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    基于优化的MaxEnt模型预测青海省祁连圆柏潜在分布区

    Predicting potential suitable distribution areas for Juniperus przewalskii in Qinghai Province of northwestern China based on the optimized MaxEnt model

    • 摘要:
      目的 预测祁连圆柏在青海省的潜在分布区,为祁连圆柏林的经营管理和保护修复提供理论依据。
      方法 利用气候、地形、土壤、生态系统类型和人类活动强度5类环境变量,基于R语言Kuenm程序包优化后的MaxEnt模型预测祁连圆柏在青海的潜在分布区,并探讨影响祁连圆柏地理分布的主导环境因子及其适宜区间,同时应用2018—2020年青海省祁连圆柏林现地调查数据对预测结果进行准确性验证。
      结果 预测的祁连圆柏潜在分布区主要分布在青海东部、东北部和北部,适生区面积为3.20万km2,用于验证的现地调查小班均落入预测的适生区。祁连圆柏适宜生长的环境条件:气候(最热月份最高温15 ~ 22 ℃、最冷月最低温−23 ~ −15 ℃、年平均降水量300 ~ 600 mm、等温性 < 39%、降水季节性变异系数88 ~ 103),地形(海拔2 800 ~ 3 950 m、坡度12° ~ 18°、坡向(阳坡、半阳坡及半阴坡)),土壤(土壤有效水含量 > 0.4 mm/m、0 ~ 30 cm土层硫酸盐含量 < 0.2%),生态系统类型(农田、林地和草地生态系统);祁连圆柏适宜分布区人类足迹指数 > 10。
      结论 优化后的MaxEnt模型可准确反映祁连圆柏的潜在适宜区分布情况。祁连圆柏地理分布是由地形、气温、降水、生态系统类型、土壤和人类活动等多种因素综合影响的结果,海拔是影响祁连圆柏在青海分布的主导环境因子。研究结果可为祁连圆柏造林适宜空间选择提供可靠的理论依据和实施方向,同时,分布区适宜性等级划分结果可为祁连圆柏林的经营管理和保护修复决策提供参考。

       

      Abstract:
      Objective This paper aims to predict the potential distribution area of Juniperus przewalskii in Qinghai Province of northwestern China, and to provide a theoretical basis for the management, protection and restoration of J. przewalskii.
      Method The potential distribution of J. przewalskii in Qinghai Province was predicted by a variety of environmental variables (climate, topography, soil, ecosystem and human activity intensity) based on the MaxEnt model optimized by the Kuenm package of R, and the dominant environmental factors and value ranges affecting the geographical distribution of J. przewalskii were discussed, and the accuracy of the prediction results was verified by the project team from 2018 to 2020 in the field survey of J. przewalskii resources in Qinghai Province.
      Result The predicted suitable areas of J. przewalskii were mainly distributed in the eastern, northeastern and northern Qinghai Province, with a suitable area of 32 000 km2. From 2018 to 2020, sub-compartment for field investigations of J. przewalskii resources in Qinghai Province fell into the predicted suitable area, and the environmental conditions suitable for the growth of J. przewalskii, i.e. climate (max. temperature of the warmest month was 15−22 ℃, min. temperature of the coldest month was −23−15 ℃, annual mean precipitation was 300−600 mm, isothermality was < 39%, the variance of precipitation was 88 − 103), topography (elevation was 2 800−3 950 m, slope was 12°−18°, slope to sunny slope, semi-sunny slope and semi-shaded slope), soil (AWC range > 0.4 mm/m), topsoil gypsum < 0.2%), ecosystem type (farmland, forest land and grassland ecosystem). The human footprint index of J. przewalskii distribution area > 10.
      Conclusion In this study, the optimized MaxEnt model can accurately reflect the distribution of potential suitable areas of J. przewalskii. The geographical distribution of J. przewalskii is the result of the comprehensive influence of topography, temperature, precipitation, ecosystem type, soil and human activities, and altitude is the dominant environmental factor affecting the distribution of J. przewalskii in Qinghai Province. The research results can provide a reliable theoretical basis and implementation direction for the selection of suitable space for afforestation in J. przewalskii, and at the same time, the results of the suitability classification of distribution area can provide a reference for the management and protection and restoration decisions of J. przewalskii.

       

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