澧阳平原更新世末-早全新世稻作农业起源与环境演变的关系研究

The middle reach of the Yangze River is one of canters for the origin of rice agriculture in China. However, the environmental background and process of the origin of rice agriculture and its relationship with environmental change are still not well understood. This is because of the few macro plant remains unearthed from archaeological sites, the difficulty in identification and the lack of evidence directly linked with environmental changes. The development of phytolith extraction and identification methods provides a promising way for the study on the origin of agriculture. Liyang Plain in the middle reach of the Yangtze River is an ideal study area for teasing out the relationship between rice agriculture and environmental evolution, because this area has continuous cultures since the late Paleolithic period and a large number of rice remains in the early Neolithic Age are found. Taking the Liyang Plain as our study area, we will first analyze phytoliths from both typical archaeological sites and natural strata. Specifically, we will extract rice phytoliths and analyze their morphology to distinguish whether they are wild or domesticated, which aims to reveal the origin and development of rice agriculture from the terminal Pleistocene and the early Holocene. Second, we will rebuild environmental evolution process from the terminal Pleistocene to the early Holocene by analyzing ancient environmental indicators (e.g., pollen and phytolith ect.from natural strata) and by dating technology. Third, we will compare the process of environmental evolution with the history of rice agriculture activities at the same time scale to analyzing the relationship between the origin of rice agriculture and environmental evolution. Our research will be helpful for understanding how humans in the past adapt to environmental changes, and provide scientific evidence for assessing human adaptability to future global changes.

长江中游是中国稻作农业起源的中心地区之一，但目前对稻作农业起源的背景、过程及其与环境变化的关系仍不清楚，究其原因与早期遗址出土植物大遗存少、鉴定难且缺乏与环境变化直接关联的证据有关。植硅体提取和鉴定技术的发展为农业起源研究觅得蹊径。澧阳平原自旧石器晚期以来文化一直连续传承，该区曾发现大量新石器早期稻作遗存,是进行稻作农业与环境演变关系研究的理想区域。本项目以澧阳平原为研究区，通过对典型考古遗址和自然地层进行植硅体分析，提取水稻植硅体进行形态分析和野生及栽培稻鉴定，揭示早期稻作农业发展变化过程；通过对自然地层进行孢粉、植硅体及其他古环境指标分析，结合年代测试，重建该区更新世末至早全新世环境演变历史；在同一年代标尺下对环境变化序列和稻作农业活动历史进行对比分析，探讨稻作农业起源与环境演变的关系。本研究不仅有助于认识过去人类适应环境变化的模式，也可为理解和评估未来全球变化的人类适应提供科学依据。

本项目以揭示澧阳平原稻作农业起源与发展同环境演变的关系为目标，主要做了以下工作：（1）重建环境演变过程。对澧阳平原十里岗剖面和典型遗址剖面进行了年代测试和粒度、磁化率、色度和地球化学元素、孢粉和植硅体等环境指标的分析，揭示出澧阳平原晚更新世以来经历了暖湿-降温-冷湿-转暖-干凉化的变化过程。（2）揭示水稻驯化过程。通过对澧阳平原典型遗址文化层样品水稻扇型植硅体鱼鳞状纹饰的统计分析，发现具有≥9个鱼鳞纹饰的水稻扇型植硅体占水稻扇型植硅体总数的比例不断增加，华垱遗址早期地层中该比例为25%~35%，优周岗和孙家岗遗址大溪文化和屈家岭文化时期已经稳定在了50%以上，至石家河文化时期达到60%，而至唐宋和明清时期分别为63%和66%，表明澧阳平原距今10000年前后就已经开始了水稻的驯化，水稻驯化经历了漫长而波动的持续发展过程。（3）探讨稻作农业同环境演变的关系。更新世末至全新世早期，澧阳平原气候环境不断向暖湿方向发展，逐渐形成水网交织的平原低丘景观。通过对澧阳平原条头岗、乌鸦山、十里岗和华垱等遗址的考古学研究，发现澧阳平原自旧石器时代中期以来古文化持续发展，石器加工技术不断进步，至新旧石器过渡时期生产性工具不断增多且开始定居生活。因此，适宜的气候、水文地貌条件和肥沃的土壤条件为稻作农业的起源和发展提供了有利的自然条件，而持续发展的古文化为稻作农业起源与发展的提供了重要的文化基础。（4）阐明人类活动对环境的影响。对铜官窑剖面的孢粉分析表明，唐代中晚期以来受瓷器生产和农业垦殖等人类活动的影响，铜官窑地区原生植被遭到严重破坏，区域人地关系也随之逐渐恶化。该研究深化了对长江中游地区古代人地关系的认识，可以为更好的理解和评估未来环境变化提供重要的科学依据。