关键词: 功能性状, 根叶性状协同, 资源获取策略, 菌根类型, 土壤性质

Abstract:

Objective: The study aims to investigate differences in root and leaf functional traits of understory woody plants with different mycorrhizal types in subtropical evergreen broad-leaved forests, reveal whether mycorrhizal types influence root and leaf traits, and examine how soil factors affect root and leaf traits in arbuscular mycorrhizal and ectomycorrhizal plants. This research aims to provide a theoretical basis for understanding how mycorrhizal types drive coordinated variations in aboveground-belowground functional traits and the environmental adaptation strategies of plants. Method: Five arbuscular mycorrhizal (AM) and five ectomycorrhizal (ECM) tree species coexisting in a subtropical evergreen broad-leaved forest were selected as the study subjects. Leaf and root functional traits, along with soil properties, were measured and analyzed to clarify the differences in root and leaf functional traits among plants with different mycorrhizal types and to elucidated the relationship between trait variation and soil factors. Result: AM tree species had significantly higher leaf water content, specific leaf area, specific root length, and specific root area, and significantly lower leaf mass per area, leaf carbon content, root tissue density, root branching ratio, branching intensity, and root carbon content than those of ECM species. AM tree species tended to adopt a “low-input, fast-return” resource acquisitive strategy, that is, they rapidly acquired resources through high specific leaf area and low leaf mass per area. ECM species follow a “high-input, slow-return” resource conservative strategy, characterized by low specific leaf area and high leaf mass per area, and they acquired resources more slowly but possessed stronger defensive capabilities. Root trait variation also involved a “do-it-yourself-mycorrhizal investment” collaboration axis, which included independent roots development (high specific root length and specific root surface area) and investment in mycorrhizal symbiosis (high branching intensity and reliance on mycorrhizal symbiosis for resource acquisition). AM species rely on high specific root length and specific root surface area to enhance their root systems’ ability to acquire soil nutrients and water, while ECM species enhance resource acquisition by increasing root branching to promote symbiosis with fungi. The correlations between leaf and root traits were different between the two mycorrhizal types. In AM species, specific leaf area was significantly positively correlated with root branching intensity, reflecting coordinated aboveground-belowground resource acquisition strategies. However, in ECM species, these relationships were mostly non-significant, suggesting a decoupled pattern. Soil factors exerted differential regulatory effects on the allocation of root and leaf traits assembly between the two mycorrhizal types. Under low pH and low inorganic nitrogen conditions, AM species increased specific leaf area and specific root length. Under high pH and low nitrate conditions, ECM species increased root tissue density and branching traits. Soil dissolved organic carbon was positively correlated with specific root length and specific root surface area in AM species (P<0.05), and positively correlated with specific leaf area (P<0.05) in ECM species, and negatively correlated with leaf carbon content in ECM species (P<0.001). Conclusion: The mycorrhizal type derives the differentiation of leaf and root traits along the resource “acquisitive-conservative” economic spectrum and the “do-it-yourself-mycorrhizal investment” collaboration axis. The soil pH and nitrogen availability are key environmental filters modulating root-leaf trait variation.

Key words: functional traits, root-leaf trait coordination, resource acquisition strategy, mycorrhizal type, soil properties