Global demand for vegetable oil and high oil palm yield have driven the rapid expansion of oil palm plantations in tropical countries. The research literature widely recognizes the effects of forest cover conversion into oil palm on biodiversity, deforestation, and carbon dynamics. However, research on the ecohydrological impacts of oil palm plantations is sparse, despite studies indicating that oil palm development may reshape land-water interactions and the availability and movement of water at different spatial and temporal scales. We address this gap by conducting a systematic literature review on oil palm development and its relation to ecohydrological processes. We found 139 relevant papers up to the year 2021, addressing different ecohydrological processes related to oil palm. We reviewed their spatiotemporal scales, geographic distribution, oil palm species and age, and the effects of land conversion from forest, cropland, and pastures. We also incorporated societal aspects regarding community perceptions of water. Our review highlights the effects of oil palm plantations on three main components of the water cycle: (i) land-atmosphere, (ii) fluvial systems, and (iii) soils and groundwater. Most studies include analyses of the Indo-Malayan and Australasian biogeographical regions (113), followed by the Neotropics (49) and the Afrotropics (15). Compared to rainforests, oil palm monocultures are warmer and drier. They have higher evapotranspiration (ET) rates, lower runoff regulation and infiltration capacity, and lower soil organic carbon (SOC). Although less often implemented, alternative oil palm management practices, including oil palm agroforestry, can help to mitigate some of these effects. Forest to oil palm conversion is the most studied land transition, while conversions from croplands, pastures, and grasslands are less studied. Overall, we identify gaps in understanding the long-term effects of management on ecohydrological processes under different land conversions, especially in the Neotropics and the Afrotropics, precluding research-informed policy to manage impacts of this expanding crop.

中文翻译：

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油棕扩张的生态水文影响：系统回顾

全球对植物油的需求和高油棕产量推动了热带国家油棕种植园的快速扩张。研究文献广泛认识到森林覆盖转化为油棕对生物多样性、森林砍伐和碳动态的影响。然而，关于油棕种植园的生态水文影响的研究很少，尽管研究表明油棕开发可能会重塑陆地与水的相互作用以及不同时空尺度上水的可用性和流动。我们通过对油棕开发及其与生态水文过程的关系进行系统的文献回顾来弥补这一差距。截至 2021 年，我们发现了 139 篇相关论文，涉及与油棕相关的不同生态水文过程。我们回顾了它们的时空尺度、地理分布、油棕树种和树龄，以及森林、农田和牧场转变为土地的影响。我们还纳入了有关社区对水的看法的社会方面。我们的评论强调了油棕种植园对水循环的三个主要组成部分的影响：(i) 陆地大气，(ii) 河流系统，以及 (iii) 土壤和地下水。大多数研究包括对印度-马来亚和澳大利亚生物地理区域 (113) 的分析，其次是新热带 (49) 和非洲热带 (15)。与热带雨林相比，油棕单一栽培更温暖、更干燥。它们具有较高的蒸发蒸腾 (ET) 率、较低的径流调节和渗透能力以及较低的土壤有机碳 (SOC)。尽管不太经常实施，替代油棕管理做法，包括油棕混农林业，可以帮助减轻其中的一些影响。森林向油棕的转变是研究最多的土地转变，而耕地、牧场和草地的转变研究较少。总体而言，我们发现在理解管理对不同土地转变下的生态水文过程的长期影响方面存在差距，特别是在新热带和非洲热带地区，排除了管理这种扩大作物影响的研究知情政策。