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

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

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population

The coastal roadside vegetation and environmental gradients in the arid lands of Egypt

A recent floristic and environmental survey was undertaken on the roadside verges along the main highway between El Arish and Rafah (31° 10'N, 33° 48'E and 31° 17'N, 34° 15'E) that extend for about 45 km on the northeastern Mediterranean coast of Sinai (Egypt). 63 stands were studied at 700-m intervals to represent the variation of vegetation, and to compile the floristic composition of the study area. Four main landform zones were distinguished (from the seashore inwards) and run parallel to the roadway: (A) coastal plain, (B) saline depressions, (C) sand plains and (D) sand dunes. There is a gradual increase in the total number of recorded species in the recognized landform units. Application of TWINSPAN analysis yielded 18 vegetation groups (VG) that comprised 7 main vegetation types (VT). These vegetation types were (I) Artemisia monosperma in the sand dunes, (II) Artemisia monosperma-Echinops spinosus in the sand plains, coastal plain and sand dunes, (III) Cyperus capitatus-Ammophila arenaria in the sand dunes, (IV) Ammophila arenaria-Pancratium maritimum in the coastal plain, (V) Zygophyllum album, (VI) Arthrocnemum macrostachyum and (VII) Arthrocnemum macrostachyum-Zygophyllum album in the saline depressions. Ordination techniques of Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to examine the relationship between the roadside vegetation and the 8 studied environmental variables: total soluble salts (TSS), pH, calcium carbonate (CaCO_), sand, fine fractions (silt and clay), distance from the seashore (DFS), landform units (LF) and altitude (Alt). Both ordination techniques indicated that soil salinity, calcareous sediments, soil texture, landform, altitude and distance from seashore were the most important factors for the distribution of the vegetation pattern along the road verges in the study area. These gradients were related closely to the first three CCA axes, and accounted for 72.4% of the species relationship among the stands. Low species richness in the vegetation types of the coastal plain and saline depressions may be related to their high soil salinity, while the high species diversity and the highest share of alien weeds of vegetation types characterized the sand dunes may be related to the high disturbance of their substrates as a result of agriculture practising, farming processes and other excessive human disturbances