A new doctoral thesis from the University of Gothenburg examines how climate driven changes in tundra vegetation could alter the region's carbon balance. The tundra's cold soils hold carbon accumulated over thousands of years, but warming is making vegetation taller and greener, which could increase CO2 uptake. At the same time, a shift from slowly decomposing bryophytes to faster decomposing graminoids could release carbon back into the atmosphere more quickly. Researchers analyzed data from nearly 200 tundra sites and found that plant community changes affect how readily dead material breaks down. The net effect is uncertain. If faster decomposition wins, the tundra could become a larger carbon source instead of a sink. The thesis argues that predicting future climate impact requires tracking which plant species dominate, not just overall greenness.
