Brundrett Mark C, Abbott L K
Soil Science and Plant Nutrition, The University of Western Australia, Nedlands, W.A. 6009, Australia.
New Phytol. 1995 Dec;131(4):461-469. doi: 10.1111/j.1469-8137.1995.tb03083.x.
Spatial variations in the capacity of propagules of arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi to form associations in their natural habitats were investigated using bioassays with bait plants grown in intact cores of forest soil. These cores were collected from a sclerophyllous forest community dominated by Eucalyptus marginata Donn ex Smith (jarrah) and E. calophylla Lindley (marri) trees with a diverse shrub understorey in the mediterranean (winter rainfall) climatic zone of Western Australia. Small-scale (adjacent core) variations in the capacity of AM fungi to form associations were found to be as substantial as differences between locations 1 5 m apart. Comparisons of AM fungus colonization patterns within the roots of seedlings growing in the same core indicated that there was considerable spatial heterogeneity in the inoculums potential of 'individual' fungi within these 1 1 volumes of soil. A second experiment included bait plants to measure ECM formation as welt as AM formation and also considered the impact of soil disturbance. The disruption of hyphal networks reduced mycorrhizal formation somewhat, but it still remained highly variable. Some of this spatial heterogeneity could be attributed to differences in the organic matter content, length of fungal hyphae, or length of old mycorrhizal roots, measured within soil cores. In jarrah forest soil, mycelial systems of AM and ECM fungi apparently were localized in separate domains, and there were also zones where non-mycorrhizal roots (mostly cluster roots produced by members of the Proteaceae) predominated. More research is required to determine the size of domains of mycorrhizal mycelial systems in soils, how these spatial patterns change with time, and if they are associated with zones of resource utilization by different 'functional groups' of roots.
利用在森林土壤完整土芯中种植诱饵植物的生物测定法，研究了丛枝菌根（AM）真菌和外生菌根（ECM）真菌繁殖体在其自然栖息地形成菌根的能力的空间变异。这些土芯取自西澳大利亚地中海（冬季降雨）气候区的一个硬叶林群落，该群落以边缘桉（jarrah）和红桉（marri）树为主，林下有多种灌木。发现AM真菌形成菌根的能力的小规模（相邻土芯）变异与相距15米的不同地点之间的差异一样大。对生长在同一土芯中的幼苗根系内AM真菌定殖模式的比较表明，在这些11立方厘米的土壤体积内，“单个”真菌的接种潜力存在相当大的空间异质性。第二个实验包括使用诱饵植物来测量ECM形成以及AM形成，并且还考虑了土壤扰动的影响。菌丝网络的破坏在一定程度上减少了菌根形成，但仍然高度可变。这种空间异质性的一些原因可归因于在土芯内测量的有机质含量、真菌菌丝长度或老菌根根段长度的差异。在jarrah森林土壤中，AM和ECM真菌的菌丝系统显然定位于不同区域，并且也存在非菌根根（主要是山龙眼科成员产生的簇生根）占主导的区域。需要更多研究来确定土壤中菌根菌丝系统区域的大小、这些空间模式如何随时间变化，以及它们是否与不同“功能组”根系的资源利用区域相关。
