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基于MaxEnt模型的四川省连香树潜在适生区模拟及其主导环境因子

Simulation of potential suitable area and exploration of dominant environmental factor of Cercidiphyllum japonicum Siebold & Zucc. in Sichuan Province based on MaxEnt model

  • 摘要: 为科学保护和可持续利用国家二级重点保护野生植物和连香树(Cercidiphyllum japonicum Siebold & Zucc.),基于野外分布数据,结合19个生物气候因子和3个地形因子,采用MaxEnt模型模拟了其潜在适生区,并分析了影响其分布的主导环境因子。结果表明:(1)模型预测精度极高,训练集和测试集的AUC值分别为0.940和0.964;(2)经贡献率和多重共线性筛选,最终确定海拔(dem)、昼夜温差月均值(bio2)、最干季均温(bio9)、等温性(bio3)、降水季节性(bio15)、最暖季降水量(bio18)和坡度(slope)为关键环境因子,其中海拔是主导环境因子,适生范围约为13003000 m;(3)适生区总面积为124,513 km2,占全省面积25.62%,其中高、中、低适生区分别占1.77%、6.02%和17.83%,总体呈东北—西南走向的弧形廊带,主要分布于四川盆地向川西高原过渡的“华西雨屏”山地。(4)超过90%的高适生区分布在海拔15002500 m区间的中山带,并呈现三种地理分布格局:四川南部山地形成被大渡河截断的核心集中区(约4100 km2),四川北部沿岷山与龙门山北段形成被涪江分隔的带状延伸区(约2800 km2),四川中部盆地西缘沿龙门山南段至大雪山中段东缘则为斑块散布的过渡区(约1600 km2)。其整体表现出对特定山地季风气候的“避难所”式生态位依赖。研究结果较好揭示了四川省连香树的潜在分布格局,为野外种质资源调查、优先保护单元划定和种群恢复等方面,提供了重要科学依据与基础参考资料。

     

    Abstract: To support the scientific conservation and sustainable utilization of the germplasm resources of Cercidiphyllum japonicum Siebold & Zucc., a nationally protected and rare relict species, in Sichuan Province, this study employed MaxEnt modeling based on field population distribution data, 19 bioclimatic variables, and three topographic factors to simulate its potential suitable habitat and identify the key environmental drivers of its distribution. The results showed that: (1) the model exhibited high predictive accuracy, with AUC values of 0.940 and 0.964 for the training and test datasets, respectively; (2) after evaluating contribution rates and multicollinearity, seven variables were identified as key environmental factors: elevation (dem), mean monthly diurnal temperature range (bio2), mean temperature of the driest quarter (bio9), isothermality (bio3), precipitation seasonality (bio15), precipitation of the warmest quarter (bio18), and slope (Slope), with elevation being the dominant factor, and the suitable elevation range approximately 1300-3000 m; (3) the total suitable area in Sichuan Province was 124,513 km2, accounting for 25.62% of the provincial area, with high, medium, and low suitability zones covering 1.77%, 6.02%, and 17.83%, respectively. Overall, the suitable habitats formed a northeast-southwest oriented arc-shaped corridor, mainly distributed in the “Sichuan Western Rain Shield” mountains along the transition from the Sichuan Basin to the western plateau; (4) over 90% of the highly suitable area was concentrated in the 1500-2500 m mid-mountain belt, exhibiting three distinct distribution patterns: the core concentrated area in the southern Sichuan mountains, interrupted by the Dadu River (4100 km2); the belt-like extension area along the Min Mountains and northern section of the Longmen Mountains in northern Sichuan, divided by the Fujiang River (2800 km2); and the patchy transitional area along the western edge of the central Sichuan Basin, from the southern Longmen Mountains to the eastern edge of the central section of the Daxue Mountains (1600 km2). Overall, the species exhibits a “refugial” ecological niche dependence on specific montane monsoon climates. These findings provide a comprehensive understanding of the potential distribution patterns and ecological requirements of C. japonicum in Sichuan Province and offer important scientific guidance and spatial reference for field germplasm surveys, priority conservation unit delineation, and population restoration.

     

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