毛竹林和阔叶林凋落物互置对土壤氮矿化的影响及微生物贡献

凋落物输入方式的改变导致凋落物数量和质量发生变化，进而对森林土壤氮矿化产生影响。选择未被入侵的次生阔叶林和毛竹入侵后形成的毛竹纯林为对象，对地表凋落物进行保留、去除与置换处理，采用室内培养法同时添加抗生素(链霉素和放线菌酮)分析真菌和细菌在土壤氮素矿化中的贡献。结果表明：(1)去除凋落物处理使阔叶林土壤净氨化速率增加27.0%,净硝化速率降低11.4%;毛竹林土壤净氨化速率增加23.4%。(2)置换凋落物处理使阔叶林土壤净氨化速率增加43.8%,净硝化速率降低33.5%;毛竹林土壤净硝化速率增加73.1%。(3)添加抗生素后，凋落物置换处理与对照相比，置换凋落物后阔叶林土壤真菌和细菌在净氨化中发挥主要作用；真菌在两种林分土壤净硝化中发挥主要作用，细菌在阔叶林土壤净硝化中发挥主要作用。(4)结合测定的凋落物化学性质可知，置换凋落物后引起真菌和细菌在土壤氮素矿化中贡献发生变化，是由于输入凋落物中木质素和纤维素含量的变化。综上，凋落物去除和置换改变了土壤氮素矿化速率，置换凋落物后改变了真菌和细菌对土壤氮素矿化的贡献。解析凋落物质量在土壤氮素矿化中的作用及微生物群落的相对贡献，有助于阐明毛竹入...

Effects of exchanging litters on soil nitrogen mineralization and microbial contributions in Moso bamboo (Phyllostachys edulis) and broad-leaved forests

The type of litter input led to change in litter quantity and quality, which ultimately affected the nitrogen (N) mineralization in the forest soil. We chose two types of forest stand, (I) uninvaded secondary broadleaved forest and (II) the bamboo forest formed after Moso bamboo (Phyllostachys edulis) invasion, which was selected to retain, remove and replace the surface litters. The antibiotics (streptomycin and actinone) were added in the incubation experiment to analyze the relative contribution of fungi and bacteria to soil N mineralization. The results showed that after removal of litters, soil net ammonification rate increased by 27.0%, and net nitrification rate decreased by 11.4% under the broadleaved forest; moreover, net ammonification rate increased by 23.4% under Moso bamboo forest. In litter replaced treatments, the net ammonification rate increased by 43.8% and the net nitrification rate decreased by 33.5% under broadleaved forest; the net nitrification rate increased by 73.1% under bamboo forest. However, after adding antibiotics, soil fungi and bacteria played a significant role in soil net ammonification in the broadleaved forest compared with the control. Fungi played an influential role in soil nitrification under two forest stands, and bacteria played a major role in soil nitrification in the broadleaved forest. Finally, along with the chemical properties of litters, the alteration of contribution of fungi and bacteria to soil N mineralization was caused by the replacement of litters, which was directly related to lignin and cellulose content in litters. In conclusion, the removal and replacement of litters could change the rate of soil N mineralization, and the replacement of litters altered the contribution of fungi and bacteria to N mineralization in the forest soils. Our study provides a theoretical basis to elaborate underground ecological mechanism of Moso bamboo invasion into the broadleaved forest.