The Citadel Hill Laboratory, Marine Biological Association of the United Kingdom, Plymouth, UK.
Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, UK.
Glob Chang Biol. 2018 Sep;24(9):4386-4398. doi: 10.1111/gcb.14303. Epub 2018 Jun 3.
Global climate change is affecting carbon cycling by driving changes in primary productivity and rates of carbon fixation, release and storage within Earth's vegetated systems. There is, however, limited understanding of how carbon flow between donor and recipient habitats will respond to climatic changes. Macroalgal-dominated habitats, such as kelp forests, are gaining recognition as important carbon donors within coastal carbon cycles, yet rates of carbon assimilation and transfer through these habitats are poorly resolved. Here, we investigated the likely impacts of ocean warming on coastal carbon cycling by quantifying rates of carbon assimilation and transfer in Laminaria hyperborea kelp forests-one of the most extensive coastal vegetated habitat types in the NE Atlantic-along a latitudinal temperature gradient. Kelp forests within warm climatic regimes assimilated, on average, more than three times less carbon and donated less than half the amount of particulate carbon compared to those from cold regimes. These patterns were not related to variability in other environmental parameters. Across their wider geographical distribution, plants exhibited reduced sizes toward their warm-water equatorward range edge, further suggesting that carbon flow is reduced under warmer climates. Overall, we estimated that Laminaria hyperborea forests stored ~11.49 Tg C in living biomass and released particulate carbon at a rate of ~5.71 Tg C year . This estimated flow of carbon was markedly higher than reported values for most other marine and terrestrial vegetated habitat types in Europe. Together, our observations suggest that continued warming will diminish the amount of carbon that is assimilated and transported through temperate kelp forests in NE Atlantic, with potential consequences for the coastal carbon cycle. Our findings underline the need to consider climate-driven changes in the capacity of ecosystems to fix and donate carbon when assessing the impacts of climate change on carbon cycling.
全球气候变化通过改变初级生产力和地球植被系统中碳固定、释放和储存的速度来影响碳循环。然而，人们对碳在源生境和接受生境之间的流动如何响应气候变化知之甚少。大型藻类占主导地位的生境，如巨藻林，正在被认为是沿海碳循环中的重要碳源，但这些生境中碳的同化和转移速率仍未得到很好的解决。在这里，我们通过沿纬度温度梯度量化 NE 大西洋最广泛的沿海植被生境类型之一——北石莼（Laminaria hyperborea）巨藻林中的碳同化和转移速率，来研究海洋变暖对沿海碳循环的可能影响。温暖气候条件下的巨藻林平均同化的碳要少三倍以上，捐赠的颗粒碳也不到寒冷气候条件下的一半。这些模式与其他环境参数的变化无关。在更广泛的地理分布中，植物向暖水的赤道边缘方向逐渐变小，这进一步表明在温暖气候下碳流减少。总体而言，我们估计北石莼森林的活生物质中储存了约 11.49 太克碳，以约 5.71 太克碳/年的速度释放颗粒碳。这种碳流动的估计值明显高于欧洲大多数其他海洋和陆地植被生境类型的报告值。总之，我们的观察结果表明，持续变暖将减少通过 NE 大西洋温带巨藻林同化和输送的碳量，这可能对沿海碳循环产生潜在影响。我们的发现强调了在评估气候变化对碳循环的影响时，需要考虑气候驱动的生态系统固定和捐赠碳的能力变化。
