CAJ | 학술논문

团聚体是土壤结构的基本构成单位。在矿物颗粒和有机质等成分参与下，通过土壤微生物以及干湿、冻融交替等自然物理过程协同作用形成不同大小的土壤团聚体。土壤有机碳的稳定机制决定着土壤固定和储备有机碳的能力，而土壤团聚体的稳定性及其有机碳的分布是反映团聚体对有机碳物理保护作用的关键。土壤冻融作用的交替收缩与膨胀可改变团聚体的结构与组成，对土壤结构和水分分布特征具有明显影响，降低土壤团聚体的水稳性。通过影响土壤温度变化速率、通气性以及水分和营养物质的迁移，冻融作用影响微生物量及其活性，冻融过程也加快土壤有机碳和植物残留物矿化分解速率，致使有机碳组分的固定与活化产生分异，进而促进土壤有机碳的迁移转化，冻融初期土壤活性有机碳含量会显著增加。受到冻融作用的土壤团聚体中各种形态的有机碳都会不同程度的暴露出来，有机碳在不同结构的团聚体中进行重新分配，影响土壤有机碳源/汇的强度及变化趋势。冻融过程中土壤水分显著提高，土壤有机碳等养分易于溶出，或通过各种途径包裹在矿物颗粒内或吸附于土壤胶体表面随水迁移而流失。冻融作用初期对土壤有机碳的流失影响较大，但频繁的冻融循环有利于增强团聚体对有机碳的保护作用。
단취체시토양결구적기본구성단위。재광물과립화유궤질등성분삼여하，통과토양미생물이급간습、동융교체등자연물리과정협동작용형성불동대소적토양단취체。토양유궤탄적은정궤제결정착토양고정화저비유궤탄적능력，이토양단취체적은정성급기유궤탄적분포시반영단취체대유궤탄물리보호작용적관건。토양동융작용적교체수축여팽창가개변단취체적결구여조성，대토양결구화수분분포특정구유명현영향，강저토양단취체적수은성。통과영향토양온도변화속솔、통기성이급수분화영양물질적천이，동융작용영향미생물량급기활성，동융과정야가쾌토양유궤탄화식물잔류물광화분해속솔，치사유궤탄조분적고정여활화산생분이，진이촉진토양유궤탄적천이전화，동융초기토양활성유궤탄함량회현저증가。수도동융작용적토양단취체중각충형태적유궤탄도회불동정도적폭로출래，유궤탄재불동결구적단취체중진행중신분배，영향토양유궤탄원/회적강도급변화추세。동융과정중토양수분현저제고，토양유궤탄등양분역우용출，혹통과각충도경포과재광물과립내혹흡부우토양효체표면수수천이이류실。동융작용초기대토양유궤탄적류실영향교대，단빈번적동융순배유리우증강단취체대유궤탄적보호작용。
Aggregate is the basic composition unit of soil structure. Under the actions of soil microbes, and the natural processes such as dry-wet, freeze-thaw cycles, the mineral particles, organic matters and other ingredients can form soil aggregates of different sizes. The stable mechanism of soil organic carbon determines the ability of organic carbon store and preserving in soil aggregates, and the soil aggregate stability and its organic carbon contents reflect the aggregate physical protection to organic carbon. The alternating contraction and expansion caused by freeze-thaw cycles can change soil aggregate structure and composition, which obviously affect the soil structure and water distribution and reduce soil aggregate water stability. Freeze-thaw cycles can influence the microbial quantity and its activity by variations of soil temperature change rate, air permeability, moisture and nutrient transfer, and therefore improve the soil organic carbon and plant residues migration and transformation. The content of soil labile organic carbon will increase significantly at the initial stages of freeze-thaw processes. Various forms of organic carbon in soil aggregates affected by the freeze-thaw cycles can be exposed in different degrees, and organic carbon in different aggregates would redistribute, which influence soil organic carbon source/sink strength. With the significantly higher soil moisture caused by freeze-thaw processes, soil organic carbon and other nutrient can be easily dissolved, or migrate through wrapping up in the mineral particles or adsorbing on the soil colloid surface. The soil organic carbon release more at the early freeze-thaw stages, but the preservation of organic carbon in soil may be enhanced by the frequent freeze-thaw cycles.