摘要:柑橘是四川省和我国主要水果产品之一。以气候为主的环境变化，对作物空间布局产生了显著影响。为合理优化柑橘生产空间，本研究基于最大熵模型（MaxEnt）构建柑橘适宜分布与环境变量的关系模型，运用受试者工作特征曲线（ROC曲线）检测模型精度，刀切法（Jackknife）筛选主导环境变量；采用ArcGIS技术对比1980年、2010年四川柑橘适宜区分布，揭示近30 a气候变化背景下四川省柑橘适宜区的分布与变化情况。结果显示：四川柑橘适宜性的主导环境变量主要体现为以光、热、水为特征的气候环境变量。近30 a四川省气候暖干化的变化趋势改变了区域生态系统的结构和功能，引起了柑橘种植适宜区的时空变化。1980—2010年柑橘种植适宜性空间格局呈现出2个变化特征，一是高适宜区呈整体向北迁移的趋势，主要分布在成都平原区与川东北地区过渡地区；中适宜区界线向东南方迁移。二是适宜性级别呈现出逐级调整，低、中适宜区的等级调整变化明显。2010年高适宜区面积约为4.22万km2，中适宜区4.19万km2，低适宜区4.4万km2，大部分地区为不适宜区。以高适宜区为参照，通过政策措施，政府部门可增加在川南地区、成都平原地区南部的柑橘生产布局。本研究客观地反映了气候变化下，四川省柑橘种植适宜性变化特征，合理确定了柑橘适宜性面积及分布，为柑橘空间优化提供了科学依据。最大熵模型在对物种分布进行准确模拟和预测时具有较强应用价值，对作物气候适宜性区划具有重要指导意义。但对于不同区域和作物应选取合适的环境变量、空间尺度和物种采样位置，减少系统累计误差，提高作物气候适宜区划定精度。
关键词:柑橘/
地理分布/
自然适宜性/
最大熵模型/
四川省
Abstract:Citrus is one of the main fruit products of Sichuan Province, China. Due to favorable market expectations and the low occurrence of citrus diseases in Sichuan basin, there is a trend of blind expansion of citrus cultivation. However, climate change has had a significant impact on the spatial distribution of crops, and has caused the instability and vulnerability of citrus production in Sichuan. In order to optimize the citrus production space, this study established a model of the relationship between the distribution of areas suitable for growing citrus and environmental variables based on the maximum entropy model (MaxEnt), used the ROC curve to determine the model's accuracy, and used the jackknife method to screen out the dominant environmental variables. The distribution of citrus-suitable areas in Sichuan Province in 1980 and 2010 were compared using ArcGIS, revealing the changes in citrus-suitable areas over nearly 30 years of climate change. The results showed that the dominant environmental variables determining citrus suitability in Sichuan were climatic variables characterized by light, heat, and water. During these 30 years, the trend of climate warming and drying in Sichuan Province changed the structure and function of the regional ecosystem, and caused temporal and spatial variations in citrus-suitable areas. There were two broad changes in the spatial pattern of citrus-suitable areas from 1980 to 2010. First, the highly suitable areas tended to migrate to the north. The boundary of moderately suitable areas located between Chengdu Plain area and northeastern Sichuan Province moved to the southeast. Second, the suitability grade changed in a stepwise fashion. The change in the grades in marginally and moderately suitable areas was obvious. In 2010, the total highly suitable area was about 42 200 km2, moderately suitable areas covered about 41 900 km2, and the least suitable areas covered 44 000 km2; most of the province was not suitable. Using this data of the highly suitable areas, government departments can create policies to increase the quantity of citrus in the south Sichuan region and the southern Shengdu Plain. This study objectively assessed the changes in suitability for planting citrus in Sichuan Province under climate change, and provided a scientific basis for the optimization of citrus space. Application of the maximum entropy model is valuable for accurate simulation and prediction of crop distribution and can be important in guiding crop climatic suitability zoning. However, appropriate environmental variables, spatial scale, and species sampling locations should be selected for different regions and crops to reduce systematic cumulative error and improve the precision of crop climatic suitability zoning.
Key words:Citrus/
Geographical distribution/
Natural suitability/
Maximum entropy(MaxEnt)model/
Sichuan Province
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