Soil environment and growth adaptation strategies ofAmorpha fruticosaas affected by mulching in a moderately saline wasteland

Understanding the growth adaptive strategies ofAmorpha fruticosain response to the changes of saline soil environment under different mulch types (plastic mulch [PM]; sand mulch [SM]; rice straw mulch [RSM]; and control with non-mulching [CK]) is very important, as this determines afforestation success in a moderately saline soil. The species' soil microenvironments, fine root traits, and biomass allocation patterns were investigated in 2016 and 2017. Compared to CK, electrical conductivity of saturated paste extracts (ECe) reduced significantly under the mulching treatments especially under PM. Both PM and SM effectively increased soil temperature (T-soil) and available nitrogen (AN), but reduced soil organic carbon (SOC) in 2016; while RSM increased soil nutrients, but reducedT(soil). TheA. fruticosaunder RSM (following PM and SM) invested more biomass, to shoots relative to roots, to coarse roots relative to fine roots, and to stems and leaves at the expense of coarse roots and fine roots from 2016 to 2017, as its saline soil environment especially the lowT(soil)improved. In both years, the fine roots ofA. fruticosaunder PM employed exploitation potential or 'extensive strategy' (fine root mass density; fine root length density) more successfully at the 0-40 cm, while the fine roots under CK used higher exploitation efficiency or 'intensive strategy' (specific root length; and specific root area). The indicators of intensive strategy at the 40-60 cm were higher under PM than SM and RSM. Therefore, PM will better helpA. fruticosaadapt to the harsh soil environment during afforestation in a moderately saline wasteland.