Cullings Kenneth W, Vogler Detlev R, Parker V Thomas, Makhija Shilpa
NASA-Ames Research Center, 94035-1000, Moffett Field, CA, USA.
USDA Forest Service, Institute of Forest Genetics, 1100 West Chiles Road, 95616-6138, Davis, CA, USA.
Oecologia. 2001 May;127(4):533-539. doi: 10.1007/s004420000610. Epub 2001 May 1.
Molecular genetic methods were used to determine whether artificial defoliation affects ectomycorrhizal (EM) colonization, EM fungal species richness, and species composition in a mixed Pinus contorta (lodgepole pine)/Picea engelmannii (Engelmann spruce) forest in Yellowstone National Park, Wyoming. All lodgepole pines in three replicate plots were defoliated 50%, while Engelmann spruce were left untreated. This was done to determine how defoliation of one conifer species would affect EM mutualisms of both treated and neighboring, untreated conifers. The results indicated no significant effect on either EM colonization (142.0 EM tips/core in control plots and 142.4 in treatment plots) or species richness (5.0 species/core in controls and 4.5 in treatments). However, the relative abundance of EM of the two tree species shifted from a ratio of approximately 6:1 without treatment (lodgepole EM:spruce EM), to a near 1:1 ratio post-treatment. This shift may be responsible for maintaining total EM colonization and species richness following defoliation. In addition, EM species composition changed significantly post-defoliation; the system dominant, an Inocybe species, was rare in defoliation plots, while Agaricoid and Suilloid species that were rare in controls were dominant in treatments. Furthermore, species of EM fungi associating with both lodgepole pine and Engelmann spruce were affected, which indicates that changing the photosynthetic capacity of one species can affect mycorrhizal associations of neighboring non-defoliated trees.
利用分子遗传学方法来确定人工落叶是否会影响怀俄明州黄石国家公园中扭叶松（黑松）/恩氏云杉混交林的外生菌根（EM）定殖、EM真菌物种丰富度及物种组成。在三个重复样地中，所有黑松都进行了50%的落叶处理，而恩氏云杉未作处理。这样做是为了确定一种针叶树的落叶会如何影响经处理和相邻未处理针叶树的EM共生关系。结果表明，无论是EM定殖（对照样地中为142.0个EM根尖/核心，处理样地中为142.4个）还是物种丰富度（对照中为5.0种/核心，处理中为4.5种）均无显著影响。然而，两种树种的EM相对丰度从未处理时约6:1的比例（黑松EM:云杉EM）转变为处理后的近1:1比例。这种转变可能是落叶后维持总EM定殖和物种丰富度的原因。此外，落叶后EM物种组成发生了显著变化；系统中的优势种——一种丝盖伞属真菌，在落叶样地中很罕见，而在对照中罕见的伞菌状和牛肝菌状真菌在处理样地中占主导地位。此外，与黑松和恩氏云杉都相关联的EM真菌物种也受到了影响，这表明改变一个物种的光合能力会影响相邻未落叶树木的菌根关联。
