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气候-土地综合影响的全国中小叶与大叶种茶树种植适宜性区划

National suitability zoning for planting large leaf and medium/small leaf tea tree under the comprehensive influence of climate and land

  • 摘要: 为揭示叶型-环境的协同调控机制,基于1961—2020年全国气候、土壤数据及茶园样点资料,利用MaxEnt模型筛选茶树种植的主导环境因子,采用自然间断点法划分不适宜区、次适宜区、适宜区和最适宜区4个等级,厘定不同叶型不同等级的主导因子阈值,结合各省茶园实际种植面积占比、实际边界样点对比以及卫星遥感进行验证。结果表明:1)春霜冻频率、年降水量、6—8月相对湿润度指数、最冷月平均气温、3—9月平均相对湿度、≥10 ℃活动积温、土壤pH值和海拔是两种叶型茶树的共同主导因子,其中春霜冻频率贡献率最高,约占52%~69%。2)模型预测精度较高,大叶种和中小叶种的AUC(area under curve)分别为0.952、0.893,区划结果与各省茶园面积占比、区划等级及边界样点总体吻合。3)大叶种对热量与湿润度需求更高,种植北界基本稳定在长江中下游;中小叶种具备较强低温耐受性,北界北扩约20~40 km。4)气候变暖推动潜在适宜区北移,但土地因子限制扩展幅度,形成“气候可行-土地受限”的格局。研究结果可为茶树品种选育、种植规划及农业政策制定提供理论支持。

     

    Abstract: Clarifying the ecological suitability patterns of different leaf types of tea plants under the combined influences of climate and land factors is essential for optimizing planting structure and improving adaptive strategies under climate change. Previous large-scale zoning studies generally treated tea as a single species and focused primarily on climatic variables, without distinguishing between large-leaf and medium/small-leaf types or incorporating comprehensive land constraints. To address these limitations, this study integrated national-scale datasets including daily meteorological observations from 2,387 stations (1961–2020), soil type, soil pH (30–100 cm depth), elevation, and 1,097 georeferenced tea garden occurrence records (205 large-leaf, 1,007 medium/small-leaf). The MaxEnt model combined with GIS techniques was employed to identify dominant environmental factors and simulate potential distribution patterns. Suitability probabilities were classified into four levels—unsuitable, marginally suitable, moderately suitable, and highly suitable—using the natural break method. Threshold ranges of dominant factors were quantified for each leaf type and suitability level. Model validation was conducted at multiple spatial scales by comparing simulated suitability proportions with provincial planting area statistics, verifying boundary consistency using field sampling points, and examining fine-scale spatial agreement with meter-level satellite remote sensing imagery. The results indicated that eight environmental variables jointly controlled the distribution of both leaf types: spring frost frequency, annual precipitation, relative moisture index from June to August, average temperature of the coldest month, average relative humidity from March to September, accumulated temperature ≥10 ℃, soil pH, and elevation. Among these, spring frost frequency was the most influential factor, contributing approximately 52%–69% to model performance, highlighting the critical role of frost risk during the bud sprouting period. The MaxEnt model demonstrated high predictive accuracy and stability, with mean AUC values of 0.952 for large-leaf tea and 0.893 for medium/small-leaf tea across repeated cross-validations. Zoning results were highly consistent with actual provincial tea planting proportions and known core production areas, and accurately distinguished planting boundaries within short spatial distances (50–60 km), confirming the robustness of the model in both macro-scale pattern recognition and micro-scale boundary identification.Significant differences were observed between leaf types. Large-leaf tea requires higher thermal accumulation and moisture availability, with optimal conditions characterized by ≥10 ℃ accumulated temperature above 6,200 ℃·d, annual precipitation between 1,000–2,000 mm, low spring frost frequency (<5%), and soil pH of 4.5–5.5. Its northern planting boundary remains generally stable along the middle and lower reaches of the Yangtze River, expanding northward by approximately 40–50 km during 1991–2020 compared with 1961–1990. In contrast, medium/small-leaf tea exhibits stronger cold tolerance and broader ecological amplitude, tolerating lower minimum temperatures and higher frost frequency, with its northern boundary shifting northward by approximately 20–40 km. During 1991–2020, the highly suitable and moderately suitable areas of large-leaf tea increased by 1.42 and 1.59 million ha, respectively, while those of medium/small-leaf tea increased by 0.29 and 1.22 million ha. Although climate warming has promoted the northward shift of potential suitable areas, land factors—particularly soil pH and elevation—impose rigid constraints on expansion, resulting in a spatial pattern characterized as “climatically feasible but land-limited.” This study establishes a climate–land integrated suitability framework that differentiates tea leaf types at the national scale and constructs a multi-level validation system from provincial statistics to township-scale remote sensing. The findings provide scientific support for tea variety selection, regional planting planning, boundary risk assessment, and adaptive agricultural policy formulation under ongoing climate change, and emphasize that future expansion strategies should follow the principle of “land diagnosis first, climate matching second.”

     

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