热带地理
熱帶地理
열대지리
TROPICAL GEOGRAPHY
2014年
2期
156-164
,共9页
湖光岩玛珥湖%叶蜡烷烃%碳同位素%植被变化%甘蔗种植%晚全新世
湖光巖瑪珥湖%葉蠟烷烴%碳同位素%植被變化%甘蔗種植%晚全新世
호광암마이호%협사완경%탄동위소%식피변화%감자충식%만전신세
Huguangyan Maar Lake%n-Alkanes%carbon isotope%vegetation change%sugarcane plantation%late Holocene
通过对广东省湛江市湖光岩玛珥湖晚全新世沉积物中叶蜡烷烃（n-C29，n-C31，n-C33）及其碳同位素（δ13C）进行分析，探讨该湖区约3.5 ka BP以来的植被变化历史，重点讨论了人类活动对该区域植被变化可能带来的影响。叶蜡烷烃δ13C在1.7 ka BP以前偏轻，例如长链烷烃碳同位素在1.78 ka BP为-33.27‰，表明湖区C3植物占绝对优势，表现为典型的C3型生态系统；在1.7 ka BP之后碳同位素明显快速偏重，在1.63 ka BP为-28.26‰，指示了C4植物出现和C4比例上升的过程。C4植物的出现通常指示气候的干旱化，但是烷烃Paq和ACL指数（平均链长）则显示湖区气候可能在1.7 ka BP后变湿润。通过与研究区甘蔗的同位素和ACL指数的比较分析，推测这一矛盾现象可能与湖区开始有一定规模的甘蔗种植活动有关。
通過對廣東省湛江市湖光巖瑪珥湖晚全新世沉積物中葉蠟烷烴（n-C29，n-C31，n-C33）及其碳同位素（δ13C）進行分析，探討該湖區約3.5 ka BP以來的植被變化歷史，重點討論瞭人類活動對該區域植被變化可能帶來的影響。葉蠟烷烴δ13C在1.7 ka BP以前偏輕，例如長鏈烷烴碳同位素在1.78 ka BP為-33.27‰，錶明湖區C3植物佔絕對優勢，錶現為典型的C3型生態繫統；在1.7 ka BP之後碳同位素明顯快速偏重，在1.63 ka BP為-28.26‰，指示瞭C4植物齣現和C4比例上升的過程。C4植物的齣現通常指示氣候的榦旱化，但是烷烴Paq和ACL指數（平均鏈長）則顯示湖區氣候可能在1.7 ka BP後變濕潤。通過與研究區甘蔗的同位素和ACL指數的比較分析，推測這一矛盾現象可能與湖區開始有一定規模的甘蔗種植活動有關。
통과대광동성담강시호광암마이호만전신세침적물중협사완경（n-C29，n-C31，n-C33）급기탄동위소（δ13C）진행분석，탐토해호구약3.5 ka BP이래적식피변화역사，중점토론료인류활동대해구역식피변화가능대래적영향。협사완경δ13C재1.7 ka BP이전편경，례여장련완경탄동위소재1.78 ka BP위-33.27‰，표명호구C3식물점절대우세，표현위전형적C3형생태계통；재1.7 ka BP지후탄동위소명현쾌속편중，재1.63 ka BP위-28.26‰，지시료C4식물출현화C4비례상승적과정。C4식물적출현통상지시기후적간한화，단시완경Paq화ACL지수（평균련장）칙현시호구기후가능재1.7 ka BP후변습윤。통과여연구구감자적동위소화ACL지수적비교분석，추측저일모순현상가능여호구개시유일정규모적감자충식활동유관。
In this study, late Holocene sedimentary records of leaf wax n-alkanes and theirδ13 C from Huguangyan Maar Lake (H.M.L) in Zhanjiang, Guangdong Province, were used to reconstruct the vegetation variations as well as human activities in the lake catchment over the past 3500 years. Carbon isotopic compositions (δ13C) of leaf wax n-alkanes (n-C29, n-C31 and n-C33) were predominantly lighter than-32‰before 1.7 ka BP, suggesting that a typically pure C3 ecosystem might exist before 1.7 ka BP; for example, carbon isotope average value of long-chain n-alkanes was -33.27 ‰ in 1.78 ka BP; after that δ13C values increased rapidly and significantly, carbon isotope value was-28.26‰in 1.63 ka BP, indicating the emergence and increase of C4 plants. C4 plants usually indicate an arid climate, however, the n-alkanes indices that both increased Paq and reduced ACL indicate a humid climate after 1.7 ka BP. This contradiction can be well explained by invoking anthropogenic sugarcane plantation in the catchment at 1.7 ka BP. Furthermore, when it comes to the isotope change of samples, we find that both C27/C29 andΔδ13 Ct had notable positive correlation with the increasing cultivation time, showing that the emergence of C4 plants might be caused by constant vegetation transformation from human. Thus, we believe that human activities characterized by sugarcane plantation occurred after 1.7 ka BP. This study can be referential for discriminating the impacts of natural and human factors on environment and vegetation changes during the past thousands of years.
