中文摘要：

反枝苋（Amaranthus retroflexus）是苋属入侵种中发生频率最多、分布最广、危害最严重的杂草。基于反枝苋在世界范围内4207个实际分布点及其对应的气候、地形和土壤3类要素28个环境因子的定量关系，利用主成分分析确定了影响其分布的主要环境因子，据此估测其中心可能分布区和最大可能分布区，并与实际分布点进行比较。结果表明：14个环境因子在决定反枝苋全球分布格局中起着重要作用。反枝苋中心分布区位于新西兰南部、澳大利亚东南部、南美洲北部少数地区、北美洲西北部及东南部部分地区、欧洲大部分地区和中国东南部，最大可能分布区位于南美洲中南部、北美洲大部分、非洲北部小部分、澳大利亚南部及北部少数区域、欧洲大部分地区和亚洲大部分地区及中国除西藏、青海、新疆、四川西部以外的地区。中心分布区的预测结果与实际分布点吻合较好，而最大分布区则过于广阔。

英文摘要：

Aims Amaranthus retroflexus is the most harmful, widely distributed invasive species in its genus. Our objective was to determine its potential worldwide distribution and compare that with its present distribution. Methods We selected 28 environmental factors including climatic, topographic and soil factors as GIS layers and determined their quantitative relationship with the actual global distribution of the species, based on 4 207 herbarium records. Principal component analysis （PCA） was used to select the environmental factors influencing the distribution of the species. Based on these results, we estimated the central and maximum potential distribution of A. retroflexus and compared them to its actual geographical distribution. Important findings Fourteen environmental factors importantly affected the distribution of A. retroflexus. The central potential distribution range was southern New Zealand, southeastern Australia, some areas in northern South America, northwestern and southeastern North America, most of Europe and southeastern China. The maximum potential distribution range was southcentral South America, most of North America, some areas in northern Africa, most of Europe, some areas in southern and northern Australia and most of Asia including most of China except Tibet, Qinghai Province, Xinjiang and western Sichuan Province. The potential central distribution of the species matched its actual distribution, whereas the potential maximum distribution was much larger.