亚热带天然常绿阔叶林转变为杉木人工林对土壤微生物呼吸的影响

Effects of the Conversion of Natural Evergreen Broadleaved Forest into Chinese fir (Cunninghamia lanceolata) Plantation on Soil Microbial Properties in Subtropical China

对福建省万木林自然保护区天然常绿阔叶林及其转变后的杉木林表层（0～10cm）和底层（40～60cm）土壤可溶性有机碳（DOC）、可溶性总氮（DN）、微生物生物量碳（MBC）、微生物生物量氮（MBN）、微生物呼吸（BR）及呼吸商（qCO2）进行研究，来分析亚热带森林转换对土壤微生物呼吸及土壤碳库质量的影响。结果显示：同一林分中，表层土壤的DOC、DN、MBC、MBN含量和BR均高于底层土壤，而土壤表层的qCO2却低于底层土壤。同一土层中，天然林转变为杉木林导致土壤DOC、DN、MBC、MBN含量和BR均降低，而qCO2却升高了。综上所述，底层土壤的土壤有机碳质量低于表层土壤，土壤微生物碳利用效率较低；天然林转变为人工林则导致土壤有机碳质量降低，土壤微生物碳利用效率降低。

In order to analyze the influence of forest conversion on soil microbial respiratory and soil carbon quality, we measured the content of soil dissolved organic carbon （DOC） , dissolved total ni- trogen （DN）, microbial biomass carbon （MBC）, microbial biomass nitrogen （MBN） and microbial respiration （BR） and respiratory quotient （ qCO2 ） in the topsoil （0 - 10 cm） and subsoil （40 - 60 cm） of a natural evergreen broadleaved forest and a Chinese fir plantation in Wanmulin Nature Re- serve, Jian＇ou, Fujian Province. The results showed that for the same stands, the topsoil had higher DOC, DN, MBC, MBN and BR, but lower qCO2 than the subsoil. For the same soil depth, Chi- nese fir （Cunninghamia lanceolata） stand had lower soil DOG, DN, MBC, MBN and BR, but high- er qCO2 than the natural forest. It can be concluded that the subsoil has lower soil carbon quality andmicrobial carbon use efficiency than the topsoil, showing that such forest conversion would decrease soil carbon quality and microbial carbon use efficiency.