved parts of them, opening cavities that miners would later enlarge. The result is a deposit that is unusually rich but awkward to work, since the salt stands almost on end.

Salt was already being taken from the ground at Wieliczka by the thirteenth century. Written records of the mine survive from the late thirteenth century, and within a hundred years the workings were among the most productive in Europe. The crown took a direct interest: Wieliczka and the nearby mine at Bochnia together formed a royal enterprise, and the revenue from the sale of salt was administered by officials appointed at court. Blocks of salt were carried by cart and barge to markets far to the north and east, and the trade paid for much of the kingdom's administration. When the crown's finances were strained, the mines were among the assets it mortgaged or leased to creditors.

Medieval mining was slow and dangerous. Miners cut the rock with hand tools, carried it out in baskets and relied on timber supports that rotted in the damp air and had to be replaced. Water was a constant enemy, since it dissolved the salt and flooded the passages, so elaborate pumps and winding gear were developed to lift it to the surface. Horses were kept underground for years at a time, turning the wheels that raised baskets up the shafts and never seeing daylight between one season and the next. Accidents were frequent, and the men who worked the seams were paid according to the amount of salt they produced rather than the hours they spent.

The most celebrated chamber is the Chapel of St Kinga, carved from the rock by miners over several decades from the end of the nineteenth century. Roughly fifty metres long and more than ten metres high, it contains altars, reliefs and a floor hewn from salt, together with chandeliers made from crystals of the same mineral. Almost everything in the chapel, apart from a few fittings, is salt. It is still used for services and concerts, and it has become the most photographed place in the mine.

Legend gives the mine a more romantic origin. According to the story, a Hungarian princess named Kinga, who was to marry a Polish duke, threw her engagement ring into a salt pit in her homeland. She later travelled to Kraków and ordered miners to dig at Wieliczka, where they found a lump of salt and, inside it, the ring she had lost. Kinga, who was canonised in 1999, became the patron saint of the miners, and her feast day is still marked underground.

Production changed out of all recognition in the twentieth century. As cheaper salt arrived by rail from other regions, and as mechanical methods replaced hand cutting elsewhere, the Wieliczka workings came to seem antiquated. Commercial extraction stopped in 1996, leaving a vast complex of chambers to be conserved. Even before then the value of the place had been recognised: in 1978 it was inscribed on the first list of World Heritage Sites drawn up by UNESCO, one of only a handful of industrial monuments chosen.

Visitors today follow a route of some three kilometres through the upper levels, passing timber supports, underground lakes and chapels and climbing or descending hundreds of steps. Because the air below ground is free of pollen and pollution and has a high humidity, the mine has also been used since the 1960s as a sanatorium where patients with asthma and other respiratory complaints spend several hours a day. The treatment is not a cure, and its benefits remain debated, but the facility still operates.

Preserving such a place is not straightforward. Salt creeps and deforms under pressure, and water seeping into the workings dissolves it, so engineers must control ventilation and humidity to prevent damage. Several chambers have been closed because their roofs became unstable, and the conservation of the mine has proved as demanding as the extraction that created it. The town above, meanwhile, sits on ground that is in places hollow, and building on it requires care.

The mine is a reminder that an industrial site need not be beautiful to be worth keeping. Its corridors and chapels record the labour of generations of miners, the wealth of a kingdom and the geology of an ancient sea, all preserved in a material that dissolves in water. Visitors leave by lift, but the impression of the place is said to last far longer.

A plant cannot walk away from a caterpillar. It cannot hide, and it cannot fight back with teeth or claws. What it can do is change its chemistry, and a growing body of research suggests that it also lets its neighbours know. When the leaves of many species are damaged, they release a burst of volatile compounds — molecules that evaporate easily and drift on the air. Plants nearby that detect these compounds often become less palatable to the insects that arrive later. The phenomenon has been studied for four decades, and it remains stubbornly difficult to explain. Whether this should be called communication, or something less deliberate, has become one of the more argumentative questions in plant ecology.

The idea is not new. In the early 1980s two American researchers, Ian Baldwin and Jack Schultz, reported an experiment on poplar and sugar maple saplings. When they damaged the leaves of some plants, the undamaged plants in the same glasshouse showed a rapid rise in the concentration of tannins and other defensive chemicals in their own foliage. The damaged trees appeared to be releasing something into the air that prepared their neighbours for attack. The finding attracted wide attention, and for a time the notion of 'talking trees' entered popular culture. Later work, however, made the picture less tidy: the effect was not always repeatable, and some of the original measurements were criticised.

What exactly is released? The best-studied signals are green leaf volatiles, fragments of molecules produced within seconds when a leaf is torn, together with substances such as methyl jasmonate and methyl salicylate, which are involved in the plant's own response to injury and infection. These compounds are small enough to drift on moving air. A receiving plant takes them in through the pores on its leaves, and the chemistry that follows is not passive: genes associated with defence are switched on, and the plant accumulates proteins that interfere with insect digestion. The response can be measured within hours, and it may make the difference between a plant that is eaten and one that is merely tasted.

Field experiments in North America have carried the argument further. The ecologist Richard Karban and his colleagues worked with sagebrush, a shrub of the dry west, and with wild tobacco plants growing close to it. When they clipped the branches of sagebrush to imitate browsing, the tobacco plants nearby suffered less damage from grasshoppers than tobacco plants beside untouched shrubs. Karban has suggested that the volatile cue is best understood as a warning that spreads through a community of plants, rather than as a private exchange between two individuals.

Communication below the soil has proved harder to study. Roots release chemicals into the surrounding soil, and some of these attract organisms that help the plant obtain nutrients. Others have less welcome effects. Strigolactones, hormones that are exuded by roots and that encourage beneficial fungi, are also detected by the seeds of parasitic plants such as witchweed, which germinate only when a suitable host is nearby; farmers in parts of Africa lose a serious part of their cereal harvest to such parasites. The same chemicals that summon help, it seems, can also advertise a plant's position to its enemies. Whether roots also send useful messages to neighbouring plants is much less certain.

The idea that plants are linked by fungal threads has caught the public imagination. Most plants form partnerships with mycorrhizal fungi, which extend fine filaments through the soil and exchange mineral nutrients for sugars made in the leaves. The filaments are thinner than a human hair and easily broken, which makes them difficult to map. Because a single fungus can associate with several plants, it is possible in principle for carbon or a chemical warning to pass from one plant to another through this network, and the phrase 'wood wide web' was coined to describe it. Careful reviews of the evidence, though, have concluded that claims of substantial transfers between adult trees often rest on experiments that cannot distinguish a fungal pathway from other explanations.

The word communication carries assumptions. In animal behaviour it usually implies a signal that evolved because it benefits the sender as well as the receiver. A plant that leaks volatiles when it is bitten may simply be unable to help it, and the neighbour that overhears them may be exploiting an accidental cue rather than receiving a message. Some researchers therefore prefer to speak of eavesdropping, or of cues rather than signals. The distinction is not merely semantic: if the release is a by-product, there is no reason to expect it to be finely tuned to the needs of neighbours, and effects seen in a glasshouse may be much weaker in a meadow.

None of this makes the chemistry unimportant. Volatile compounds are already used in agriculture, where growers may plant a species that repels a pest beside the crop they wish to protect, and where traps baited with insect attractants are standard equipment. If a spray could prime a crop's own defences before an infestation began, it might reduce the need for insecticides, and several research groups are trying to develop one. The difficulty is that a defence switched on in advance is expensive for a plant to maintain, and may reduce the yield that the grower actually wants. The conversation, in other words, is real; what it means is still being worked out.

Few transport policies are as easy to sell as the abolition of fares. Tallinn, the Estonian capital, made its buses, trams and trolleybuses free for residents in 2013; the French port of Dunkirk did the same for its buses in 2018; Luxembourg removed fares from almost all public transport throughout the country in 2020; and Kansas City, Missouri, became the first large American city to make its buses free in the same year. Campaigners present these schemes as an obvious matter of fairness. The evidence is more mixed, and the argument more interesting, than the slogans suggest.

The first objection is arithmetic. In most cities fares cover only part of the cost of operating a service, and in some they cover very little; the rest already comes from taxation. Abolishing fares therefore does not make public transport free, it changes who pays and how. Economists who study transport finance make two points. The money that replaces fare revenue is money that cannot be spent on more frequent buses, longer operating hours or better vehicles, and a city with a generous fare policy and a thin timetable has done little for the passenger whose shift ends at midnight. The subsidy also goes to every rider, including the well-paid commuter who would have travelled by bus in any case. Whether that is a good use of public money is a question of values, not of accounting.

Against this, supporters of free travel argue that the benefit to poorer households is considerable and that targeted discounts are less effective than they look. Schemes that require registration and proof of income reach only a proportion of those entitled to them, and applying can feel like a means test. There is also the cost of collecting money: ticket machines, smart-card systems, inspectors and the staff who deal with disputes all have to be paid for, and on a small network these costs are not trivial. Some operators report that enforcement is the most unpleasant part of the job, a source of conflict with passengers that a fare-free system quietly removes.

The environmental case is the one most often heard, and the least well supported. If fares fall, the argument runs, drivers will leave their cars at home. Evaluations of the schemes so far give only modest comfort. In Tallinn, passenger numbers rose, but studies of the change suggest that much of the new demand came from people who had previously walked, and that car use fell only slightly. In Dunkirk, bus journeys increased sharply, yet a large share of the new passengers had also been pedestrians or cyclists. Free buses may well improve life in a city, but there is as yet little evidence that they take cars off the road in large numbers.

Public health researchers approach the question from a different direction. Their interest is in the two ways transport affects health: through the pollution that vehicles produce and through the exercise that their users do not take. On this view the prize is the short car journey — the school run, the trip to the supermarket — and the question is what would persuade people to abandon it. Free fares are not obviously the answer, because the deterrent for most drivers is not the price of a ticket but the time, reliability and comfort of the journey; researchers in this field tend to argue that frequency and simplicity matter more than cost.

Organisations representing disabled passengers make a related point. For many of their members the obstacle to using a bus is not the fare but the step at the door, the gap between the platform and the pavement, the absence of a ramp, or a driver who will not wait while someone boards slowly. In some cities, they argue, enthusiasm for free travel has diverted attention and money from these problems, and a free service that a wheelchair user cannot board is not a service at all. Their preferred order of priorities is accessibility first, then frequency, then price.

There is a political dimension too. A fare is visible, and removing it is a gift that voters notice at once, unlike an improvement to a timetable that they may never consult. Once a city has made travel free, restoring charges is politically painful, and the commitment can outlast the conditions that justified it. Critics therefore warn of a trap: a popular policy that is cheap to announce, expensive to sustain and hard to reverse may crowd out the duller spending on which a good network actually depends.

My own view is that the strongest argument for abolishing fares is neither environmental nor economic but distributive. A city is entitled to decide that no resident should be deterred from boarding a bus by the price of a ticket, and the money involved, in the context of a municipal budget, is not enormous. But that decision should be taken with the arithmetic in view, and it should not be presented as a substitute for investment. The policy I would defend is a good, frequent network, free at the point of use for those on low incomes and cheap for everyone else, with the savings from simpler ticketing spent on later departures and accessible vehicles. Fare-free travel for all is a defensible ambition; fare-free travel instead of a decent service is not.