THE PALEOVEGETATION AND PALEOCLIMATE DURING TIME OF HOMUDU PEOPLE
Sun Xiang-jun Du Nai-qiu Chen Ming-hong (Palaeobotanical Loboratory,Institute of Botany,Academia Sinica)
The Homudu site was discovered closed to the northeastern part of the village Homudu in the Lo-chiang Commune of Yu-yao zhejiang sheng.The excavations were conducted in 1973-1974 and 1977-1978.Four layers of cultural deposits are super- posed one upon the other.The first and topmost layer corresponds to the middle layer at Sun-ts'e in Ch'ing-p'u Country,while the second layer represents the Ma-jia-bin Cul- ture of Chia-hsing Country.The third and fourth layers belong to a hitherto unknown culture,which has been provisionally named as the Homudu Culture. A palynological and paleobotanical study is made for showing the paleovegetation and palcoclimate of that time. 1.The first sporo-pollen assemblage,obtaind from the fourth and lower part of third layers is marked by predominence of Gramineae pollen(11-71%).The majority of Gra- mineae pollen is of large size.Exine is thin and more psilate.Annulus of the single pore is about 2.5-3.7μm in wide.This kind of pollen very much resembles that of the recent rice(Oryza sativa). Besides that,the herbaceous pollen of Artemisia,Caulophyllum,Actinostemma,Poly- gonum,Rubia and some elements of Cyperaceae,Chenopodiaceae,Umbelliferae are noted. Pollen of trees and shrubs belong to Quercus,Castanopsis,Liquidambar,Mallotus,etc. Fern spores are of Lygodium.Ophioderma,Lemmaphyllum,Microsorium and Pyrrosia.A lot of plant remains(leaves and seeds)have been observed in the fourth layer:Chloran- thus fortunei,Magnolia coco?,Phoebe sheareri,Lindera glauca,Camptotheca acuminata Prunus davidiana,Choerospondias axillaris,Trapa bispinosa,Quercus myrsinaefolia,Cas- tanopsis tibetana,etc. Sporo-pollen assemblage and plant remains reflect a subtropical everygreen and de- ciduous broad-leaved mixed forests flourished on mountain slopes and some rice fields scattered in the plains around the site.The climate of that time was warm and humid and rather warmer than that of the present. Radiocarbon tests of an acorn and a wood fragment unearthed from the fourth layer reveal that they date from about seven thousand years ago,corresponding to the Atlan- tic period of Europe.2.The second sporo-pollen assemblage,obtained from the middle and the upper parts of third layer is prcdominent by pollen of trees,such as Quercus spp., Liquidambar formosana and others.In herbs,the pollen of Gramineae,Cyperaceae and water plants deereased,but those of Artemisia and Chenopodiaceae increased.The climate than was warm but somewhat drier than that of previous period.3.The sporo-pollen as- semblages from the second and the first layers were mainly composed of temperate ele- ments,such as Quercus,Ulmus,Salix,Where the subtropical elements Liquidambar and Altingia decreased or completely disappeared.These indicate that the climate become cooler than that of the previous periods. Radiocarbon tests of a wood fragment obtained from the second layer reveal that its date was from 5600 years ago,then the age of the second layer would correspond to the Subboreal period of Europe. A lot of rice pollen grains,along with a large amount of the remains of rice busks were obtained from the fourth layer in the site,which indicats that the rice plants were cultivated in China at least seven thousand years ago.