González Jonathan B, Petipas Renee H, Franken Oscar, Kiers E Toby, Veblen Kari E, Brody Alison K
Department of Biology, University of Vermont, Burlington, VT, 05465, USA.
Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA.
Oecologia. 2018 May;187(1):123-133. doi: 10.1007/s00442-018-4124-4. Epub 2018 Mar 29.
The functional relationship between arbuscular mycorrhizal fungi (AMF) and their hosts is variable on small spatial scales. Here, we hypothesized that herbivore exclusion changes the AMF community and alters the ability of AMF to enhance plant tolerance to grazing. We grew the perennial bunchgrass, Themeda triandra Forssk in inoculum from soils collected in the Kenya Long-term Exclosure Experiment where treatments representing different levels of herbivory have been in place since 1995. We assessed AMF diversity in the field, using terminal restriction fragment length polymorphism and compared fungal diversity among treatments. We conducted clipping experiments in the greenhouse and field and assessed regrowth. Plants inoculated with AMF from areas accessed by wild herbivores and cattle had greater biomass than non-inoculated controls, while plants inoculated with AMF from where large herbivores were excluded did not benefit from AMF in terms of biomass production. However, only the inoculation with AMF from areas with wild herbivores and no cattle had a positive effect on regrowth, relative to clipped plants grown without AMF. Similarly, in the field, regrowth of plants after clipping in areas with only native herbivores was higher than other treatments. Functional differences in AMF were evident despite little difference in AMF species richness or community composition. Our findings suggest that differences in large herbivore communities over nearly two decades has resulted in localized, functional changes in AMF communities. Our results add to the accumulating evidence that mycorrhizae are locally adapted and that functional differences can evolve within small geographical areas.
丛枝菌根真菌（AMF）与其宿主之间的功能关系在小空间尺度上是可变的。在这里，我们假设食草动物排除会改变AMF群落，并改变AMF增强植物对放牧耐受性的能力。我们在肯尼亚长期围栏实验收集的土壤接种物中种植多年生丛生禾本科植物三角草（Themeda triandra Forssk），自1995年以来，该实验设置了代表不同食草水平的处理。我们在田间使用末端限制性片段长度多态性评估AMF多样性，并比较不同处理之间的真菌多样性。我们在温室和田间进行了刈割实验，并评估了再生情况。接种来自野生食草动物和牛可进入区域的AMF的植物比未接种的对照具有更大的生物量，而接种来自大型食草动物被排除区域的AMF的植物在生物量生产方面未从AMF中受益。然而，相对于未接种AMF生长的刈割植物，只有接种来自有野生食草动物且无牛区域的AMF对再生有积极影响。同样，在田间，仅存在本地食草动物区域的植物刈割后的再生高于其他处理。尽管AMF物种丰富度或群落组成差异不大，但AMF的功能差异很明显。我们的研究结果表明，近二十年来大型食草动物群落的差异导致了AMF群落的局部功能变化。我们的结果进一步证明了菌根是局部适应的，并且功能差异可以在小地理区域内进化。
