石漠化区生态治理措施对土壤团聚体稳定性及有机碳的影响

Effects of Ecological Control Measures on Soil Aggregate Stability and Organic Carbon in Rocky Desertification Area

探究石漠化环境不同生态恢复措施下土壤团聚体粒径组成、稳定性水平及有机碳变化特征,为石漠化生态治理模式优化配置提供理论依据。以农耕地为对照,选择石漠化治理中具有代表性的人工核桃林、黑麦草地、刺梨地和天然恢复的灌草地为研究对象,分析不同恢复环境中0~20 cm土层土壤团聚体稳定性及其有机碳储量变化。结果表明:相比农耕地,核桃、黑麦草和天然灌草样地内水稳定性大团聚体含量增加,微团聚体含量减少,灌草地和核桃林地团聚体MWD、GMD分别显著高于农耕地,表明利用方式转变为灌草地和核桃林后团聚体稳定性提高,土壤结构得到改善。农耕地利用方式转变后,人工核桃林、黑麦草地和天然灌草地各级团聚体有机碳含量及储量增加,其中以灌草地尤为明显,同时核桃林、黑麦草地和天然灌草地三者有机碳储量增量主要源于>5和2~5 mm两个粒级团聚体贡献。总体而言,相比人工林草治理措施,天然灌草地在增强土壤团聚结构稳定性和促进有机碳积累方面更优。

In order to provide a theoretical basis for the optimal allocation of ecological management model of rocky desertification,the characteristics of particle size distribution,stability and organic carbon change of soil aggregates under different ecological restoration measures were explored.Five sample plots were set up on lands of typical in the rocky desertification region under with Land use(farmland,walnut forest,rye grassland,Rosa roxburghii and natural shrub grass).the effects of different artificial and natural sample plots on the stability of soil aggregates and the organic carbon storage in 0-20 cm soil layer were analyzed.The results showed that:(1)Compared with the farmland,the content of water stable macro-aggregate increased and the quantity of micro-aggregate decreased in the environment of walnut forest,rye grassland and natural shrub grassland.The MWD and GMD of shrub grassland and walnut forest aggregate were significantly higher than those in the farmland and Rosa roxburghii,respectively.indicating that the stability of aggregates and soil structure were improved after the change of utilization mode to shrub grassland and walnut forest.(2)After the transformation of farmland,the organic carbon content and reserves of aggregates at all levels of walnut forest,rye grassland and natural irrigated grassland increased,especially in irrigated grassland.At the same time,the increase of organic carbon storage in walnut forest,rye grassland and natural shrub grassland was mainly due to the contribution of>5 mm and 2-5 mm aggregates.In general,compared with the control measures of artificial forest and grass,natural shrub grassland is better in enhancing the stability of soil aggregation structure and promoting the accumulation of organic carbon.