摘要
A consecutive sediment core (CC2) was drilledin Chen Co (lake) of southern Tibet using a PISTON samplerin 1998 AD. Cladoceran remains including their species,amount richness and ecological features are analyzed for thetop 117 cm sections of the core, upon which 5 cladoceranassemblages are distinguished. CL0 is an assemblage withoutany cladocera in the depth between 117-105 cm. CL1 as-semblage (depths between 101-77 cm, ca. 1407-1533 AD)possesses total 9 cladoceran species that appear in the core,and performs the greatest richness in the whole sequence.This assemblage reflected that there was plenty of exotic coldwater and organic debrises inputing to the sedimentary siteunder the warmer conditions. The lake was wide and shallowthat satisfied the big hydrophyte living. Cladoceran speciesand richnesses of CL2 assemblage (depths between 77-29cm, ca. 1533-1831 AD) perform much more decreasing thanthose of CL1. There was only less Chydorus sphaericus whichwas acclimatized to wide environmental ranges. This impliedthat the sedimentary environment is so execrable that mostof cladoceran lost their living abilities. Compared with CL1assemblage, CL3 assemblage (depths between 29-10 cm, ca.1831-1941 AD) possesses nearly the same dominant speciesbut lower richnesses. Especially, the cladoceran preferringorganic debris also decrease in their amounts. This meantthat the surface vegetation in the drainage basin was stillpoor though the environment turned to be better. Except the2 zooplankton species, the other 7 species of cladoceran inthis core are found in CL4 assemblage (depths between 10-0 cm, ca. 1941-1998 AD), in which the eurythermal specieshad not performed their competition ability comparing withnarrow-temperatures adapted species. It implied that watertemperatures were stable and much more influenced by airtemperatures under the shallow-water conditions. The envi-ronmental features reflected by cladocera assemblages ofCC2 core are fully supported by the evidences from ostra-coda assemblages, diatom-salinity transfunct
A consecutive sediment core (CC2) was drilled in Chen Co (lake) of southern Tibet using a PISTON sampler in 1998 AD. Cladoceran remains including their species, amount richness and ecological features are analyzed for the top 117 cm sections of the core, upon which 5 cladoceran assemblages are distinguished. CLO is an assemblage without any cladocera in the depth between 117-105 cm. CM assemblage (depths between 101-77 cm, ca. 1407-1533 AD) possesses total 9 cladoceran species that appear in the core, and performs the greatest richness in the whole sequence. This assemblage reflected that there was plenty of exotic cold water and organic debrises inputing to the sedimentary site under the warmer conditions. The lake was wide and shallow that satisfied the big hydrophyte living. Cladoceran species and richnesses of CL2 assemblage (depths between 77-29 cm, ca. 1533-1831 AD) perform much more decreasing than those of CL1. There was only less Chydorus sphaeticus which was acclimatized to wide environmental ranges. This implied that the sedimentary environment is so execrable that most of cladoceran lost their living abilities. Compared with CM assemblage, CL3 assemblage (depths between 29 - 10 cm, ca. 1831-1941 AD) possesses nearly the same dominant species but lower richnesses. Especially, the cladoceran preferring organic debris also decrease in their amounts. This meant that the surface vegetation in the drainage basin was still poor though the environment turned to be better. Except the 2 zooplankton species, the other 7 species of cladoceran in this core are found in CL4 assemblage (depths between 100 cm, ca. 1941-1998 AD), in which the eurythermal species had not performed their competition ability comparing with narrow-temperatures adapted species. It implied that water temperatures were stable and much more influenced by air temperatures under the shallow-water conditions. The environmental features reflected by cladocera assemblages of CC2 core are fully supported by the evidences from ostra-coda assemblages
基金
jointly funded by Knowledge Innovalion Project of Chinese Academy of Sciences(Grant Nos.KZCX3-SW-321 and KZCX3-SW-339)
Innovation Project of Institute of Geographical Sciences and Natural Resources Research,Chinese Academy of Sciences(Grant No.CXIOG-E01-05-02)
Sino-Slovenia Bilateral Technological Cooperation Project of Ministry of Science and Technology China
关键词
环境变化
水蚤
西藏
湖泊沉积物
生态学
lake sediments
cladoceran
environmental change
southern Tibet
Chen Co
