Trees Can Help Save the World – Chapter 5
Watch complete playlist (Chapters 1-7) https://www.youtube.com/playlist?list=PLeR2DZtnlTQtik4SxT9unDrVP5Gu2aEPb
For more information about the Canadian Agricultural Greenhouse Gases Program, visit: http://agr.gc.ca
To contact researchers:
In the previous chapters of this video series you’ve seen how Canadian researchers are quantifying how trees reduce greenhouse gas emissions in farm fields.
Funded by Canada’s Agricultural Greenhouse Gases Program, the research project focuses on tree- based intercropping systems in Ontario and Quebec. Intercropping involves planting trees in rows and planting farm crops in the alleys between the rows of trees.
Here at the University of Guelph intercropping site, researchers are busy collecting samples for a number of different research studies.
Daniel Jefferies is a graduate student at the University of Guelph. He’s here to collect soil samples to study the relationship between soil structure and greenhouse gas emissions. The research focuses on the soil under four tree species: red oak, black walnut, Norway spruce and hybrid poplar.
X-ray computer tomography is used to closely study the structure of the soil under these trees. Dr. Richard Heck and his team are investigating how pores in the soil can affect the emission of greenhouse gases.
Dr. Heck: One of the most significant dimensions that structure brings to this equation is the nature of the porosity and whether or not those pores may be filled with air or water thereby determining to what extent aeration is going to be taking place and how quickly organic matter could potentially be turned over.
Here at the intercropping site, trees and crops are flourishing, thanks to good soil structure. Deep in the soil, there are networks of pores or void spaces that facilitate the flow of air and carbon.
Jefferies: Soil is seen as a sink for carbon and depending on the access to oxygen organisms may be releasing more carbon than actually is being stored or it could be vice versa. So the void space plays an important role in that relationship.
Dark void spaces can be clearly seen in these images captured by X-ray computer tomography.
Jefferies: And so the bright stuff we’re seeing in the image is more dense material, whereas the darker areas are the least dense. And so when I’m referring to void space, I’m referring to the areas that are the darker, black areas and the bright whitish areas, that’s the soil solid phase.
The bulk of their work is interpreting these images.
Jefferies: We use software called Imaging J. It’s open source software, so many developers around the world contribute to it. And we use that to identify different aspects of the soil, quantifying the amount of void space, the connectivity of void space. We can look at the variability of the soil in terms of its density for example, which is essentially what the X-Rays are seeing.
The software produces a three dimensional view of images that were captured using the X-Ray computer tomography machine.
Jefferies: So we have the X and the Y axes, but we can rotate the sample to also view the Z direction, so down into the sample as if we were digging a hole.
This research could reveal that more void spaces in the soil can result in lower greenhouse gas emissions
Jefferies: I think soil void space has a relationship to how carbon is stored in the soil. And perhaps there could be a relationship between a greater void space and carbon sequestration.
Their research has revealed that the soil under some species of trees has more small void spaces. Jeffries found distinct differences between hybrid poplar and Norway spruce.
Jefferies: Underneath these trees I’ve found that poplar has a greater proportion of its soil volume represented by void space and also has a greater connectivity in the soil structure.
The research indicates that the structure of soil can play an important role in reducing greenhouse gas emissions.
The tree-based intercropping project brings together many scientists working toward a common goal – to quantify how trees can reduce greenhouse gas emissions in farm fields.
Dr. Heck: As a soil scientist who has spent quite a number of years studying the structure of soils, certainly it is a wonderful opportunity to be able to bring this in a quantitative way into an interdisciplinary study such as this one which has significant implications in greenhouse gas production.