植被恢复对干旱区生态光伏电站土壤团聚体组成及有机碳的影响

为给干旱区生态光伏电站植被恢复,土壤结构稳定性以及有机碳固持提供理论依据,选取光伏电站生态示范区内3种典型的人工植被樟子松、黄芪和苜蓿为研究对象,以未进行植被恢复工作的土地为对照,探究了不同植被恢复措施下0—40 cm土壤各粒径团聚体分布特征、稳定性水平和有机碳变化特征。结果表明:相比于对照,樟子松、黄芪和苜蓿地的水稳定性大团聚体(>0.25 mm)含量增加,微团聚体(<0.25 mm)含量降低,尤其是樟子松样地大团聚体含量最高。3种植被的水稳性团聚体MWD(平均重量直径)和GMD(几何平均直径)均显著高于对照,而D值明显低于对照,在整个土壤剖面中,土壤团聚体稳定性指标均以樟子松样地最佳,表明樟子松样地土壤结构改善效果明显,团聚体稳定性较高。土地的利用方式转变后,樟子松、黄芪和苜蓿地的有机碳含量和有机碳贡献率均增加,其中以樟子松样地最为突出,并且3种植被的有机碳含量增量主要源于0.25～0.053 mm粒级团聚体的贡献。樟子松样地较黄芪和苜蓿地土壤团聚体稳定性更高,更有利于提高有机碳累积量。

Effects of Vegetation Restoration on Soil Aggregate Composition and Organic Carbon of Eco-Photovoltaic Power Station in Arid Area

In photovoltaic power station ecological demonstration area, three types of typical artificial vegetation, Pinus sylvestris L, stragalus membranaceus and Medicago sativa L. were selected as the research objects, and the land without vegetation restoration was taken as the control to explore the particle size of aggregate distribution characteristics, the stability level and the changes of organic carbon of 0—40 cm soil layer under different vegetation restoration measures, and to provide a theoretical basis for the vegetation restoration, soil structure stability and organic carbon sequestration of ecological photovoltaic power stations in arid areas. The results showed that: compared with the control, the content of water-stable large aggregates(>0.25 mm)increased in Pinus sylvestris L., stragalus membranaceus and Medicago sativa L., while the content of micro-aggregates(<0.25 mm)decreased, especially the content of large aggregates was the highest in Pinussylvestris var. mongolica; the water stability of aggregate MWD(mean weight diameter)and GMD(geometric mean diameter)of the three plants were significantly higher than those of the control, while the D values were significantly lower than that of the control; in the whole soil profile, the soil aggregate stability index was the best in Pinussylvestris var. mongolica, which indicated that the improvement effect of soil structure in the Pinus sylvestris L. was obvious and the stability of soil aggregates was higher; the organic carbon content and organic carbon contribution rate of Pinus sylvestris L., stragalus membranaceus and Medicago sativa L. increased, after the change of land use pattern, and Pinus sylvestris L. land was the most prominent one; moreover, the organic carbon content increments of the three plantlets were mainly due to the contribution of 0.25～0.053 mm particle size aggregate. These results showed that soil aggregates in Pinus sylvestris L. land were more stable than those in stragalus membranaceus and Medicago sativa L. lands, which was more beneficial to increase the organic carbon accumulation.