12 February 2020

Exploring Indonesia's Lesser Sunda Islands

From Bali to Timor, the Lesser Sunda Islands are an understudied botanical paradise.

Green forest and the sea

In the south of Indonesia lies a chain of small volcanic islands – the Lesser Sunda Islands.

Stretching from Bali to Timor, to tourists they’re an untouched paradise. But beyond the clear blue waters and secluded sandy beaches, lies much more.

For researchers, these islands are bursting with a unique, yet little studied, flora.

Unlike most of everwet Indonesia, the Lesser Sundas have both a wet and dry season. This means the islands’ species have to tolerate conditions not found elsewhere. How this affects the forests on the islands lacks empirical data.

Forests of Wallacea

Alongside colleagues from a number of Indonesian institutions, not only are we aiming to build the largest inventory of the islands’ plants, but we are going to try to understand the effects of the changing climate and how this will affect the forests’ contribution to future sustainable economic development

Sunny forest
Sumbawa in the Lesser Sunda Islands © Liam Trethowan / RBG Kew.

Studying Sumbawa

Back in October, our fieldwork got underway on the island of Sumbawa.

Our first target was the village of Mataiyang. Gateway to the largest tract of intact forest across the islands. One reason for this is that it's honey country – locals rely on good quality forest for the product, which is delicious.

We set up camp as darkness descended. We were a team of 13 - by far the largest group I’ve entered a forest with.

With such large numbers, the issue we had at the campsite is the same issue that the plants have to deal with in these seasonal forests - not enough water.

As we began to survey the forests, the effects of the months of drought are clear.

A rather stunted canopy around 10-12m with occasional emergents reaching 30m. It was rather similar to the forests on the harsh soils of Sulawesi in the Greater Sunda Islands.

It was also clear in the phenology, where individuals around the almost dry riverbeds were those in flower, whereas, in the interior, flowers and fruits were rarely seen. Unlike the trees, however, we were able to up sticks and find a campsite with a plentiful water supply.

Two people sat in a forest
Fieldwork in Sumbawa © Liam Trethowan / RBG Kew.

What species?

After 10 days in the forest I waved goodbye to the rest of the team from both Herbarium Bogoriense and the Indonesian conservation department (BKSDA) and returned to the forest to continue to pursue my main aim of setting up forest plots.

By establishing 50 x 50m plots we get an idea of what species are in tree communities and how common or rare species are.

We also collected tree height and diameter to allow a first estimate of how much carbon is stored within these forests.

Having finished in Mataiyang, the next stop was Pedauh nature reserve on the coast. Here I was joined by Dr Himmah Rustiami (from Herbarium Bogoriense) and my Kew colleagues Dr Gemma Bramley and Dr Carmen Puglisi.

The soils here were sandier and deeper than those inland. The canopy was still fairly stunted however, rarely reaching 20m. Large diameter trees greater than 100cm were more frequently seen.

The presence of large Garcinia and Syzygium trees also marked these forests as different from those in Mataiyang.

Understanding the islands

The data gathered in Sumbawa is only the first step towards understanding these islands.

Next we will establish more plots on both Sumba and Flores and gather more herbarium specimens.

The herbarium specimens we have collected will contribute to our growing database of occurrence records for all endemic species. In turn this data will be used to assess the extinction threat of each of these species. 


We are indebted to Azim, Ghani, Jhon, Mus, Wira and Manunggal from BKSDA and Himmah, Debi, Gede, Mega and Wahyu from Bogor. Thanks go to Carmen and Gemma for putting up with their neighbours. Huge thanks go to Muis, Dola, Jaya, Suhar and Gepeng from Mataiyang.

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