Mangrove Litterfall Dynamics And The Relationships With Climatic Factors

Litterfall is one of an important index to measure ecosystem net primary productivity(NPP).Studying the litterfall production and dynamic characteristics would be helpful to understand the correlation between the NPP and the environmental drivers.In this study,we collected the litterfall data of typical mangrove communities in five study sites within three provinces in southern China with at least 1 yrs's study period.We analyzed litterfall production,the composition,and the dynamics of the litterfall of different mangroves.On the other hand,we also collected the historical data of mangrove litterfall in Jiulong River Estuary and Futian Mangrove Nature Reserve published in the past 30 years.By combining the historical meteorological data collected from the observatory during the same period,we analyzed the correlation between the dynamic change of litterfall production and climate factors,as well as the phenological change of propagates.The key findings of the current study are as the followings.(1)The litterfall production of different mangroves at the same location are different.In Yunxiao,Avicennia marina forest had the highest litterfall production(517.2 g·m-2),followed by Kandelia obovata(349.8 g·m-2).In Futian,Sonneratia apetala forest had the highest litterfall production(3195.0 g·m-2),followed by Avicennia marina(2395.4 g·m-2),Kandelia obovata(1544.0 g·m-2)and then Sonneratia caseolaris(1522.0 g·m-2).In Sanjiang of Dongzhaigang,Sonneratia apetala forest had the highest litterfall productions(804.0 g·m-2),followed by Sonneratia caseolaris(754.0 g·m-2),Aegiceras corniculatum(213.0 g·m-2),and Kandelia obovata(169.0 g·m-2).Different litterfall productions of same species of mangroves were different among locations.For Kandelia obovata communities,Futian had the highest litterfall production(1544.0 g·m-2),followed bywhich in Zini(1001.0 g·m-2),andin Yunxiao(349.8 g·m-2),then Sanjiang(160.0 g·m-2).While for Avicennia marina communities,Futian had the larger litterfall production(2395.4 g·m-2)thanwhich inYunxiao(5 17.2 g·m-2).For Sonneratia apetala species,Futian had the higher litterfall production(3195.0 g·m-2)than which in Sanjiang(804.0 g·m-2).(2)The proportion of each component in the litterfall of mangroves was different,but the main component was leaf litterfall,which accounted for more than 40%of the total litterfall.(3)Litterfall production variation(AY)in the same month was affected by different climate factor variation,and the litterfall production variation(AY)in adjacent month was affected by different climate factor variation,which was related to the species and location of mangroves.(4)Extreme climate typhoon has a significant effect on the litterfall of mangroves,and typhoon can greatly increase the production of branch litterfall of mangroves.On the aspect of propagule litterfall phenology,the phenology of the propagule of Kandelia obovata community in Jiulong river has changed in the past 36 years from 1982 to 2018.