Land degradation caused by deforestation seriously affects the soil environmental capacity (SEC), with potential risks to soil health. However, conventional SEC theory is unable to quantitatively describe the saturation capacity of different soil fractions and environmental pollution levels of a heterogeneous system. Thus, a new concept, the soil pool capacity (SPC), was introduced to fill this gap. We undertook space‐for‐time substitution to investigate the responses of SPCand soil safety capacity (SSC) to changes in the soil physiochemical properties, chemical species, and molecular characteristics of soil lead (Pb) in the conversion of tropical secondary rainforest (TSR) to rubber (Hevea brasiliensis) monoculture plantations with 15‐ and 60‐year histories (RP_15/60). Conversion of TSR to RP_15/60 caused adverse effects on soil properties (i.e., lower soil organic matter [SOM] and higher bulk density [BD]). The saturated SPC (SPC_sat) for Pb in bulk soils under RP₁₅ (2,203.17 g m⁻²) and RP₆₀ (1,634.09 g m⁻²) decreased compared with that in TSR (2,227.10 g m⁻²). The contribution rates of SPC_sat in the exchangeable (P1) and carbonate (P2) pools to the total capacity stabilized at approximately 94%. The contribution rate of potential SPC_sat in P4 (OM‐bound Pb) significantly decreased with increasing agricultural intensity. The SSC of labile fractions (P1 + P2) accounted for 81–85% (a critical level) of the total SSC when the soil loading capacity for Pb reached the SSC in bulk soil regardless of land‐use type. Fourier transform infrared and X‐ray diffraction spectra revealed the Pb‐loaded species of SPC_sat in TSR and RP_15/60 (i.e., TSR: Pb₂SiO₄ in P2, (CH₃COO)₂Pb in P4, RP_15/60: Pb₅Si₈O₂₁ and Pb₂(P₄O₁₂) in P2, and (CHOO)₂Pb in P4). Correlation and factor analyzes showed that SOM and BD were key factors that had an opposite impact on SPC_sat and SSC. These results are helpful to choose appropriate agronomic measurements to reduce land degradation and crop safety risks caused by deforestation.

中文翻译：

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海南岛雨林向橡胶林的转化对铅土壤储量的影响

森林砍伐造成的土地退化严重影响土壤环境容量（SEC），对土壤健康具有潜在的风险。但是，传统的SEC理论无法定量描述不同土壤组分的饱和能力和异构系统的环境污染水平。因此，引入了一个新概念，即土壤池容量（SPC）来填补这一空白。我们进行了时空替代研究，以研究SPC和土壤安全能力（SSC）对热带次生雨林（TSR）转化过程中土壤理化性质，化学物种和土壤铅（Pb）分子特征变化的响应_已有15年和60年历史的橡胶（巴西橡胶树）单种人工林（RP _15/60）。将TSR转化为RP _15/60会对土壤特性产生不利影响（例如，较低的土壤有机质[SOM]和较高的堆积密度[BD]）。RP ₁₅（2,203.17 g m ^-2）和RP ₆₀（1,634.09 g m ^-2）下的块状土壤中铅的饱和SPC（SPC _sat）低于TSR（2,227.10 g m ^-2）。SPC的贡献率_坐在在可更换（P1）碳酸酯（P2）和池在大约94％稳定的总容量。潜在的SPC的贡献率_坐随着农业强度的提高，P4中的元素（OM结合的铅）显着降低。当土壤的铅载量达到散装土壤中的SSC时，无论土地利用类型如何，不稳定级分（P1 + P2）的SSC占总SSC的81–85％（临界水平）。傅里叶变换红外和X射线衍射光谱显示SPC的铅加载物种_坐在在TSR和RP _15/60（即，TSR：铅₂的SiO ₄在P2，（CH ₃ COO）₂的Pb在P4，RP _{15 / 60}：P2中的Pb ₅ Si ₈ O ₂₁和Pb ₂（P ₄ O ₁₂）和（CHOO）₂P4中的Pb）。相关性和因素分析表明，SOM和BD是对SPC _sat和SSC具有相反影响的关键因素。这些结果有助于选择适当的农艺措施，以减少因森林砍伐而导致的土地退化和作物安全风险。