Abstract

Yassin Mohamed Al-Sodany

Invasions by alien plant species are causing major conservation problems in many regions of the world and are viewed as an important component of human caused global change. Lake Burullus (one of the protected areas and RAMSAR site in Egypt) and its surroundings are subjected to ecological constraints that relate to excessive use of resources such as the construction of an International Highway that runs along its sand bar. This paper aims in evaluating the extent of the new invaded species in Burullus Wetland and in studying the demography of the populations of these species in terms of size structure, natality, mortality, survival and demographic flux. Such type of study helps in understanding the invasive ability of these species in this area, which consequently helps in managing their populations in the wetland. The questions addressed are: 1- How many invaded plant species does Burullus Wetland have? 2- What is the Egyptian geographical origin of these species? 3- Which population can be established and which can be excluded in this area? and 4- Which population can't be adapted? Thirteen perennial species were recoded in the last 8 years: four were recoded for the first time in 2001 at Kassarah site and were established up till 2008 (Convolvulus lanatus, Artemisia monosperma, Cornulaca monacantha and Panicum turgidum), Nine species were recoded in 2006 at Kassarah and along International Highway; five of them were established themselves up till 2008 (Thymelaea hirsuta, Astragalus spinosus, Deverra tortuosa, Zygophyllum coccineum and Retama raetam). Four species can't be adapted in this region (Stipa capensis in Kassarah site and Salsola tetrandra, Astragalus Siberi and Zilla spinosa along International Highway). The yearly variation in the demographic variables indicated that 2006 and 2008 had the maximum natality for all species, while 2004 had the maximum mortality. The size distribution at the end of the monitoring period indicated that the invaded species may approximate J-shape, stationary or inverse J-shaped size distributions. The number of individuals along the International Highway decreased from 2006 to 2008, but the individual dimensions (That is, size) increased for some species and decreased for another. The present study suggested that, carrying out long-term studies and monitoring on the vegetation and the invaded species of the International Highway and its surrounding habitats, especially Kassarah site (That is, conservation of biodiversity).