Study finds Japan’s abandoned land is harming wildlife instead of helping it
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It’s not unusual to see abandoned houses in Japan. These vacant homes – akiya in Japanese – are found in urban prefectures from Tokyo to Osaka, but are particularly noticeable in the country’s rural areas. In Wakayama and Tokushima, both largely rural prefectures in southwestern Japan, more than 20 per cent of homes are sitting empty, the once carefully tended rice paddies now overgrown. In 2023, a government survey found that there are now nine million empty houses in Japan, a figure that’s expected to continue rising.
A few years ago, science writer Dennis Normile approached Peter Matanle – a sociologist at the University of Sheffield and an expert in Japan’s population decline – for a story on Japan’s fallow rice paddies and what they meant for the country’s biodiversity. At the time, Matanle says, much of the existing research on the link between depopulation and biodiversity was somewhat anecdotal, or based on small-scale studies in specific regions. ‘We wanted our results to be applicable across the whole of Japan.’ The result – a study co-authored by Matanle, Kei Uchida (a biodiversity researcher at Tokyo City University), Yang Li, Taku Fujita and Masayoshi Hiraiwa – reveals that having fewer people doesn’t automatically lead to better outcomes for nature.
Focusing on areas that aren’t managed for biodiversity, such as national parks, Matanle and Uchida looked at biodiversity data collected by hundreds of citizen scientists across 158 nationwide monitoring sites since 2003 – a total of 1.5 million recorded observations. They found that while unmanaged, natural succession is occurring in a few places where land has become disused or abandoned, it’s often different species – or invasive species – that are displacing the unique wildlife that had flourished in farmed environments. Overall, however, the researchers found that while biodiversity was declining in both growing and shrinking populations, the loss was much less pronounced in areas with a stable human population. ‘Depopulation, and the outcomes of depopulation, are creating conditions whereby species find it more difficult to find their niche,’ explains Matanle. ‘There are fewer niches, those niches are smaller, and so on.’
Matanle says there’s a pervasive belief that nature does better when people are no longer around. It ignores the fact that humans have been present for thousands of years, acting in many ways like any other keystone species. ‘We’re mammals – highly disruptive mammals for sure – but in some places we’ve achieved such a comfortable equilibrium with other species that removing humans is detrimental to local biodiversity.’
In Japan, which is shrinking by roughly 900,000 people each year (a figure that Matanle equates to the entire population of a city such as San Francisco or Stockholm), maintaining the status quo is proving to be a challenge. ‘There are stories of people – you might want to call them adventurers, or perhaps entrepreneurs – who leave Tokyo to buy a patch of land and practise a bit of farming,’ says Matanle. The popular economic terms for this so-called trend are U-turn (people born in urban areas who move to rural areas) and J-turn (people born in rural areas who move to urban areas and then move back). ‘It isn’t really a trend,’ Matanle refutes. ‘When you actually look at the large-scale data, you see that rural-to-urban migration is continuing, and the agricultural workforce is ageing. I think the average age of farmers in Japan is somewhere in the region of 68 years old.’
What’s more, the Japanese government has been attempting to maintain rural populations with various policies and initiatives since the 1950s, when migration from rural areas was first identified as an issue. It has had little success. ‘Firstly, pretty much none of the programmes worked in the way that they were intended. And secondly, a lot of the economic stimulus has been directed into building things like infrastructure, factories, workplaces, tourist resorts and so on. That, of course, damages biodiversity still further.
Crucially, Matanle says, these results aren’t unique to Japan. ‘The primary point we wanted to make is that Japan is a “depopulation vanguard country”; a forerunner for similar changes we might expect to see in comparable nations in the region, countries such as South Korea, Taiwan and northeast China.’ These nations, he explains, all share key socio-economic and geographical characteristics – including a widespread reliance on wet-rice paddy farming. In the same way, Italy – a country with a consistently low birth rate and significant rural-to-urban migration – could be considered a ‘depopulation vanguard country’ for many nations in southern Europe.
So what’s the alternative? ‘That is the million-dollar question,’ says Matanle, although he’d like to see the government protect wetlands and grasslands, creating a haven for species that have adapted to farmed fields and rice paddies. In Japan, at least, he also believes that changes to the country’s land taxes and regulations are necessary to help local authorities identify landowners (current laws often make it cheaper and easier for families to simply abandon a dilapidated property they inherit). A 2016 survey estimated that there were approximately 4.1 million hectares, an area twice the size of Wales, of unclaimed land in Japan that have been left to ruin.
