Mycorrhizal symbiosis and phosphorus supply determine interactions among plants with contrasting nutrient-acquisition strategies

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 belowground interactions on community dynamics is underexplored.

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.

Our data show evidence of plant-plant facilitation at low P supply and competition at high P supp...

生长于养分贫瘠土壤中的高度多样植物群落，是物种共存理论研究的试验平台。在此类群落中，相邻的菌根植物（mycorrhizal plants）与非菌根植物（non-mycorrhizal plants）会竞争有限的磷资源，而地下相互作用对群落动态的影响尚未得到充分探索。
本研究采用实验方法，探究了丛枝菌根（arbuscular mycorrhizal, AM）真菌接种与磷供应梯度对微宇宙（microcosms）内木本植物混合群落中竞争与促进相互作用的影响。实验所用植物包含1种簇生根（cluster-root, CR）形成植物与4种丛枝菌根植物，均原产于澳大利亚西南部养分贫瘠土壤中的红柳桉（jarrah）林。我们设置了接种丛枝菌根真菌根内球囊霉（Rhizophagus irregularis）与不接种两组微宇宙实验，并设置了0、9、27、243 mg P/kg土壤的磷供应梯度，以此测定植物生长情况。
本研究数据表明，在低磷供应条件下存在植物间的促进作用，而在高磷供应条件下则表现为竞争……