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接菌影响模拟重构土层水分布及水同位素分馏

Simulated reconstruction of soil water distribution and isotope fractionation under the influence of AMF inoculation

  • 摘要: 水资源决定着生态恢复过程中的植被结构和种类,是矿区实现绿色生产、生态修复的主要限制因素。为了研究半干旱煤矿区接种丛枝菌根真菌(Arbuscular Mycorrhiza Fungi,AMF)对植物根系提水、模拟土壤水分分布及水同位素分馏的影响,本研究以玉米为供试植物,布设室内分层土柱模拟试验。设置纯土柱(CK1)、土柱+玉米(CK2)、土柱+接菌玉米(AMF)三个处理,每个处理3个重复,测定土柱毛细水上升高度、土壤含水率以及玉米茎水与土壤水的氢氧同位素。分析了不同处理之间玉米生长发育情况、水分运移规律以及不同深度土壤水同位素分馏的差异,结果表明:①接菌有效促进玉米生长发育,株高、地上生物量、地下生物量、总根长比CK2处理分别提高15.78%、23.39%、43.40%、21.0%。②AMF促进根系吸收底部黏土层内的蓄水,提高毛细水上升高度18.9%,玉米吸水空间扩大约50%,进而影响土柱水分分布。③土柱表层、深层土壤水与初始水相比分馏差异较大。在表层0~10 cm处,CK2与AMF处理的18O、2H富集系数显著低于CK1处理,在深层60~70 cm处,AMF处理的18O、2H富集系数显著高于CK2处理,表明AMF可以增强深层土壤水同位素分馏的现象。综上,接菌可以提高玉米对重构土层内深部土壤水的吸收,促使根系通过提水效应反释至上部干燥土壤,提高水分重分配能力,影响不同深度的土壤水同位素分馏,该结果为解决半干旱煤矿区排土场土地复垦水资源短缺问题提供了科学依据和技术支持。

     

    Abstract: Water resources determine the vegetation structure and types in the ecological restoration process, and are the main limiting factor for achieving green production and ecological restoration in mining areas. To investigate the effects of inoculation of Arbuscular Mycorrhiza Fungi (AMF) on plant root water extraction, simulated soil water distribution and water isotope fractionation in a semi-arid coal mining area, this study conducted  the indoor stratified soil column simulation experiment with maize as the test plant. Three treatments were set up as pure soil column (CK1), soil column + maize (CK2), and soil column + inoculated maize (AMF), with three replicates for each treatment. Meanwhile, the height of capillary water rise in soil columns, soil water content, as well as hydrogen and oxygen isotopes of maize stem water and soil water were measured. The growth and development of maize, water transport patterns, and discrepancies in soil water isotope fractionation at different depths among different treatments were also analyzed in this article. Results showed that: (1) Inoculation could effectively promote the growth and development of maize, with plant height, aboveground biomass, underground biomass and total root length increased by 15.8%, 23.4%, 43.4% and 21.0%, respectively, compared to CK2 treatment. (2) AMF have also promoted the root system to absorb the retain water in the bottom clay layer, increased the capillary water elevation by 18.9%, and expanded the water absorption space of maize by approximately 50%, thereby  affecting the water distribution in the soil columns. (3) There were significant fractionation differences between the surface and deep soil water of soil column compared to the initial water. At the surface layer of 0 ~ 10 cm, the 18O and 2H enrichment coefficients of CK2 and AMF treatments were significantly lower than those of CK1 treatment, while at the deep layer of 60 ~ 70 cm, the 18O and 2H enrichment coefficients of AMF treatment were significantly higher than those of CK2 treatment, indicating that AMF could enhance the phenomenon of isotopic fractionation in deep subsoil water. In summary, inoculation can improve the absorption of deep soil water by maize in the reconstructed soil layer, prompt the root system to counter-release to the upper dry soil through the water lifting effect, improve the water redistribution capacity, and affect the soil water isotope fractionation at different depths. The results could provide scientific basis and technical support for addressing the shortage of water resources for land reclamation in semi-arid coal mining areas.

     

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