A Continuous Palynological Record of Forest Clearing at Rano Kao (Easter Island, SE Pacific) During the Last Millennium: Preliminary Report

Irantzu Seco,Núria Cañellas-Boltà,Alberto Sáez,Valentí Rull,Raymond S Bradley,Olga Margalef,Sergi Pla-Rabes,Encarni Montoya,William J D’Andrea,Santiago Giralt

doi:10.3390/quat2020022

Abstract

Easter Island (Rapa Nui) deforestation has traditionally been viewed as a single event, synchronous in time and space across the island and caused by Polynesian settlers. However, recent studies have challenged this idea, introducing the concept of spatiotemporal heterogeneity and suggesting a role for climate change. This paper presents a continuous paleovegetation record of the last millennium (~960 to ~1710 CE), based on palynological analysis of a core from Lake Kao. During this time interval, deforestation was gradual, with three main pulses at ~1070 CE, ~1410 CE, and ~1600 CE, likely driven by drought, anthropogenic practices (mostly fire), or the coupling of both. Some forest regeneration trends have been documented after the first and the second deforestation pulses. Forests were totally removed by 1600 CE, coinciding with the full permanent human settlement of the Kao area. Comparison with other continuous palynological records available for the last millennium (Aroi marsh and Lake Raraku) confirms that forest clearing was heterogeneous in time and space, rather than synchronous island-wide.

Highlights

The deforestation of Easter Island (Rapa Nui) was considered for a long time as an abrupt and island-wide event due to the overexploitation of natural resources by the first Polynesian settlers, who were assumed to have caused their own cultural collapse after their arrival on the island, which different authors situated between 800 CE and 1200 CE [1,2]
Recent detailed litho- and chronostratigraphic studies of the Easter Island sedimentary basins have and the occurrence of numerous inconsistencies that demonstrated the complexity of sedimentary patterns and the occurrence of numerous inconsistencies complicate paleoecological reconstructions [7,8]
Based on the known sedimentary patterns is fundamental for obtaining reliable paleoecological a careful selection of the coring sites based on the known sedimentary patterns is fundamental records

Summary

Introduction

The deforestation of Easter Island (Rapa Nui) was considered for a long time as an abrupt and island-wide event due to the overexploitation of natural resources by the first Polynesian settlers, who were assumed to have caused their own cultural collapse after their arrival on the island, which different authors situated between 800 CE and 1200 CE [1,2]. New coring campaigns developed during the last decade, times, have yielded continuous (gap-free) and chronologically coherent paleovegetation records with emphasis on the more recent times, have yielded continuous (gap-free) and chronologically (without age inversions) for Lake Raraku and the Aroi marsh, as shown, two of the three coherent paleovegetation records (without age inversions) for Lake Raraku and the Aroi marsh, as Easter Island sedimentary basins suitable for paleoecological research [9,10]. A remained problematical due to gaps and frequent age inversions that prevented the development of single continuous and chronologically coherent record exists for Lake Kao covering the last reliable age-depth models [11,12,13].

Methods

Results

Conclusion