开放式空气CO2浓度增高对中国稻田生态系统线虫营养类群产生的影响

土壤动物在农田生态系统腐屑食物网中占有重要地位 ,它们参与土壤有机质分解、植物营养矿化及养分循环作用 .国内外许多研究表明 ,土壤动物对全球变化 ,尤其是大气CO2 浓度升高能够产生正向、中性和负向的影响 .土壤线虫是这类土壤动物的典型代表 ,因为它们在大多数土壤中分布是丰富的 ,而且营养类群是多样的 .应用自由空气CO2 浓度增高 (FACE)技术设计 3个处理水稻圈暴露在大气CO2 增高(浓度为 5 70 μmol·mol-1)条件下 ,3个对照水稻圈为环境中的CO2 浓度 (370 μmol·mol-1) .在中国无锡稻田生态系统水稻生长期内 ,本项研究监测了 0～ 5cm和 5～ 10cm土层中线虫营养类群 .研究结果显示 ,线虫总数、食细菌线虫、植物寄生线虫、杂食 捕食类线虫在取样深度和取样日期上存在显著差异 ;在整个取样日期中 ,FACE处理 5～ 10cm深度中线虫总数、食细菌线虫数量比对照中的高 ;在 0～ 5cm深度中 ,FACE处理食细菌线虫数量比对照中的高 ,而杂食 捕食类线虫数量则表现出相反的趋势 .食真菌线虫在FACE处理与对照之间也存在极显著差异 .

Effects of elevated atmospheric CO2 on nematode trophic groups in a Chinese paddy-field ecosystem

Soil fauna plays significant roles in the detritus food webs of agroecosystems, they are the essential contributors to the decomposition of soil organic matter, mineralization of plant nutrients and nutrient cycling. Some evidences indicate that soil fauna of the detritus food webs appears to show positive, neutral or negative responses to global change, especially atmospheric CO2 enrichment across different studies. Soil nematodes are representative of a large portion of this fauna, since they are abundant and trophically diverse in most soils. The free-air CO2 enrichment (FACE) technology was used to expose three plots of rice (Oryza sativa) under elevated (ambient + 200 mumol.mol-1) atmospheric CO2, while three control plots were outfitted with FACE apparatus under ambient CO2. Nematode trophic groups were monitored in this study at depths of 0-5 cm and 5-10 cm during rice jointing and ripening stages in Wuxi site, China. Significant differences were found between depths and sampling dates in the total numbers of nematodes, bacterivores, plant parasites and omnivores-predators during the study period. The total numbers of nematodes and bacterivores at the 5-10 cm depth were higher in treatment plots than in control plots across all sampling dates. At 0-5 cm depth, the numbers of bacterivores were higher in treatment plots than in control plots, while those of omnivores-predators exhibited an inverse trend during the study period. Significant differences were also observed between treatment plots and control plots in the numbers of fungivores in our experiment.