Effects of soil amelioration of saline-alkali soils on forest-grass ecological patterns

The studies on soil amelioration effects of two forest-grass ecological patterns of Medicago sativa–Populus alba ‘Berolinensis’ and Sesbania cannabina–P.alba ‘Berolinensis’(M.sativa and S.cannabina were both saline-alkali tolerant grasses),and pure P.alba ‘Berolinensis’ plantations which planted in the raised fields established by soil preparation engineering measures were conducted in the typical saline-alkali soils along muddy seacoast in Liaohe River Delta.The results indicate that canopy densities of the three patterns were more than 90%,and the survival rates of those were more than 89%.M.sativa–P.alba ‘Berolinensis’ pattern significantly improved the growth of tree height and DBH,and the pattern's tree height increased by 15.8%,16.7% compared with S.cannabina–P.alba ‘Berolinensis' and pure P.alba ‘Berolinensis’ patterns respectively,and DBH increased by 15.8% and 16.6% respectively.The desalination effects of M.sativa–P.alba ‘Berolinensis’ pattern was the best in the three patterns as well.The soil total salt content,pH,bulk density of M.sativa –P.alba ‘Berolinensis’ pattern were significantly reduced,the soil porosity was increased,the soil moisture condition was improved,and the soil organicmatter,total N,total P,available N and P increased.The soil amelioration effects in the 0～10 cm soil depth were better than that in 10～30 cm and 30～50 cm.