This text is part of the special Research section: climate issues
The boreal forest is less lush than the tropical forest, but its soils are much richer. The stumps, trunks, branches, more or less degraded roots, the thousands of species of moss, the peat bogs contain more carbon than the trees themselves. How much ? Mystery.
“We do not have a clear idea of the carbon footprint of the boreal forest, and therefore of its real sequestration capacity. And we know even less about the impact of logging on the carbon contained in the soil, as well as the effect of climate change,” explains Xavier Cavard, professor at the University of Quebec in Abitibi-Témiscamingue (UQAT). and holder of the UQAT-MRNF Research Chair on forest carbon management.
The researcher is therefore at the head of a vast research project to measure the carbon reserves of soils according to the type of forest management. This project is based on the observation that Quebec, due to a lack of knowledge of soil carbon reserves, is not able to exploit the sequestration potential of Quebec’s forests in the form of carbon credits.
“Strangely,” he says, “the forest is not integrated into the Quebec carbon market. Many Quebec issuers buy California credits of dubious quality and poorly controlled, which encourages capital flight. However, forest carbon credits could provide another source of income for this sector, and therefore encourage more sustainable exploitation of forests. »
A complex study
To achieve a total carbon footprint of the forest, it is therefore necessary to measure the carbon in the soil. The idea is excellent. Except that in practice, it’s more complicated than digging a hole with a shovel. Because this study mobilizes almost all disciplines in the natural sciences. We must fight the cold, the snow, the fires and the mosquitoes to prepare the ground and deploy a whole bunch of instruments to accumulate vast series of samples — which must then be modeled and analyzed.
Research must also take into account a wide variety of wood harvesting and silvicultural techniques that vary in varying rates of decomposition and carbon stability in the soil. “Certain plantations will require, for example, mechanical soil preparation, such as scarifying,” explains Xavier Cavard. “This type of plowing promotes plant growth while reducing competition, but it accelerates decomposition and the release of carbon contained in the soil. However, no study considers these two aspects on the same site. »
The diversity of what needs to be studied is impressive. This involves analyzing carbon levels at various depths, measuring the rate of degradation of materials, and quantifying the effect of temperature and the mineral environment on these processes. We must also be able to measure soil respiration, that is to say the exchange of carbon between the soil and the atmosphere resulting from microbial activity and the work of the roots. All this depends on weather events such as droughts, fires, but also less snowy winters, for example.
The UQAT Forest Research Institute, of which Xavier Cavard is a part, is the largest group of its kind outside Laval University. Its director, Nicole Fenton, collaborates on her colleague’s research project as a bryophyte specialist. These mosses, described by the more technical terms “sphagnum”, “liverworts” and “anthocerotes”, form a very important part of forest biomass. “That represents thousands of species,” she said. It is the largest group of land plants after flowering plants. »
These very diverse mosses constitute a green carpet in the forest which influences the interaction with the surface in particular by stabilizing the temperature and capturing a lot of water. If climate change or forest management modifies the type of moss, what will be the result on the carbon footprint? “We are therefore going to study the effect of reducing the snow cover on moss,” explains Nicole Fenton. I have a Nepalese student who is due to arrive to work there. I haven’t told her yet, but she’s going to shovel snow all winter to thin the snow cover. »
Ultimately, Xavier Cavard, with the help of his colleagues, hopes to be able to establish various reference scenarios depending on the type of logging and silvicultural development in various contexts: natural regrowth, accelerated regrowth, fires, drought, etc.
“Currently, the way we manage the forest is done according to an ecosystem logic, that is to say we try to reproduce natural disturbance patterns. » But is ecosystem planning compatible with carbon planning? Does this approach really promote carbon sequestration, or should we try something else? “We don’t know yet, but we want to be able to show what good practices would be. »
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