It’s not just precious metals such as gold that countries are keen to amass, a whole host of products from cheese to maple syrup have become quirky nest eggs for nations across the globe. While some collections have now been consigned to history, such as the European butter mountain, other unusual hoards are still being squirrelled away. We take a look at the weird and wonderful reserves that are worth a small fortune around the world.

North Americans have been tapping the sap from Maple trees and boiling it into the golden elixir that is maple syrup for hundreds of years. Over 70% of the world's maple syrup is produced in the French-speaking province of Quebec in eastern Canada. The Fédération des producteurs acéricole du Québec (FPAQ) is a cooperative marketing group run by the region's syrup producers that controls the supply and demand of maple syrup and it has built up quite a syrupy stockpile.

In 2019, 159.4 million pounds of maple syrup was harvested, which generated an estimated C$800 million ($612m/£469m) in income for FPAQ members. To keep the price high, not all of this is released straight on to the market, however. And this stockpile is now heavily secured after thieves made off with 3,000 tons of the syrup over several months between 2011 and 2012, the equivalent of 10,000 barrels of the sweet stuff. The "Great Canadian Maple Syrup Heist" has since been made into an episode of the Netflix documentary show Dirty Money.

China is thought to be the largest producer and consumer of pork in the world and the Chinese government has often intervened to control the supply and price of its people's favourite food. Rising food prices have been known to trigger periods of civil unrest in the country, which is thought to be one of the reasons the Chinese government likes to control the supply of pork. National and local governments have kept reserves of the meat since the 1970s.

The growing middle class has increased the demand for pork in China and as more people can afford to buy it the price has risen. In March 2016 it was reported that the price of pork in China had gone up nearly 30% year on year. However, due to the recent outbreak of African swine fever that killed millions of pigs the producer price surged over 125% between July and November 2019, according to international food consultancy Girafood. In a bid to compensate the shortage, in December 2019 the government announced that it was going to release 40,000 tonnes of frozen pork from its state reserves for the upcoming holidays.

But China isn't the only country stockpiling pork. In October 2019, the US reportedly had 40 million pounds of pork belly (used to make bacon) sitting in refrigerated warehouses across the country, the biggest excess in 48 years. According to Bloomberg, the production accelerated during the summer due to increased imports from China. Only a few years back though, America was in panic of a bacon shortage.

In December 2016, the US pork belly reserves hit a 60-year low, with just 17.8 million pounds left. As a result, prices surged 20% the following month and there were fears the country could run out of its much-loved bacon. The problem has now been reversed and America has a huge pile of uneaten pork belly. But as the trend for exporting pork to China continues, experts suggest that the surplus may soon stabilise.

A record grain harvest in 2016 meant that many countries produced more wheat than they required. Russia recorded its second highest crop in its history, only beaten by its yield in 1978. Improved farming practices and technology have also helped boost Russia's wheat production and it's predicted the country could add 25 million metric tonnes of wheat to its yield over the next ten years. The increase in Russia's grains stores has had a huge impact on the global economy.

Not all of Russia's excess wheat is being stored up for a rainy day. Russia was once largely reliant on foreign exports for its grain supplies, but now it has more grain than it knows what to do with at home it can offload it in Europe and America, undercutting local suppliers as it does so. In turn, this is leading to unwanted European grain being put into storage by farmers unwilling to sell at a price much lower than they desired.

Since 2016 America has produced more cheese than it can eat or sell, leading to huge caches of cheese stacking up in cold-storage facilities across the nation. In January 2019 there was reportedly 1.4 billion pounds of cheese in America's largest stockpile ever. This surplus is partly a result of American cows producing more milk than required, with the excess being put into cheesemaking, but Trump's tariff policy and millennials' tastes have a hand in this too.

In response to Trump's trade policy, three top importers of American milk products, Mexico, Canada and China, set tariffs on US cheese in 2018, resulting in slumping international sales for the US. But what's more, Americans have turned away from processed American-made cheddar in favour of "fancier", more European-style cheeses. Mozzarella sales, for instance, have surged over the past decade, as many millennials prefer natural cheeses without preservatives, as Bloomberg reports.

Japan has built up quite a stockpile of plutonium. It is the only state that doesn’t make nuclear weapons from the spent commercial plutonium produced by its nuclear reactors. But it means that Japan has a lot of potentially weapons-usable plutonium in stock, prompting international calls for the country to rethink its nuclear reactor processing procedures as a result.

Japan did reportedly reduce its plutonium stores by about 1.6 tonnes, as of the end of 2018, to about 45.7 tonnes. Of this, only about 9 tonnes are said to be stored within Japan. The remaining 36.6 tonnes is said to be held in Britain and France, where spent nuclear fuel from Japanese nuclear plants is sent for reprocessing.

In December 2019, the Malaysian Fisheries Development Authority announced that it would provide 165 tonnes of high-quality frozen fish the the domestic market over the next three years, known as 'Q' fish, held in storage centres across the country. During times of hardship or high demand, such as Chinese New Year and Ramadan, when the price of fish is very high, frozen fish stocks have been released at less than market price, in a bid to stabilise pricing in the country.

Malaysians reportedly consume 53kg of fish per capita each year and are the highest consumers of fish in Southeast Asia. Keeping a stockpile of frozen fish not only helps to control the price of fish in the country, it also ensures that there are supplies that the population can draw on during the inevitable low-catch seasons.

In 1986, the European Union member states were said to be storing around 1.5 million tonnes of surplus butter and were spending $1.3 billion a year storing it. This excess was blamed on modern intensive farming practices increasing yields, rising prices in Europe which shrunk the traditional export markets for butter abroad, and the Common Agricultural Policy, which gives protection to European farmers against foreign competition through levies on imports.

More than 30 years later, Europe's butter mountain is now little more than a puddle. In May 2017, the European Union was reported to have just 1,369 tonnes in its reserves, down from the 92,548 tonnes held just a year before. It is thought this fall was down to a reduction in milk production and a growth in butter consumption, with many people now seeing butter as healthier than vegetable oil margarine-type alternatives. Butter prices have risen as a result.

In 2008 the Svalbard Global Seed Vault was built inside an abandoned arctic coal mine, deep within a mountain on a remote island in Norway's Svalbard archipelago. The vault was designed to hold the seeds of as much of the world's crops and plants as possible and it's been a success. In the event of a vast man-made or natural disaster people from all over the world could call on the vault to restore natural flora and fauna to their land.

But the seed bank, which was built to withstand any eventuality, didn't have quite what was needed to protect it against global warming. It was built underneath permafrost, but unusually high temperatures have caused parts of this to melt and, while the water didn't get inside the seed bank itself, it penetrated the entrance. Norway has set aside $13 million (£9.9 million) to upgrade the facility to ensure its 890,000 seed samples stay out of harm's way.

The ice found in mountain glaciers can tell scientists a phenomenal amount about the world's climate and environment. It is thought that this ice can help to predict and perhaps even avert future environmental changes. As parts of these glaciers are melting, the Ice Memory project was developed to store ice cores from high-mountain glaciers most at risk from climate change. These are now stored in a snow cave in Antarctica.

Glaciers most at risk of global warming around the world are earmarked for the ice bank before a drilling mission extracts two or three full ice cores for storage. These cores are then carefully carried down the glacier in specially-insulated boxes and transported by ship to Antartica, where they enter the archive facility.

Read more about the Antarctica and the secret battle to own the world's forgotten continent

India is the world's largest cotton producer. Between 2019 and 2020 it has been forecast to produce around six million tonnes of cotton with about one tonne of this lined up for export. The government-run Cotton Corporation of India is designed to protect the interests of cotton farmers and to ensure they get a fair price for their cotton. As part of this mission it stockpiles cotton too. At one point in 2015 it was said to have held 6.5 million bales of cotton in its stores.

The Cotton Corporation of India had to sell off a chunk of its surplus cotton bales in 2015. This was a result of an unsustainable cotton surplus due to a bumper harvest and a fall in demand for cotton exports to China, where an expanding homegrown cotton industry has reduced the demand for foreign imports.

The Frozen Ark Project, based at the University of Nottingham in England, was originally set up to focus on the evolution of the biology of the land snail. However, the research quickly turned into a study of extinction as the scientists discovered that about a hundred species of snails had died out in just 15 years. The project then rapidly expanded its remit and it became dedicated to collecting, preserving and storing the cells and DNA of all the world's endangered species.

Museums, researchers and zoos worldwide are now members of the Frozen Ark Project consortium. So far, over 48,000 DNA samples have been collected and stored in its -80°C (-112°F) freezers based in Nottingham, England. These include samples from the scimitar horned oryx, which is extinct in the wild, and a variety of endangered species such as the Colombian spider monkey, pileated gibbon, siamang gibbon, lar gibbon, snow leopard and Malayan tapir.

Between 2018 and 2019, Vietnam, one of the world’s top rice exporters, produced 27.8 million tonnes of rice, according to the U.S. Department of Agriculture’s Foreign Agricultural Service (FAS). That might sound a lot, but it was a smaller harvest year as the weather was drier than usual, a drop which is expected to continue into 2020 as the government is encouraging farmers to switch to other crops in areas where water is sparse. However, to protect the nation's staple food from unforeseen circumstances, Vietnam has a national rice reserve that can be dipped into in times of need.

According to Vietnam's National Food Authority, in August 2019 the rice buffer was large enough to feed the whole country for 13 days, with 425,000 tonnes stockpiled in 8.5 million bags. In December 2019, over 110,700 tonnes of rice, worth more than VN$1 trillion ($43.3m/£33.1million), were released from the national reserve to support people after natural disasters.

Thailand is the world's largest producer and exporter of natural rubber. Rubber farmers cut the bark of rubber trees and extract the milky substance known as latex from it. This is then refined to produce rubber, used in thousands of everyday objects from car tyres to gloves. As this material is so key to the Thai economy, the Thai government keeps state stockpiles of rubber in order to have some control over its supply and demand.

In 2017, the Thai government announced it was selling 98,000 tonnes of rubber from its national reserves. This sale, worth around 6.64 billion Thai baht ($211m/£161m), was designed to minimise the damage to the economy caused by recent flash floods in Thailand's main rubber-plantation region. Most recently the government has approved a 20-year plan to reduce rubber plantations in order to increase its value of exports.

In order to sustain the supply of tobacco for its world-famous Cuban cigars, Habanos, the Cuban company that produces and sells the cigars, has built up a stockpile of its precious tobacco leaves. This stockpile has been a useful safety net to fall back on when the tobacco crop has been severely damaged by detrimental weather, pests or disease.

In 2010, Cuba's tobacco harvest was cut right back in response to a fall in global demand for cigars. This was triggered by a global economic crisis and a reduction in tobacco smoking for health reasons: in 2009 Cuba reportedly exported 73 million cigars, down from 217 million in 2006. At this time, instead of buying in fresh leaves, Habanos began drawing on its stockpile. New demand for cigars from China has helped Habanos to recover, however, raking in $537 million (£410m) in global sales in 2018.

Rhino horns attract a very high price on the black market, leading to poachers taking great risks to procure them. When rhinos die of natural causes in the wild their horns are immediately removed to ensure they're not snatched by poachers. As a result of there are said to be many secure rhino horn stockpiles across Africa, many of which come from natural rhino mortalities, as well as horns obtained during botched poaching operations.

Those that manage rhino horn stockpiles have to adhere to a strict code of conduct and maintain detailed records of their stock, which must also be carefully stored to protect them from damage. This, together with the high security required, makes storing the horns very expensive. Some call for the horns to be destroyed, while others say they should be sold legally to help end the black market trade. Some scientists argue that they should be kept for their research value.

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