川南地区毛竹和林下植被芒箕细根分解特征

揭示竹林与其林下植被细根单独和混合分解特征,探讨竹林细根与其林下植被细根之间相互影响的潜在机制,为毛竹林林下植被的合理经营管理提供理论参考。采用原位分解袋法研究了四川长宁毛竹(Phyllostachys edulis)与林下植被芒箕(Dicranopteris pedata)细根分解和养分释放过程,试验周期为1年。结果表明(1)毛竹和芒箕细根初始化学组分有着明显差异,碳(C)含量、碳氮比(C/N)和碳磷比(C/P)毛竹显著高于芒箕(P0.05),而氮(N)含量、磷(P)含量和氮磷比(N/P)均芒箕高于毛竹(P0.05)。(2)毛竹和芒箕细根分解系数(k)分别为0.66±0.04和0.42±0.41,毛竹细根分解速率显著高于芒箕;土壤温度与分解速率呈显著正相关,是影响细根分解速率的关键环境因子。(3)毛竹和芒箕细根碳(C)、氮(N)、磷(P)养分释放均表现为净释放,毛竹细根碳(C)释放速率高于芒箕,但细根氮(N)和磷(P)释放率均低于芒箕。(4)混合分解的实测值和期望值对比结果表明毛竹和芒箕细根混合对分解速率和磷(P)元素的释放没有显著影响,但显著促进了碳(C)元素的释放,抑制了分解初期氮(N)元素的释放。毛竹与林下植被芒箕单独细根分解和养分释放特征均表现不同;细根混合分解速率无显著混合效应,但养分释放的混合效应表现出不同阶段性和不同方向(正或负),说明林下植被通过影响细根养分释放而影响竹林生态系统的养分循环。

Decomposition characteristics of the fine root of Phyllostachys edulis and Dicranopteris pedata in southern Sichuan

This study revealed the single and mixed decomposition characteristics of fine roots in bamboo forest and its understory vegetation, explored the potential mechanisms of interaction and function between them,and provides a theoretical reference for the rational management of understory vegetation in Moso bamboo forest. The fine-root in situ decomposition and nutrient release processes of Phyllostachys edulis and understory vegetation (Dicranopteris pedata) in Changning, Sichuan, were investigated using a litter bag, and our test period is 1 year.Our results showed that (1) the initial chemical components of the fine roots of P. edulis and D. pedata were significantly different. The C content and C/N and C/P ratios of P. edulis were significantly higher than those of D. pedata (P < 0.05), while the N content, P content, and N/P ratio of D. pedata were all higher than those of P. edulis (P < 0.05). (2) The decomposition coefficients (k) of P. edulis and D. pedata were 0.66±0.04 and 0.42±0.41, respectively. The rate of fine-root decomposition of P. edulis was higher than that of D. pedata. The soil temperature was positively correlated with the decomposition rate, and it was the key environmental factor affecting the decomposition rate of fine roots. (3) The C, N, and P nutrients showed a net release, and the release rate of C in P. edulis was higher than that in D. pedata, while the release rates of N and P in D. pedata were higher than those in P. edulis. (4) The fine-root mixtures of P. edulis and D. pedata had no significant effect on the decomposition rate and release of P, but significantly promoted the release of C and inhibited the release of N at the initial stage of decomposition. The characteristics of single fine-root decomposition and nutrient release were different between P. edulis and D. pedata. No significant mixed effect of decomposition rate was observed, but the mixed effect of nutrient release showed different stages and directions (positive or negative). The understory vegetation affected the nutrient cycle of the bamboo forest ecosystem by affecting the release of nutrients from the fine roots.