Buried hurricane legacies: increased nutrient limitation and decreased root biomass in coastal wetlands

Plant identity and cover in coastal wetlands is changing worldwide, many subtropical salt marshes dominated by low-stature herbaceous species are becoming woody mangroves. Yet, how changes affect soil biogeochemical processes belowground biomass before after storms uncertain. We experimentally manipulated the percent mangrove (Avicennia germinans) 3 × m cells embedded 10 plots (24 42 m) comprising a gradient of marsh (e.g., Spartina alterniflora, Batis maritima) Texas, USA. Hurricane Harvey made direct landfall over our site on 25 August 2017, providing unique opportunity to test plant composition mitigates hurricane effects surface sediment accretion, chemistry (carbon, C; nitrogen, N; phosphorus, P; sulfur, S), root biomass. Data were collected (2013 2016), one-month (2017), one-year (2018) crossed area, allowing us measure stocks hurricane. The accretion depth was higher fringe compared with interior plots, more variable than mangrove, declined increasing plot-scale cover. concentrations P δ34S storm-driven accreted sediments, N, P, S, underlying soils (0–30 cm), decreased post-hurricane, whereas C both compartments unchanged. Root reduced 80% 2017 previous dates remained 2018. Post-hurricane loss correlated enhanced nutrient limitation. Total sulfide accumulation as indicated δ34S, increased limitation, mangroves hurricanes may ecosystem function increase vulnerability subsequent disturbances. Understanding ecosystems affects responses disturbances needed assess vulnerability.