Effects of Betula platyphylla invasion in North China on soil aggregate stability, soil organic carbon and active carbon composition of larch plantation

Aims In order to better understand the changes of soil carbon sequestration capacity in forest after forest mixing, the effects of broadleaf tree invasion on soil aggregate stability and carbon sequestration were studied. Methods In northern China, the pure Larix principis-rupprechtii plantations and the Larix principis-rupprechtii plantations invaded by Betula platyphylla at various degrees with the same site conditions were selected ( Betula platyphylla had mixed degrees of 0.2 and 0.4). The distribution and stability of soil aggregates were analyzed, and soil organic carbon and active carbon components were determined. Results The distribution of soil macroaggregates (> 0.25 mm) increased with the increase in the mixed degree of Betula platyphylla. The mixture of Betula platyphylla could effectively increased SOC, EOC, DOC and MBC of the original soil and soil aggregates of different diameter classes. The invasion of Betula platyphylla had a positive indirect impact on soil carbon sequestration by affecting the soil physical and chemical properties and the aggregate stability. Conclusion The invasion of Betula platyphylla had significant positive effects on soil aggregate stability, erosion resistance and soil nutrient status in Larix principis-rupprechtii plantation. Maybe the selection of suitable broadleaf mixed species can improve the soil quality and soil organic carbon sequestration of the Larix principis-rupprechtii plantation in this area.