Izvorni znanstveni članak

Vegetation associates of the endangered Randonia africana Coss. and its soil characteristics in an arid desert ecosystem of western Egypt

M.M. Abd El-Ghani
A.H. Marei

Sažetak

Randonia africana Coss. (Resedaceae) is a perennial endangered vascular plant species in Egypt. It inhabits the sandy plains along the Mersa Matruh-Siwa Oasis road crossing the Western Desert of Egypt, where it represents the easternmost limit of distribution in North
Africa. The vegetation associates within each of the five known population sites of R. africana were studied, and their edaphic correlates were analysed. Eight soil variables were included: electric conductivity, pH, calcium carbonate, soil moisture, organicmatter, sand, silt and clay. Classification and ordination techniques were employed to the importance values (IV) of the recorded 29 species in 25 stands. Application of TWINSPAN classified the floristic data into five vegetation groups: (A) Randonia africana-Capparis spinosa var. aegyptia, (B) R. africana, (C) R. africana-Pulicaria undulata, (D) R. africana-Zilla spinosa subsp. biparmata and (E) R. africana-Zygophyllum coccineum. These groups were separated along Detrended Correpondence Analysis (DCA) axes 1 and
2. Group E was the most diversified (10.0 ± 5.6 species stands-1) among the vegetation groups, while monotypic stands of R. africana (group B) were the least (5.1 ± 2.3). Stands of R. africana group (group B) were characterised by the highest levels of soil salinity and
fine sediments, and the lowest levels of moisture content and sand. Detrended Canonical Correspondence Analysis (DCCA) indicated that the distribution of R. africana and its associates was mainly controlled by soil salinity, percentages of surface sediments of different size classes, calcareous deposits, and organic matter. The resulted gradients were related closely to the first three canonical axes, and accounted for 68.5% of the species-environment relationship among stands.

Ključne riječi

Randonia africana; desert; vegetation; soil; conservation; Egypt

Hrčak ID:

3341

URI

https://hrcak.srce.hr/3341

Datum izdavanja:

15.5.2006.

Posjeta: 2.660 *