Soil is the world’s largest natural store of carbon. In the Northern ecosystems especially a lot of carbon is stored, but they are also particularly affected by global warming. A study recently published in the Biology of Climate Change of an international team led by Michael Bahn at the University of Innsbruck investigated how continued warming affects the uptake and release of carbon dioxide in subarctic grasslands. Researchers are using a geothermally active area in Iceland as a natural “climate chamber.”
Subarctic ecosystems store a lot of carbon. As the climate continues to warm, more and more carbon is released into the atmosphere. There are uncertainties about the extent to which the loss of carbon from the soil can be compensated by the arrival of carbon through plant photosynthesis.
“In fact, if warming increases the decomposition of organic matter in the soil and thus the supply of nutrients to plants, then plants should grow better and absorb more carbon dioxide from the atmosphere. ,” said Bahn of the Department of Ecology. “Surprisingly, this may not be the case, as our new study shows.”
Iceland’s geothermal rifts provide ideal conditions for researchers to study the longer-term effects of climate warming on ecosystems in the far north. A team led by Bahn used a geothermally active site in Iceland as part of an international project to study the effect of warming and nitrogen supply on the carbon cycle.
“The research plots are located at different distances from the rift line and, thus, are heated to a greater or lesser extent,” Bahn explained. “By fertilizing part of the plots with nitrogen we were able to study the interactive effects of warming and nitrogen supply on the carbon cycle.”
Warming speeds up the carbon cycle
Warming has led to a massive loss of carbon in the soil. “In our study area in Iceland, up to 40% of the carbon is released into the atmosphere in the first few years after warming,” Bahn said. “In the following years, the microbial biomass adjusted and the carbon balance in the soil returned again.”
To understand the path of carbon in this cycle from the atmosphere through plants and soil and back to the atmosphere, the research team added stable carbon isotopes 13C during the experiment. “Using the isotope, we were able to trace the path of carbon as it moves through the ecosystem,” the ecologist explained. “We observed that with increasing warming, the carbon taken up by plants is transferred more rapidly to microbes and released from the soil faster.
“From fertilization experiments it can be concluded that under warming plants become nitrogen limited. Consequently, the photosynthetic uptake of carbon dioxide in the ecosystem decreases. While warming also accelerates the release of carbon from the soil, the ecosystem’s ability to store carbon is thus gradually reduced.”
Kathiravan Meeran et al, Individual and interactive effects of warming and nitrogen supply on CO2 fluxes and carbon allocation in a subarctic grassland, Biology of Climate Change (2023). DOI: 10.1111/gcb.16851
Provided by the University of Innsbruck
Citation: Team investigates how warming affects carbon dioxide uptake and release in subarctic grasslands (2023, July 18) retrieved July 18, 2023 from https://phys.org/news/2023- 07-team-affects-uptake-carbon-dioxide. html
This document is subject to copyright. Except for any fair dealing for the purpose of private study or research, no part may be reproduced without written permission. Content is provided for informational purposes only.