Assessing the impact of anthropogenic activities on the ecological quality of arid Mediterranean ecosystems (case study from the northwestern coast of Egypt)

Abstract

Northwestern coastal desert of Egypt is under pressure of human-induced changes due urban sprawl and agricultural practices leading to negative impacts on existing natural habitats. Assessing the impact of land-use changes on the ecological integrity is crucial for management and conservation efforts in the region. Floristic quality (FQ) assessment indices are important bioassessment tools that can be used to evaluate how anthropogenic changes may influence vegetation quality, species composition and environmental integrity. The approach is primarily stationed on floristic composition and disturbance tolerance at study sites. The objectives of this study were to: 1) study how anthropogenic disturbances due to land use/cover changes in the northwestern coastal desert affected its ecological quality as indicated by FQ indices; and 2) to evaluate the use of FQ indices as tools for characterizing anthropogenic disturbance among the habitats of Mediterranean desert ecosystem. Stands representing the main habitats were surveyed during 2011 through 2015 and data were compared to historic data collected before the developmental activities. The study revealed a trend of decline with time in the floristic quality of the study area as was indicated by floristic quality measures used (mean coefficient of conservatism, FQAI, and adjusted FQAI). Similar trend of decline in native and perennial species richness, and increase in non-native and annual species richness was observed for the period investigated from 1980s to time. At the habitat level, similar trend of decline in the floristic quality was observed, with the current time attaining the least values of FQ indices for all the habitats. The anthropogenic disturbance index (ADI) was developed in the current study as a quantitative measure of the level of disturbance and as an indicator to evaluate site’s ecological condition. The ADI exhibited significant negative relationship with the FQ indices, revealing that it can be recognized as useful index of anthropogenic disturbance that would complement the use of FQ indices in evaluating site ecological condition. The high association between ADI and the adjusted FQAI compared to the FQAI, confirms that the former signals the level of disturbance better than later. Although the adjusted FQAI has been developed and used in assessing vegetation quality of wetland, the current study revealed that it can be employed successfully for assessing and monitoring changes in vegetation quality and ecological integrity of deserts and arid ecosystems. For full and comprehensive evaluation of site’s ecological condition, the use of multiple bioindicators is recommended.