福建琅岐岛表土孢粉与植硅体组合对农业活动的指示

Pollen and phytolith assemblages in topsoil as indicators of agricultural activities in Langqi Island, Fujian Province

  • 摘要: 孢粉和植硅体是重建古人类农业景观及环境变化的重要指标,明确它们在表土中的分布规律及其与现代植被组成之间的关系对于精确解释化石孢粉和植硅体数据具有重要的意义。本研究对福建琅岐岛3种土地利用类型的22个表土样品进行了孢粉与植硅体分析,基于地理信息系统和遥感技术,展示了不同类型孢粉百分比的空间分布及其与植被覆盖度间的数量对应关系。孢粉分析表明,以松属(Pinus)为代表的外来花粉普遍存在于表土样品中,这削弱了采样点周围植物的孢粉表现力,导致了果园和农田植被组成与表土孢粉组合间的巨大差异。与此同时,农业收割活动进一步降低了农田植物的花粉表现力。从遥感影像中提取的植被覆盖度数据仅与荒地上的木本植物花粉含量存在较强的相关性(R2=0.7764),这显示茂密的草本植物降低了外来木本花粉的相对含量,证明了该植被类型具有良好的孢粉表现力。植硅体分析表明,表土样品含有丰富的竹亚科(Bambusoideae)、水稻(Oryza sativa)和杂草的植硅体。与孢粉指标相比,植硅体提供了更丰富的草本植物信息。

     

    Abstract: Pollen and phytolith are valuable proxies for reconstructing ancient agricultural landscapes and environmental changes. Understanding their distribution patterns in the topsoil and their relationship with vegetation composition is vital for accurately interpreting fossil pollen and phytolith data. We analyzed pollen and phytolith data from 22 topsoil samples representative of three land-use types in Langqi Island, Fujian Province. We presented the spatial distributions of different pollen taxa and their quantitative relationship with fractional vegetation cover (FVC) based on geographic information system and remote sensing techniques. Pollen analysis revealed that Pinus pollen, as an exotic species, were pervasive in the samples, which diluted the representation of local components, and generated obvious bias between pollen assemblages and vegetation composition of local agricultural lands. Furthermore, agricultural harvesting decreased the pollen representation of cultivated plants. The FVC extracted from remote sensing images is linearly correlated with the abundance of arboreal pollen in the uncultivated land (R2=0.7764), implying that dense herbs on the uncultivated land decreased the share of exotic arboreal pollen, and confirming excellent pollen representation of this vegetation type. Phytolith analysis indicated that numerous phytoliths occurred in the samples, such as Bambusoideae, Oryza sativa, and weeds; they provided more detailed information on non-arboreal plants than pollen proxy.

     

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