海南儋州橡胶林下土壤微生物功能研究
Soil Microbial Functions of Rubber Plantation in Danzhou, Hainan Island

对海南儋州地区种植5 a（幼龄林）、10 a（中龄林）和25 a（老龄林）的橡胶林、30 a桉树人工林、海南热带次生林的土壤微生物功能多样性进行研究。结果表明，橡胶林与桉树林和热带次生林相比，5种不同微生物功能之间差异并不显著；不同林龄橡胶林之间，微生物在旱季的呼吸作用、雨季的氨化作用、旱季-雨季和雨季的硝化作用以及3个季节中的固氮作用差异性极显著，并且均是中、幼龄林强于老龄林；微生物功能作用受季节变化影响明显，从旱季进入雨季，纤维素分解作用是逐渐增强，氨化作用基本不变，呼吸作用呈现明显先下降后上升的过程，而硝化作用和固氮作用则是明显的下降；在0~30 cm深的土层内，微生物纤维素分解作用、呼吸作用、硝化作用和固氮作用的强度随深度逐渐降低，氨化作用的强度逐渐增强，但是0~10、10~20 cm和20~30 cm这3个土层之间土壤微生物功能强度差异不显著。
Rubber plantations with the ages of 5 a（young）, 10 a（middle-age) and 25 a（old），as well as a 30 year-old eucalyptus plantation, and tropical secondary forests were selected to investigate the vertical variations of the soil microbial diversity in Danzhou, Hainan island. No significant differences were observed in microbial functions of five different soils. Among the soils of the rubber plantations with different ages, significant differences were found in the respiration in dry season, the ammoniation in rainy season, the nitrification in dry-wet season and rainy season, and the nitrogen fixation in three seasons. The functions mentioned above were all stronger in the soils of young plantations than old ones. Microbial functions significantly influenced by the changing seasons: entering the rainy season from dry season, cellulose decomposition increased, the ammoniation unchanged, the respiration underwent down and up procedure, and nitrification and nitrogen fixation obviously decreased. Within 0 to 30 cm deep soil, microbial cellulose decomposition, respiration, nitrification and nitrogen fixation strength gradually reduced, the strength of the ammoniation gradually increased, but the differences in soil microbial functional intensity were not significant among the layers of 0-10, 10-20, and 20-30 cm