You should expect Frankia species, as there form nitrogen-fixing structure with this species.
There is very little work done on this species, but more on a related species. See, e.g., Oremus P, Otten H. 1981. Factors affecting growth and nodulation of Hippophaë rhamnoides L. ssp. rhamnoides in soils from two successional stages of dune formation. Plant and Soil 63: 317-331.
You may also be interested in: Basistha B, Sharma N, Lepcha L, Arrawatia M, Sen A. 2010. Ecology of Hippophae salicifolia D. Don of temperate and sub-alpine forests of North Sikkim Himalayas—a case study. Symbiosis 50: 87-95.
Thanks for the information, if you have any supplementary material regarding this i.e. PDF of any paper regarding Hippophae salicifolia D.Don or related species. Please provide me as soon as possible.