Into the Forests of Samoa

By Dr. David Lorence, Director, Science and Conservation      

NTBG’s mission is unique among botanical gardens worldwide: our research is focused on plants of the Pacific, a diverse region covering 64 million square miles with thousands of tropical islands. Pacific floras are some of the most threatened on the planet, facing competition from non-native plants and animals, severe deforestation and habitat loss, and impacts from climate change.

Even today plant life on many Pacific islands remains poorly studied from a scientific perspective. With rampant deforestation and habitat alteration, expertise in plant taxonomy (classification and naming) and systematics is needed to identify and name new species so that researchers can best determine how to prioritize species for conservation.

Plants of the Pacific

Because of NTBG’s location in the central Pacific, our primary focus is on plants of Hawaii and other archipelagos including the Marquesas Islands, Samoa, and various islands in Micronesia and Melanesia. Over three decades, our scientists have discovered and named dozens of new species from Hawaii and the Marquesas Islands.

Last year, NTBG’s Herbarium Collections Manager Tim Flynn, Research Biologist Ken Wood, and I took part in a collecting expedition to Samoa along with Senior McBryde Research Fellow Dr. W. Arthur Whistler. The expedition was planned as Dr. Whistler was completing a written Flora of Samoa to be published as a book by NTBG and online at the Smithsonian Institution’s Pacific Island Floras website.

Although Dr. Whistler began studying the Samoan flora over 40 years ago and has collected thousands of herbarium specimens, a number of areas in Samoa remain poorly known and undocumented. Additionally, some species have not been seen or documented in over a century — and in one case in nearly two centuries. On our “to find” list were 16 species considered lost on the islands of Upolu and Savaii in Independent Samoa.

With grant funding from the National Geographic Society and the Mohamed bin Zayed Species Conservation Fund and additional support from NTBG’s McBryde Fund, we were able to organize a six-week botanical expedition between May – July 2016.

Exploring the Unknown

Our objectives were to conduct botanical field surveys of poorly known or unexplored areas of Samoa’s two main islands Upolu and Savaii; collect herbarium voucher specimens of the vascular plants, bryophytes (mosses and liverworts), and lichens; attempt to relocate rare and poorly known flowering plant and fern species; document the state of the natural vegetation and threats; and to help build local capacity in botany and the conservation of rare Samoan plant species. 

This project is urgent because the threats to Samoa’s upland ecosystems will likely lead to reduced populations and possibly the loss of native species. We see great importance in contributing to the Flora of Samoa which will be an invaluable reference tool for Samoan conservation efforts.

The expedition included Mereia Tabua (University of the South Pacific, Fiji) who studies bryophytes (mosses and liverworts), and Melissa Johnson, then a Ph.D. candidate at Claremont College and Rancho Santa Ana Botanical Garden, California who studies the genus Cyrtandra (Gesneriaceae). Mereia, recipient of NTBG’s McBryde Young Investigator Fellowship for capacity building in tropical botany, worked closely with Tim while Melissa’s participation provided an opportunity to study Samoan Cyrtandra species in the field.

The two young investigators — one of whom was selected as our first McBryde Young Investigators Fellowship — were part of an effort that consisted of working alongside NTBG senior scientists and in close collaboration with Samoan Ministry of Natural Resources and the Environment (MNRE) and Samoan Conservation Society (SCS) staff, who were essential for organizing the expedition, obtaining collection permits, gaining permission to conduct field work on village lands, and obtaining guides and trail cutters.

After flying from Honolulu to Pago-Pago (American Samoa), we took a small plane to Upolu, where our team spent three weeks collecting, using the Vailima Botanical Garden as our base of operations. Later we traveled by inter-island ferry to Savaii, where I joined the others members of the expedition for the next three weeks.

In the Field

Fieldwork phases included valuable collaborations and training MNRE staff in identification and collecting techniques, gathering population data, taking GPS points, and collecting, pressing, and drying specimens. We generally drove into the mountains as far as possible then hiked to areas of relatively intact native vegetation which is mostly confined to mountain slopes and summits.

In addition to searching for the 16 rare species, we carried out general collecting in these remote and rarely-visited areas to document the vegetation, including both native and invasive species, for the Flora of Samoa project. We took photographs to supplement vouchered specimens, and collected leaf material in silica gel for molecular phylogenetic studies. Since ferns are of special interest to NTBG staff, including me, they were given special emphasis. The resulting images and collections contributed to the Flora of Samoa project and the joint Smithsonian Institution-NTBG website.

A population of an extremely rare fern not collected in over a century, Botrychium daucifolium (Ophioglossaceae), was also discovered on Savaii. Additional species collected but not on the list include two possibly undescribed ferns from Savaii. 

In the end, we were able to achieve the majority of our goals collecting a total of 2,607 herbarium specimens, including 264 bryophytes, with the primary set deposited at Herbarium PTBG (the official name of NTBG’s herbarium). Ultimately, only two of the lost species were encountered during our field work, the others being either extremely rare or possibly extinct. 

Because time and access to other remote mountainous areas on Savaii were limited, it is possible that additional field work could reveal populations of these species and perhaps even new species. Certainly more field work is needed, especially on Savaii. Three healthy populations of Abutilon whistleri, a rare tree belonging to the Malvaceae (hibiscus family) were located in montane wet forests on Savaii.

Lost but not Forgotten

Finally, all 16 “lost” Samoan species were added to The IUCN Red List of Threatened Species. Although not providing legal protection, red listing draws attention to a species rarity and threats they face and provides information to guide conservation measures. The expedition provided the opportunity to help grow NTBG’s herbarium collection with the addition of over 2,000 new herbarium specimens, another valuable contribution to the Flora of Samoa project. 

Beyond our botanical goals, we were able to strengthen and make new contacts with colleagues in Samoa while laying the foundation for future collaborations. With respect to our rediscovered rare species, we were thrilled to find they were alive and well, and remain hopeful that others will eventually be found.

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