Understanding how alien plant species establish and persist alongside native flora is a central question in invasion ecology, particularly in arid regions where resource availability is tightly constrained by seasonal conditions. Using 833 herbarium-derived phenological records (773 native, 60 alien; representing 363 species, 226 genera, and 60 families) from the Herbarium of the Botany Department, Faculty of Science, Beni-Suef University (BSUH), we compared the phenological timing of native and alien plant species in Egypt using circular statistics. Alien species showed a broader, less concentrated pattern of flowering and fruiting activity across the year (rho = 0.282) compared to native species (rho = 0.485), and Watson's U2 test suggested a significant difference in the overall shape of their circular distributions (U2 = 0.5154, p < 0.001). This difference persisted, and was in fact more pronounced, when the analysis was restricted to annual species (rho = 0.537 native vs. 0.254 alien; U2 = 0.5618, p < 0.001), where alien annuals displayed a distinct bimodal pattern with activity peaks in spring and in late summer–autumn, unlike the single spring peak of native annuals. This divergence was not evident among perennial and shrub species, though the small alien sample size in this subgroup (n = 14) limits the strength of this conclusion. At the family level, the proportion of alien species varied significantly (χ2 = 72.976, df = 17, p < 0.001), with Solanaceae, Amaranthaceae, and Euphorbiaceae showing disproportionately high alien representation, while well-represented native-dominated families such as Zygophyllaceae contained no alien records at all. Comparison with the Flora of Egypt showed variable representation of the key families (43–100% of known species), so this pattern should be interpreted with caution.Taken together, these findings suggest that phenological flexibility, particularly a secondary late-summer–autumn reproductive window, may be an important, life-form-dependent strategy contributing to the establishment of alien annual species in Egypt's arid flora.
Climate change is expected to reshape species distributions in arid and semi-arid regions through changes in temperature and water availability. We modelled the present and future climatic suitability of the Egyptian cobra (Naja haje) across North African drylands and adjacent Mediterranean transition zones using ecological niche modelling. Occurrence records from the Global Biodiversity Information Facility (GBIF) were filtered to obtain 112 high-quality presence records. Models were calibrated with the maxnet implementation of the maximum entropy algorithm within the biogeographically defined calibration area (M) and projected using the MIROC6 climate model under SSP2–4.5 and SSP5–8.5 for mid-century (2041–2060) and late-century (2061–2080).Model performance was acceptable (validation AUC = 0.669; CBI = 0.923). Climatic suitability currently forms a broad belt across North African drylands, with highest suitability in southern tropical and subhumid sectors. Future projections indicate a 14.0–19.0% contraction of climatically suitable area within the calibration area (M), with declines across parts of the hyper-arid Sahara and persistence or localized increases in southern and transitional regions. These results indicate climate-driven contraction and spatial reorganization of climatically suitable conditions along existing aridity gradients, providing a regional framework for biosecurity, environmental management, and surveillance of human-mediated introductions.
Vegetation and biocrust activity in hyper-arid ecosystems depends on infrequent rainfall pulses that trigger rapid but short-lived biological activity. In the Sechura Desert of northern Peru, extreme El Niño events trigger exceptional rainfall, but the frequency, spatial distribution, and climatic controls of the resulting greening events have not been quantified. Here, we quantified episodic greening across the Sechura Desert from 2001 to 2025 using 250-m MODIS NDVI and examined its relationship with rainfall events. We found that hyper-arid coastal ecosystems remained largely dormant and greened almost exclusively during the extreme rainfall events in 2017 and 2023. In contrast, inland ecosystems experienced more frequent greening pulses over 2001-2025. Highly episodic greening events exhibited a critical activation threshold, remaining dormant until cumulative seasonal rainfall exceeded approximately 0.38–0.58 m, a value only reached during Coastal El Niño years. Areas exhibiting episodic greening covered 3183.51 km2 (12.3% in the Sechura Desert) and over 12,100 km2 along the Peruvian coastal desert. These results provide the first long-term, spatially explicit assessment of greening pulses in the Sechura Desert and demonstrate that, during the 25-year MODIS era, these hyper-arid ecosystems remained functionally dormant for most of the period, awakening only during extreme coastal warming events.
