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The Tall and the Small of Tropical Asian Trees

Posted on by Jean Linsky
In her role as Southeast Asia Botanic Gardens Network Coordinator, Jean Linsky works with botanic gardens across the region on the conservation of plants in tropical Asia.  Here she shares five threatened Asian tropical trees, both tall and small, which are in urgent need of conservation.

The world’s largest trees often get a lot of attention for their beauty and the singularity of their existence in the landscapes they inhabit. These trees become beloved tourist attractions and are mourned in the event of their decline and death such as the recent loss of the giant sequoia ‘Tunnel Tree’ in California during a winter storm. These large trees are certainly inspiring, interesting to study and create great icons for tree conservation, but there are many trees around the world, both tall and small which are equally fascinating and are often threatened in the wild.

The Tallest Tropical Tree

The 2016 discovery of the tallest tropical tree by a team from Carnegie Institute of Science in the Danum Valley of Sabah was an exciting find using advanced laser technology for mapping landscapes (and now species) from aircraft. The height of the tree, 94.1 metres and species, (Shorea faguetiana of the Dipterocarpaceae family), were confirmed during a follow-up field trip by the Sabah Forest Department in early 2017. Commonly known as the ‘yellow meranti’ the species is Endangered and is found in Indonesia, Malaysia and Thailand. The wood of this species is a valuable timber in the region and the discovery of the tallest tropical tree in the Danum Valley Conservation Area presents a great opportunity to inspire future conservationists and for education on the threats surrounding tree species in Malaysia.

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The tallest tropical tree, a yellow meranti in Sabah, Malaysia. Credit: Sabah Forestry Department.

A distant separation

Hopea bilitonensis, or ‘Pelepak’, a species in the same family as the tall yellow meranti, exists in two disjunct locations in Indonesia and Malaysia, a separation which means the existing individuals of this species live in isolated populations. The species is found on Belitung Island, which is southeast of Sumatera and in Perak state of Malaysia. Belitung Island is a part of the ‘tin belt’ of Southeast Asia, an area historically producing some 54% of the worlds tin. The unique heath forest habitat of Pelepak has been degraded across the island by tin mining activity, leaving more than 70% of the island’s native habitats in poor condition from mine expansion and a lack of restoration. Understanding the status of Pelepak populations in Indonesia and conserving this species is a key priority of researchers at Bogor Botanic Garden who are currently growing the species in ex situ collections.

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Characteristic dipterocarp seeds of Pelepak from Peramun Hill, Belitung Island, Indonesia. Credit: Peniwidiyanti/ Bogor Botanic Garden.

An ‘exceptional’ species

Water pine or Glyptostrobus pensilis falls under the ‘small’ side of our investigation of interesting trees, in both population and taxonomy. Water pine is the only species in its genus, meaning it is a unique part of the coniferous branch of the tree of life. The species was previously widespread, but has been reduced to an estimated population size of 700 in central Vietnam, central Laos and southern China due to wetland habitat conversion. In Vietnam and Laos, the last wild individuals are threatened by expanding agriculture and over harvesting of its valuable, scented wood, and few of the remaining trees currently produce viable seed. This lack of viable seed contributes to the species classification by scientists as an ‘exceptional species’, those that cannot be conserved long-term using conventional seed banking methods. A GTC project with partners in China, Vietnam and Laos, to conserve the remaining genetic diversity of this species using other methods such as vegetative propagation is currently underway.

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Water pine (Glyptostrobus pensilis) is the sole species in its genus. Credit: Xiangying Wen/ BGCI China.

Tea Time

The easily recognized importance of tree species often comes from their use by humans. The case is no different for the Wuwei camellia. This species, Pyrenaria buisanensis, a member of the tea family, was once thought to be part of the Camellia genus, hence its common name. While it was found to be in a different genus, the species is also sometimes used to make tea in its habitat in Taiwan. Found in just three localities in southern Taiwan, historical logging in the area pushed this species to its current small population of fewer than 50 individuals. GTC partners at the Dr. Cecilia Koo Botanic Conservation Center and National Museum of Natural Science in Taiwan are carrying out field surveys to determine the status of the species, and are growing living collections in the botanic garden which contain genetic material from all three populations, which will ensure ex situ conservation efforts are ready to back up wild populations.

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The flower of Wuwei camellia, an endemic tree of Taiwan. Credit: Aleck Yang/ NMNS, Taiwan

One is the loneliest number

Think of a type of tree well known for its acorns and distinct leaves in North America. Did you think of oaks? While oak trees are well-known and loved across North America and Europe, the family, Fagaceae, spans across Central America as well as Asia. After Mexico, the second centre of Fagaceae diversity is Asia with some endemic genera such as Lithocarpus or the ‘stone oaks’. One recently discovered species, L. orbicarpus was found in a single area of Thailand, Ton Pariwat Wildlife Sanctuary, hence its common name of Ton Pariwat stone oak. Only a single individual was located. Searching for more individuals and protection is paramount to understanding the biology, evolution and phylogenetic position of this rare and endemic species.

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The acorn of the Ton Pariwat stone oak. Credit: Joeri Strijk/ Guangxi University

The trees of Asia are some of the most diverse in the world, with Indonesia recently being recognized as the country with the third highest tree diversity in the world. These trees excel in their roles as sentinels of the forest, interesting geographical research subjects, providers of resinous wood, food and beverages as well as sheer mysterious beings. Their diversity, from the tallest, to those with the smallest populations is inspiring and the high risk of their extinction gives all of us a lot of reasons to keep working to conserve Asia’s amazing megaflora.

Resources:

Swartz, M.O. et al. 1995. The South East Asian tin belt. Earth-Science Reviews 38(2): 95-293.

This blog was written with help from Iyan Robiansyah (Bogor Botanic Gardens), Eyen Khoo (Sabah Forestry Department), Dr. Arthur Chung (Sabah Forestry Department) and other members of the Southeast Asia Botanic Gardens (SEABG) Network.

Written by Jean Linsky

Jean coordinates the Southeast Asia Botanic Gardens (SEABG) Network. Based in Taiwan, she is involved in working with network members to develop and facilitate the regional conservation programme. Jean contributes to the Global Trees Campaign, through project management on practical tree conservation projects around the Asia Pacific region.

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