Synergies for Improving Oil Palm Production and Forest Conservation in Floodplain Landscapes

Lowland tropical forests are increasingly threatened with conversion to oil palm as global demand and high profit drives crop expansion throughout the world’s tropical regions. Yet, landscapes are not homogeneous and regional constraints dictate land suitability for this crop. We conducted a regional study to investigate spatial and economic components of forest conversion to oil palm within a tropical floodplain in the Lower Kinabatangan, Sabah, Malaysian Borneo. The Kinabatangan ecosystem harbours significant biodiversity with globally threatened species but has suffered forest loss and fragmentation. We mapped the oil palm and forested landscapes (using object-based-image analysis, classification and regression tree analysis and on-screen digitising of high-resolution imagery) and undertook economic modelling. Within the study region (520,269 ha), 250,617 ha is cultivated with oil palm with 77% having high Net-Present-Value (NPV) estimates ($413/ha−yr–$637/ha−yr); but 20.5% is under-producing. In fact 6.3% (15,810 ha) of oil palm is commercially redundant (with negative NPV of $-299/ha−yr-$-65/ha−yr) due to palm mortality from flood inundation. These areas would have been important riparian or flooded forest types. Moreover, 30,173 ha of unprotected forest remain and despite its value for connectivity and biodiversity 64% is allocated for future oil palm. However, we estimate that at minimum 54% of these forests are unsuitable for this crop due to inundation events. If conversion to oil palm occurs, we predict a further 16,207 ha will become commercially redundant. This means that over 32,000 ha of forest within the floodplain would have been converted for little or no financial gain yet with significant cost to the ecosystem. Our findings have globally relevant implications for similar floodplain landscapes undergoing forest transformation to agriculture such as oil palm. Understanding landscape level constraints to this crop, and transferring these into policy and practice, may provide conservation and economic opportunities within these seemingly high opportunity cost landscapes.

随着全球需求攀升与高额利润驱动油棕作物在全球热带区域持续扩张，低地热带森林正日益面临被改造为油棕种植园的威胁。然而，景观并非均质统一，区域层面的限制条件决定了该作物的土地适宜性。为此，我们针对马来西亚婆罗洲沙巴州下基纳巴唐岸河（Lower Kinabatangan）的热带洪泛平原区域开展了一项区域性研究，旨在探究森林被改造为油棕种植园过程中的空间与经济特征。基纳巴唐岸河生态系统拥有丰富的生物多样性，栖息有全球受威胁物种，但该区域已遭受森林丧失与破碎化问题。我们采用面向对象影像分析（object-based-image analysis）、分类与回归树分析（classification and regression tree analysis）以及高分辨率影像屏幕数字化技术，对油棕种植区与森林景观进行了制图，并开展了经济建模。本次研究区域总面积为520269公顷，其中250617公顷已被开垦为油棕种植园，77%的种植园净现值（Net-Present-Value, NPV）较高，区间为413美元/(公顷·年)至637美元/(公顷·年)；但另有20.5%的种植园产量不足。实际上，6.3%（即15810公顷）的油棕种植园已丧失商业价值，其净现值为-299美元/(公顷·年)至-65美元/(公顷·年)，这是由于洪水淹没导致油棕植株死亡所致。这些区域原本应为重要的河岸林或洪泛林类型。此外，区域内仍保留有30173公顷未受保护的森林，尽管这些森林对生态连通性与生物多样性保护具有重要价值，但其中64%已被规划用于未来油棕种植。经估算，其中至少54%的区域因洪水淹没事件并不适宜种植油棕。若按规划开展油棕种植园改造，预计另有16207公顷油棕种植园将丧失商业价值。这意味着该洪泛平原内超32000公顷的森林将因此被改造为油棕种植园，此举不仅经济收益微薄甚至无利可图，还会对生态系统造成显著损害。我们的研究结果对于全球范围内类似正经历森林向油棕等农业用地改造的洪泛平原景观具有重要借鉴意义。深入厘清该作物种植的景观尺度限制条件，并将相关结论转化为政策与实践举措，或可为这类看似机会成本高昂的景观带来生态保护与经济发展的双重机遇。