How are trees good for us? ‘Sentinels’ may hold the answer

An extremely ambitious research project provides a new way to approach landscapes.
A “sentinel landscape” is one that is monitored over time for changes—and for the effects of those changes on the environment and on local people’s livelihoods. Bruno Locatelli / CIFOR.

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NAIROBI, Kenya—It’s a unique, massive—and massively ambitious—research initiative, spanning nine landscapes across 20 countries on three continents.

It involves scores of scientists and practitioners from 60 organizations, and employs a panoply of research methods from household surveys to soil sampling, from vegetation inventories to satellite imagery.

And it’s all to answer an unusual, perhaps counterintuitive question:

Are trees “good” for landscapes—and “good” for us? (And if so, how much?)

“What we hope to achieve is to find out when trees in landscapes lead to better livelihoods, better nutrition, better income, happier people,” said Anja Gassner, a researcher with the World Agroforestry Centre (ICRAF). Gassner leads the Sentinel Landscape initiative, a component of the CGIAR Research Program on Forests, Trees and Agroforestry (FTA), led by the Center for International Forestry Research (CIFOR). “Can we quantify their contributions to a healthier environment, a more sustainable environment?”

The purpose of looking at “landscapes” for such analysis, according to Gassner, is to move beyond the limitations of the ecosystem approach, which emerged around conservation and biodiversity work. “We use the term ‘landscapes’ because people can relate to that,” she said. “It’s where we as humans interact with the environment, where we shape the environment and the environment shapes us.”

The “landscape approach,” experts contend, can help achieve the right balance between conservation needs in the landscape, oriented primarily to nature, and the development needs of people. It can help bring to the discussion different groups with competing interests to find common ground and complementary interests in a landscape.

The landscape approach is, as CIFOR Director General Peter Holmgren recently wrote, “not about achieving pre-defined biophysical performance targets, but rather about negotiating multiple values.”

As for the term “sentinel landscape”—that’s what makes the initiative unique.


A “sentinel landscape” is one that is monitored over time for changes—and for the effects of those changes on the environment and on local people’s livelihoods. Gassner explained that the term “sentinel” is borrowed from medical science, where it refers to clinical indicators used to monitor health over time.

Launched in 2011, the Sentinel Landscapes initiative is intended to test the hypothesis that there is a measurable relationship between environmental and rural livelihood outcomes independent of the environmental and cultural context. But it also responds to calls for broader-based research: In order for findings to be useful for policymakers, particularly at regional and global levels, site-specific case studies were not nearly as useful as ones showing global patterns, a 2009 review of social science in the CGIAR found.

Thus, lessons from one sentinel landscape could help to inform development projects in other places, with high-resolution global and long-term datasets.

I have done helicopter surveys over the Malaysian state of Sabah, and you don’t see anything but oil palm for miles and miles and miles

Anja Gassner

FTA and its work on landscapes is a truly collaborative effort, engaging six international research organizations: CIFOR, ICRAF, Bioversity, the International Center for Tropical Agriculture (CIAT), the French research center CIRAD, and the Costa Rican institute CATIE.

During the first phase of FTA, the Sentinel Landscapes initiative established interdisciplinary research teams that tackled the process of selecting seven priority landscapes with geographical boundaries, two each in Latin America and Africa and three in Asia. For practical purposes, they then identified four specific “sentinel sites” in each landscape, where data is collected. They also developed a standardized methodology and set to work collecting livelihood, environmental and institutional data across the network of seven landscapes.

Regional sentinel landscapes

  1. Borneo – Sumatra
  2. Central Africa Humid Tropic Transect
  3. Mekong
  4. Nicaragua – Honduras
  5. West Africa (includes Niger Basin in southeast Mali and Volta Basin in Burkina Faso, northern Ghana and northern Togo)
  6. Western Ghats in India
  7. Western Amazon (Peru, Bolivia and Brazil)


As FTA also comprises a research theme focusing on the effects of global trade and value chains on landscapes, the researchers recognized the need for two additional “theme-based” landscapes on all three continents that had in common a particular commodity.

One, the Tropical Managed Forest Observatory, focuses on timber. It links 24 experimental sites comprising 462 sites and a total of nearly 1,000 years of monitoring data collected by timber companies and researchers over many decades, which are used to assess the impact of selective logging on forest dynamics, carbon storage and tree species composition. Forty-five researchers are involved in this meta-analysis of data in the Amazon and Congo Basins, and in Southeast Asia.

The Oil Palm Value Chain Landscape looks at one of the world’s fastest growing commodity crops. Although oil palm originated in West Africa, it has been primarily in Malaysia and Indonesia that it has been cultivated in large-scale plantations as a global commodity.  One of the most controversial crops of our time, it is also the most efficient oil-producing plant, with very attractive revenues for smallholders. Its rapid expansion has been very localized, destroying one unique habitat, which has led to an environmental outcry, Gassner says.

“I have done helicopter surveys over the Malaysian state of Sabah,” she said. “And you don’t see anything but oil palm for miles and miles and miles.”

While oil palm has been the backbone of Malaysia’s impressive economic growth, it did come at a price. Today, Sabah’s famous lowland dipterocarp forests, home to flagship species such as orangutan and Sumatran rhino, can be found only in protected areas; traditional smallholder farms that supported diverse livelihood strategies and the backbone for domestic food production have been replaced by monoculture oil palm stands. So we want to learn from that for places where oil palm is just starting to expand on a massive scale.”

For this reason, the sentinel landscape teams are looking both at established oil palm landscapes in Indonesia and Malaysia and at new ones in Colombia, Peru, Cameroon and Nigeria.

“The objective,” Gassner said, “is to see how the local settings in each of these landscapes actually influence a global commodity value chain and shape different oil palm business models and their impacts at the landscape scale.”

The Sentinel Landscapes teams are in the final stages of data collection, aiming to provide answers to many questions about the interactions between trees and the environment and trees and people.

“If we can actually quantify what are the environmental and institutional constraints that enable or disable people to value trees in forests and on the farms, then we can give recommendations to policymakers to enable local people as well as politicians to harvest the best benefit out of those trees in landscapes,” Gassner said.

“So by June 2015 we hope to be able to tell you whether a tree is good for you.”

For more information about sentinel landscapes, contact Anja Gassner at or Robert Nasi at

CIFOR’s work on sentinel landscapes forms part of the CGIAR Research Program on Forests, Trees and Agroforestry.

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