| 香榧主产区SOC、STN和C:N空间异质性及其关键影响因素 |
| 摘要点击 1511 全文点击 455 投稿时间：2023-10-14 修订日期：2023-12-28 |
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| 中文关键词 亚热带经济林 空间变异 影响因素 随机森林（RF） 结构方程 香榧 |
| 英文关键词 subtropical plantation forest spatial variability influencing factors random forest（RF） structural equation Torreya grandis cv. Merrillii |
| DOI 10.13227/j.hjkx.20240943 |
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| 中文摘要 |
| 土壤有机碳（SOC）和全氮（STN）是反映森林生态系统平衡和土壤肥力质量的重要指标.全面掌握区域SOC、 STN和C∶N的空间分布格局及其影响因素对于精准施肥和土壤健康至关重要.以浙江省特色经济林——香榧主产区为研究区域,基于1 km×1 km网格布点采集表层土壤样品（0~20 cm）117个.采用多元统计方法（随机森林模型、 结构方程模型、 冗余分析以及变异分解）结合多种空间分析手段（地统计学和Moran's I 指数等）,揭示香榧主产区的SOC、 STN和C∶N的空间分布及其影响因素.结果表明,土壤ω（SOC）、 ω（STN）和C∶N的平均值分别为17.63 g·kg-1、 1.48 g·kg-1 和12.65,与其他地区均值相比处于较高水平,其变异系数分别为68.08%、 67.41%和46.03%,均存在中等程度变异；半方差函数结果表明,SOC、 STN和C∶N存在中等程度的空间自相关,块基比[C0 /（C0 + C）]值分别为 49.98%、 45.88%和49.93%；空间分布结果表明,SOC、 STN和C∶N由东北向西南逐渐降低,且绝大部分区域的SOC的肥力水平处于中等以上.相关分析和冗余分析结果表明,碱解氮、 速效磷和速效钾与SOC和STN均呈显著相关（P<0.05）.随机森林模型、 结构方程模型和变异分解结果表明,土壤速效养分（碱解氮、 速效磷和速效钾）是影响SOC和STN的主控因子.基于此,可通过合理施肥和种植林下植被等生态措施,提升浙江省特色经济林土壤碳、 氮库潜力,增强林地应对区域气候变化的能力. |
| 英文摘要 |
| Soil organic carbon （SOC） and soil total nitrogen （STN） serve as important indicators of the elemental balance within forest ecosystems reflecting soil fertility and quality. Accurate knowledge regarding the spatial variability of regional SOC, STN, and C∶N ratio and their influencing factors is of great significance for precise fertilization and soil health. In this study, a total of 117 topsoil samples （0-20 cm in depth） based on a 1 km×1 km grid were collected in the Torreya grandis cv. Merrillii plantation in Zhejiang Province. A combination of multi-dimensional statistical approaches （random forest model, structural equation model, redundancy analysis, and variation partitioning analysis） and diverse spatial analytical techniques （geostatistics, Moran's I index, etc.） were applied to reveal the spatial distributions and influencing factors of SOC, STN, and C∶N ratio in the Torreya. grandis cv. Merrillii region. The results showed that the average ω（SOC）, ω（STN）, and C∶N ratio were 17.63 g·kg-1, 1.48 g·kg-1, and 12.65, respectively, and their coefficients of variation were 68.08%, 67.41%, and 46.03%, respectively, indicating a moderate degree of variability. In general, the SOC, STN, and C∶N ratio of the Torreya grandis cv. Merrillii plantations were at an intermediate level in the national plantation. The semi-variance results showed that the nugget/sill values of SOC, STN, and C∶N ratio were 49.98%, 45.88%, and 49.93%, respectively, demonstrating a moderate level of spatial autocorrelation. The spatial distribution results showed that SOC, STN, and C∶N ratio decreased from northeast to southwest, with the majority of the region exhibiting above-medium fertility levels of SOC. The results of correlation analysis and redundancy analysis indicated that AN, AP, and AK were significantly correlated with both SOC, STN, and C∶N ratio （P<0.05）. The results of random forest, structural equation model, and variation partitioning analysis evidenced that the main influencing factors of SOC and STN were soil-available nutrients （AN, AP, and AK）. Therefore, our results could provide important insights for enhancing soil carbon and nitrogen pools in special plantations in Zhejiang Province, enhancing the capacity of plantations to adapt to regional climate change through ecological measures such as appropriate fertilization practices and strategic understory vegetation cultivation. |
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