Modern pollen spectra from dakhleh oasis, western egyptian desert
作者:
J.C. Ritchie,
期刊:
Grana
(Taylor Available online 1986)
卷期:
Volume 25,
issue 3
页码: 177-182
ISSN:0017-3134
年代: 1986
DOI:10.1080/00173138609427719
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The Dakhleh Oasis lies at the heart of the Western Egyptian Desert. Measurable precipitation occurs at rare intervals and the mean annual rainfall is <0.5 mm. Artesian water supports the pastoral agricultural economy of the oasis. The vegetation consists of fragmentary natural communities of Saharo-Arabian species and a predominant anthropogenic component. Twenty-five samples were analysed for modern pollen—5 Tauber traps placed in a horticultural station; 18 surface muds from permanent pools or ditches; and 2 relict pond sediments on the plateaux above the oasis depression. The Tauber trap spectra are dominated by local, introduced taxa, with small percentages (1–3) of long-distance (Mediterranean region) elements and Saharo-Arabian, native elements (0–2). The relict pond samples and to a lesser extent the ditch and pond muds contain constant though small percentages (5–7%) of native desert species of indicator value, large proportions of ubiquitous taxa (chiefly Cheno-Amaranth, Cyperaceae and Gramineae), smaller proportions of naturalized anemophilous trees (CasuarinaandEucalyptus), and scattered occurrences in low frequencies of such allochthonous, Mediterranean taxa as alder, birch, pine and oak.
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