Detrital traits affect substitutability of a range-expanding foundation species across latitude

Climate-driven range shifts of foundation species could alter ecosystem processes and community composition by providing different resources than resident foundation species. Along the US Atlantic coast, the northward expanding foundation species, black mangrove, Avicennia germinans, is replacing the dominant salt marsh foundation species, marsh cordgrass, Spartina alterniflora. These species have distinct detrital attributes that ostensibly provide different resources to epifauna. We experimentally examined how detritus of these species affects decomposition and community composition in different habitat contexts at regional and local scales. First, we manipulated detritus identity (Avicennia, Spartina) at 13 sites across a 5° latitudinal gradient spanning mangrove, mixed marsh-mangrove, and salt marsh habitats. Across latitude, we found that Avicennia detritus decomposed 2-4 times faster than Spartina detritus, suggesting that detrital turnover will increase with mangrove expansion. E...