Hartnett D C, Samenus R J, Fischer L E, Hetrick B A D
Division of Biology, Kansas State University, 66506, Manhattan, KS, USA.
Department of Plant Pathology, Kansas State University, 66506, Manhattan, KS, USA.
Oecologia. 1994 Sep;99(1-2):21-26. doi: 10.1007/BF00317079.
The effects of mycorrhizal symbiosis on seedling emergence, flowering and densities of several grasses and forbs were assessed in native tallgrass prairie and in sown garden populations at the Konza Prairie in northeastern Kansas. Mycorrhizal activity was experimentally suppressed with the fungicide benomyl. Flowering and stem densities of the cool-season grass, Dichanthelium oligosanthes, sedges (Carex spp.), and the forb Aster ericoides were higher in non-mycorrhizal (benomyl-treated) than in mycorrhizal plots and the magnitude of these differences was significantly affected by burning. Mycorrhizae significantly enhanced flowering of the warmseason grasses Andropogon gerardii and Sorghastrum nutans in burned prairie, but not in unburned sites. These patterns suggest that mycorrhizal effects on the dynamics of cool-season graminoid and forb populations are likely to be mediated indirectly through effects of the symbiosis on the competitive dominance of their neighbors. Seedling emergence rates of the cool-season C grasses Elymus canadensis and Koeleria cristata were significantly reduced in the benomyl-treated plots, whereas benomyl treatment had no significant effect on seedling emergence of the warm-season C grasses A. gerardii and Panicum virgatum. The forbs showed variable responses. Seedling emergence of Liatris aspera was greater under mycorrhizal conditions, but that of Dalea purpurea was unaffected by mycorrhizal treatment. These results show that effects of mycorrhizal symbiosis on the population dynamics of co-occurring prairie plants vary significantly both among species and among different life history stages within species. The results also indicate that mycorrhizas and fire interact to influence competitive interactions and demographic patterns of tallgrass prairie plant populations.
在堪萨斯州东北部的孔扎草原，对原生高草草原和播种的花园种群中，菌根共生对几种禾本科植物和杂类草的幼苗出土、开花及密度的影响进行了评估。使用杀菌剂苯菌灵对菌根活性进行了实验性抑制。在非菌根（经苯菌灵处理）地块中，冷季禾本科植物少花三毛草、莎草（苔草属物种）和杂类草紫菀蒿的开花和茎密度高于菌根地块，且这些差异的程度受火烧的显著影响。在火烧过的草原中，菌根显著促进了暖季禾本科植物糙毛须芒草和垂穗草的开花，但在未烧过的地块中则没有。这些模式表明，菌根对冷季禾本科植物和杂类草种群动态的影响可能是通过共生关系对其邻体竞争优势的影响而间接介导的。在经苯菌灵处理的地块中，冷季C4禾本科植物加拿大披碱草和猬草的幼苗出土率显著降低，而苯菌灵处理对暖季C4禾本科植物糙毛须芒草和柳枝稷的幼苗出土没有显著影响。杂类草表现出不同的反应。糙毛蛇鞭菊在菌根条件下的幼苗出土更多，但紫花苜蓿的幼苗出土不受菌根处理的影响。这些结果表明，菌根共生对同时存在的草原植物种群动态的影响在物种间以及物种内不同生活史阶段均有显著差异。结果还表明，菌根和火烧相互作用，影响高草草原植物种群的竞争相互作用和种群统计学模式。
