Department of Environmental Science & Technology, University of Maryland at College Park, 1423 Animal Science Building, College Park, MD, 20742, USA.
Glob Chang Biol. 2014 Mar;20(3):835-50. doi: 10.1111/gcb.12378. Epub 2013 Dec 30.
Atmospheric warming may influence plant productivity and diversity and induce poleward migration of species, altering communities across latitudes. Complicating the picture is that communities from different continents deviate in evolutionary histories, which may modify responses to warming and migration. We used experimental wetland plant communities grown from seed banks as model systems to determine whether effects of warming on biomass production and species richness are consistent across continents, latitudes, and migration scenarios. We collected soil samples from each of three tidal freshwater marshes in estuaries at three latitudes (north, middle, south) on the Atlantic coasts of Europe and North America. In one experiment, we exposed soil seed bank communities from each latitude and continent to ambient and elevated (+2.8 °C) temperatures in the greenhouse. In a second experiment, soil samples were mixed either within each estuary (limited migration) or among estuaries from different latitudes in each continent (complete migration). Seed bank communities of these migration scenarios were also exposed to ambient and elevated temperatures and contrasted with a no-migration treatment. In the first experiment, warming overall increased biomass (+16%) and decreased species richness (-14%) across latitudes in Europe and North America. Species richness and evenness of south-latitude communities were less affected by warming than those of middle and north latitudes. In the second experiment, warming also stimulated biomass and lowered species richness. In addition, complete migration led to increased species richness (+60% in North America, + 100% in Europe), but this higher diversity did not translate into increased biomass. Species responded idiosyncratically to warming, but Lythrum salicaria and Bidens sp. increased significantly in response to warming in both continents. These results reveal for the first time consistent impacts of warming on biomass and species richness for temperate wetland plant communities across continents, latitudes, and migration scenarios.
大气变暖可能会影响植物生产力和多样性，并促使物种向两极迁移，从而改变整个纬度的群落。更为复杂的是，来自不同大陆的群落进化历史不同，这可能会改变它们对变暖及迁移的响应。我们使用来自种子库的实验性湿地植物群落作为模型系统，以确定变暖对生物量生产和物种丰富度的影响是否在不同大陆、纬度和迁移情景中具有一致性。我们从欧洲和北美的大西洋沿岸三个河口的三个潮汐淡水沼泽中采集了土壤样本。在一个实验中，我们将每个纬度和大陆的土壤种子库群落暴露在温室中的环境和升高（+2.8°C）温度下。在第二个实验中，我们将每个河口内的土壤样本进行混合（有限迁移），或在每个大陆的不同纬度的河口之间进行混合（完全迁移）。这些迁移情景的种子库群落也暴露在环境和升高的温度下，并与无迁移处理进行对比。在第一个实验中，变暖总体上增加了欧洲和北美的生物量（增加了 16%），减少了物种丰富度（减少了 14%）。与中纬度和高纬度的群落相比，低纬度群落的物种丰富度和均匀度受变暖的影响较小。在第二个实验中，变暖也刺激了生物量的增加和物种丰富度的降低。此外，完全迁移导致物种丰富度增加（北美的增加了 60%，欧洲的增加了 100%），但这种更高的多样性并没有转化为生物量的增加。物种对变暖的反应是特殊的，但柳枝稷和鬼针草在两个大陆都因变暖而显著增加。这些结果首次揭示了变暖对跨大陆、纬度和迁移情景的温带湿地植物群落的生物量和物种丰富度的一致影响。
