Interactions of plant species mediated plant competition for inorganic nitrogen with soil microorganisms in an alpine meadow

• Published in: Plant and soil Vol. 297; no. 1-2; pp. 127 - 137
• Main Authors: Song, Minghua, Xu, Xingliang, Hu, Qiwu, Tian, Yuqiang, Ouyang, Hua, Zhou, Caiping
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.08.2007; Springer; Springer Nature B.V
• Subjects: Agronomy. Soil science and plant productions; Alpine environments; Ammonium; Animal, plant and microbial ecology; Biological and medical sciences; Competition; Elymus; Facilitation; Fundamental and applied biological sciences. Psychology; graphic removed; Grassland soils; Herbs; Immobilization; Kobresia; Meadows; Microorganisms; N recovery; Nitrate; Nitrates; Nitric oxide; Nitrogen; Plant competition; Plant growth; Plant interaction; Plant species; Plants; Soil; Soil ecology; Soil interactions; Soil microorganisms; Soil plant interactions; The Tibetan Plateau; Tracers; The Tibetan Plateau; 15NH+4; 15NO-3, 15N recovery; Soil plant relation; Competition, Facilitation
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-007-9326-1

Sources of competition for limited soil resources, such as nitrogen, include competitive interactions among different plant species and between plants and soil microbes. We hypothesized that plant interactions intensified plant competition for inorganic nitrogen with soil microorganisms. To test these competitive interactions, one dominant species (Kobresia humilis Serg) and one less abundant gramineous herb (Elymus nutans Griseb) in an alpine ecosystem were selected as target species to grow under interactions with their neighboring plants and without interaction treatments in field plots. ¹⁵N-labeled ammonium and nitrate were used to quantify their partition between plants and soil microorganisms for 48 h after tracer additions. Responses of K. humilis to interactions from their surrounding plants were negative, while those of E. nutans were positive. Species identity, inorganic nitrogen forms, and plant interactions significantly affected the total amount of nitrogen utilization by soil microorganisms and plants. Although plant interactions have negative effects on nitrogen uptake of K. humilis, there is an increase in microbial immobilization of nitrogen under presence of its neighbors. For E. nutans, facilitation from surrounding plants is in favor of their nitrogen uptake. Compared with K. humilis, competition for [graphic removed] and [graphic removed] was less intensive between E. nutans and microorganisms. [graphic removed] recovery by soil microorganisms and plants were not more than or much lower than their utilization of [graphic removed] under different interaction treatments. These results suggested that the partitioning of inorganic nitrogen between plants and soil microorganisms is mediated by plant-plant interactions and interactions between plants and soil microorganisms.