Seventy years of continuous encroachment substantially increases 'blue XXXX ' capacity as mangroves replace intertidal salt marshes.

@entity505 @entity4612
UNASSIGNED: Shifts in ecosystem structure have been observed over recent decades as woody plants encroach upon grasslands and wetlands globally. The migration of mangrove forests into salt marsh ecosystems is one such shift which could have important implications for global 'blue @entity505 ' stocks. To date, attempts to quantify changes in ecosystem function are essentially constrained to climate-mediated pulses (30  years or less) of encroachment occurring at the thermal limits of mangroves. In this study, we track the continuous, lateral encroachment of mangroves into two south-eastern Australian salt marshes over a period of 70  years and quantify corresponding changes in biomass and belowground C stores. Substantial increases in biomass and belowground C stores have resulted as mangroves replaced salt marsh at both marine and estuarine sites. After 30  years, aboveground biomass was significantly higher than salt marsh, with biomass continuing to increase with mangrove age. Biomass increased at the mesohaline river site by 130      18  @entity4612 biomass km(-2)   yr(-1) (mean      SE), a 2.5 times higher rate than the marine embayment site (52      10  @entity4612 biomass km(-2) yr(-1) ), suggesting local constraints on biomass production. At both sites, and across all vegetation categories, belowground C considerably outweighed aboveground biomass stocks, with belowground C stocks increasing at up to 230      62  @entity4612  C  km(-2) yr(-1) (    SE) as mangrove forests developed. Over the past 70  years, we estimate mangrove encroachment may have already enhanced intertidal biomass by up to 283  097  @entity4612 and belowground C stocks by over 500  000  @entity4612 in the state of New South Wales alone. Under changing climatic conditions and rising sea levels, global blue @entity505 storage may be enhanced as mangrove encroachment becomes more widespread, thereby countering global warming.
