围栏封育对退化高寒草甸土壤团聚体组成及稳定性的影响OACHSSCD
Effects of Grazing Exclusion on Soil Aggregate Composition and Stability in Degraded Alpine Meadows
围栏封育是恢复青藏高原退化高寒草甸的重要措施,但其对土壤团聚体组成及稳定性的影响仍不明确.本研究以长江源区退化高寒草甸(DM)、围封 4 a 高寒草甸(GE4)和围封 12 a 高寒草甸(GE12)为研究对象,采集0～20 cm 土层样品,采用干筛法和湿筛法分离不同粒级的机械稳定性与水稳性团聚体,分析团聚体的平均重量直径(MWD)、几何平均直径(GMD)、大团聚体质量分数(R0.25)和团聚体破损率(PAD),探究围封后土壤团聚体组成与稳定性的变化特征,并结合植物、土壤与微生物指标,识别其关键驱动因子.结果表明,围封后干筛>5 mm 和湿筛>0.25 mm 团聚体的质量分数呈上升趋势,并在围封 12 a 后达显著水平,表明长期围封促进了大团聚体的形成.相反,干筛<2 mm 和湿筛<0.25 mm 团聚体的质量分数在围封 12 a 后显著降低,反映出团聚体粒径分布向粗粒级转移.土壤团聚体稳定性整体按照 GE12>GE4>DM 的顺序递减,围封 4 a 后,仅水稳性团聚体的稳定性呈现显著提升,而至围封 12 a 时,机械稳定性和水稳性团聚体的稳定性均显著增强.此外,土壤团聚体的 PAD 由退化前的47.44%显著降至围封后的 15.98%～20.20%.随机森林和偏最小二乘路径模型分析表明,土壤 pH 值、植物生物量、土壤总有机碳和土壤微生物生物量碳是影响土壤团聚体稳定性的关键因子.综上所述,围封可通过促进土壤大团聚体的形成来增强团聚体的稳定性,是改善退化高寒草甸土壤结构的有效措施.
Grazing exclusion is a widely implemented measure for restoring degraded alpine meadows on the Qinghai-Ti-betan Plateau,yet its effects on soil aggregate composition and stability remain unclear.In this study,0-20 cm soil sam-ples were collected from a degraded alpine meadow,an alpine meadow subjected to 4 years of grazing exclusion,and an alpine meadow subjected to 12 years of grazing exclusion in the Yangtze River source region.Dry sieving and wet sieving methods were employed to separate mechanically stable and water-stable aggregates of different sizes.Key aggregate stabil-ity indices,including mean weight diameter(MWD),geometric mean diameter(GMD),mass fraction of macroag-gregates(R0.25),and percentage of aggregate destruction(PAD),were determined to assess changes in aggregate stabili-ty following grazing exclusion.Furthermore,plant,soil,and microbial properties were measured to identify the key drivers underlying soil structural recovery.The results showed that the mass fractions of dry-sieved>5 mm and wet-sieved>0.25 mm aggregates increased after grazing exclusion,with significant differences observed after 12 years of enclosure,indica-ting that long-term grazing exclusion promoted the formation of macroaggregates.In contrast,the mass fractions of dry-sieved<2 mm and wet-sieved<0.25 mm aggregates significantly decreased after 12 years of enclosure,reflecting a shift in aggregate size distribution toward coarser fractions.The stability of soil aggregates followed the order GE12>GE4>DM.After 4 years of enclosure,water-stable aggregate stability significantly increased,while both mechanical and water-stable aggregate stability showed significant improvements after 12 years.Additionally,the PAD decreased significantly from 47.44%in DM to 15.98%-20.20%in GE4 and GE12.Random forest and partial least squares path modeling(PLS-PM)analyses revealed that soil pH,plant biomass,soil total organic carbon,and microbial biomass carbon are key drivers of soil aggregate stability.In conclusion,grazing exclusion enhanced aggregate stability by promoting the formation of macroaggregates,demonstrating its effectiveness as a management strategy for restoring soil structure in degraded alpine meadows.
秦文萍;袁晖;孙铭阳;向明学;田丽慧;李晓燕;千文睿;刘翔
青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016||中国科学院武汉植物园水生植物与流域生态重点实验室,湖北 武汉 430074青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016青海大学省部共建三江源生态与高原农牧业国家重点实验室,青海 西宁 810016
农业科技
围栏封育高寒草甸土壤团聚体土壤结构生态治理
grazing exclusionalpine meadowsoil aggregatessoil structureecological restoration
《生态与农村环境学报》 2026 (8)
1104-1113,10
青海省科技厅项目(2024-ZJ-734)国家自然科学基金项目(42067070,32401448)
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