Positive interspecific interactions in resource capture and soil property modification benefit the establishment of mixed plantations, contingent on environmental conditions. However, primary species frequently reject companion tree species frequently arises in forest management practices. To understand this contradiction, we investigated the effects of five planting patterns involving two local companion tree species (Phoebe chekiangensis and Torreya grandis) and Phyllostachys edulis on the soil nitrogen (N) and phosphorus (P) content, enzyme activities, net N mineralization rates, microbial composition, fungal functional groups, and the AMO gene abundance under both shade and full light conditions using a pot experiment. Under the full light condition, altered soil properties were predominantly influenced by interspecific interaction compared to intraspecific interactions, leading to an overall enhancement in nutrient availability and enzymatic activities. Under the shade condition, mixing with P. edulis similarly facilitated increased NH4+-N content, ammonification rate, and urease activity. However, P. edulis significantly decreased ammonia monooxygenase and its encoding gene, as evidence by the unbalanced ratio of net ammonification to net nitrification (2.2-fold) under the shade condition, resulting in high NH4+-N/NO3–-N ratios. Additionally, the shade condition induced soil microbial communities in the mixture to resemble those of monocultured dominant species (P. edulis). Our findings also indicated that specific plant-fungal associations in companion species were disrupted when intercropped with P. edulis. Therefore, this study highlights how the performance of companion species, linked to soil NH4+-N/NO3–-N ratios and plant-fungal associations, leads to their suppression by P. edulis under shade conditions.

中文翻译：

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土壤铵态氮比和营养共生体的变化增强了 Phyllostachys edulis 对阴凉处异质竞争者的抑制


资源捕获和土壤特性改性中的正种间相互作用有利于混合种植园的建立，具体取决于环境条件。然而，原生树种经常排斥森林管理实践中经常出现的伴生树种。为了理解这一矛盾，我们研究了涉及两种当地伴生树种 （Phoebe chekiangensis 和 Torreya grandis） 和 Phyllostachys edulis 的 5 种种植模式对土壤氮 （N） 和磷 （P） 含量、酶活性、净氮矿化速率、微生物组成、真菌官能团以及 AMO 基因丰度的影响在阴凉和全光条件下使用盆栽实验。在全光照条件下，与种内相互作用相比，改变的土壤特性主要受种间相互作用的影响，导致养分可用性和酶活性的整体增强。在阴凉条件下，与 P. edulis 混合同样促进了 NH4+-N 含量、氨化速率和脲酶活性的增加。然而，毛竹显著降低氨单加氧酶及其编码基因，在阴凉条件下净氨化与净硝化比不平衡（2.2 倍）证明了这一点，导致 NH4+-N/NO3–-N 比值高。此外，阴凉条件诱导混合物中的土壤微生物群落类似于单一栽培的优势物种 （P. edulis） 的微生物群落。我们的研究结果还表明，当与 P. edulis 间作时，伴侣物种中的特定植物-真菌关联被破坏。 因此，本研究强调了与土壤 NH4+-N/NO3–-N 比率和植物-真菌关联相关的伴生物种的性能如何导致它们在阴凉条件下被毛竹抑制。