Miller Susan P, Bever James D
Institute of Ecology, University of Georgia, Athens, GA 30605-2202, USA, , , , , , GE.
Department of Ecology and Evolutionary Biology, University of California-Irvine, 321 Steinhaus Hall, Irvine, CA 92696-2525, USA, , , , , , US.
Oecologia. 1999 Jun;119(4):586-592. doi: 10.1007/s004420050823.
Although wetland plant species usually aggregate into zones that correspond with their water depth/dryness tolerances, it is not known whether associated arbuscular mycorrhizal (AM) fungi show a similar zonation. We assessed the distribution of AM fungi in two similar depressional wetlands dominated by the semi-aquatic grass Panicum hemitomon by sampling soil in plots along dry-to-wet gradients that spanned 80 cm in relative elevation, and identifying/counting viable AM fungal spores. We found that eight of nine AM fungal species were common to both of the wetlands. Within each wetland, there were significant differences in species composition related to relative water depth. The zonation patterns were not identical between wetlands but revealed that certain species were relegated to the drier portions of the gradient in both. No species were relegated to only the wet portions of the wetlands; those that dominated there were also present in the drier areas. Our data show that water depth is an important factor determining the distribution of the AM fungi, even when, as in our study wetlands, the host plant remains constant along a dry-to-wet gradient. This suggests that the fungi are not physiologically equivalent in their tolerance to wetland conditions.
尽管湿地植物物种通常会聚集在与其耐水深/耐干燥程度相对应的区域，但尚不清楚相关的丛枝菌根（AM）真菌是否也呈现出类似的分区现象。我们在两个以半水生草本植物半枝稷为主的类似洼地湿地中，沿着相对海拔跨度为80厘米的干到湿梯度在样地中采集土壤，鉴定并计数存活的AM真菌孢子，以此评估AM真菌的分布情况。我们发现，9种AM真菌中有8种在两个湿地中都很常见。在每个湿地内，与相对水深相关的物种组成存在显著差异。两个湿地的分区模式并不相同，但显示出某些物种在两个湿地中都被限制在梯度较干燥的部分。没有物种仅被限制在湿地较湿润的部分；在那里占主导地位的物种在较干燥的区域也有出现。我们的数据表明，水深是决定AM真菌分布的一个重要因素，即使像在我们研究的湿地中那样，宿主植物在干到湿的梯度上保持不变。这表明这些真菌在对湿地条件的耐受性方面生理上并不等同。
