Coastal wetland environments are an important sub-tropical ecosystem and a significant sink of carbon dioxide. They are under threat globally from coastal development, climate change, and sea level rise. Here we present eddy covariance measurements of carbon and water fluxes over three contrasting sub-tropical coastal ecosystems in eastern Australia: a wetland, an intermittently inundated swamp, and a commercial pine plantation. The aim is to quantify net ecosystem exchange and evapotranspiration to identify the meteorological and environmental factors that control carbon and water flux in these ecosystems. Results show that annual net ecosystem production ranged from 396 and 514 gC m^-2 year^-1 at the wetland, 571 and 694 gC m^-2 year^-1 at the pine plantation, and -74 and 108 gC m^-2 year^-1 at the swamp. In addition to photosynthetically available radiation and temperature, the strongest drivers of carbon flux were volumetric water content, vapour pressure deficit, and evapotranspiration at the wetland and swamp; at the swamp, leaf area index was also strongly correlated with carbon flux. In contrast, at the pine plantation, in addition to photosynthetically available radiation and temperature, only vapour pressure deficit had a strong correlation to carbon flux, with much weaker contribution from volumetric water content and leaf area index, and negligible correlation with evapotranspiration. Annual gross ecosystem production of the wetland site (2664–2739 gC m^-2 year^-1) was similar to those of tropical forests, while the pine plantation was the most effective at carbon capture from the atmosphere. Results provide valuable insight to these ecosystems and their water/carbon exchanges with the atmosphere, from which future change in response to climate change and land use change can be quantified.

沿海湿地环境是重要的亚热带生态系统和重要的二氧化碳汇。它们在全球范围内受到沿海发展，气候变化和海平面上升的威胁。在这里，我们介绍了澳大利亚东部三个不同的亚热带沿海生态系统上的碳和水通量的涡度协方差测量：湿地，间歇性淹没的沼泽和商业化的松树人工林。目的是量化生态系统的净交换和蒸散量，以确定控制这些生态系统中碳和水通量的气象和环境因素。结果表明，湿地的年净生态系统净产量范围为396和514 gC m - ² 年^-1，^{- 1年}为571和694 gC m - ² 年^-1在松树人工林中，以及-74和108 gC m - ² 年^-1在沼泽中。除光合作用的辐射和温度外，碳通量的最强驱动力是体积水含量，蒸气压赤字和湿地和沼泽的蒸散量。在沼泽地，叶面积指数也与碳通量密切相关。相反，在松树人工林中，除了光合作用的辐射和温度外，仅蒸气压亏缺与碳通量有很强的相关性，而体积水含量和叶面积指数的贡献则弱得多，与蒸散量的相关性可忽略不计。湿地站点的年度生态系统总产量（2664–2739 gC m - ² 年^-1）类似于热带森林，而松树种植园是最有效的从大气中捕获碳的方法。结果为这些生态系统及其与大气的水/碳交换提供了宝贵的见识，从中可以量化应对气候变化和土地利用变化的未来变化。