Can trees soften the blow of a natural disaster?

Tacloban City in the Philippines was devastated by Tropical cyclone Haiyan

Tacloban City in the Philippines was devastated by Tropical cyclone Haiyan

In November of 2013 one of the strongest-ever tropical cyclones landed on the Philippines’ shoreline. Haiyan practically flattened its epicenter, Tacloban City, killed more than 6,000 people and set the country back an estimated US$ 1 billion in damage to property and infrastructure. Such extreme weather events are among the most dramatic of the phenomena that could worsen with a changing climate.

As agroforestry experts, we must ask in the face of such devastation: Can trees and agroforestry systems enhance resilience to climate-related disasters?

Particularly after cyclone Haiyan, there is renewed interest in the Philippines to better understand the role of trees and forest in disaster-prone environments. We already know, for instance, that mangroves protect coastlines and that forests and agroforests guard against landslides, avalanches and rockfalls, regulate freshwater flow, and control flooding. Forests, in fact, save between US$ 2 to 3.5 billion per year in disaster damage worldwide.

But how can trees in human settlements help in disaster mitigation and recovery?

Research conducted soon after the 2004 Tsunami in Indonesia showed clear influence of coastal vegetation on tsunami wave impact and casualties. Vegetation in front of tsunami-hit settlements reduced casualties by an average 5%; in contrast, dense vegetation behind villages endangered human lives and increased structural damage, from debris carried by wave backwash.

These divergent effects of land cover tell us that the spatial arrangement of coastal vegetation matters, and point to the importance of more research in this area. We should, however, bear in mind that such vegetation, which includes trees, is often an important component of people’s livelihoods and not just a bioshield.

What about the evidence on mangroves and storm surges?

During Cyclone Haiyan, storm surge caused perhaps the worst damage and led to much loss of life in the Philippines.

Recent research has shown that as rule of thumb, for every half a metre reduction in storm surge height, you need a kilometre of dense mangrove. This means that to significantly reduce storm surges in the Philippines (which can reach more than 5 meters during a typhoon), we would need very wide and long bands of mangroves.

Such ecosystem-based disaster risk reduction would involve decision-making that takes into consideration current and future human livelihood needs and bio-physical requirements of ecosystems. And recognizes the role of ecosystems in supporting communities to prepare for, cope with, and recover from disaster situations.

But do farmers appreciate the role of trees?

Recently in the Philippines, we studied whether farmers in one watershed valued the environmental services of trees. These include providing shade, maintaining soil fertility, increasing water resources, maintaining soil moisture, improving the microclimate for crops, and so on.

We were rather shocked to find that up to a half (32% to 50%) of the hundreds of farmers we surveyed mentioned not a single environmental-service benefit of trees!

We asked the same farmers about the tangible economic benefits they got from trees. These include fuelwood, construction materials, and so on. Again, and even more surprisingly, 41% to 63% of the farmers did not mention a single role of trees in this respect.

These results challenge our long-held assumption that farmers value trees. Evidently, we need to show people how important trees are to the environment as well as to their livelihoods, as the entry point to agroforestry adoption. More research in farmers’ perceptions of the role of trees is also needed.

Some of the key research questions we could ask are: What are the barriers the hinder incorporation of trees on farms in areas prone to extreme weather events? Can agroforestry systems help smallholders build resilience against and recover faster from climate-related disasters?

As the climate change community interacts better with the disaster and risk-reduction community, there is a real opportunity to highlight the evidence of the role agroforestry in buffering the impacts of climate-related disasters. An important new player in climate-risk management is the private sector.

How can the private sector partner with scientists in disaster mitigation?

In recent years the private sector has become increasingly concerned about the dangers posed by climate-related disasters to assets and businesses, and is showing more interest in supporting research than ever before.

A case in point is the Lopez Group of companies in the Philippines, which has put forward more than USD 3 million to start a research foundation dedicated to climate and disaster research. We are partnering with one of the foundation’s centres, known the OML Centre—named after the chairman of the Group, Mr. Oscar M. Lopez—whose guiding principle is ‘Science for sustainable development’.

ICRAF has received an OML grant of USD 300,000 for three years initially and we are helping to manage the Centre, which awards research grants, builds networks, fosters capacity building, enables solutions and recognizes scientists’ achievements with prizes.

Last year OML awarded 7 grants for research into topics ranging from food and environmental security to engineering solutions (e.g. a car floatation device), the use of remote sensing and GIS, crowd sourcing apps and mobile apps to help people cope with climate change.

The OML Centre collaborates with many stakeholders, such as the Department of Science at the University of the Philippines, the Climate Change Commission of the Philippines and the Tropical Forest Foundation. And we recently organized a summit for climate change adaptation with CSIRO-Australia.

Resilient ecosystems, of which trees in forests and on farms are an integral part, can support livelihoods, contribute to climate change adaptation, and foster sustainable development.

Through ecosystem-based disaster risk reduction, we can leverage science and partnerships to mitigate climate-related disaster. And when disaster strikes, resilient ecosystems can help people cope and recover better.

By Rodel Lasco, with input from Daisy Ouya

Dr Rodel Lasco is the ICRAF-Philippines coordinator and the scientific director of OML Centre.

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Daisy Ouya

Daisy Ouya is a science writer and communications specialist with the World Agroforestry Centre (ICRAF). Over the past 15 years she has been packaging and disseminating scientific knowledge in the fields of entomology, agriculture, health, HIV/AIDS research, and marine science. Daisy is a Board-certified Editor in the Life Sciences ( and has a Masters’ degree in chemistry from the University of Connecticut, USA. Her BSc is from the University of Nairobi in her native Kenya. She has worked as a journal editor, science writer, publisher, and communications strategist with various organizations. She joined ICRAF in July 2012. Twitter: @daisyouya

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