末次冰期以来中国西南地区火灾活动历史及其对植被生态系统的影响  

RECONSTRUCTING THE HISTORICAL FIRE ACTIVITY AND ITS INFLUENCE ON THE VEGETATION ECOSYSTEM IN SOUTHWEST CHINA SINCE THE LAST GLACIAL PERIOD

作　　者：张潇 黄康有 贾鑫 万秋池 汤永杰 陈聪 郑卓 ZHANG Xiao;HUANG Kangyou;JIA Xin;WAN Qiuchi;TANG Yongjie;CHEN Cong;ZHENG Zhuo(School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,Guangdong;School of Geography,Nanjing Normal University,Nanjing 210023,Jiangsu;School of Geographical Sciences,South China Normal University,Guangzhou 510631,Guangdong)

机构地区：[1]中山大学地球科学与工程学院,广东珠海519082 [2]南京师范大学地理科学学院,江苏南京210023 [3]华南师范大学地理科学学院,广东广州510631

出　　处：《第四纪研究》2024年第1期59-71,共13页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42072205和42077414);国家重点研发计划项目(批准号:2022YFF0801501)共同资助。

摘　　要：我国西南地区森林火灾频发,多与人类活动有关。第四纪地质时期的火灾变化过程及与气候变化和人类活动之间的关系一直是学术界关注的焦点。本研究利用腾冲青海湖(25.1312°N,98.5731°E)和贵州草海湿地(26.8140°N,104.3405°E)沉积物岩芯(长度分别为4.6 m和4.05 m),进行炭屑和孢粉统计分析。在区域数据对比的基础上,试图重建中国西南地区约25 ka B.P.以来的火灾变化历史及植被的响应。研究结果表明,末次冰期(25.0~10.3 ka B.P.)与晚全新世(4.2~0 ka B.P.)时期森林火灾十分活跃,但两个阶段的火灾对植被的影响差异十分明显。末次冰期阶段(25.0~10.3 ka B.P.)区域内乔木类型以常绿硬叶栎、云杉/冷杉属等为主,这些地带性植被在末次冰期火灾增强时仍维持主要优势;而在晚全新世(4.2~0 ka B.P.)火灾增强阶段,次生林的桤木属、松属等则成为优势种属,草海记录中禾本科花粉在近2 ka B.P.以来也达到最大值,反映出人类活动的影响。高频率火灾导致原来在中全新世的顶级常绿阔叶林遭到反复焚烧,并难以恢复。通过对比区域火灾和气候记录,本研究认为西南地区末次冰期的火灾变化主要受控于干冷的气候条件,尤其是冰期夏季风减弱使区域内降水减少和湿度降低。中全新世时期(9.5~5.0 ka B.P.)季风增强,降雨充沛,火灾强度和频率降到最低。这些变化特征与石笋氧同位素基本一致。晚全新世的频繁火灾则与人类活动增强叠加于夏季风减弱有关,且前者成为引发森林火灾的最主要因素。本研究深入探讨了中国西南地区末次冰期以来火灾强度变化历史及其对植被的影响,揭示了自然与人为因素的火灾触发机制,为灾害预测、植物保护及区域规划等提供了新的数据。The prevalence of forest fires in Southwest China is primarily attributed to human activities.Investigating the dynamics of fire evolution during the Quaternary,as well as its correlation with climate change and human interventions,has been a key focus of research.In this study,two continuous sediment cores from Tengchong Qinghai Lake(25.1312°N,98.5731°E)in Yunnan and Caohai Wetland(26.8140°N,104.3405°E)in Guizhou,measured 4.6 m and 4.05 m respectively,were utilized to conduct charcoal and pollen analysis.In comparison with regional records,we present a comprehensive fire history since ca.25 ka B.P.in Southwest China and investigate vegetation responses.The findings indicate that the Last Glacial Period(LGP)(25.0~10.3 ka B.P.)and the Late Holocene(4.3~0 ka B.P.)represent two distinct periods with heightened forest fire activity,while exhibiting notable variations in their impacts on vegetation succession.The dominant arboreal taxa in the study area during the LGP consisted of evergreen sclerophyllQuercus,Pieca/Abies,andPinus.These zonal vegetation types maintained their primary advantages even during periods of intensified fire activity.However,during the fire-intensified period in the Late Holocene(4.3~0 ka B.P.),secondaryAlnusandPinusemerged as the dominant taxa and Poaceae peaked within the last 2 ka B.P.in CH core,indicating clearly human-induced influences.The frequent occurrence of fires led to the repeated burning of dominant evergreen broadleaved taxa during the mid-Holocene,posing challenges for their recovery.By comparing the regional fire and climate records,we propose that variations in fire activity during the LGP in Southwest China were primarily driven by arid and cold climatic conditions,specifically the reduction in rainfall and humidity resulting from weakened summer monsoons during the Last Glacial Period.During the mid-Holocene(9.5~5.0 ka B.P.),abundant monsoon rainfall led to a significant reduction in both fire intensity and frequency to their minimum levels,which are essentially consist

关 键 词：炭屑 西南地区 末次冰期 森林火灾 人类活动 

分 类 号：P534.651[天文地球—古生物学与地层学] P532[天文地球—地质学] Q948[生物学—植物学]