Abstract
• Increased soil temperature shortens fine root lifespan. • Warming-decreased soil moisture prolongs fine root lifespan. • Thinner roots, deeper rooting, changed seasonal root emergence under warming. • Warming-induced adjustments in root architecture and phenology affect root lifespan. • C limitation of root respiration under warming indicate reduced root C supply. The mechanisms by which warming affects fine root lifespan remain unclear. In a large-scale soil warming experiment in a Chinese fir plantation, fine root dynamics were monitored for four years using minirhizotrons, and the effects of increasing temperature and co-varying factors on fine root lifespan, such as soil moisture, fine root phenology and architecture, were analysed. Fine root non-structural carbohydrate concentrations and respiration rates were measured to test if fine root lifespan is affected by carbon (C) supply. Warming shortened the overall fine root lifespan by 27.6% (warming vs. control: 197.0 ± 3.5 d vs. 272.0 ± 4.5 d). Cox regression models suggest that increased soil temperature directly and negatively affects root lifespan, whereas decreased soil moisture prolongs root lifespan. Fine roots grew thinner and deeper in warm soil and showed higher emergence in winter but lower emergence in summer; all factors affected the fine root lifespan in an integrated manner. Glucose addition stimulated fine root respiration only in warm soil, indicating a depletion of readily available carbohydrates under warming. Overall, our findings suggest that warming could accelerate the input of C by roots into soil due to shortened fine root lifespans, highlighting the important consideration of simultaneously increasing temperature and its co-varying factors to predict root lifespan under climate change.
Published Version
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