陈永康 谭许脉 李萌 徐浩成 莫雪青 肖纳 尤业明 黄雪蔓 温远光 朱宏光

摘 要：該研究以二代巨尾桉/降香黄檀混交林（MP）作为研究对象，并以邻接的二代巨尾桉纯林（PP）作为对照（CK），采用磷脂脂肪酸（PLFAs）和土壤酶活性分别表征土壤微生物群落结构和功能，重点探究南亚热带PP引入降香黄檀混交种植对土壤微生物群落结构和功能的影响。结果表明：（1）与PP相比，MP的土壤有机碳（SOC）、总氮（TN）、铵态氮（NH4+-N）、硝态氮（NO3--N）和pH值分别显著或极显著增加了61.92%（P<0.05）、60.12%（P<0.05）、72.87%（P<0.01）、488.49%（P<0.01）和15.97%（P<0.05）;（2）MP的真菌/细菌（F/B）显著降低，但总微生物生物量、革兰氏阴性菌/阳性菌（G-/G+）并无显著变化;（3）MP的土壤微生物群落组成发生了显著变化，而pH值、NH4+-N和凋落物质量（C/Nlitter）是驱动其微生物群落组成发生变异的最显著性因子;（4）MP的β-葡萄糖苷酶（BG）和N-乙酰-葡萄糖苷酶（NAG）活性显著提高，而过氧化物酶（PER）活性显著降低，酚氧化酶（PO）和酸性磷酸酶（ACP）活性没有显著变化。该研究说明在连续短周期经营的桉树林中套种固氮树种降香黄檀，将可能是提高桉树林土壤质量的一种有效的经营管理措施。

关键词：桉树人工林，固氮树种，土壤养分，土壤微生物群落结构，土壤酶活性，南亚热带

中图分类号：Q948

文献标识码：A

文章编号：1000-3142（2021）09-1476-10

Abstract：In this study，the mixed second-generation Eucalyptus urophylla and Dalbergia odorifera plantation （MP）was taken as our object，and the adjacent pure second-generation E. urophylla plantation （PP）was taken as the control （CK）. We used phospholipid fatty acids （PLFAs）as biomarkers to assess soil microbial community composition and measured soil enzyme activity as an indicator of soil microbial function. We focused on the effects of mixing N-fixing species with E. urophylla on soil microbial community composition and function in subtropical China. The results were as follows：（1）Soil organic carbon （SOC），total nitrogen （TN），ammonium nitrogen （NH4+-N），nitrate nitrogen （NO3--N）and pH in MP were significantly or extremely significantly increased by 61.92% （P<0.05），60.12% （P<0.05），72.87% （P<0.01），488.49% （P<0.01）and 15.97% （P<0.05）compared with that in PP，respectively. （2）The ratios of fungal-to-bacterial biomass （F/B）were significantly lower in MP than that in PP. However，there were no significant differences between the PP and the MP in total PLFAs and the ratios of gram-negative bacteria to gram-positive bacteria （G-/G+）. （3）The soil microbial community structure was significantly differed between MP and PP，and we found that the soil microbial community structure is strongly influenced by the variations of pH，NH4+-N and ratios of organic carbon to total nitrogen in litter （C/Nlitter）. （4）The activities of β-glucosidase （BG）and N-acetyl-glucosidase （NAG）involved in soil carbon and nitrogen transformation were significantly higher，but the activities of peroxidase （PER）were lower in MP than that in PP. Nevertheless，the differences in phenoloxidase （PO）and acid phosphatase （ACP）activities were not significant between MP and PP. The results indicate that interplanting of nitrogen-fixing species in Eucalyptus plantations may be an effective management measure to improve soil quality in subtropical region.

Key words：Eucalyptus plantation，N-fixing species，soil nutrient，soil microbial community structure，soil enzyme activity，south subtropical

桉树具有生长速度快，适生于酸性红壤和木材用途广等特点，因此在我国水热条件均佳的热带、亚热带地区被广泛种植。目前，我国桉树的种植面积约为450万hm2，约占全国林地面积的1.4%，每年的木材产量约为3 000万m3，约占全国木材年产量的26.9%，在满足社会对木材的迫切需求和应对全球气候变化等方面发挥着重要作用（中国林学会，2016;温远光等，2018;陶彦良等，2018）。然而，在土地资源短缺、木材供需紧张的情况下，种植单一树种并采用短周期的经营模式往往会导致土壤肥力衰退、林下生物多样性锐减、水土流失严重以及生态系统功能急剧退化等生态问题的产生（Huang et al.，2014，2017），这已成为众多国内外科学家尤其是林业生态学家们普遍关注和亟待解决的问题。

固氮树种的根系能够与固氮菌共生，利用固氮菌的持续固氮作用提高土壤氮的含量及其有效性（Huang et al.，2014）。……