Analysis on Changes of Forest Sediment Retention Function in Nanliujiang River Basin

Taking the Nanliujiang River basin in Gulf of Tonkin, Guangxi as the study area, using the secondary survey data of forest resources in 2009, 2014 and 2019 and the ″One map″ data of forest resources management, combining ArcGIS and InVEST models, quantitative assessment of soil conservation in the Nanliujiang River basin, and the use of field data to verify.The results showed that the soil conservation function was continuously enhanced and the soil conservation amount increased by 100.8% from 2009 to 2019.From 2009 to 2019, the total amount of soil conservation of eucalyptus, broad-leaved tree and bamboo forest showed an increasing trend, economic forest, Chinese fir and pine showed a decreasing trend.The average soil conservation amount of each forest landscape type was Chinese fir & GT In the study area, the distribution of serious soil erosion is scattered, it is mainly distributed in northern Beiliu, western and northeastern Yuzhou District, northern Luchuan County, Central Bobai County and northeastern Pubei County.In order to enhance the soil conservation function of the watershed, it is necessary to change the stand structure, develop the mixed planting pattern of pine and fir, improve the forest quality, optimize the landscape pattern of forest land use, and perfect the related engineering measures.