Issue 6: May 2010

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Our feature story in this issue highlights how the study of tree rings and the stable isotopes they contain is helping us to learn more about how trees adapted to past climate and environmental changes. We have produced a new manual for molecular markers, a working paper with insights into the viability of biofuels in East Africa and have been active in showcasing our work through events for the International Day of Biodiversity and scientific meeting of the UNFCCC.

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Uncovering the past with trees
Uncovering the Past with trees

Aster and colleagues collect samples from dead tree stumps for tree ring analysis in Burkina Faso

Tree rings are providing insights into past fluctuations in climate and may hold key information about how trees will cope with what lies ahead.

“Knowledge of the past is a must in order to make predictions about the future and adapt to climate change,” says Aster Gebrekirstos, Post Doctoral Fellow at the World Agroforestry Centre and Göttingen University, Germany.

“By learning more about the way plants responded and adapted to their environment and changes in climate in the past, we can better determine which species will grow best under future climatic conditions.”

In working towards this, Aster has been studying the growth patterns in tree stems; an area of science known as dendrochronology. In addition to a study site in Ethiopia, Aster has been able to add sites in Burkina Faso and Tanzania through a climate change adaptation initiative of BMZ/GTZ.

Dendrochronology can give a picture of what past climates were like because the growth of tree rings depends mainly on temperature in temperate regions, and on the amount and distribution of rain in the tropics.

Taking this one step further and measuring the stable carbon and oxygen isotopes that are present in the tree rings provides further insights into several tree species in semi-arid Africa. These isotopes react differently to different physical conditions, making them extremely useful in studying the interactions among plants, climate and the environment. For example, in drought years trees form narrow rings and have greater amounts of the heavier carbon isotope d13C compared to ‘normal’ or moist years.

“We are able to see how tolerant certain agroforestry species have been to drought, how efficiently they use water, and better understand the relationship between tree growth and climate,” Aster explains.

“This is valuable information that will inform decisions about the right tree species for the right place, a key catch-cry of the World Agroforestry Centre.”

Aster’s research has been able to prove that the Ethiopian climate is affected by the El Niño southern oscillation. With only 30 years of climate data available from  her study site, Aster used tree ring analysis to create a climate chronology that dates back more than 70 years. Her chronology shows recurring droughts (marked by narrow tree rings) every 2 to 8 years.

“Results such as these have important implications for early warning systems to avoid or minimize loss of human lives due to drought,” Aster highlights.

She hopes her work will lay the foundation for a model that can be used to investigate the long-term climate history across eastern and western Africa.

Story by Kate Langford
Getting molecular genetic studies right

A new technical manual, Molecular Markers for Tropical Trees: Statistical Analysis of Dominant Data, has been developed by the World Agroforestry Centre to help molecular laboratories in developing countries ensure their data sets on molecular markers are effectively handled and analyzed. Molecular markers are used to determine patterns of genetic diversity of a tree species.

Measuring carbon in complex landscapes with trees

At a side event during the scientific meeting of the UNFCCC on 7 June 2010 the Centre will present case studies on carbon measurement from Africa, Latin America and Southeast Asia. The event will look at the challenges in choosing the right tools and methods for the context, ensuring measurements are accurate, statistically relevant, and can be scaled up.

Slowing the losses

According to the 7 April 2010 issue of The Economist, efforts to slow the world's rate of deforestation are working. The article cites early results from FAO’s Global Forest Resources Assessment 2010 and quotes World Agroforestry Centre scientist, Andreas Wilkes on the situation in China. It warns that while new forests can be planted with trees well suited to the market and in convenient places, they are inferior to old forests in terms of biodiversity and carbon storage.

Are Biofuels worth the investment in East Africa?

A new study shows that investment in jatropha for biofuel in n orthern Tanzania is still a risky and long-term investment, with insecure prospects and high opportunity costs. The authors suggest that the traditional way of growing jatropha in hedgerows, combined with local processing of oil for local use, is viable for rural communities in the short-term.

New vision needed for biodiversity conservation

Growing high priority fruits and nuts and how the nutritious Moringa tree can help to combat malnutrition formed the basis of a display at the National Museum of Kenya on 22 May to celebrate International Day for Biological Diversity. The theme for the day this year was Biodiversity for Development and Poverty Alleviation.


Transformations is produced by the World Agroforestry Centre Communications Unit.
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