Late Pleistocene Vegetation of Kings Canyon, Sierra Nevada, California

Abstract

AbstractSeven packrat midden samples make possible a comparison between the modern and late Pleistocene vegetation in Kings Canyon on the western side of the southern Sierra Nevada. One modern sample contains macrofossils and pollen derived from the present-day oak-chaparral vegetation. Macrofossils from the six late Pleistocene samples record a mixed coniferous forest dominated by the xerophytic conifersJuniperus occidentalis, Pinuscf.ponderosa, andP. monophylla. The pollen spectra of these Pleistocene middens are dominated byPinussp., Taxodiaceae-Cupressaceae-Taxaceae (TCT), andArtemisiasp. Mesophytic conifers are represented by low macrofossil concentrations.Sequoiadendron giganteumis represented by a few pollen grains in the full glacial. Edaphic control and snow dispersal are the most likely causes of these mixed assemblages.The dominant macrofossils record a more xeric plant community than those that now occur on similar substrates at higher elevations or latitudes in the Sierra Nevada. These assemblages suggest that late Wisconsin climates were cold with mean annual precipitation not necessarily greater than modern values. This conclusion supports a model of low summer ablation allowing for the persistence of the glaciers at higher elevations during the late Wisconsin. The records in these middens also suggest thatS. giganteumgrew at lower elevations along the western side of the range and thatP. monophyllawas more widely distributed in cismontane California during the Pleistocene.