Sonneratia is a genus of mangrove living in the tropical coasts.Its most concentratedarea is located in the coast line of South Asia

There are 4 species(S。 alba

S

caseolaris

S. ovataand S。 hainanensis)occurring in extreme south of China

where their distribution is limited in theHainan island

about 19 degrees north latitude. Palynological studies undertaking along the coastsof south一east China

where the present mongrove is abeent of Sonneratia

revealed that Some ofpollen types belonging to this genus( especially S

alba and S

caseolaris)occurred in the sedi-ments of Late Pleistocene

particularly in the period between 40000 and 25000 a BP

Pollen as-semblages of this age contain a number of taxa

having affinities with modern tropical species andgroups.A sharp decrease and lately disappearance of this genus from Guangdong coast line tookplace at about 20000 a BP

which reflects the influence of environmental change during the latestglaciation episode

New mangrove associations restored during the Holocene is similar to that oftoday(absence of Sonneratia)

which is living under the climate of pronounced mnscon patern。