Earthworms play a crucial role in regulating soil aggregates and soil organic carbon content. However, the effects of earthworm density on the composition, stability, and organic carbon of various soil aggregate fractions in Moso bamboo (Phyllostachys edulis) forest remain poorly understood. We conducted a 180-day in situ experiment to investigate the effects of different earthworm densities on composition, stability, organic carbon content of soil aggregates in a Moso bamboo forest. There were three treatments, including control (CK, no earthworm), local earthworm density (OE, 8 earthworms added in 50 cm×50 cm×40 cm), and double earthworm density (DE, 16 earthworms added in 50 cm×50 cm×40 cm). Compared to CK, the OE and DE treatments significantly increased the proportion of water-stable large macroaggregates (>2 mm) by 62.8% and 35.1%, respectively. Earthworm density improved soil aggregate stability, with stronger impacts of DE treatment than the OE treatment. Both OE and DE treatments increased organic carbon content across all soil aggregate fractions, with the organic carbon contents in bulk soil rising by 19.1% and 24.0%, respectively. Organic carbon contents in bulk soil were significantly correlated with the composition, stability, and organic carbon content of soil aggregates. Results of random forest analysis showed that organic carbon content in the bulk soil under the OE treatment was more strongly influenced by the organic carbon content in various soil aggregate fractions, whereas it was more strongly influenced by aggregate stabi-lity under the DE treatment. In conclusion, earthworms improved soil aggregate properties, thereby increasing organic carbon content in bulk soil, as indicated by the fact that higher earthworm densities promoted the formation of more aggregate organic carbon and enhanced soil aggregate stability.
蚯蚓在调节土壤团聚体和土壤有机碳上发挥着重要作用,但不同密度蚯蚓如何影响毛竹林土壤团聚体组成、稳定性和各粒级团聚体有机碳尚不清楚。为研究不同密度蚯蚓活动对毛竹林土壤团聚体组成、稳定性、有机碳含量及分布的影响机制,在毛竹林中设置对照(CK,无蚯蚓)、当地蚯蚓密度(OE,50 cm×50 cm×40 cm添加8条蚯蚓)和2倍蚯蚓密度(DE,50 cm×50 cm×40 cm添加16条蚯蚓)处理,进行180 d的野外原位培养试验。结果表明: 与CK相比,OE和DE处理水稳性大团聚体(>2 mm团聚体)比例分别显著提高了62.8%和35.1%。添加蚯蚓处理提高了土壤团聚体稳定性,且DE处理的提升效果大于OE处理。OE和DE处理均提高了土壤各粒级团聚体有机碳含量,且全土有机碳含量分别提高了19.1%和24.0%。全土有机碳含量与土壤团聚体组成、稳定性和有机碳含量均显著相关。随机森林分析显示,OE处理的全土有机碳含量受各粒级土壤团聚体有机碳含量的影响较大,而DE处理的全土有机碳含量受土壤团聚体稳定性的影响较大。综上,蚯蚓对土壤团聚体的改良提升了全土有机碳含量,且高密度的蚯蚓会促进更多的团聚体有机碳形成,提高土壤团聚体稳定性。.
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