Abstract: Using Phragmites australis litter as test material;two kinds of its mother liquid;i.e.;water extract and decomposed products;were obtained by the methods of solution extraction and anaerobic decomposition. The two liquids with concentration 100% and 25% were used to treat the seeds and seedlings of Spartina alterniflora and the endemic beneficial fungi (Mortierella sp.) of S. alterniflora under 5‰ and 10‰ salinity;aimed to study the effects of different salinity on the germination and growth of S. alterniflora and the growth of the fungi. Salt stress promoted the seed germination and young root growth of Spartina alterniflora as well as the growth of Mortierella sp. significantly (P＜005). The water extracts promoted the germination and growth of Spartina alterniflora and the growth of Mortierella sp. when the salinity was 10‰;but the promotion effect disappeared when the salinity was reduced to 5‰. The decomposed products of Phragmites australis restrained the germination of Spartina alterniflora significantly (P＜005) when the salinity was 5‰;but promoted the growth of Mortierella sp. significantly (P＜005) when the salinity was 10‰. Under the two salinities;the decomposed products restrained the growth of Spartina alterniflora seedlings and young roots significantly (P＜005).

Key words: allelopathy, salinity, beneficial fungi of Spartina, Spartina alterniflora, Phragmites australis, eddy covariance, CO₂ flux, net ecosystem exchange, carbon sink, Phyllostachys edulis forest.