Seeing the wood for the trees

F I E L D W O R K
Seeing the
wood
for the
trees
KEW SCIENCE
With the forests of Sumatra disappearing at a
worrying rate, Rachel Mason Dentinger explores
how Kew scientists are using the latest technology to
create an innovative vegetation map that will enable
restoration efforts to be targeted more effectively
The rivers that cut
through the dense
rainforest provide the
scientists with access
routes into many of
their survey areas
Photo: Jenny Williams
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Harapan Rainforest botanist
Dafid Pirnanda records the plant
species that are present in a
regenerating area of forest
F I E L D W O R K
One hundred years ago, a bird’s-eye view of the
Indonesian island of Sumatra would have shown
a vast swathe of green. Covering an estimated
16 million hectares, this dry lowland rainforest was
extremely rich – in species and in the resources that humans
covet. Soon enough, logging and oil palm plantations ate
away at that green expanse and today only 500,000 hectares
of forest remain. But a team of Kew researchers, armed with
21st-century satellite images and technology, is determined to
help reconstruct a piece of the Sumatran rainforest – an area
named Harapan or ‘hope’ in Indonesian – and use it as a
foundation for regeneration in the next century.
Harapan is a 100,000-hectare expanse of rainforest that
has been leased for the next 100 years to a consortium of
conservation experts, namely BirdLife International, Burung
Indonesia (a local non-governmental organisation) and the
UK’s Royal Society for the Protection of Birds (RSPB). These
organisations are working to restore the forest to health.
More ambitiously, they also hope to reinstate the original
composition of the forest prior to human exploitation.
Kew’s botanists have been involved in this undertaking
since 2008, when Rogier de Kok and his team, who specialise in
South-East Asian flora, helped to establish a local herbarium and
trained staff to collect indigenous plants (see Kew magazine,
winter 2009). Earlier this year, in a project funded by the
Department for Environment, Food and Rural Affairs’ International
Sustainable Development Fund, Kew staff returned to Harapan
to carry out ‘a rapid survey for the whole area’, which, according
to project leader Justin Moat, ‘is what is desperately needed.
This gives an idea of what’s happening on the ground, which
can drive restoration planning by the forest’s managers.’
For over a decade, Justin has headed up Kew’s Geographic
Information Science (GIS) team generating vegetation maps –
large-scale views of regions that record their different classes
of vegetation (see Kew magazine, spring 2011). However, for
many more decades – centuries in fact – generations of Kew
botanists have traversed the same regions and have returned
with a very different view of the world – one focused on
individual species, where a detailed fine-scale examination of
individual plants is paramount. This field trip brought together
these two perspectives on plant life, requiring Kew’s botanists
Photos: Marie Briggs, Roki Afriandi/Harapan Rainforest
to break with tradition. Instead of collecting hundreds of
plants to bring back to Kew’s Herbarium, they collected the
data necessary to summarise and map different vegetation
types within the whole of Harapan Rainforest.
In the first phase of the project, geospatial scientist
Jenny Williams used specialised software to analyse the few
existing images of the region. In an area most often covered
in clouds, she was fortunate to obtain a clear satellite image
of the forest from 2009, with resolution down to 10 m. The
software she uses automatically differentiated the rainforest
into sections, based on the similarities and differences
apparent in the vegetation from above.
But what do these sections represent? Even from above,
not all green is equal. In the next stage of analysis, Jenny
examined the differentiated regions and attempted to roughly
identify the type and quality of vegetation they represented.
Is this tract of green a healthy forest with a high canopy?
Or is it ‘more uniform and brighter green, perhaps suggesting
bamboo, or unstructured re-growth of a recently deforested
area?’ she questions. Infrared wavelengths add another layer
of useful data, as higher quality forest tends to reflect infrared
light. Jenny drew on her previous mapping experience
(assessing the overwintering sites of monarch butterflies in
Mexico, and orangutan habitat in Borneo) to categorise the
regions differentiated by the software. The result was a
prototype vegetation map of the Harapan area.
Finally it was time for the field team to head to Harapan
for ‘ground-truthing’ – visiting each distinct region of vegetation
to test and refine the labels they had already been given. Two
teams, each composed of Kew scientists, botanists from the
Indonesian Bogor Herbarium and Harapan Rainforest scientists,
moved swiftly through the forest, recording data from a
staggering 300 plots along the way.
Dwarfed by a towering Gluta tree,
botanists Marie Briggs and Lucia
Lopez use a smartphone to pinpoint
their location on an electronic map
This type of mass data collection doesn’t come
naturally to botanists, Justin says. ‘We are forcing the
botanists to observe the landscape. “Look around you,”
we tell them, “we don’t need to focus on individual plants
now.”’ Botanists may sometimes miss the forest for the
trees, but here in Harapan the forest was their primary
focus. ‘This is mainly about observing what’s going on,
on the ground, about recording the information within
each 500 sq m plot,’ says Justin. This includes the size of
the trees and the height of the canopy, the dominant tree
species in a plot and evidence of negative impacts on the
forest, such as illegal logging and invasive species. ‘Then we
can place information back onto the imagery,’ explains Justin.
Kew researchers are determined to help
reconstruct a piece of rainforest in an area
named Harapan or ‘hope’ in Indonesian
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F I E L D W O R K
Harapan’s threatened rainforest
is home to many intriguing and
eye-catching plants, including
this vivid-fruited species in the
family Sterculiaceae
Kew’s Marie Briggs gathers data on
the edge of a swamp forest amid the
fallen flowers of a Barringtonia tree
– a characteristic species of this area
Photos: Roki Afriandi/Harapan Rainforest, Marie Briggs, Jenny Williams
Both the collection and analysis of this immense amount
of data are made possible by the savvy use of technological tools.
Team members recorded data from each plot on smartphones
that were pre-loaded with maps of the region and the relevant
data fields. Their phones guided them to the target sites within
the forest and helped them fluidly adjust their expectations and
daily research plans based on what they found. Each evening
the amassed data was uploaded and transferred to Justin,
who worked back at Kew to create a live map. The map, which
can be viewed on the GIS team’s webpages, also includes
geo-tagged photographs and tweets from the field.
Jenny’s job now is to take these discrete points of data and
create a two-dimensional summary of the state of the forest in
the whole region. The practical value of this vegetation map is
best understood in terms of the investment required to restore
Harapan. ‘We are trying to work out essentially where to put
the effort in and where not to put the effort in,’ explains Justin.
‘Some parts of the forest can be left alone to recover, but if any
area needs some help, we can show where they get the best
bang for their buck.’ While almost all of Harapan Rainforest
has been logged in the past, and some of it continues to be
threatened by illegal logging today, the Kew team has returned
from Sumatra with good tidings. Much of the forest is already
on its way to recovery and Harapan Rainforest itself is proving
to be a great restoration investment.
And, if Rogier has his way, Kew’s botanists should soon
have a chance to leave this large-scale view of the forest behind
and get back to their higher-resolution examination of the
plants, as he hopes to conduct a detailed survey of Harapan’s
flora. Understanding the species-level composition of the forest
is just as essential to restoration as the creation of a vegetation
map. The custodians of Harapan want to encourage the return
of the original forest, but ‘what that actually means is another
matter’, Rogier points out. Botanists will need to account for
the species that thrive in Harapan today, but they will also be
asked to hypothesise about the historical composition of the
forest. ‘They want to restore the forest to some sort of natural
state’, Rogier says, but ‘is that what it was before human
intervention, or is that what is possible?’
Kew scientists can provide two scales of analysis –
large and small – which attempt to describe both what
is in Harapan today and what once was. By creating a
management plan that synthesises these two perspectives,
the forest’s managers can determine what can be in
Harapan Rainforest for the next one hundred years.
––
Rachel Mason Dentinger is a freelance science writer
»»
Kew’s vegetation mapping project of Harapan Rainforest
has been made possible thanks to a grant from the Department
for Environment, Food and Rural Affairs. Its results – and Kew’s
expertise in South-East Asian flora – will be used to guide the
restoration of this dry lowland rainforest
Discover more online
Harapan Rainforest is located on Sumatra, the largest island
in Indonesia. The dry lowland forests of Sumatra are among the
most biologically diverse yet most critically threatened habitats
on Earth. A consortium of the RSPB, Burung Indonesia and
BirdLife International manages Harapan Rainforest – see
harapanrainforest.org. You can find out much more about the
Kew project, including photos, maps, tweets and fascinating
blogs, by going to www.kew.org and searching for ‘Harapan’.
Jenny Williams, Lucia Lopez
and the team pore over a
satellite image of Harapan
to work out the best ways
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