Historical retrospection on mangrove development using stable carbon isotopes and pollen analysis, and its response to climate change and human activity
Mangrove evolution is the long time-scale process under the condition of climate change and human activity, and is clearly recorded by the surrounding sediments.It is a new palaeoecological approach to trace mangrove evolution using organic carbon isotopes and mangrove pollen from sedimentary records.In the study, a sediment core was collected from a mangrove swamp of the Qinzhou Bay, Guangxi.Based on the three end-number model, delta~(13) C and C/N analysis were used to calculate the contribution of mangrove-derived organic carbon.Compared with mangrove pollen assemblage and ~(210)Pb dating, it revealed the temporal evolution of mangrove development and its community succession in the recent 150 years.The mangrove evolution could be divided into three major stages:flourish(1864-1918A.D.), degradation(1918-1968A.D.)and low-level period(1968-2007A.D.), which was consistent with the previous reports.An significantly degradation in mangrove ecosystem recently corresponded to the increase of reclamation area(especially for the shrimp-pond reclamation)and artificial seawalls, rather than the climate change as recorded in the region.