Unusual mass flowering in Malaysian rainforests provides seeds for endangered tree 'arks'

ROYAL BELUM STATE PARK IN PERAK, MALAYSIA—It has been a year of color and sex for the lowland rainforests of Malaysia and Indonesia. This is a "mast year," when dozens of tree species produce bumper crops of flowers, fruits, and seeds simultaneously. Since April, the canopy has been a splendid mosaic of yellow, orange, and red set against green. It has been 5 years since the spectacle was last seen.

The unusual event is also a busy time for conservationists: a chance to collect seeds from endangered trees so species can be preserved. On a wet Saturday morning last month, 10 people walked through this park looking for seeds of the Dipterocarpaceae family, a group of more than 400 species that dominate many Southeast Asian rainforests. When one of the team's leaders, Mohd Burhanuddin bin Mat, noticed a towering tree, he chipped it with his machete and sniffed the exposed cream-colored wood. "Smells like young coconut juice," he said. He identified the tree as Shorea pauciflora, an endangered species. The entire team crouched around and started to pick up the fruit, easily recognizable by its long wings, and seeds. They stopped only to peel persistent leeches off their legs.

The group, mostly staffers from the Tropical Rainforest Conservation & Research Centre (TRCRC), where Mohd Burhanuddin manages a nursery, is building what it calls "living collections"—arks for endangered trees. It has already planted a 224-hectare collection in Sabah, a Malaysian state on Borneo; the next one, more than twice that size, will start here in Peninsular Malaysia. The plots will provide seeds for future reforestation projects, as well as opportunities for scientists to study the trees. TRCRC, headquartered in Kuala Lumpur, started with Dipterocarps because they are "the most critically endangered and most difficult to conserve," says Executive Director Dzaeman bin Dzulkifli David.

Dipterocarps occur around the tropics, but most species live in Southeast Asia; in some Borneo rainforests, they make up 80% of the canopy. These hardwoods, which can grow to a height of 100 meters, are favorite among loggers. Habitat fragmentation means those that remain standing can suffer from inbreeding, which can result in seeds that fail to germinate. A "red list" published in 2010 by the Forest Research Institute Malaysia (FRIM) in Kuala Lumpur lists 92 of the 165 taxa in Peninsular Malaysia as threatened.

Conserving Dipterocarps by creating reserves is difficult because individual trees can be widely scattered, says Chris Kettle of Bioversity International, a research organization headquartered in Rome, who studies the forest in Sabah. Freeze storage in seed banks isn't possible either; Dipterocarp seeds must germinate within a few days or they die. Getting enough seeds to start a collection takes patience. Dipterocarps mostly produce seeds during masting, which occurs at intervals of 3 to 10 years, often after an El Niño year, which brings drought to Southeast Asia. Masting likely evolved to improve seed survival by overwhelming herbivores with a sudden surge of seeds.

In 2 months of this year's masting, the TRCRC team here has collected 16,000 Dipterocarp seeds of seven species, compared with 26,000 seeds in all of 2016, 2017, and 2018. The seeds, as well as seedlings found in the forest—also known as wildlings—were transferred to a nursery outside the forest. There, the team stripped the wings off seeds, trimmed the leaves of wildlings, and planted both in seed beds. Once they have grown into 2-meter young trees, they will be moved from the nursery to the living collection.

"This is my most prized collection," Dzaeman said, pointing to a batch of seedlings labeled Vatica kanthanensis. The Dipterocarp species was discovered just 6 years ago at Gunung Kanthan, a forested limestone hill in Perak that hosts perhaps 50 trees. Working with a cement company that mines the hill, TRCRC collected 1000 seeds and wildlings from two of the trees. Half are kept here at the nursery; the company keeps the other half for future restoration of the site, Dzaeman says.

To search for seeds, the team has also enlisted Malaysia's Indigenous people, who know the forest far better. During last month's trip, the researchers visited Kampung Klewang, a village of the Jahai tribe, where a man named Zamri led nursery manager Suhaili binti Mohamed to his hut. Zamri had collected 40 kilograms of seeds the previous week in return for a fee; this time, he had four new sacks, to Suhaili's excitement. She says her group will soon teach the villagers to run nurseries in their villages.

TRCRC's approach, called ex situ conservation, isn't unique. FRIM has long held live collections of Dipterocarps from Peninsular Malaysia, and state forestry departments on Borneo have also established collections. But TRCRC takes extra steps to preserve the genetic diversity of wild Dipterocarps, Dzaeman says. For each species in an area, it collects seeds from five individual trees that are at least 300 meters apart. (For very rare species the distance may be shorter.)

Not everybody is convinced all these efforts are needed. Colin Maycock, a forest conservation scientist at the University Malaysia Sabah in Kota Kinabalu, says most Dipterocarps in Malaysia are already conserved in protected areas and well-managed forestry sites. "These strategies allow us to conserve a far greater portion of the genetic diversity than is possible in ex situ collections," he says.

Indeed, the focus should be on saving populations in existing forests, says Robert Ong, who leads the Natural Forest Management program at the Forest Research Centre of the Sabah Forestry Department in Sandakan. TRCRC's strategy "makes sense only for the rarer and critically endangered Dipterocarps," Ong says. And there might be fewer of those than some scientists think, Maycock adds: A reassessment of the International Union for Conservation of Nature's (IUCN's) red list for Borneo's Dipterocarps, to be published by Ong's center and other Malaysian and Indonesian agencies later this year, will likely show a good number of species to be less threatened than IUCN states.

Dzaeman agrees it is vital to protect forests and the Dipterocarps within them. But he says the pressure on Malaysian rainforests makes ex situ conservation essential as well. The living collections will become valuable as a source of plants for reforestation, he says. TRCRC is looking for funding to reforest several sites across Malaysia.

Chuck Cannon, who heads the Center for Tree Science at the Morton Arboretum in Lisle, Illinois, is also an enthusiastic supporter of the approach. It's better to have several conservation strategies in place, says Cannon, who visited TRCRC in September. And the living collections will help scientists understand forests' genetic diversity, he says. "As we grow the plants, we learn about them."