Digging deep – how carbon changes underfoot
- liyuenchiew
- Dec 19
- 3 min read
Updated: 6 days ago
Hello everyone! We’re Dr Nanette Raczka and research assistant Sonia Lee from the TEE Lab. Nanette is an ecologist whose research focuses include plant nutrient acquisition processes and plant-microbial interactions, and Sonia is a research assistant who has an interest in entomology.
Background
A little background into our project – a great challenge lies in quantifying the change in belowground root carbon between land use types such as restored forests and secondary forests, and if this carbon changes with future environmental change. To better understand and quantify this, our project incorporates quantifying above- and belowground biomass across four forest types: open sites filled with resam, restored sites planted with trees, secondary forest, and mature secondary forest. By doing so we can account for variations in carbon stocks between these forests for carbon accounting. We also plan to use this data in the future to parameterize a terrestrial earth system model which will allow us to predict how these belowground carbon stocks will be resilient to future global change scenarios.
Fieldwork
As with most fieldwork in our lab, we trekked far and wide to plots within forests around Singapore. A bonus was that we got to take the ferry across Upper Seletar Reservoir to a few of the more secluded sites, during which we could sit and enjoy the scenery of the reservoir.
We selected plots from each of four ecosystem types – open, restored, secondary and mature forests – and chose trees within each plot which represented the species within those plots. In total, we had 12 plots and 56 trees in this project. At each plot, 5 soil core samples were taken with an 8 cm diameter soil auger approximately 1 meter or less from a representative tree to obtain root biomass down to 10 cm. We also measured the diameter at breast height (DBH) of each tree.
We took it one step further and wanted to track the biotic controls on carbon belowground – so how do roots, fungi, or invertebrates impact the amount of carbon put into the system or taken out of it?
To answer this, we installed tubes with different sizes of mesh called ingrowth cores, each around 5 representative trees per plot for each ecosystem type. Each treatment was placed close to 5 common tree species/families that were dominant across all forest types for ecosystem-level measurements. Treatments consisted of the different size mesh tubes filled with pre-sieved sand/soil mixes with one size allowing roots, all sized invertebrates and fungi to grow into the core, altering the amount of carbon put into or taken out. In the next treatment, a smaller size mesh took away root and large invertebrate access, only allowing small invertebrates and fungi to grow into them. This allows us to track how carbon is cycled and moved within the mesh tube over a set time and separating out the impacts different organisms have on this carbon.
These cores are now resting in the soils, allowing invertebrates, roots and fungal hyphae to move around and influence carbon and nutrient flux for 5 months. Thanks to our collaborator, Ng Jing Cheng, from NUS, we managed to navigate all our sites quickly and safely!
Fun things found in fieldwork
We chanced upon lots of amazing plants and animals during fieldwork, such as a Wagler’s pit viper sitting in the forest taken by Jing Cheng:
A wild species of durian we have here in Singapore (Durio singaporensis), which has golden leaves:
...and some pretty pink mushrooms growing on the trunk of a tree, also taken by Jing Cheng:
Upcoming lab-work:
After 5 months, we will be going back to our sites to retrieve the soil cores. What follows this will be processing the invertebrates, roots and fungal hyphae collected. We will be writing up a blog post following this process much more closely when the time comes, so be sure to keep an eye out on our blog for part 2!
Until then, happy holidays everyone! See you in the new year!
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