Abstract: Abstract Aims This study aims to reveal the effects of climate warming on the growth and morphological characteristics of fine roots in subtropical evergreen broad-leaved forests in China. Methods An in-situ soil warming experiment was conducted at the Fujian Sanming Forest Ecosystem National Observation and Research Station. The effect of soil warming on the growth and morphological characteristics of absorptive and transport roots in evergreen broad-leaved natural forests during the rainy season (May) and dry season (November) were investigated by using the in-growth core method. Imortant findings Compared with the control, during the rainy season, the warming treatment significantly reduced the growth of absorptive roots by 41.2%, and there was no significant change in the growth of transport roots. There was no significant change in the diameter and length of absorptive and transport roots. The absorptive roots SRL and SRA were significantly reduced by 53.2% and 42.9%, respectively, and the absorptive roots RTD was significantly increased by 28.8%; During the dry season, warming treatment significantly increased the growth of absorptive roots, transport roots and fine roots. The length of absorptive and transport roots increased by 38.5% and 33.5%, respectively. However, there were no significant changes in the diameter, SRL, SRA, and RTD of absorptive and transport roots. Evergreen broad-leaved forests in mid-subtropical areas show strong adaptability to future warming. During the rainy season, fine roots exhibit higher plasticity, mainly by adjusting the characteristics of absorptive roots to reduce the effect of warming on the resource absorption and growth of fine root; during the dry season, fine roots adopt a relatively conservative defense strategy, mainly by increasing the length of absorptive and transport roots to expand resource absorption space. This study provides a scientific basis for investigating the ecological adaptation mechanisms and resource acquisition strategies of fine roots with different functions in subtropical forest ecosystems under global warming scenarios.

Key words: soil warming, mid-subtropical, natural forest, fine root growth, morphological character, functional traits