Trees in forests store carbon. So too, do trees in agroforestry systems. But just how much can agroforestry contribute to mitigating climate change?
Finding an answer to this question is problematic due to a lack of knowledge about the amount of carbon individual tree species store both above and below the ground, especially those grown in smallholder farming systems.
Measuring the carbon content of trees generally relies on laborious techniques that involve cutting down and digging up trees of differing diameters, weighing the biomass of their various components (stems, branches, roots etc.) then translating this into the amount of CO2 sequestered.
With a focus on South Asia, several scientists at the World Congress on Agroforestry shared their research using such techniques to determine the potential of different tree-based systems to mitigate climate change.
“To persuade farmers to plant trees on farms, we need hard data about how it will benefit them,” emphasized Richmund Palma in his presentation on timber yields from bagras (Eucalyptus deglupta Blume). In northern Mindanao in the Philippines, bagras is grown alongside corn in hedgerows. Palma hopes to develop a model for measuring carbon density that can be used to determine which places will be suitable for growing bagras.
Tree plantations can be an important tool for mitigating climate change,” concluded Samritika Thakur after presenting her findings from a study into an abandoned plot of 21 year old Grevillea robusta in Kerala, India which has significant below ground carbon content.
Homegardens too are an important carbon sink, as Mangala Premakumara De Zoysa demonstrated while speaking about how there has been a 22 per cent increase in land under forest cover in Sri Lanka. Homegardens tend to contain indigenous species for many different purposes, so they are helping to conserve biodiversity as well as providing farmers with alternative livelihoods
However, if farmers are to benefit from the carbon they sequester through agroforestry then Payment for Environmental Services (PES) schemes need to be in place, and these rely on sound measurement techniques.
“Research can create basis for a PES Scheme,” said Bao Huy as he explained his work on the indigenous Litsea glutinosa tree which is grown in the Central Highlands of Vietnam together with cassava. While farmers tend to harvest these trees after 4 to 6 years, strong growth and greater carbon sequestration occurs after 10 years.
This session at the Congress provided an insight into just how much research is needed to calculate the carbon stored in smallholder agroforestry systems let alone develop mechanisms that can ultimately reward farmers for growing trees.
Blogpost by Kate Langford
Photo courtesy of USAID
3 People have left comments on this post
This session demonstrated the immense potential of Agroforestry in carbon sequestration. Since the carbon is stored mainly in the top soil, research needs to take into consideration soil and tree management practices of the farmers. This session presented potential indicators for monitoring carbon. These indicators need to be customised for broader application.
PES payment for agroforestry will be very helpful during the growth period. It is not the subsidy, it is for the good service they provide.
Instead of trying to be more exact, even with some approximation is better, instead of nothing.
This measurement job shall be given to Agri / Forestry college students, may be with little payment. Let us all benefit in this process
Already late, need to act fast to improve the tree plantations.
Dear Kate
Good blog, pls check http://www.thetreesolution.com . I wrote a book about carbon farming, you can download it there. I am Pieter Hoff, inventor of the Groasis Waterboxx. With this instrument we can plant deserts, eroded and rocky areas, without irrigaation. Kind regards