【摘要】 【目的】探究毛竹向杉木林和阔叶林扩张过程中毛竹及原有森林优势种的细根分解特征、养分动态及主要影响因素，揭示毛竹扩张对森林地下碳周转和养分循环的影响机制。【方法】在幕阜山区选择毛竹向杉木林和阔叶林扩张形成的连续生态界面（杉木林→竹杉混交林→毛竹林；阔叶林→竹阔混交林→毛竹林），采用原位与异位分解相结合的方法，探讨2种毛竹扩张序列中的杉木、喜树、毛竹细根分解干质量剩余率及C、N、P含量变化动态。【结果】喜树细根的初始C含量、C/N、C/P、N/P显著低于杉木和毛竹（P<0.05），初始N、P含量显著高于杉木和毛竹（P<0.05），杉木和毛竹二者间无显著差异（P>0.05）。在毛竹向杉木林扩张序列中，毛竹细根分解速率以及C、N、P释放速率均高于杉木细根，且毛竹细根阶段性干质量损失率与土壤温度呈显著正相关。在毛竹向阔叶林扩张序列中，喜树细根分解速率显著高于毛竹（P<0.05），且毛竹细根分解速率随扩张强度增加显著增加，呈明显主场效应。与毛竹细根相比，喜树细根具有较高的C释放速率、较低的N释放速率，P释放速率相差不大。【结论】毛竹扩张一定程度上可促进杉木和喜树细根分解，但细根养分释放特征因扩张森林类型不同而存在差异。细根初始化学性质是调控毛竹向杉木林和阔叶林扩张过程中细根分解和养分释放的主要因素，毛竹细根分解在毛竹向阔叶林扩张序列具有明显主场效应。更多还原

【Abstract】 【Objective】This study aimed to understand the fine root decomposition characteristics, nutrient dynamics, and main influencing factors during the expansion of Phyllostachys edulis into Cunninghamia lanceolata forest and broad-leaved forest. The goal was to reveal the mechanisms underlying the effects of bamboo expansion on belowground carbon turnover and nutrient cycling in forest.【Method】Utilizing continuous ecological interfaces formed by P. edulis expansion into C. lanceolata forest(C. lanceolata forest → bamboo and fir mixed forest → P. edulis forest) and broad-leaved forest(broad-leaved forest → bamboo and broad-leaved mixed forest → P. edulis forest) in the Mufu Mountain area, we combined in-situ and ex-situ decomposition methods to investigate the dry mass residual rate and the dynamics of carbon(C), nitrogen(N), and phosphorus(P) content in the fine roots of C. lanceolata, Camptotheca acuminata, and P. edulis along these two expansion sequences.【Result】The initial C content, C/N ratio, C/P ratio and N/P ratio of C. acuminata fine roots were significantly lower than those of C. lanceolata and P. edulis(P<0.05). Conversely, its initial N content and P contents were significantly higher than those of them(P<0.05). However,there were no significant differences in these initial elemental traits between P. edulis and C. lanceolata. In the sequence of the expansion of P. edulis into C. lanceolata forest, the decomposition rate of P. edulis fine roots and their C, N and P release rates were significantly higher than those of C. lanceolata(P<0.05). The decomposition rates of fine roots for both species did not change significantly with increasing bamboo expansion intensity. The phased dry mass loss rate of the moso bamboo fine root was positively correlated with soil temperature. In the sequence of the expansion of P. edulis into broad-leaved forest, the decomposition rate and C, N, P release rates of C. acuminata fine roots were significantly higher than those of P. edulis(P<0.05).P. edulis fine roots decomposition accelerated with increasing expansion intensity, exhibiting a home-field advantage.C. acuminata roots released C faster but N more slowly than P. edulis roots, while P release showed no significant difference between the two species.【 Conclusion】 P. edulis expansion enhanced the fine root decomposition of C. lanceolata and C. acuminata to some extent. However, the patterns of nutrient release from fine roots varied significantly between the two expanded forest types. Initial fine root chemical traits were identified as the primary factor regulating fine root decomposition and nutrient release during bamboo expansion into both C. lanceolata forest and broad-leaved forest. Notably, P. edulis fine roots exhibited a distinct home-field advantage effect along the expansion sequence into broad-leaved forest.更多还原