基于土壤线虫群落成熟度指数的拉沙山土壤生态系统稳定性评价及可行性研究

土壤生态系统被誉为是生物圈的能量储存介质,稳定健康的土壤生态系统是维持陆地生态系统生产力的关键,但系统内部各种生物作用和复杂过程很难直接观测,很难利用陆地生态系统的评价体系评价其稳定性。近年来土壤线虫群落成熟度指数作为土壤生态系统稳定性的指示类群被广泛认可和利用,拟通过拉沙山区域13个固定大样地中的52个样方的土壤线虫成熟度指数对区域土壤生态系统稳定性进行评价,并对评价的可行性进行验证。采用宏基因技术共获取线虫扩增子序列变体(Amplicon Sequence Variant, ASV)963个,隶属于2纲10目41科67属,群落结构以食细菌线虫和捕食-杂食类线虫为主,群落以K-策略者(c-p 3-5)生活类群为主导。研究结果表明,土壤线虫的成熟度指数均值为3.24±0.32,评价结果认为拉沙山区域土壤生态系统整体较为稳定,且土壤线虫成熟度指数在空间上不存在统计差异(P>0.05)。通过利用样地监测获得的人为干扰强度与利用土壤线虫成熟度指数所评价出的结果呈现显著的负相关关系(P<0.05),表明稳定性较低的样地其人类活动干扰也较大;同时对土壤线虫成熟度指数的评价结果与样地地表生态系统现状验证结果显示,在中海拔的区域主要因其河谷较深,同时两侧山体陡峭且时有塌方发生导致土壤生态系统的不稳定且土壤线虫成熟度指数偏低,评价结果与实际地表生境状态相符,所以利用土壤线虫成熟度指数评价区域大样地是可行的,该研究为未来区域的土壤生态系统健康评价完善提供了新的指标。

Stability evaluation of soil ecosystem assessment based on maturity index of soil nematodes and feasibility study in Lasha Mountain

Soil ecosystems are recognized as crucial energy reservoirs within the biosphere. Stable and healthy soil ecosystems play a pivotal role in maintaining the productivity of terrestrial ecosystems. However, evaluating soil ecosystem stability remains a challenge due to the complexity of biological reactions and soil processes and the difficulty of directly observing subsurface systems'' dynamics. For the past few years, the utilization of the soil nematode community maturity index has gained widespread implementation and has been utilised as indicator taxa for the assessment of soil ecosystem stability. Therefore, this study aimed to evaluate soil ecosystem stability within the Lasha Mountain region by employing the soil nematode community maturity index across a total of 52 sample plots from 13 fixed major quadrats, and to verify the feasibility of this evaluation method. Furthermore, we aimed at assessing the practicability of this evaluation system when metagenimics technology was employed. We identified a total of 963 nematode amplicon sequence variants, distributed across 2 classes, 10 orders, 41 families, and 67 genera. Among them, the bacterivorous and omnivorous-predatory nematodes emerged as the dominant groups, with the majority of them displaying K-strategy characteristics (c-p 3-5). The average soil nematode community maturity index was measured at 3.24±0.32, suggesting that the soil ecosystem was relatively stable, while the spatial distribution of the soil nematode community maturity index in Lasha Mountain area exhibited no significant variation (P>0.05). A significantly negative correlation was found between the artificial disturbance intensity obtained by using the plot monitoring and the results evaluated by using the soil nematode community maturity index (P<0.05), indicating that the plots with low stability also showed greater interference with human activities. Concurrently, the assessment results of the soil nematode maturity index and the validations of surface ecosystems of the sample plot revealed an elevational pattern, with mid-altitude regions showing lower nematode community maturity index values, attributed mainly to the deep river valleys and extreme steepness of the slopes on both sides characteristic of the region which experiences frequent landslides. This particular situation results in soil ecosystem instability and the loss of soil nematode community maturity index. These assessment outcomes align with the real conditions of the surface habitat. Consequently, it reaffirms the feasibility of the soil nematode community maturity index as an assessment tool for soil ecosystems stability, potentially paving the way for its application in the evaluation of regional ecosystem health in future assessments.