Abstract. Oil palm is a controversial crop, primarily because it is associated with negative environmental impacts such as tropical deforestation. Mapping the crop and its characteristics, such as age, is crucial for informing public and policy discussions regarding these impacts. Oil palm has received substantial mapping efforts, but up-to-date accurate oil palm maps for both extent and age are essential for monitoring impacts and informing concomitant debate. Here, we present a 10-meter resolution global map of industrial and smallholder oil palm, developed using Sentinel-1 data for the years 2016–2021 and a deep learning model based on convolutional neural networks. In addition, we used Landsat-5, -7, and -8 to estimate the planting year from 1990 to 2021 at a 30-meter spatial resolution. The planting year indicates the year of establishment for an oil palm plantation as of 2021, either newly planted or replanted oil palm in an existing plantation. We validated the oil palm extent layer using 17,812 randomly distributed reference points. The accuracy of the planting year layer was assessed using field data collected from 5,831 industrial parcels and 1,012 smallholder plantations distributed throughout the oil palm growing area. We found oil palm plantations covering a total mapped area of 23.98 Mha, and our area estimates are 16.66 ± 0.25 Mha of industrial and 7.59 ± 0.29 Mha of smallholder oil palm worldwide. The producers’ and users’ accuracy is 91.9 ± 3.4 % and 91.8 ± 1.0 % for industrial plantations, and 72.7 ± 1.3 % and 75.7 ± 2.5 % for smallholders, which improves upon a previous global oil palm dataset, particularly in terms of omission of oil palm. The overall mean error between estimated planting year and field data was -0.24 years and the root-mean-square error was 2.65 years, but the agreement was lower for smallholders. Mapping the extent and planting year of smallholder plantations remains challenging, particularly for wild and sparsely planted oil palm, and future mapping efforts should focus on these specific types of plantations. The average oil palm plantation age was 14.1 years, and the area of oil palm over 20 years was 6.28 Mha. Given that oil palm plantations are typically replanted after 25 years, our findings indicate that this area will require replanting within the coming decade, starting from 2021. Our dataset provides valuable input for optimal land use planning to meet the growing global demand for vegetable oils. The global oil palm extent layer for the year 2021 and the planting year layer from 1990 to 2021 can be found at https://doi.org/10.5281/zenodo.11034131 (Descals, 2024).

中文翻译：

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1990年至2021年全球油棕种植年份图

摘要。油棕是一种有争议的作物，主要是因为它与热带森林砍伐等负面环境影响有关。绘制作物及其特征（例如年龄）对于为有关这些影响的公众和政策讨论提供信息至关重要。油棕已得到大量测绘工作，但最新准确的油棕范围和年龄地图对于监测影响和为随之而来的辩论提供信息至关重要。在这里，我们展示了一张 10 米分辨率的工业和小规模油棕全球地图，该地图是使用 2016-2021 年 Sentinel-1 数据和基于卷积神经网络的深度学习模型开发的。此外，我们使用Landsat-5、-7和-8以30米的空间分辨率估算了1990年至2021年的种植年份。种植年份是指截至 2021 年油棕种植园的建立年份，无论是新种植的还是在现有种植园中重新种植的油棕。我们使用 17,812 个随机分布的参考点验证了油棕范围层。种植年份图层的准确性是使用从分布在整个油棕种植区的 5,831 个工业地块和 1,012 个小农种植园收集的现场数据进行评估的。我们发现油棕种植园的地图总面积为 23.98 Mha，我们的估计面积为全球 16.66 ± 0.25 Mha 工业油棕种植园和 7.59 ± 0.29 Mha 小农油棕种植园。工业种植园的生产者和用户的准确度为 91.9 ± 3.4 % 和 91.8 ± 1.0 %，小农的准确度为 72.7 ± 1.3 % 和 75.7 ± 2.5 %，这比之前的全球油棕数据集有所改进，特别是在遗漏了油棕。估计种植年份与田间数据之间的总体平均误差为-0.24年，均方根误差为2.65年，但小农的一致性较低。绘制小农种植园的范围和种植年份仍然具有挑战性，特别是对于野生和稀疏种植的油棕，未来的绘图工作应重点关注这些特定类型的种植园。油棕平均种植年龄为14.1年，20年以上油棕面积为6.28兆公顷。鉴于油棕榈种植园通常在 25 年后重新种植，我们的研究结果表明，从 2021 年开始，该地区将需要在未来十年内重新种植。我们的数据集为优化土地利用规划提供了宝贵的信息，以满足全球对植物油日益增长的需求。 2021 年全球油棕范围图层和 1990 年至 2021 年种植年份图层可在 https://doi.org/10.5281/zenodo.11034131 上找到（Descal，2024）。