杉木叶片内生真菌定殖对凋落物分解及其微生物活性的影响

【背景】植物内生真菌在植物组织由衰亡转入腐生过程中发挥重要的作用,但这种作用可能因植物及其内生真菌种类不同而具有差异。【目的】分析不同优势度种类内生真菌定殖对于凋落物分解及其相应微生物活性的影响。【方法】采用凋落物分解袋法,选取优势树种杉木凋落叶作为分解底物。【结果】不同优势度类型的内生真菌单菌或组合定殖在分解过程前期几乎均显著加速了凋落物分解,而在分解后期,除了Irpex lacteus和Colletotrichum sp.,这种加速效应几乎均在减弱,甚至抑制了分解过程。微生物活性各变量对内生真菌定殖处理的响应与失重率并不完全一致,这依赖于分解时期。CO2释放速率在前期与失重率相关性不强,而后期则密切相关;分解前期羧甲基纤维素酶(carboxymethylcellulase,Cx酶)对失重率贡献较大,然而后期漆酶与过氧化物酶对失重率的贡献升高。总之,内生真菌定殖对凋落物分解及相应的微生物活性均产生了较大影响。【结论】对内生真菌定殖效应的研究有助于人们对森林生态系统土壤碳库平衡和养分循环维持机制的理解,同时对于贫瘠人工林土壤肥力的恢复研究也具有重要的意义。

Effects of colonization by endophytic fungi of Cunninghamia lanceolata leaves on litter decomposition and associating microbial activities

Background] Plant endophytic fungi begin to play an important role in litter decomposition with the death of plant tissues into the saprophytic process. However, this effect may vary with plant species and endophytic fungi species. Objective] in order to analyze the effects of endophytic fungi with different dominance on litter decomposition and associating microbial activity. Methods] Leaf litters of Cunninghamia lanceolata were selected in this study as the decomposition substrate with litterbag method. Results] The colonization of endophytic fungi or their combinations almost significantly accelerated litter decomposition at the former stage of decomposition process, but at the later stage this acceleration effect was weakened, and even their colonization inhibited the decomposition process except Irpex lacteus and Colletotrichum sp. The responses of each variable of microbial activity to endophytic colonization were not completely consistent with the mass loss, and these responses depended on decomposition stage. CO2 releasing showed a poor correlation to mass loss at the former stage of decomposition, but a close correlation at the later stage. Carboxymethyl cellulose (Cx enzyme) greatly contributed to mass loss at the former stage of decomposition, but the contributions of laccase and peroxidase to mass loss were improved at the later stage. In a word, the colonization of endophytic fungi had a great influence on litter decomposition and associating microbial activities. Conclusion] The colonization effect of endophytic fungi will contribute to the understanding of the mechanism on supporting soil carbon pool balance and nutrient cycle of forest ecosystem, and is of great significance for studying the restoration of soil fertility in barren plantation.