对滨海盐碱地防护林树种刺槐、沙枣、紫穗槐、沙棘根瘤固氮研究表明，不同林龄、季节、土壤盐碱化程度及孔隙度，树种的固氮活性和根瘤量均不同。刺槐、沙枣、沙棘随年龄增加而增大，紫穗槐则随林分郁闭度增大而减少。刺槐、沙枣、紫穗槐的最大固氮量分别出现在９、７、７月份，其固氮量分别为１１３９、５８８、０８０ｋｇ／ｈｍ２ａ；沙枣根瘤量随土壤全盐量和ｐＨ降低及孔隙度增大而增多，而其固氮酶活性则随之显著降低，当年均土壤全盐量为０２３％，ｐＨ９２７时，固氮量最大，为４８２ｋｇ／ｈｍ２ａ。 Studies on the nitrogen fixation of rhizophorous nodules of Robinia pseudoacacia, S.japonica, Amorpha fruticosa and Seabuckthorn showed that different age, season, degree of soil salinization and porosity, nitrogen fixation activity and nodule amount of tree species were different. Black locust, date date, seabuckthorn increased with age, and Amorpha fruticosa decreased with the canopy density increasing. Acacia, date jujube and Amorpha fruticosa appeared in September, July and July respectively, with nitrogen fixation rates of 1139, 588 and 0.80 kg / hm2a, respectively. The salt content and pH decreased, the porosity increased, and the nitrogenase activity decreased significantly. When the total salt content of soil was 023%, the maximum amount of nitrogen fixation was 482kg / hm2  a.