华北平原中部早中全新世高分辨植被重建

East Asia vegetation reconstruction is important method of knowing the ecology and climate change, and North China Plain is important area of understanding east Asia monsoon and vegetation response to the climate change. But restricted by research conditions, the North China Plain has been lack of high resolution vegetation and climate record in the early and mid Holocene, and no quantitative reconstruction vegetation result, making different views about vegetation during the early-mid Holocene, and little know about vegetation response to climate change events. We intend to select Da Caozhuang section in NingJin as the research object which is continuous lake record covering the whole early-mid Holocene. We cut samples in 1 cm (resolution: about 30-40a). Through high resolution chronology and pollen analysis and conventional proxies, vegetation succession and climate change will be reconstructed during the early-mid Holocene. Combined with modern pollen process and relative pollen production data, we will quantitatively reconstructed vegetation succession, and reconstructed native zonal vegetation and vegetation coverage of the main types in the central North China Plain during the early and mid Holocene using Landscape Reconstruction Algorithm. By contrast with the surrounding area, we will discuss the vegetation response characteristics and mechanism to the climate change. The project will provide important reference for climate simulation and prediction, and provide scientific basis for regional ecological environment restoration and construction.

东亚植被重建研究是认识过去生态及气候变化的重要手段，华北是认识东亚季风气候及植被响应的重要区域，但受条件限制，华北平原一直缺乏高分辨率的早中全新世植被和气候研究记录，没有植被定量重建成果，使得对早中全新世植被的认识存在差异，以及植被对气候突变事件的响应等问题更鲜有涉及。本项目拟选取华北平原中部宁晋泊地区能覆盖早中全新世的连续的湖泊记录-大曹庄剖面为研究材料，以1cm（约30-40a分辨率）切分样品。通过高分辨率的年代学和孢粉分析，并结合常规代用指标，重建早中全新世气候变化和植被演替序列；结合现代花粉过程及相对花粉产量的研究数据，利用景观重建算法定量重建华北平原中部早中全新世植被的变迁过程，还原华北平原中部早中全新世地带性原生植被及主要种类的覆盖度；通过与周围地区对比，揭示早中全新世植被对全球气候变化的响应特征及机制，为植被和气候模拟与预测提供重要参考，也为华北平原生态建设提供科学依据。

本研究基于宁晋泊连续高分辨率的湖泊沉积和植被景观重建算法重建华北平原早中全新世的植被状况。结论如下1)在新仙女木事件-早全新世，11440cal.a B.P.之前，孢粉组合以禾本科、蒿属、菊科等草本花粉为主，植被为草原或森林草原；在早全新世早段（深度512-489cm，11450-9160 cal aB.P.）以松-禾本科-菊科-蒿属为主针叶林-草原景观，松属植被含量为69%，栎属的平均含量3.2%，菊科植物含量为5.7%，蒿属7.4%，禾本科植物较花粉增高9.4%。早全新世后段（深度488-434 cm，9160-7230 cal aB.P.）：定量重建显示为以松-菊科-禾本科-蒿属为主的针叶林-草原景观，松属植物含量为64%，菊科植物百分比为20%，蒿属植物百分4%，藜科植物占比下降约4.5%，禾本科植物占比略有上升5.6%。中全新世（7320~3300 cal aB.P.）松属植物占绝对优势，落叶阔叶树植物含量占比不到1%，草本植物也有所下降，定量重建后显示为松林，显然不符合常理。在5500cal aB.P.前后，松属的含量高达80%，经过粒度分析发现在5500-3500cal aB.P.其沉积相发生明显变化，初步判断大量松属是河流带来。2）常规指标显示出对华北平原中部8.3kaBP、7.2kaBP前后和5.5kaBP前后以及4kaBP前后气候突变事件表现明显，其中植被对气候突变事件响应不敏感。3)太行山区相对花粉产量结果：以禾本科（PPE为1）为参考种，计算了石竹、栎属等10种花粉类型相对花粉产量。太行山森林区相关花粉源范围大致为600m。