- A brilliant blue butterfly species has been declining in Japan as the grassland-mimicking agricultural landscapes its host plant relies on fade, due to urban migration, the ageing of the population, and the nation importing food from abroad.
- The key lies in preserving this traditional landscape called satoyama, a mosaic of various ecosystems like grasslands, woodlands and human uses such as farms and rice fields.
- Researchers with the University of Tokyo have teamed up with the town of Iijima in Nagano prefecture and a local agricultural cooperative to maintain this mixed landscape while reintroducing populations of the butterfly, whose population has grown.
- Though it seems counterintuitive, there are many successful global projects connected via the International Partnership for the Satoyama Initiative, which prevent human-dominated landscapes from reverting naturally to ecosystem types like forests that rare species aren’t adapted to.
IIJIMA, Japan – Since the last ice age, a butterfly species called the Reverdin’s blue (Plebejus argyrognomon, known as miyamashijimi in Japanese), has survived in the nation’s grasslands maintained by human agricultural activities. But as the country’s population ages and leaves the countryside, letting the seminatural grasslands change to forests, the butterfly is now endangered.
For the past five years, a small agrarian town called Iijima in Nagano prefecture has partnered with researchers from the University of Tokyo to bring the butterfly back from the brink.
The key to their efforts lies in a traditional Japanese landscape called satoyama, a mosaic of various ecosystems such as rice paddies, grasslands, woodlands and human activities integrating communities with the natural world. Through these landscapes, humans have historically maintained a reciprocal relationship with native plants and animals over generations – the miyamashijimi among them.
“In order to conserve species adapted to human-managed landscapes like the satoyama, we need to strike a balance between overuse and underuse,” said Tadashi Miyashita, a professor at the University of Tokyo (Todai) who initiated the partnership with Iijima. “For so long, humans have been concerned with overuse of the environment, but underuse is also a problem.”
Since the fossil fuel revolution, satoyama landscapes have become increasingly abandoned and underused in Japan as imports of food and energy from abroad decreased local demand, threatening biological diversity on a national scale. Similar trends echo throughout the northern Mediterranean, particularly in Spain, Italy and France. In places that aren’t abandoned, management intensification simultaneously degrades ecosystems.
This principle of moderate land use forms the basis of Iijima’s conservation efforts. The collaboration between the town of Iijima, Todai and the local Kamiina Agricultural Cooperative Association is just one of many such initiatives across the world seeking to reconnect humans with landscapes to combat biodiversity loss.
A delicate balance
So far, the partnership has established sanctuaries for the butterfly in four previously abandoned grasslands in Iijima. Mimicking the satoyama landscape, these grasslands neighbor rice fields and woodlands and follow a moderate maintenance schedule.
According to Miyashita, landscape maintenance can generally be divided into three categories: frequency, intensity, and timing. For the miyamashijimi, this looks like mowing its grassland habitat just once or twice per year, to a height of 10 centimeters (4 inches) above ground level, and only after its host plant, false indigo (Indigofera pseudotinctoria), reaches maturation.
But it’s a delicate balance. Yen‐hua Yeh, a Todai graduate student, found that too little frequency or too much height increases the parasitism of the butterfly larvae by nematodes and flies, as the indigo plants can be covered by grasses.
When a balance is struck, however, benefits can spill over to other species in the landscape. The revived human-nature relationship in Iijima may also hold promise for the town’s buckwheat industry, a crop that Nagano prefecture is known for.
“A modest level of landscape use may help to maintain high diversity and abundance of insects and plants in Iijima,” said Yuta Nagano, another Todai graduate student researching pollinator interactions with buckwheat. “In turn, these diverse insect populations will pollinate buckwheat flowers and help ensure high buckwheat yield.
“It just goes to show how intricately connected species are across landscapes,” he added.
According to Syuji Saito, chief of agricultural administration in Iijima’s local government, Iijima has made strides in moving away from intensive land management to increase buckwheat yield. “Until recently, heavy pesticide use and grass mowing was a trend among farmers in this town,” he said. Jun Ito, farm manager of the local government, agrees: “This research is shining light on the benefits of coexisting with nature,” he said.
Yet there’s still a long way to go. Some farmers in Iijima still mow the edges of their buckwheat fields for pest control and for convenient movement between fields. Pollinators, however, prefer fields with unmown edges for the food and shelter they provide. The partnership believes it will take both community leadership and education to ensure lasting changes in land management.
‘The town must lead the way’
To ensure long-term success, Todai researchers aren’t doing this work in isolation. Central to the partnership’s approach is community-based governance.
Hisao Saito, retired chief of the Iijima agricultural administration, said the power lies in the local government rather than the national government or corporations to activate the local community.
“The town must lead the way to ensure the long-term preservation of the miyamashijimi,” Saito said. “Without local leadership and collaboration, land will slowly but surely fall to underuse.”
To foster local leadership, the partnership has prioritized education by organizing courses and workshops on wildlife conservation at local elementary and junior high schools. Hidenori Deto, another graduate researcher from Todai, who teaches multiple workshops and lectures on the issue at local schools, said, “We can see the light at the end of the tunnel.” In 2023 alone, Deto and other researchers collaborated with the town to host 11 grassland management and nature observation events and four public lectures to educate the community.
Identity and pride attached to the butterfly’s presence is also a powerful conservation agent in the Iijima community, Saito said. Iijima is one of the few towns in Japan where the butterfly is commonly found around farmland, making it a local treasure. The local government has worked to bolster community pride by disseminating updates on the miyamashijimi conservation efforts through social networking services, the town hall website, and a permanent display site and contact point in the town hall.
“In the short term, we researchers are doing what we can to save the miyamashijimi from extinction,” Deto said. “But the hope is that even after we are gone in 10 or 20 years, the townspeople will take the initiative to maintain a relationship with nature so the next generation of miyamashijimi will flourish.”
The threat of climate change
While Deto said he hopes the miyamashijimi will serve as a flagship species for wildlife conservation efforts in Iijima and the rest of Japan, this would have to happen despite broader social changes such as depopulation and population ageing.
And with high temperatures radiating across the globe, climate change poses an additional threat to species like the miyamashijimi. Results from a study on the effects of land abandonment on butterfly communities in rural Japan raise a conservation concern that species negatively impacted by land abandonment will decline even more due to warming because species susceptible to land abandonment tend to prefer low temperatures common in the Pleistocene.
In response, some grassland butterflies in Europe have expanded their range northward. But butterflies in Japan are too isolated from the Asian mainland to move northward in response to climate change, so range expansion beyond the Japanese archipelago isn’t expected.
Nevertheless, the study on the effects of land abandonment on butterfly communities suggests that continued, modest land management in rural areas would be an effective measure of climate change adaptation for their conservation in Japan.
“We often forget that humans are part of the ecosystem,” said Todai graduate researcher Kae Natsume. “Ecosystem services have a direct relationship to human diets and lifestyles, and they will respond to climate change in much the same way.”
For now, researchers are studying whether reintroduction can restore balance to the grasslands. Approximately 1,200 pupae were raised indoors and released at seven sites that miyamashijimi are believed to have once inhabited. In five of these sites, the butterflies were still present after four generations.
In August, researchers also discovered two new colonies a kilometer away from one of the release sites, suggesting that the reintroduction program could establish new metapopulations.
A global effort
The collaboration between Iijima, Todai and the local agricultural cooperative to conserve the miyamashijimi through reviving the satoyama landscape is just one of the local initiatives in alignment with the International Partnership for the Satoyama Initiative (IPSI).
Co-initiated by the United Nations University Institute for the Advanced Study of Sustainability and the Ministry of the Environment of Japan, IPSI is a network of hundreds of member organizations dedicated to working together to realize societies in harmony with nature.
Central to the approach is conservation and sustainable management of these socioecological production landscapes and seascapes (SEPLS) around the world. On IPSI’s website, the global partnership defines SEPLS as “bio-cultural mosaics of habitats and land and sea uses where the interaction between people and the landscape maintains or enhances biodiversity while providing humans with the goods and services needed for their well-being.”
Global examples of such integrated landscapes include dehesa in Spain, ahupua’a in Hawai‘i, and satoyama in Japan. With 282 case studies of community SEPLS efforts spanning Oceania, Asia, Europe, the Caribbean, Africa and the Americas, IPSI seeks to realize large-scale maintenance and revival of these landscapes driven by communities at the grassroots.
The initiative takes a threefold approach: consolidating wisdom on maintaining diverse and coupled human-natural ecosystems; integrating traditional ecological knowledge and modern science to promote innovations; and exploring new forms of co-management systems or evolving frameworks of “commons” while respecting traditional communal land tenure.
In Taiwan, for instance, the town of Tainan restored its pheasant-tailed jacana (Hydrophasianus chirurgus) population by reviving pesticide-free, traditional rice agriculture, in which the species had thrived for centuries. The town’s approach was holistic, combining traditional farming practices with livelihood considerations, scientific research, community leadership, and education.
All parties needed to ensure that the socioecological landscape would be resilient in order to succeed: today, Tainan records a population of more than 1,000 of these waterbirds annually, and the community shares a renewed pride in traditional farming practices, as does Iijima with its vibrant butterflies.
Together with similar initiatives around the world, these communities are reintegrating human societies with the environment to give wings to conservation.
This feature is part of Mongabay’s series on conservation solutions, see related coverage here:
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