Coastal wetlands can sequester large amounts of organic carbon (OC), providing an additional motivation for the preservation and restoration of these ecosystems. In Tampa Bay (Florida, USA), created coastal wetlands are initially planted with Spartina spp., but nearly all sites naturally transition into mangrove forests. It was hypothesized that carbon storage in the created wetlands would increase with site age due to the accumulation of soil organic carbon and replacement of salt marsh vegetation with mangrove forests. Mature, mangrove-dominated sites had higher total organic carbon stocks (138.7 ± 13.8 Mg C ha⁻¹) than middle-aged transitional sites (85.6 ± 25.5 Mg C ha⁻¹) or young salt marshes (34.5 ± 7.7 Mg C ha⁻¹). Mature sites consisted of tall trees (> 130 cm tall) and scarce salt marsh vegetation. Transitional sites contained mangrove scrubs (30–130 cm tall) and seedlings (< 30 cm tall) while still supporting salt marsh vegetation; younger sites were dominated by salt marsh vegetation and had no trees. Belowground OC constituted the greatest carbon pool (59.4% of the total OC stock), but belowground OC stocks were not significantly different among the site age classes, suggesting that aboveground OC stocks drove the difference in total OC stocks. The total carbon accumulation rate, including both aboveground and belowground OC, was 4.7 Mg C ha⁻¹ year⁻¹ across the 26-year chronosequence. This study has demonstrated that carbon storage in created coastal wetlands is correlated to wetland age, indicating that these ecosystems have the potential to become significant sources of OC storage.

中文翻译：

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在美国佛罗里达州坦帕湾，盐沼过渡到红树林的过程中，碳储量随土地使用年限的增加而增加

沿海湿地可以隔离大量的有机碳（OC），为保护和恢复这些生态系统提供了额外的动力。在坦帕湾（美国佛罗里达州），最初使用Spartina spp种植了人工湿地。，但几乎所有地点都自然过渡到红树林。据推测，由于土壤有机碳的积累和盐沼植被被红树林替代，人工湿地的碳存储量将随着场地年龄的增长而增加。成熟，红树为主的网站有较高的总的有机碳的股票（138.7±13.8的MgÇ公顷^-1比中年过渡网站（85.6±25.5的MgÇ公顷）^-1）或年轻盐沼（34.5±7.7的MgÇ公顷^{- 1个}）。成熟的地点包括高大的树木（> 130厘米高）和稀缺的盐沼植被。过渡点包括红树林灌木丛（高30-130厘米）和幼苗（<30厘米高），同时仍支持盐沼植被。年轻的地区以盐沼植被为主，没有树木。地下OC构成了最大的碳库（占总OC存量的59.4％），但是地下OC存量在不同地点年龄类别之间没有显着差异，这表明地下OC存量推动了总OC存量的差异。包括地上和地下OC在内的总碳累积速率为4.7 Mg C ha - ¹ 年^-1在26年的时间序列中 这项研究表明，沿海湿地中的碳储存与湿地年龄有关，表明这些生态系统有可能成为重要的OC储存来源。