Department of Biological Sciences, State University of New York at Binghamton, Binghamton, New York, 13902, USA.
Ecology. 2017 Dec;98(12):3096-3105. doi: 10.1002/ecy.2030. Epub 2017 Nov 9.
Evaluating plant community response to atmospheric CO rise is critical to predicting ecosystem level change. Freshwater lakes offer a model system for examining CO effects as submersed macrophyte species differ greatly in their growth responses to CO enrichment, and free CO concentrations among these habitats show a wide range of natural, spatial variation. We determined free CO concentrations in the water column and sediment porewater in littoral zones with pH < 6.0 in Adirondack Mountain (New York, USA) lakes, and derived a community CO responsiveness index (CCRI) based on quantitative sampling of 15 submersed macrophyte communities coupled with greenhouse-derived growth responses to CO enrichment of constituent species to test two hypotheses: (1) CCRI, which is higher for communities dominated by species with greater growth responses to CO enrichment, is positively correlated to free [CO ] in the water column, and (2) in natural communities, the percent of sediment CO -using species, which are relatively unresponsive to CO enrichment, is negatively correlated to free [CO ]. A significant positive correlation (P = 0.003) between our physiologically based CCRI and the concentration of free CO in the water column supported our primary hypothesis that sites with higher levels of free CO are dominated by species with greater growth responses to CO enrichment. Our CCRI is also highly significantly correlated (P < 0.001) to the first axis scores for the same vegetation data from polar ordination. Finally, the relative importance of species that use sediment CO as a photosynthetic carbon source is significantly negatively correlated (P = 0.029) with the concentration of free CO in the water column. Our results indicate that natural variations in CO levels are important determinants of submersed macrophyte community composition. Further, we demonstrate the utility of a physiologically-based index of community composition, our CCRI, as an ecologically valid measure of community response to CO .
评估大气 CO 上升对植物群落的影响对于预测生态系统水平的变化至关重要。淡水湖泊为研究 CO 效应提供了一个模型系统，因为沉水植物物种在对 CO 富集的生长反应方面存在很大差异，并且这些栖息地之间的自由 CO 浓度存在广泛的自然、空间变化。我们测定了 Adirondack 山脉（美国纽约州）湖泊中 pH<6.0 的浅水区水柱和沉积物孔隙水中的自由 CO 浓度，并基于对 15 个沉水植物群落的定量采样，以及对 CO 富集的种间温室衍生生长反应，得出了一个群落 CO 响应指数（CCRI），以检验两个假设：（1）CCRI 较高的群落，其优势种对 CO 富集的生长反应较大，与水柱中的自由[CO ]呈正相关，（2）在自然群落中，相对不受 CO 富集影响的沉积物 CO 利用物种的比例，与自由[CO ]呈负相关。我们基于生理的 CCRI 与水柱中自由 CO 浓度之间存在显著的正相关（P=0.003），这支持了我们的主要假设，即自由 CO 浓度较高的地点由对 CO 富集生长反应较大的物种主导。我们的 CCRI 也与极序排列相同植被数据的第一轴得分高度显著相关（P<0.001）。最后，作为光合作用碳源利用沉积物 CO 的物种的相对重要性与水柱中自由 CO 浓度呈显著负相关（P=0.029）。我们的结果表明，CO 水平的自然变化是沉水植物群落组成的重要决定因素。此外，我们证明了基于生理的群落组成指数 CCRI 的有效性，它是衡量群落对 CO 响应的生态有效指标。
