Processes at the soil–root interface determine the different responses of nutrient limitation and metal toxicity in forbs and grasses to nitrogen enrichment,Journal of Ecology

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Processes at the soil–root interface determine the different responses of nutrient limitation and metal toxicity in forbs and grasses to nitrogen enrichment
Journal of Ecology ( IF 5.3 ) Pub Date : 2020-10-09 , DOI: 10.1111/1365-2745.13519
Qiuying Tian ₁ , Peng Lu ₁ , Pengfei Ma _{1,

2} , Huirong Zhou _{1,

2} , Ming Yang _{1,

2} , Xiufeng Zhai _{1,

2} , Mengmeng Chen _{1,

2} , Hong Wang ₃ , Wenchao Li ₁ , Wenming Bai ₁ , Hans Lambers _{4,

5} , Wen‐Hao Zhang _{1,

2}

Affiliation

Nutrient limitation and metal toxicity have been implicated in changes of grassland communities by nitrogen (N) deposition. Below‐ground processes, especially those at the soil–root interface, play important roles in determining variation in nutrient concentrations in plants. However, few studies have specifically focused on the roles of these processes in mineral‐element acquisition in grassland plants in response to N enrichment.
Here we investigated the contributions of below‐ground processes at the soil–root interface to the differential acquisition of phosphorus (P), calcium (Ca) and manganese (Mn) by forbs and grasses of a temperate steppe in response to N addition by combining field and glasshouse experiments.
Nitrogen addition increased the concentrations of both leaf P ([P]) and Mn ([Mn]) and decreased leaf [Ca] of forbs while it had little effects on leaf concentrations of these elements in grasses. Nitrogen addition led to a higher activity of acid phosphatase in the rhizosphere of forbs, and greater release of protons and carboxylates from forb roots than grass roots, contributing to the differential [P], [Ca] and [Mn] in the leaves of forbs and grasses. Applying oxalate to soil to simulate the release of carboxylates by N enrichment enhanced [P] and [Mn], and decreased [Ca] in the soil solution. However, addition of hydrogen‐ion increased [P], [Mn] and [Ca] in the soil solution. Lime addition mitigated the N‐addition‐induced soil acidification while it did not abolish the stimulatory effect of short‐term N addition on leaf [P] and [Mn] of forbs. Therefore, we conclude that differences in the eco‐physiological processes at the soil–root interface account for changes in leaf [P], [Ca] and [Mn] under short‐term N addition, and that soil acidification aggravates the responses of these elements, especially [Ca] and [Mn], to long‐term N enrichment.
Synthesis. Our results highlight the contribution of below‐ground processes, especially those at the soil–root interface, to variation in plant element concentrations between dominant forbs and grasses in the temperate steppe. These findings greatly enhance our mechanistic understanding of the effects of N deposition on grassland communities.

中文翻译：

土壤-根界面的过程决定了营养元素限制和前菜和草中金属毒性对氮富集的不同响应

营养限制和金属毒性已被氮（N）沉积牵连到草地群落的变化中。地下过程，尤其是在土壤-根部界面的过程，在确定植物中养分浓度的变化中起着重要作用。但是，很少有研究专门关注这些过程在响应氮素富集的草原植物矿质元素获取中的作用。
在这里，我们研究了土壤-根部界面地下过程对温带草原的草和草响应氮添加的差异获取磷（P），钙（Ca）和锰（Mn）的贡献。场和温室实验。
氮的添加增加了叶上的P（[P]）和Mn（[Mn]）的浓度，降低了前叉的叶片[Ca]，而对草中这些元素的叶片浓度的影响很小。氮的添加导致了福布斯根际中酸性磷酸酶的活性更高，并且福布斯根中的质子和羧酸盐的释放量比草根更大，这导致了福布斯叶片中的[P]，[Ca]和[Mn]存在差异。和草。在土壤中施用草酸盐模拟土壤中羧酸盐的释放会增强土壤溶液中的[P]和[Mn]，并降低[Ca]。但是，添加氢离子会增加土壤溶液中的[P]，[Mn]和[Ca]。石灰的添加减轻了氮的添加引起的土壤酸化，但并未消除短期氮的添加对小叶的叶片[P]和[Mn]的刺激作用。
综合。我们的结果突出了地下过程，特别是在土壤-根界面的过程，对温带草原优势草和草之间植物元素浓度变化的贡献。这些发现极大地增强了我们对氮沉降对草地群落影响的机理认识。

更新日期：2020-10-09

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