This study demonstrates that phosphate oxygen isotope (δ18OPO4) analysis effectively detects and monitors fire‐induced transformation in soil phosphorus (P). Fires increase bioavailable P, potentially limiting primary production in terrestrial ecosystems. However, understanding the effects of fire on soil P dynamics in the field remains challenging due to the interaction between fire spread and soil properties with high spatial heterogeneity. Soil burning experiments were conducted using a surface soil sample collected in central Japan. The soil was burned in an electric furnace from 50 to 550°C for 3 h, and P concentrations and δ18OPO4 values were determined. The results revealed that high temperatures (>350°C) depleted the soil of organic P (Po) and increased labile and stable inorganic P (Pi) concentrations while significantly decreasing δ18OPO4 values. By contrast, low temperatures (150°C) increased labile Pi and Po concentrations without isotopic shift, indicating that low‐intensity fires could increase bioavailable P while conserving soil organic matter. These findings indicate that δ18OPO4 analysis can provide insight into the relationship between P transformations and fire intensity and track subsequent changes in P dynamics over time. Our research highlights the potential of δ18OPO4 in predicting and managing postfire ecological and agricultural impacts.

中文翻译：

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使用磷酸盐氧同位素比值追踪火烧引起的土壤磷转化


这项研究表明，磷酸氧同位素 （δ18OPO4） 分析可有效检测和监测火灾引起的土壤磷 （P） 转化。火灾会增加生物可利用的 P，可能会限制陆地生态系统的初级生产。然而，由于火势蔓延与土壤特性之间的相互作用具有高度的空间异质性，因此了解火灾对田间土壤 P 动力学的影响仍然具有挑战性。使用在日本中部收集的表层土壤样本进行土壤燃烧实验。将土壤在 50 至 550°C 的电炉中燃烧 3 h，测定 P 浓度和 δ18OPO4 值。结果表明，高温 （>350°C） 耗尽了土壤中的有机 P （Po） 并增加了不稳定和稳定的无机 P （Pi） 浓度，同时显著降低了 δ18OPO4 值。相比之下，低温 （150°C） 增加了不稳定的 Pi 和 Po 浓度，而没有同位素变化，这表明低强度火灾可以提高生物可利用度 P，同时保持土壤有机质。这些发现表明，δ18OPO4 分析可以深入了解 P 变换与火灾强度之间的关系，并跟踪 P 动态随时间的后续变化。我们的研究强调了 δ18OPO4 在预测和管理火灾后生态和农业影响方面的潜力。