A Critical Review of Oil Palm Plantations: Effects on Biodiversity with Particular Reference to Mizoram

Abstract

Oil palm cultivation has expanded rapidly across the humid tropics over the past four decades, driven by rising global demand for vegetable oils and the crop's exceptional per-hectare yield. This expansion has delivered substantial economic returns to producer nations, but it has also been linked repeatedly to biodiversity loss, particularly where plantations replace primary or secondary tropical forest. India has entered this landscape relatively recently, with the north-eastern state of Mizoram serving as the country's pioneering site for commercial oil palm cultivation since 2005. Mizoram presents a distinctive case: a biodiversity-rich, hilly terrain historically shaped by shifting cultivation, locally termed jhum, now undergoing a state-sponsored transition toward permanent monoculture plantations under successive land-use policies. This review synthesises the global evidence on oil palm's biodiversity consequences and situates Mizoram within that broader literature, drawing on avifaunal, mammalian, arthropod, and vegetation studies conducted in and around Dampa Tiger Reserve and other parts of the state. The review finds consistent evidence that oil palm plantations support markedly lower species richness and abundance than both primary forest and traditional jhum landscapes, with birds, understorey vegetation and soil biota showing the sharpest declines. Comparative work from Mizoram indicates that shifting cultivation mosaics retain considerably more forest-associated biodiversity than oil palm or teak monocultures, challenging simplistic narratives that frame jhum as inherently more destructive than settled plantation agriculture. Mitigation strategies, including riparian buffer retention, agroforestry enrichment, and voluntary certification, show mixed but generally modest effectiveness, and site-specific spatial planning appears to offer the more reliable pathway toward reconciling edible-oil self-sufficiency with biodiversity conservation. The review closes by identifying priority research gaps, offering policy-relevant conclusions, and acknowledging the constraints inherent in a narrative synthesis of a still-developing regional evidence base.