Effects of warming on root diameter, distribution, and longevity in an alpine meadow

Abstract

Roots form one of the most important carbon (C) pools in alpine ecosystems. Uncertainty about the effects of warming on root dynamics limits our ability to predict how C will transfer between biological and atmospheric pools in alpine regions under global warming. We used a minirhizotron technique to gain a better understanding of the response of alpine plant roots to warming. We looked for effects on root diameter, root depth in the soil, and root lifespan under a controlled asymmetrical warming (1.2/1.7 °C during daytime/nighttime) experiment during the growing season of 2009 in an alpine meadow on the northern Tibetan plateau. Roots became smaller in diameter, moved toward the upper soil layers, and showed significantly shorter lifespans in heated (H) than in unheated (UH) plots. Furthermore, in H treatment plots root lifespan was more strongly influenced by the time of root emergence rather than by root diameter. These results provide evidence that alpine plants may respond to climate change by altering their roots so that they are thinner, distributed shallower and turning over faster, suggesting that soil C flow and nutrient cycling would be accelerated resulting from the fast turnover of fine roots under elevated temperatures.