【目的】 Bt棉已在我国种植广泛。而温室气体（CO₂和O₃）浓度升高会进一步改变植物的化学成分，从而通过凋落物可能会引起土壤动物（甲螨）种群数量的变化。【方法】 本文应用开顶式气室（OTC），研究了CO₂和O₃浓度升高下转Bt棉花凋落物对土壤甲螨种群数量的影响。【结果】 研究结果发现，不同取样时间对甲螨种群数量有显著影响，甲螨种群数量的最高值出现在7月份的采样中。CO₂浓度升高通过棉花凋落物显著降低了甲螨的种群数量。O₃浓度升高通过棉花凋落物降低了常规棉凋落物中的甲螨种群数量，对转Bt作物凋落物中甲螨种群数量无显著影响。【结论】 不同温室气体（CO₂和O₃）浓度升高对土壤甲螨作用不同，其中CO₂浓度升高通过棉花凋落物可以显著降低土壤动物的种群数量，而O₃浓度升高作用较小。转Bt作物可以缓冲温室气体（CO₂和O₃）浓度升高通过作物凋落物对土壤动物（甲螨）的影响。

    [Objectives]  Transgenic Bt cotton was modified to express a gene derived from the bacterium Bacillus thuringiensis (Bt) to combat lepidopteran pests. Elevated CO₂ and O₃ are expected to further alter the chemical composition of cotton, and may thus affect the role that soil fauna plays in the decomposition of Bt plants. [Methods]  A three month litterbag field study, consisting of eight treatments using leaves from Bt cotton and near-isolines of non-Bt cotton grown under normal control, OTC control, elevated O₃ and CO₂ levels, was conducted to investigate the abundance of soil Acari that developed on the decaying leaf materials. [Results]  The abundance of Acari was significantly impacted by sampling times. Acari abundance was highest in July and significantly decreased in elevated CO₂ treatments. Moreover, only the common Simian3 significantly decreased in elevated CO₂ levels. Acari abundance was significantly reduced in Bt cotton litter in the OTC control but not in the normal control, elevated CO₂ and O₃ treatments. [Conclusion]  Soil fauna were not affected by elevated O₃ cotton litter but cotton litter grown under elevated CO₂ levels could significantly reduce the abundance of Acari compared to those found under the normal control, OTC control and elevated O₃ treatments.