黄土高原半干旱区不同苜蓿-作物种植方式下土壤线虫群落组成及代谢足迹

线虫群落在土壤生态系统物质循环和能量流动过程中起着重要的作用。本研究以宁夏南部山区3种苜蓿-作物种植方式苜蓿连作(A-A)、苜蓿-玉米轮作(A-C)、苜蓿-马铃薯轮作(A-P)]为对象,探讨不同种植方式下土壤理化性质、线虫群落组成结构及代谢足迹特征,评价黄土高原半干旱区苜蓿-作物种植方式对土壤食物网结构和功能的影响。结果表明: 1)与苜蓿连作相比,苜蓿-玉米和苜蓿-马铃薯轮作方式下土壤有机碳含量分别增加了4.6%、7.4%,全氮含量分别增加了4.0%、5.2%,土壤微生物生物量碳和氮也有显著提高;2)在苜蓿连作方式下,线虫总多度为211 条·100 g^-1干土,植食线虫为优势营养类群(35.7%),而在苜蓿-玉米和苜蓿-马铃薯轮作方式下,土壤线虫总多度较苜蓿连作有所增加(分别增加49.5%、93.7%),捕-杂食线虫成为优势营养类群(所占比例分别为45.7%、37.6%);3)相较于苜蓿连作,苜蓿-作物轮作方式下,植物寄生线虫指数(PPI)显著降低,表明植物寄生线虫在土壤食物网中的危害减轻;而线虫通路指数(NCR)有所增加,表明苜蓿-作物轮作方式下,土壤有机质分解过程中细菌分解作用进一步增强;4)苜蓿-作物轮作方式下,土壤线虫成熟度指数(MI)及其复合足迹、富集足迹、结构足迹均显著提高,土壤线虫的生产力和代谢活性显著增强,线虫群落的结构和功能更为成熟稳定。研究表明,相比苜蓿连作,苜蓿-作物轮作改善了土壤养分状况,使得土壤食物网的资源输入和能量利用效率均有所增加,受干扰程度显著降低,土壤生态系统更为稳定健康,因而有利于农业的可持续发展。

Compositions and metabolic footprints of soil nematode communities under different alfalfa-crop planting patterns in semi-arid region of the Loess Plateau,Northwest China.

Soil nematode communities play an important role in ecosystem material cycling and energy flow. In this study, soil samples were collected from three rotation systems in southern Ningxia mountainous region, including alfalfa continuous cropping (A-A), alfalfa-corn rotation (A-C), alfalfa-potato rotation (A-P). Soil physicochemical properties, nematode community composition and their metabolic footprints were measured. Compared with the A-A plot, the concentrations of soil organic carbon (SOC) and total nitrogen (TN) were significantly increased by 4.6% and 7.4% for SOC, 4.0% and 5.2% for TN in the A-C and A-P plots, respectively. Soil microbial biomass carbon and nitrogen were significantly higher in the A-C and A-P plots when compared with the A-A plot. The total abundance of soil nematodes in the A-C and A-P plots was higher by 49.5% and 93.7% than that in the A-A plot, respectively, with the dominant trophic group being changed to omnivores-predators from plant parasite. Compared to the A-A plot, the plant parasite index (PPI) was decreased significantly in the A-C and A-P plots, indicating that the harm of plant-parasites was reduced in soil food web. The nematode channel ratio (NCR) in the A-C and A-P plots were higher than that in the A-A plot, indicating that the role of bacterial decomposition was enhanced in soil organic matter decomposition. The maturity index (MI), the total nematode metabolic footprint, enrichment footprint, structure footprint in the A-C and A-P plots were all significantly higher than those in the A-A plot, suggesting that the structure and function of soil food web were more mature and stable, and the productivity and metabolic activity of nematodes were significantly enhanced. In general, the alfalfa-crop rotations improved soil nutrient status and reduced the disturbance degree of soil food web. Furthermore, soil ecosystem developed in the stable and healthy direction, which would be beneficial to the sustainable development of agriculture.