Miao S L, Wayne P M, Bazzaz F A
Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave, 02138, Cambridge, MA, USA.
Oecologia. 1992 May;90(2):300-304. doi: 10.1007/BF00317191.
To determine the effects of elevated CO and soil moisture status on growth and niche characteristics of birch and maple seedlings, gray birch (Betula populifolia) and red maple (Acer rubrum) were experimentally raised along a soil moisture gradient ranging from extreme drought to flooded conditions at both ambient and elevated atmospheric CO levels. The magnitude of growth enhancement due to CO was largely contingent on soil moisture conditions, but differently so for maple than for birch seedlings. Red maple showed greatest CO enhancements under moderately moist soil conditions, whereas gray birch showed greatest enhancements under moderately dry soil conditions. Additionally, CO had a relatively greater ameliorating effect in flooded conditions for red maple than for gray birch, whereas the reverse pattern was true for these species under extreme drought conditions. For both species, elevated CO resulted in a reduction in niche breadths on the moisture gradient; 5% for gray birch and 23% for red maple. Species niche overlap (proportional overall) was also lower at elevated CO (0.98 to: 0.88: 11%). This study highlights the utility of of experiments crossing CO levels with gradients of other resources as effective tools for elucidating the potential consequences of elevated CO on species distributions and potential interactions in natural communities.
为了确定二氧化碳浓度升高和土壤水分状况对桦树和枫树幼苗生长及生态位特征的影响，在大气二氧化碳浓度处于环境水平和升高水平的条件下，沿着从极端干旱到水淹的土壤水分梯度，对灰色桦树（纸皮桦）和红枫进行了实验培育。因二氧化碳浓度升高导致的生长增强幅度在很大程度上取决于土壤水分条件，但枫树和桦树幼苗的情况有所不同。红枫在土壤适度湿润条件下，二氧化碳浓度升高带来的生长增强最为显著，而灰色桦树在土壤适度干燥条件下生长增强最为显著。此外，在水淹条件下，二氧化碳浓度升高对红枫的改善作用相对大于灰色桦树，而在极端干旱条件下，这两个物种的情况则相反。对于这两个物种，二氧化碳浓度升高均导致在水分梯度上生态位宽度减小；灰色桦树减小了5%，红枫减小了23%。在二氧化碳浓度升高时，物种生态位重叠（总体比例）也较低（从0.98降至0.88，降幅为11%）。本研究强调了将二氧化碳浓度水平与其他资源梯度交叉设置实验作为有效工具的作用，用于阐明二氧化碳浓度升高对自然群落中物种分布和潜在相互作用的潜在影响。
