Abstract Global biodiversity is being lost due to extensive anthropogenic land cover change. In Southeast Asia, biodiversity-rich forests are being extensively logged and converted to oil-palm monocultures. The impacts of this land-use change on freshwater ecosystems, and particularly on freshwater biodiversity, remain largely understudied and poorly understood. We assessed the differences between fish communities in headwater stream catchments across an established land-use gradient in Sabah, Malaysia (protected forest areas, twice-logged forest, salvage-logged forest, oil-palm plantations with riparian reserves, and oil-palm plantations without riparian reserves). Stream fishes were sampled using an electrofisher, a cast net and a tray net in 100 m long transects in 23 streams in 2017. Local species richness and functional richness were both significantly reduced with any land-use change from protected forest areas, but further increases in land-use intensity had no subsequent impacts on fish biomass, functional evenness, and functional divergence. Any form of logging or land-use change had a clear and negative impact on fish communities, but the magnitude of that effect was not influenced by logging severity or time since logging on any fish community metric, suggesting that just two rounds of selective impact (i.e., logging) appeared sufficient to cause negative effects on freshwater ecosystems. It is therefore essential to continue protecting primary forested areas to maintain freshwater diversity, as well as to explore strategies to protect freshwater ecosystems during logging, deforestation, and conversion to plantation monocultures that are expected to continue across Southeast Asia.

中文翻译：

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土地利用变化与马来西亚沙巴的淡水鱼类物种和功能丰富性的显着丧失有关

摘要 由于广泛的人为土地覆盖变化，全球生物多样性正在丧失。在东南亚，生物多样性丰富的森林被大面积砍伐并转变为油棕单一栽培。这种土地利用变化对淡水生态系统的影响，特别是对淡水生物多样性的影响，在很大程度上仍未得到充分研究和了解。我们评估了马来西亚沙巴州已建立的土地利用梯度（受保护的森林区、两次采伐林、抢救性采伐林、具有河岸保护区的油棕种植园和油棕种植园）上游河流集水区鱼类群落之间的差异。没有河岸储备）。2017 年，在 23 条溪流的 100 m 长断面中，使用电捕鱼器、抛网和托盘网对溪流鱼类进行了采样。随着保护区林区土地利用的任何变化，当地物种丰富度和功能丰富度均显着降低，但土地利用强度的进一步增加对鱼类生物量、功能均匀度和功能差异没有后续影响。任何形式的采伐或土地利用变化对鱼类群落都有明显的负面影响，但这种影响的程度不受采伐严重程度或自登录任何鱼类群落指标以来的时间的影响，这表明只有两轮选择性影响（即伐木）似乎足以对淡水生态系统造成负面影响。因此，必须继续保护原始森林地区以维持淡水多样性，并探索在伐木、森林砍伐、