Effect of natural and artificial afforestation reclamation on soil properties and vegetation in coastal saline silt soils.

• Effect of natural and artificial reclamation in coastal saline wasteland was studied. • Soil physical and chemical properties were improved rapidly for artificial method. • Plant and bacteria species diversity increasing obviously for artificial method. • Artificial reclamation process is faster than natural reclamation. • Special attention should be given to alkalization and nutrient losses. Sparse vegetation and soil desertification are widespread phenomena in coastal regions due to the accumulation of excess sodium in soil, which results in degraded land quality and ecological impairment. Artificial reclamation approaches, including physical, chemical, hydro-technical, and phytoremediation techniques, have failed mainly due to freshwater shortages, high costs, and a relative lack of salt-tolerant plant types suitable for the landscape ecology. In recent years, a method based on water-salt regulation through drip irrigation combined with agronomic engineering including soil removal, layout of a gravel and sand layer, soil backfilling and land leveling, has been developed and was successfully applied in coastal saline wastelands in China. This paper presents the results of a study concerning responses of soil properties and vegetation in coastal saline wastelands reclaimed through natural and artificial afforestation using water-salt regulation based on drip irrigation. Different reclamation time spans (4–6 years) and afforestation modes (orchard, protection forest, poplar forest, and mixed forest) were compared. The results showed that after 4 years of drip irrigation, the soil bulk density decreased from 1.7 to 1.8 g/cm3 to levels typical of farmland and field water holding capacity increased. Additionally, the soil electrical conductivity and sodium adsorption ratio decreased significantly as the severely saline soil shifted to non-saline conditions, thereby creating a suitable environment for the soil microbial community and plant seed germination. As a result, vegetation cover and plant and bacteria species diversity increased and the soil received increasing organic matter inputs; thus, developing a higher organic carbon content and carbon to nitrogen ratio. These results suggested the feasibility of using water-salt regulation through drip irrigation to develop a good quality environment in coastal saline wastelands without soil amendments, especially with a rapid reclamation process. This approach could help to arrest desertification due to salinity, aid the rehabilitation of wastelands, and thus contribute to improvements in the local environment. [ABSTRACT FROM AUTHOR]