The impact of plants on soil enzymatic activity and their potential for remediation of oil-contaminated soil has been widely studied but information about tree species is scarce. Here, we used seedlings of four tree species (Ailanthus altissima Mill, Fraxinus rotundifolia Mill, Melia azedarach L. and Robinia pseudoacacia L.) to investigate rhizosphere effects on key soil enzymes (dehydrogenase, urease, alkaline and acid phosphatase) and to evaluate oxidative stress in response to oil sludge-contaminated soil (0, 100, 200, 400 g kg⁻¹). We observed a large species-specific stimulation of soil enzyme activity often far exceeding the figures in unplanted soil with peaks mostly occurring under low oil contamination (100 g kg⁻¹). The strongest stimulatory effect on dehydrogenase and urease activity produced R. pseudoacacia at the low and intermediate and F. rotundifolia at the highest contamination level. No clear pattern emerged for acid phosphatase activity, which was equally stimulated by all species at the highest contamination level. Alkaline phosphatase stimulation was dominated by F. rotundifolia at the low and by R. pseudoacacia at the higher oil contamination levels. Foliar H₂O₂ rose significantly in a species-specific manner in response to oil contamination, triggering an upregulation of the antioxidant defence, which began to show signs of exhaustion at the highest pollution level and revealed that oxidative stress was highest in A. altissima. Our results imply that phytoremediation efforts can be optimized through carefully designed plant species assemblages aligning stimulatory effects on soil enzyme activity and oxidative stress tolerance with the severity of the oil pollution.

植物对土壤酶活性的影响及其对油污染土壤的修复潜力已得到广泛研究，但是关于树种的信息却很少。在这里，我们使用了四种树种的种子（臭椿，水曲柳、,子和刺槐）的幼苗，以研究根际对关键土壤酶（脱氢酶，脲酶，碱性和酸性磷酸酶）的影响，并评估其氧化能力。受到油泥污染的土壤产生的应力（0，100，200，400 g kg ^-1）。我们观察到对土壤酶活性的大物种特异性刺激，通常远远超过未种植土壤中的酶，其峰值大多发生在低油污（100 g kg ^-1）下。对脱氢酶和脲酶活性的最强刺激作用在低和中级产生了刺槐，在最高污染水平下产生了圆叶镰刀菌。酸性磷酸酶活性没有清晰的模式出现，所有物种在最高污染水平下均同样受到刺激。碱性磷酸酶刺激在较低的油污染水平下主要由圆叶镰刀菌和在较高的油污染水平下由伪阿拉伯芥子球菌所控制。叶面H ₂ O ₂在应对石油污染的物种特异性的方式显著上升，引发了抗氧化防御，开始展现在最高污染水平疲惫的迹象，表明氧化应激是最高的上调臭椿。我们的结果表明，可以通过精心设计的植物物种组合来优化植物修复工作，从而使组合物对土壤酶活性和氧化胁迫耐受性的刺激效果与油污染的严重程度相吻合。