Supplementary file 1_Global climate change and Macadamia habitat suitability: MaxEnt-based prediction under future scenarios.docx

Global climate change poses a major challenge for contemporary forestry. Macadamia is an economically valuable tree genus that is widely cultivated across multiple countries and regions. However, few studies have focused on its adaptive distribution and spatiotemporal dynamics under projected global warming scenarios. In this study, we collected the global occurrence records of two commercial Macadamia species (Macadamia integrifolia Maiden & Betche and Macadamia tetraphylla L.A.S. Johnson) and employed a parameter-optimized MaxEnt model to project their suitable habitats under current and future climate scenarios. The optimized model exhibited excellent predictive performance (AUC = 0.979), with a regularization multiplier of 0.5 and linear–quadratic–hinge feature combination. Key bioclimatic variables include: annual Mean temperature (bio1), isothermality (bio3), min temperature of coldest month (bio6), annual precipitation (bio12), and precipitation of driest month (bio14), which collectively comprise 88.2% of the model’s explanatory power. Under the current scenario, the most suitable cultivation areas were determined to be located in Australia, China, South Africa, Brazil, Madagascar, Argentina, and the United States. Compared with the current scenario, total habitat areas under future scenarios (specifically SSP126/585 in the 2030s and 2050s; SSP126/245/370 in the 2070s) are projected to increase by 1.13–7.51%, while reductions of 0.03–2.98% are projected under the other scenarios (SSP245/370 in the 2030s and 2050s; SSP585 in the 2070s). Notably, Brazil exhibits habitat reductions of 2.59–20.06% across all scenarios, while China shows increases of 0.70–45.11%. Furthermore, M. integrifolia was determined to exhibit greater cultivation potential and global expansion feasibility in range than M. tetraphylla. This study elucidates the dominant environmental drivers, current habitat suitability, and climate-driven shifts in Macadamia distribution, providing an empirical basis for sustainable cultivation under climate change.

全球气候变化是当代林业面临的重大挑战。澳洲坚果属（Macadamia）是一类具有重要经济价值的乔木属，目前已在全球多个国家和地区广泛种植。然而，目前鲜有研究聚焦于其在未来全球变暖情景下的适应性分布与时空动态变化。
本研究收集了两个商业化澳洲坚果物种——光壳澳洲坚果（Macadamia integrifolia Maiden & Betche）和四叶澳洲坚果（Macadamia tetraphylla L.A.S. Johnson）的全球分布记录，并采用参数优化后的最大熵模型（MaxEnt），预测了当前及未来气候情景下二者的适宜生境。优化后的模型展现出优异的预测性能（受试者工作特征曲线下面积（Area Under the Receiver Operating Characteristic Curve，AUC）=0.979），其正则化乘数为0.5，特征组合采用线性-二次-铰链特征组合。
核心生物气候变量（bioclimatic variables）包括年平均气温（bio1）、等温性（bio3）、最冷月份最低气温（bio6）、年降水量（bio12）以及最干月份降水量（bio14），上述变量共同贡献了模型88.2%的解释能力。
在当前气候情景下，最适宜的种植区域主要分布于澳大利亚、中国、南非、巴西、马达加斯加、阿根廷及美国。与当前情景相比，未来情景下的总生境面积预计将增长1.13%~7.51%，其中2030年代和2050年代涉及的共享社会经济路径（Shared Socioeconomic Pathways，SSP）情景为SSP126/585，2070年代涉及的SSP情景为SSP126/245/370；而其余情景下总生境面积预计将减少0.03%~2.98%，包括2030年代和2050年代的SSP245/370，以及2070年代的SSP585。
值得注意的是，巴西在所有情景下的生境面积均减少2.59%~20.06%，而中国的生境面积则增长0.70%~45.11%。此外，光壳澳洲坚果相较于四叶澳洲坚果，展现出更高的种植潜力与全球扩张范围可行性。
本研究阐明了主导澳洲坚果分布的环境驱动因子、当前生境适宜性状况以及气候变化驱动下的分布格局变化，为气候变化背景下的可持续种植提供了实证依据。