Saving last wild azalea shrub shows fragility of biodiversity

Kyodo

A lone wild azalea shrub growing on one of the Ogasawara Islands in the Pacific is a reminder of a simple rule of nature — what is lost can take decades to recover.

Dwindling to the very last shrub by the early 1980s, the Rhododendron boninense, a species of azalea on Chichi Island remains an endangered plant despite efforts to protect it from farming, animal grazing and plant collectors.

The shrub, more than a century old, is now surrounded by only around 30 artificially raised young shrubs.

The Ogasawara Islands, which Japan is seeking to have designated as a UNESCO World Natural Heritage site by next year, is abundant in rare animals and plants that have adapted to the distinct subtropical environment.

As a result, the species are difficult to breed outside of the region, making preservation efforts in other parts of Japan a complicated task.

“If you have 10 different plants, they grow in 10 different conditions, and there is no guideline on how to grow them,” said Jin Murata, director of the Botanical Gardens of the University of Tokyo’s Graduate School of Science.

The gardens, commonly called the Koishikawa Botanical Gardens, have been leading efforts to conserve the Rhododendron boninense and other rare Ogasawara plants and have around 90 of the approximately 140 types of vegetation unique to the islands.

After the Koishikawa gardens took over the restoration project around 1980, the difficult process of growing the plants in central Tokyo and returning them to the islands, located around 1,000 km south of the capital, began under government sponsorship.

Using trial and error to work out how to grow them artificially, the efforts have revealed the intricate web of species among the plants and underscored the difficulties of restoring biological diversity by human hand.

Roots did not sprout from cuttings under usual procedures, requiring special growth hormones. Young plants failed to grow beyond a certain size unless they were grown in soil from Ogasawara, likely because only certain fungi found in the soil there could help their growth, according to Murata.

To regain genetic variations from the remaining wild shrub, the team must continue growing the plants for generations and mate them.

“Ecosystems are extremely sensitive,” Murata said, adding that thinking about the situation sometimes makes him feel overwhelmed.

Several years ago, the sensitive nature of the ecosystem put on hold the activities to reintroduce the plants to the islands due to concern that the soil attached to the plants grown in central Tokyo could have a different balance and types of bacteria, and disrupt the original environment when reintroduced.

“You can eliminate harmful insects by treatment, but it is hard to prevent the introduction of different bacteria and fungi when you bring them back,” said Kazunori Hirai, technical section chief of the Koishikawa gardens.

While talks over formulating a guideline for such replanting efforts started at a government panel this year, the gardens are continuing to grow the plants and testing different ways to raise them as they await the green light to resume bringing them to the islands.

Such work is not exclusive to the Koishikawa gardens at the national university in Tokyo, with a nationwide network of botanical gardens trying to prevent critical biodiversity loss in Japan.

The Japan Association of Botanical Gardens, with more than 100 member organizations, has around 30 key botanical gardens that focus on collecting and conserving plants, and educating people about the necessity of protecting biodiversity.

The association has been working toward holding 55 percent of endangered Japanese plants at botanical gardens within the country by 2010, a goal it set in 2002 when the sixth Conference of the Parties to the Convention on Biological Diversity was held in The Hague, and is certain to have achieved the goal, with 58 percent or more secured, according to the association.

Still, it is by no means an indication that restoring biodiversity has or will become easy. The Koishikawa gardens team notes that the factors that need to be improved in the course of restoration efforts are multifaceted.

Hirai said that during his more than 30 visits to the Ogasawara Islands, he saw a type of small orchid facing problems with reproduction due to a decline in the number of small insects for pollination, as newly introduced organisms such as the green anole lizard feed on such insects.

“The increase in green anoles has hit the insects directly and the plants indirectly,” he said, explaining that the team may need to begin working with experts on insects and in other fields to carry out their project effectively.

Funding is also a concern for the Koishikawa gardens, a 160,000-sq.-meter site run by eight people, as the government is seeking to cut spending by reviewing the various projects it funds.

Hirai warned that if the project is suspended, everything would be brought back to zero and the team would have to start anew if the government decided to resume it later on.

“You can lose a species in one day, but restoring it could take 10 years or even 100 years of continuous efforts,” he said.