Eucalypts cover most of Australia. Here, we investigate the relative contribution of climate and geochemistry to the distribution and diversity of eucalypts. Using geostatistics, we estimate major element concentrations, pH, and electrical conductivity at sites where eucalypts have been recorded. We compare the median predicted geochemistry and reported substrate for individual species that appear associated with extreme conditions; this provides a partial evaluation of the predictions. We generate a site‐by‐species matrix by aggregating observations to the centroids of 100‐km‐wide grid cells, calculate diversity indices, and use numerical ecology methods (ordination, variation partitioning) to investigate the ecology of eucalypts and their response to climatic and geochemical gradients. We find that β‐diversity coincides with variations in climatic and geochemical patterns. Climate and geochemistry together account for less than half of the variation in eucalypt species assemblages across Australia but for greater than 80% in areas of high species richness. Climate is more important than geochemistry in explaining eucalypts species distribution and change in assemblages across Australia as a whole but there are correlations between the two sets of environmental variables. Many individual eucalypt species and entire taxonomic sections (Aromatica, Longistylus of subgenus Eucalyptus, Dumaria, and Liberivalvae of subgenus Symphyomyrtus) have distributions affected strongly by geochemistry. We conclude that eucalypt diversity is driven by steep geochemical gradients that have arisen as climate patterns have fluctuated over Australia over the Cenozoic, generally aridifying since the Miocene. The diversification of eucalypts across Australia is thus an excellent example of co‐evolution of landscapes and biota in space and time and challenges accepted notions of macroecology.

中文翻译：

---

气候和地球化学是澳大利亚桉树多样化的驱动力。

桉树覆盖澳大利亚大部分地区。在这里，我们调查了气候和地球化学对桉树分布和多样性的相对贡献。利用地统计学，我们估计了记录有桉树的地点的主要元素浓度，pH值和电导率。我们比较了与极端条件有关的单个物种的预测地球化学中值和报告底物的中位数；这提供了对预测的部分评估。我们通过将观测值汇总到100 km宽的网格单元的质心来生成按地点分类的矩阵，计算多样性指数，并使用数值生态学方法（定向，变异划分）来调查桉树的生态学及其对气候的响应和地球化学梯度。我们发现，β多样性与气候和地球化学模式的变化相吻合。在澳大利亚，桉树物种组合的变化中，气候和地球化学的变化不足一半，而在物种丰富度高的地区，气候变化和地球化学的变化却占80％以上。在解释整个澳大利亚的桉树种类分布和组合变化方面，气候比地球化学更重要，但两组环境变量之间存在相关性。许多单个的桉树种和整个分类学部分（在解释整个澳大利亚的桉树种类分布和组合变化方面，气候比地球化学更重要，但两组环境变量之间存在相关性。许多单个的桉树种和整个分类学部分（在解释整个澳大利亚的桉树种类分布和组合变化方面，气候比地球化学更重要，但两组环境变量之间存在相关性。许多单个的桉树种和整个分类学部分（郁金，Longistylus亚属的桉树，Dumaria，并Liberivalvae亚属金娘）具有通过地球化学强烈影响分布。我们得出的结论是，桉树多样性是由陡峭的地球化学梯度所驱动的，这是由于新生代以来澳大利亚各地气候模式的波动所引起的，自中新世以来普遍干旱。因此，澳大利亚各地桉树的多样化是景观和生物群在空间和时间上共同进化的一个很好的例子，并挑战了公认的宏观生态学观念。