Restoring oil palm rivers: assessing the effects of riparian re-vegetation and in-channel modifications on biodiversity and functionality

大片热带森林，主要在印度尼西亚和马来西亚，已被单一种植的油棕（Elaeis guineensis）所取代。热带森林向油棕种植园的转变减少了生境的异质性，并与陆地生物多样性和生态系统功能的下降有关。对opp内淡水生境的环境和生态影响了解较少，但包括泥沙淤积、河岸侵蚀和污染增加，河流形态和水文制度改变，对淡水动植物产生负面影响。河岸缓冲区（即沿河没有化学物质投入的森林和/或非生产植被区域）可以减轻OPPs对河流生物多样性和功能的负面影响，现在是印度尼西亚的一项法律要求。然而，许多较老的保护区经常延伸到河岸。在这些情况下，恢复河岸区、增加河道内特征和/或改变河道形态可能提供有效的缓解策略。虽然有多个大型项目侧重于温带河流的恢复，但热带河流的恢复工作却很少。因此，迫切需要确定opp河流的恢复方法，以最大限度地提高生物多样性和功能，同时保持油棕作物的生产力。本项目利用印度尼西亚一项大规模、长期的河岸恢复试验——热带农业河岸生态系统恢复项目，旨在确定恢复opp河流的有效战略。目标是：(1)量化不同河岸植被恢复处理在长期和短期内对河流形态和过程、水质和生物多样性的影响；(2)量化河流内恢复结合/不结合河岸恢复方法对河流形态和过程、水质和生物多样性的影响；(3)量化所测试的恢复处理对特定生态系统功能和生物多样性服务的支持程度。

Vast areas of tropical forest, predominantly in Indonesia and Malaysia, have been replaced by monocultures of oil palm (Elaeis guineensis). Conversion of tropical forest to oil palm plantations (OPPs) reduces habitat heterogeneity, and is associated with declines in terrestrial biodiversity and ecosystem functioning. The environmental and ecological effects on freshwater habitats situated within OPPs are less well understood but include increased sedimentation, bank erosion and pollution, and altered river morphology and hydrological regimes, with negative implications for freshwater fauna and flora.Riparian buffer zones (i.e. areas of forest and/or non-production vegetation with no chemical inputs along the river) can mitigate negative impacts of OPPs on riverine biodiversity and functioning, and are now a legal requirement in Indonesia. However, many older OPPs often extend to riverbanks. In these cases, restoration of riparian areas, addition of in-channel features and/or alteration of channel morphology may provide effective mitigation strategies. Although multiple large-scale projects have focused on the restoration of temperate rivers, much less work has been done on tropical river restoration. As such, there is an urgent need to identify restoration approaches in OPP-rivers that maximise benefits to biodiversity and functioning whilst maintaining oil palm crop productivity.Making use of a large-scale, long-term riparian restoration experiment in Indonesia - the Riparian Ecosystem Restoration in Tropical Agriculture (RERTA) Project, this project aims to identify effective strategies for restoring OPP-rivers. Objectives are to:(O1) Quantify how different riparian vegetation restoration treatments affect river morphology and processes, water quality and biodiversity in the long- and short-term;(O2) Quantify how in-stream restoration combined with/without riparian restoration approaches affect river morphology and processes, water quality and biodiversity; and(O3) Quantify to what extent specific ecosystem functions and services of biodiversity are supported by the restoration treatments tested.