How the current distribution of tea cultivation is influenced by specific environmental conditions in Sri Lanka is yet to be explored. Therefore, this study aims to assess the differences between tea and non-tea growing areas with respect to climatic and topographic covariates, and to determine the major covariates that control tea distributions. Climatic data of temperature and rainfall were extracted from WorldClim-Global Climate Data; the elevation, slopes, and aspects were obtained from Global Multi-resolution Terrain Elevation Data; and the solar radiation data was computed using a clear-sky solar radiation model. Random points were created on rasterised environmental layers for tea-growing and non-tea growing areas, stratified into low, mid, and high regions, using ArcGIS version 10.4.1 (Environmental Systems Research Institute: ESRI Redlands, CA, USA).Correlations were derived between covariates and tea and non-tea growing areas. According to the logistic regression analysis, there was no significant influence of the south-west, west, and north-west aspect compared to the north aspect when all other covariates were held constant. The odds ratio indicated that an area with a one-unit higher solar radiation was 1.453 times more likely to be a tea growing area. Similarly, a per unit increase in slope increases the likelihood of an area being suitable for tea cultivation by 1.039 times. When the annual mean temperature increased, the suitability of tea cultivation decreased, but an increased rainfall had increased the suitability of an area for tea cultivation. Areas with a north facing slope had the highest suitability for tea cultivation. This research demonstrated that tea growing could be expanded into a variety of locations as long as these variables are either found or managed in order to obtain the critical levels. In addition, it is proposed that the results of this study could be utilised in the assessment of the climate or/and land suitability for tea.

中文翻译：

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斯里兰卡环境协变量与锡兰茶栽培的关系

斯里兰卡特定环境条件如何影响当前茶叶种植的分布方式。因此，本研究旨在评估茶与非茶产区之间在气候和地形协变量方面的差异，并确定控制茶分布的主要协变量。温度和降雨的气候数据摘自WorldClim-Global Climate Data；高程，坡度和方面是从“全球多分辨率地形高程数据”中获得的；太阳辐射数据是使用晴空太阳辐射模型计算的。使用ArcGIS版本10.4.1（环境系统研究所，在茶种植区和非茶种植区的栅格化环境层上创建了随机点，分为低，中和高区域）。美国加利福尼亚州ESRI雷德兰兹市）相关性是在协变量与茶和非茶种植区之间得出的。根据逻辑回归分析，当所有其他协变量保持恒定时，与西北方面相比，西南，西部和西北方面没有显着影响。比值比表明，太阳辐射高一个单位的区域是茶叶种植区的1.453倍。同样，每增加一个斜率，使该区域适合茶叶种植的可能性增加1.039倍。当年平均温度升高时，茶树种植的适宜性下降，但是降雨增加则增加了茶树种植区域的适宜性。朝北的地区最适合茶叶种植。这项研究表明，只要找到或管理这些变量以获得临界水平，就可以将茶树种植扩展到各种位置。另外，建议该研究的结果可以用于评估气候或/和土地对茶叶的适宜性。