Distribution of soil moisture and salt of Tamarix ramosissima plantation in desert saline-alkali land of Hexi Corridor Region, China

Abstract

Soil salinization is a global problem. Afforestation is a major improvement practice for desert saline-alkali land. To examine ecological improvement effects and spatial distribution of soil moisture and salinity in Tamarix ramosissima plantation with the age of 10 years in desert saline-alkali land, soil moisture and salt content between rows and under shrubs with row distance of 2, 4, 6, and 8 m were measured. The structural equation model was used to quantify the effects of soil water and salt changes on plant growth. The results indicated that soluble salt in shallow soil (0-40 cm) of T. ramosissima plantation was significantly lower than that outside the plantation, but soil moisture under shrubs was higher than that between rows. Among different row distances, the maximum values of height and canopy size of T. ramosissima and coverage and biomass of vegetation under the shrubs were found in row distance of 6 m. The enrichment degree of soil cations around taproot was in order of Na+>K+>Ca2+>Mg2+ and anions were enriched with Cl->HCO3->SO42-. There were five kinds of salts in soil, with MgSO4 being the most abundant, followed by CaCl2, NaCl and MgCl2, and the lowest being KHCO3. Soil moisture had the strongest effects on vegetation, followed by soil salinity, and the lowest was soil pH, with values of 50.6%,29.5% and 19.9%, respectively.