carbon-cycling
Carbon cycling refers to the continuous movement of carbon through Earth's atmosphere, soil, water, and living organisms via processes like photosynthesis, respiration, and decomposition. Plants are central to this cycle, acting as primary carbon fixers that convert atmospheric CO2 into organic matter, making them critical regulators of global carbon balance. Understanding how plants influence and respond to carbon cycling informs research on climate change mitigation, ecosystem productivity, and soil carbon sequestration.
open_in_new WikipediaPubMed · 2026-04-11
Cutting winter rainfall in half causes soil microbes to nearly stop growing after summer drought ends, even though they keep releasing CO2 at normal rates. This decoupling means less carbon gets locked into the soil as microbial biomass, and the soil's organic matter shifts toward harder-to-decompose plant material.
Microbial growth dropped by approximately 10-fold (one order of magnitude) in soils receiving 50% of normal rainfall, while respiration rates remained unchanged.
Microbial mortality declined by roughly 100-fold (two orders of magnitude), meaning far less nutrient-rich microbial necromass was cycling through the soil.
Soil organic carbon shifted away from microbial-derived compounds (lipids, amino sugars, proteins) toward oxidized, plant-derived compounds like lignin and tannins, indicating reduced soil fertility building.