Charles Heather, Dukes Jeffrey S
Department of Biology, University of Massachusetts, Boston, Massachusetts, USA.
Ecol Appl. 2009 Oct;19(7):1758-73. doi: 10.1890/08-0172.1.
Salt marsh structure and function, and consequently ability to support a range of species and to provide ecosystem services, may be affected by climate change. To better understand how salt marshes will respond to warming and associated shifts in precipitation, we conducted a manipulative experiment in a tidal salt marsh in Massachusetts, USA. We exposed two plant communities (one dominated by Spartina patens-Distichlis spicata and one dominated by short form Spartina alternifora) to five climate manipulations: warming via passive open-topped chambers, doubled precipitation, warming and doubled precipitation, extreme drought via rainout shelter, and ambient conditions. Modest daytime warming increased total aboveground biomass of the S. alterniflora community (24%), but not the S. patens-D. spicata community. Warming also increased maximum stem heights of S. alterniflora (8%), S. patens (8%), and D. spicata (15%). Decomposition was marginally accelerated by warming in the S. alternifora community. Drought markedly increased total biomass of the S. alterniflora community (53%) and live S. patens (69%), perhaps by alleviating waterlogging of sediments. Decomposition was accelerated by increased precipitation and slowed by drought, particularly in the S. patens-D. spicata community. Flowering phenology responded minimally to the treatments, and pore water salinity, sulfide, ammonium, and phosphate concentrations showed no treatment effects in either plant community. Our results suggest that these salt marsh communities may be resilient to modest amounts of warming and large changes in precipitation. If production increases under climate change, marshes will have a greater ability to keep pace with sea-level rise, although an increase in decomposition could offset this. As long as marshes are not inundated by flooding due to sea-level rise, increases in aboveground biomass and stem heights suggest that marshes may continue to export carbon and nutrients to coastal waters and may be able to increase their carbon storage capability by increasing plant growth under future climate conditions.
盐沼的结构和功能，进而其支持一系列物种和提供生态系统服务的能力，可能会受到气候变化的影响。为了更好地理解盐沼将如何应对变暖和相关的降水变化，我们在美国马萨诸塞州的一个潮汐盐沼中进行了一项控制性实验。我们将两个植物群落（一个以互花米草-穗状狐米草为主，另一个以矮型互花米草为主）暴露于五种气候处理条件下：通过被动式开放式顶棚温室增温、降水量加倍、增温和降水量加倍、通过遮雨棚造成极端干旱以及环境条件。适度的白天增温使互花米草群落的地上总生物量增加了24%，但对互花米草-穗状狐米草群落没有影响。增温还使互花米草、互花米草和穗状狐米草的最大茎高分别增加了8%、8%和15%。在互花米草群落中，增温略微加速了分解过程。干旱显著增加了互花米草群落的总生物量（53%）和活互花米草的生物量（69%），这可能是由于减轻了沉积物的涝渍。降水增加加速了分解，而干旱减缓了分解，特别是在互花米草-穗状狐米草群落中。物候对处理的响应最小，两个植物群落的孔隙水盐度、硫化物、铵和磷酸盐浓度均未显示出处理效应。我们的结果表明，这些盐沼群落可能对适度的变暖和降水量的大幅变化具有恢复力。如果气候变化导致生产力增加，盐沼将有更大的能力跟上海平面上升的速度，尽管分解的增加可能会抵消这一点。只要盐沼不会因海平面上升而被洪水淹没，地上生物量和茎高的增加表明盐沼可能会继续向沿海水域输出碳和养分，并且可能能够通过在未来气候条件下增加植物生长来提高其碳储存能力。
