马尾松人工林土壤各粒径团聚体湿筛后的有机碳分配

选取25a、45a和65a马尾松人工林为研究对象，采用湿筛法对各粒径土壤团聚体分别湿筛。探究了马尾松人工林各粒径团聚体湿筛后的团聚体有机碳分配，以探讨各粒径团聚体湿筛后分配到同一粒级团聚体有机碳含量及其对团聚体水稳性的贡献差异。结果表明：种植年限增加显著降低土壤团聚体水稳性（P<0.05）；各粒径团聚体湿筛后分配的有机碳随粒级减小含量呈先降后增趋势，以保持原粒级团聚体有机碳（12.96-32.01 g/kg）含量最高，其次是<0.25 mm粒级（8.08-23.53 g/kg）。各粒径团聚体湿筛分配到同一粒级的有机碳以保持原粒级的含量最高（P<0.05）；土壤团聚体水稳性与各粒径团聚体湿筛后保持原粒径的有机碳呈显著或极显著正相关（P<0.05或0.01），分配到越小的粒级正相关性越不显著。此外，团聚体水稳性与各粒径团聚体湿筛分配到同一粒级的有机碳呈正相关，以保持原粒级相关性最高（P<0.01或0.05）；回归方程及相关性系数表明，有机碳与保持原粒径团聚体呈显著呈或极显著正相关（P<0.05或0.01），与消散到其他粒级的团聚体呈负相关或极显著负相关（P>0.05或<0.01）。本研究得出有机碳含量增加促进更大粒径团聚体形成。反之，促使大粒径团聚体向较小粒径团聚体转化。同一粒级团聚体间，保持原粒级团聚体比易转化形成更大粒级团聚体有更高的有机碳含量和更强的水稳性，这对团聚体的固碳提供了新的认识。

Distribution of organic carbon after wet sieving of soil aggregates of various particle sizes in Masson Pine plantation

Compared with the traditional Elliott wet screen method, the modified wet screen method can be used to analyze the difference in organic carbon for the wet sieving of each particle size aggregate to the same size. This study selected 25a, 45a and 65a Masson Pine plantations as the research objects. Soil aggregates with different particle sizes were wet-screened by wet screening method. The organic carbon distribution of soil aggregates with different particle sizes in Masson Pine plantation was investigated after wet screening. The purpose is to explore the difference of the organic carbon distribution to the same size after wet screening of aggregates of various particle sizes and its influence on the water stability of aggregates. The results showed that the increase of planting years significantly decreased the water stability of soil aggregates (P<0.05); After wet screening, the organic carbon content of each particle size aggregates decreased firstly and then increased with the decrease of grain size, so as to maintain the highest organic carbon content of the original particle size aggregates (12.96-32.01 g/kg), followed by <0.25 mm particle size aggregates (8.08-23.53 g/kg). Wet sieve agglomerates of various particle sizes allocated to the same size of organic carbon to maintain the highest content of the original size (P<0.05); There was significantly or extremely significantly positive correlation between the water stability of soil aggregates and the organic carbon of the aggregates with the original particle size after wet screening (P<0.05 or 0.01). The smaller the particle size was allocated, the less significant the positive correlation was. In addition, the water stability of aggregates was positively correlated with the organic carbon allocated to the same grain size in the wet screen of aggregates with different particle sizes, and it had the strongest correlation with the organic carbon that maintained the original grain size (P<0.01 or 0.05). The regression equation and correlation coefficient showed that the organic carbon had a significantly or extremely significantly positive correlation with the aggregates with original particle size (P<0.05 or 0.01), and an extremely significantly negative correlation with the aggregates dispersed to other particle sizes (P>0.05 or <0.01). This study concludes that organic carbon is an important cementing material for the formation of aggregates, and the increase of organic carbon content can promote the formation of larger size aggregates. On the contrary, it promotes the conversion of large particle size aggregates to small particle size aggregates. In addition, comparison among aggregates of the same grain size, maintaining the original particle size aggregates have higher organic carbon content and stronger water stability than easily transforming into larger particle size aggregates, which provides a new understanding for the carbon sequestration of aggregates.