Ecological significance of common nonarboreal pollen: examples from drylands of the Middle East

摘要: Surface pollen assemblages within the continental Middle East and ecology of common pollen-producers provide basis for analyzing past. Sparse psammophilous vegetation is found hyperarid zone. It primarily produces Cyperus conglomeratus Calligonum. Within arid zone Chenopodiaceae, Plantago insect-pollinated herbaceous dominates. Artemisia becomes important semi-arid climates. Both Chenopodiaceae are characteristic highly climates with cold winters dry summers. Because increases decreases decreasing aridity ratio their (C/A) used as a moisture indicator. This should be applied narrow geographical limits non-forested areas. Grasses (Poaceae) not well-adapted to summer drought percentages low in most region. They somewhat higher where favorable edaphic conditions occur or summers less arid. A C/A during pleniglacial suggests moist rainfall regime similar today. Increases at expense indicate intense late glacial times. An early Holocene phase evident region-wide replacement Chenopodiaceae/Artemisia by grasses spread deciduous trees sites.