Geographical comparison of soil and vegetation variables between sampling areas
Vegetation variables (vegetation height; quadrat-scale plant alpha-diversity, SQ; abundance of three dominant species: Table.1) showed significant differences between the seven sampling areas, though no consistent pattern between oil-contaminated areas and unaffected areas was apparent. Our survey results suggested that Haloxylon salicornicum tended to be abundant at sampling areas located in northern Kuwait, and was absent from southern sampling areas. The other two species occurred in both northern and southern areas and showed high frequency values at individual areas in both regions of Kuwait.
A similar pattern of significant differences in soil moisture (though all values were very low in absolute terms), Table 1, was seen between the sampling areas, again apparently unrelated to the presence or absence of oilfield installations.
In contrast, the TPH and individual PAHs in soil samples from the seven areas showed a significant correlation to the presence of oilfield installations within or close to the sampling areas (Table 1). The semi-quantitative Oil Damage Score (ODS) indicates the severity of oil-pollution in soils of impacted areas (Um Al-Aish, Sabriya, Burgan, and Um Ghadair Oilfields), with greater ODS indicating more severe contamination and lower ODS for the less impacted areas (Bahra, Sabah Al-Ahmad Protected Area) and Um Al-Rros Military Base).