摘要
全新世以来,全球增温、人类活动加剧,使得火演化规律和火机制愈加复杂。系统性地研究全新世火活动的时空演化规律,不仅可以更清晰地理解区域火活动机制与气候因子、植物特征以及人类活动之间的关联,而且对预测未来火的演化趋势具有现实的指导意义。文章综合对比分析了中国中东部季风区域全新世以来的炭屑/黑碳沉积记录,发现该区域全新世火活动呈现出较大的时空差异。空间分布上,该区域火活动最活跃期从东北至东南呈现随纬度降低而趋晚的趋势,即东北地区早、中全新世,黄土高原和长江流域的中全新世(分别约为8.0~6.0 ka B.P.、6.0~4.5 ka B.P.),以及南部地区晚全新世(4.0~2.0 ka B.P.)火活动较强;时间序列上,该区域火活动在4.0 ka B.P.前后呈现明显不同的变化规律,其中中国南部地区、黄土高原及东北地区自约4.0 ka B.P.后火活动有明显增强;长江流域该时段前后火活动有所减弱,直至约2.2 ka B.P.前后火活动有所回升。综合分析认为,在中早全新世,不同地区火活动最活跃期主要受控于水热配置影响,但生物量和局域人类活动因素不可忽略;在晚全新世约4.0 ka B.P.前后长江流域火活动因先民伐林活动导致植被覆盖下降而有所抑制,而其他地区约4.0 ka B.P.以来的人类活动对于当地火事件具有增强的影响。此外,通过综合不同沉积环境的炭屑/黑碳记录来反演火历史规律,需要考虑燃料来源、搬运沉积过程以及研究方法差异性的影响。不仅如此,有效区分人为火活动和自然火活动是预测未来增温背景下火活动变化和控制因素的一个亟需解决的科学难题。
Under the background of global warming,the relationship between the evolution of fire activity and climate,vegetation and human activities has become a hot research topic.Wildfire is not only an integral part of terrestrial ecosystem and closely related to climate,vegetation changes and human activities.Since the turn of the Holocene,the evolution and the regime of wildfire have become much more complex,due to global warming,great fluctuation of climate,and increased human activity.The systematic study of fire history over a long-time scale and in a large area can not only provide a clearer understanding of the relationship between fire regime and climate factors,plant characteristics and human activities,but also provide practical guidance for predicting the evolution trend of fire in the future.In this research,it is found that the Holocene fire activity presents a large spatial and temporal difference in the monsoon region of central and eastern China,based on a comprehensive comparative analysis of the records of charcoal/black carbon deposition since the Holocene in this region.And the strong natural fire activity in the Holocene in Eastern China usually occurred when the climate was relatively warm and dry,by comparing the records of fire activity,hydrothermal configuration curve,solar radiation and vegetation biomass.In terms of spatial distribution,the most active period of fire activity in this region tends to be later with decrease of latitude from northeast to southeast.Specifically,fire activities were strong in the Northeast China during the Early and Middle Holocene,the Loess Plateau and the Yangtze River Basin during the Middle Holocene(8.0~6.0 ka B.P.and 6.0~4.5 ka B.P.)and the Southern China in 4.0~2.0 ka B.P.On time series,the fire activity showed a different change pattern before and after 4.0 ka B.P.The fire activity increased significantly after4.0 ka B.P.in the south of China,the Loess Plateau and Northeast China,but decreased before and after this period,and then increased until ca.2.2 ka B.P.in the Yangtze River Basin.In the Early and Middle Holocene,the most active period of fire activity in different regions was mainly controlled by hydrothermal configuration.The warm and dry climate in Northeast China was the main reason for the strong fire activity in Early-Middle Holocene.But biomass and local human activities could not be ignored,and it is prone to intense fire activity when trees increasing during the Middle Holocene(8.5~4.0 ka B.P.)in the Loess Plateau.In the Yangtze River Basin,human activities had an important influence on fire activity,and agricultural activities and civil fires in Early and Middle Holocene may have led to local strong fire activity.Around 4.0~2.2 ka B.P.,the fire events in the Yangtze River Basin were restrained due to a general decrease of forest cover with increasing human activities,but increased until ca.2.2 ka B.P.for a high tide of human activity,while the fire events in other regions were enhanced by human activities since ca.4.0 ka B.P.It is worth noting that it is necessary to consider the effects of fuel sources,transportation and deposition processes,and the influence of difference of research methods,when using charcoal/black carbon records from different depositional environments to invert the laws of fire history.In addition,more and more studies believe that the fire activity in the Late Holocene was mainly influenced by climate and human activities.However,how to effectively distinguish anthropogenic fire activity from natural fire activity may be a difficult problem to be solved for discussing the change and control factors of natural fire activity under the background of future warming.
作者
庞洋
周斌
徐向春
胡圆峰
周雪航
PANG Yang;ZHOU Bin;XU Xiangchun;HU Yuanfeng;ZHOU Xuehang(Key Laboratory of Earth Surface Geochemistry,Ministry of Education,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,Jiangsu)
出处
《第四纪研究》
CAS
CSCD
北大核心
2022年第2期368-382,共15页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:41977378)
国家自然科学基金重大研究计划项目(批准号:41991323)
国家重点基础研究发展计划项目(批准号:2015CB953804)共同资助。
关键词
火活动
元素碳
碳同位素
人类活动
气候控制因素
fire activity
elemental carbon
carbon isotope ratio
human activities
climatic controlling factors
