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<p>The present study provides a modern palynological record for the Majuli Island (the world’s largest river island) of Assam through 26 surface sediment samples obtained from wetlands (Garamur and Pharam) and Lohit River margins. It aims at establishing pollen–vegetation relationships and assessing climate, along with anthropogenic impact on the present ecology of the island. The Garamur wetland assemblages reflect tropical semievergreen to moist deciduous forests with associated riparian and grassland components, indicating relatively consolidated vegetation under strong monsoonal conditions. In contrast, the Pharam wetland samples are characterized by abundant anthropogenic marker pollen taxa such as cereal, <i>Brassica</i>, and Apiaceae, highlighting intensive domestic settlement, whereas the Lohit River margin samples are dominated by extraregional arboreal taxa like <i>Pinus</i> and <i>Ulmus</i>, suggesting strong fluvial transport and sediment reworking. The generalized linear models also show that there is a significant negative correlation between NDVI and arboreal pollen, with a slope of −2.326 (<i>p</i> value &lt; 0.001), suggesting a lower abundance of arboreal pollen in greener areas, which was expected due to sparse tree cover and poor pollen preservation due to frequent fluvial activity. LST exerts a strong negative control on the abundance of arboreal (slope = −0.149, <i>p</i> value &lt; 0.001) and marshy pollen, while the impact is weak and statistically nonsignificant in aquatic pollen (slope = −0.013, <i>p</i> value = 0.594). The findings from the above models demonstrate that thermal stress has stronger inhibitory effects on woody vegetation and marshy vegetation compared to the different functional groups of pollen taxa. Multivariate analysis (Bray–Curtis dissimilarity analysis, principal component analysis, and box-and-whisker plots) highlights the presence of strong compositional differences among different depositional environments. This study establishes modern pollen analogues on this endangered fluvial island and identifies climatic stress along with anthropogenic pressure as key drivers of vegetation degradation and increasing ecological vulnerability.</p>

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Quantitative assessment of modern pollen analogue from Majuli Island, Northeast India: insights into vegetation–climate dynamics and human impact

  • 期刊论文

  • 发表日期：

    2026年2月27日

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  • Arya Pandey,
  • Swati Tripathi,
  • Pujarini Samal,
  • P. Morthekai,
  • Hema Singh

摘要

The present study provides a modern palynological record for the Majuli Island (the world’s largest river island) of Assam through 26 surface sediment samples obtained from wetlands (Garamur and Pharam) and Lohit River margins. It aims at establishing pollen–vegetation relationships and assessing climate, along with anthropogenic impact on the present ecology of the island. The Garamur wetland assemblages reflect tropical semievergreen to moist deciduous forests with associated riparian and grassland components, indicating relatively consolidated vegetation under strong monsoonal conditions. In contrast, the Pharam wetland samples are characterized by abundant anthropogenic marker pollen taxa such as cereal, Brassica, and Apiaceae, highlighting intensive domestic settlement, whereas the Lohit River margin samples are dominated by extraregional arboreal taxa like Pinus and Ulmus, suggesting strong fluvial transport and sediment reworking. The generalized linear models also show that there is a significant negative correlation between NDVI and arboreal pollen, with a slope of −2.326 (p value < 0.001), suggesting a lower abundance of arboreal pollen in greener areas, which was expected due to sparse tree cover and poor pollen preservation due to frequent fluvial activity. LST exerts a strong negative control on the abundance of arboreal (slope = −0.149, p value < 0.001) and marshy pollen, while the impact is weak and statistically nonsignificant in aquatic pollen (slope = −0.013, p value = 0.594). The findings from the above models demonstrate that thermal stress has stronger inhibitory effects on woody vegetation and marshy vegetation compared to the different functional groups of pollen taxa. Multivariate analysis (Bray–Curtis dissimilarity analysis, principal component analysis, and box-and-whisker plots) highlights the presence of strong compositional differences among different depositional environments. This study establishes modern pollen analogues on this endangered fluvial island and identifies climatic stress along with anthropogenic pressure as key drivers of vegetation degradation and increasing ecological vulnerability.