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Mycorrhizal symbiosis and phosphorus supply determine interactions among plants with contrasting nutrient-acquisition strategies
Journal of Ecology ( IF 5.3 ) Pub Date : 2021-08-17 , DOI: 10.1111/1365-2745.13766
Rachel J. Standish 1 , Felipe E. Albornoz 2, 3 , Tim K. Morald 4 , Richard J. Hobbs 4 , Mark Tibbett 2, 4, 5
Affiliation  

  1. Highly diverse plant communities growing on nutrient-impoverished soils are test beds for theories on species coexistence. Here, neighbouring mycorrhizal and non-mycorrhizal plants compete for limited phosphorus. The impact of below-ground interactions on community dynamics is underexplored.
  2. We used an experimental approach to investigate effects of inoculation with arbuscular mycorrhizal (AM) fungi and a phosphorus supply gradient on competitive and facilitative interactions among mixed assemblages of woody plants in microcosms. The plant species, one cluster root-forming (CR) species and four AM species, are native to jarrah forest that grows on nutrient-impoverished soils in south-western Australia. We measured plant growth in microcosms, with and without inoculation with the AM fungus Rhizophagus irregularis, and across a gradient of P supply: 0, 9, 27 and 243 mg P per kg of soil.
  3. Our data show evidence of plant–plant facilitation at low P supply and competition at high P supply. Growth of the CR species, Hakea undulata, was highest in microcosms with 0P and without AM inoculation. One AM species, Bossiaea aquifolium, also performed better at lower P levels, possibly benefitting from P mobilised by H. undulata. The other three AM species, one strongly obligates, performed better at higher P levels. Data for Acacia celastrifolia suggested it was facultatively mycotropic, and because there was no correlation between AM colonisation and the relative inoculum effect, we suggest positive effects of AM inoculation at 9P might be due to benefits other than P acquisition, such as pathogen defence. Benefit of AM inoculation diminished for three of four mycorrhizal species at the highest P level as we had predicted. The fourth species, Eucalyptus marginata (jarrah), had higher growth in microcosms that were not inoculated with AM, perhaps because the species benefits more from ectomycorrhizas.
  4. Synthesis. Our experimental data suggest spatial heterogeneity of soil P, coupled with a diversity of nutrient-acquisition strategies, and plasticity among plant–plant and plant–AM fungi interactions, contributes to plant species coexistence in the nutrient-impoverished jarrah forest. Our research highlights the importance of below-ground mechanisms for understanding factors determining community structure including a potential role of AM fungi in plant pathogen defence.


中文翻译:

菌根共生和磷供应决定了植物之间具有对比养分获取策略的相互作用

  1. 在营养贫乏的土壤上生长的高度多样化的植物群落是物种共存理论的试验台。在这里,相邻的菌根植物和非菌根植物竞争有限的磷。地下互动对社区动态的影响尚未得到充分探索。
  2. 我们使用一种实验方法来研究接种丛枝菌根 (AM) 真菌和磷供应梯度对微观世界中木本植物混合组合之间竞争性和促进性相互作用的影响。该植物物种,一种簇生根 (CR) 物种和四种 AM 物种,原产于澳大利亚西南部营养贫乏的土壤上生长的 jarrah 森林。我们测量了微观世界中的植物生长,接种和不接种 AM 真菌Rhizophagus normis,以及 P 供应梯度:每公斤土壤0、9、27和 243 毫克 P。
  3. 我们的数据显示了低磷供应下植物间促进和高磷供应竞争的证据。CR 物种Hakea undulata 的生长在具有 0P 和没有 AM 接种的微观世界中最高。一种 AM 物种Bossiaea aquifolium在较低的磷水平下也表现得更好,这可能得益于H. undulata动员的磷。其他三个 AM 物种,一个强专性,在较高的 P 水平下表现更好。金合欢数据表明它具有兼性霉菌性,并且因为 AM 定植和相对接种效果之间没有相关性,我们认为在 9P 接种 AM 的积极影响可能是由于 P 获取以外的好处,例如病原体防御。正如我们所预测的那样,在最高 P 水平下,四种菌根物种中的三种接种 AM 的好处减少。第四个物种Eucalyptus marginata (jarrah) 在未接种 AM 的微观世界中具有更高的生长,这可能是因为该物种从外生菌根中获益更多。
  4. 合成。我们的实验数据表明,土壤磷的空间异质性,加上营养获取策略的多样性,以及植物 - 植物和植物 - AM 真菌相互作用之间的可塑性,有助于营养贫乏的 jarrah 森林中的植物物种共存。我们的研究强调了地下机制对于理解决定群落结构的因素的重要性,包括 AM 真菌在植物病原体防御中的潜在作用。
更新日期:2021-08-17
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