Human land use in urbanizing areas is often seen as distinct from ecological processes, with very little attention paid to the interactions of social and ecological processes that shape how land is allocated during urbanization. Such interactions in the Bull Creek watershed, located northwest of Austin, Texas, have resulted in an urban fringe area with structure and function considered desirable to humans for residence and recreation, but also containing a very diverse flora and suitable habitat for a variety of rare and endangered species. A dynamic tension currently exists between expansion of urban development and social/ regulatory forces that advocate expansion of preserves, riparian buffers, and maintaining environmental integrity. Fragmentation of natural habitats, homogenization of species composition, disruption of hydrological systems, and alteration of energy flow and nutrient cycling has been shown to reduce cross-scale resilience in urbanizing areas. A broad understanding of the key components of ecological integrity and the potential for undesirable shifts in structure and function is critical to ensuring long-term adaptability and resilience. An integrative assessment methodology that incorporates hydrogeologic, biophysical, economic and demographic data is proposed to identify drivers and processes affecting ecological integrity in the study area and to assess adaptive capacity. The assessment includes characterization of hydrologic context, examination of trends in streamflow and water quality over 26 years, review of trends in vegetation and faunal patterns over 100 years, analysis of land use changes over four decades using classified aerial photography and city planning data, examination of population and demographic trends, surveys and interviews with long-term residents and key stakeholders. Information on population demographics, land use, current and future management plans were analyzed in relation to data collected on vegetation, wildlife, hydrology, and water quality to identify trends and linkages between various components of the social-ecological system. Presence/ absence of critical elements for adaptive capacity, identified in management literature, are hypothesized based on this analysis.
Results/Conclusions
Results show that while portions of the Bull Creek watershed (i.e. those associated with preserves) provide greater habitat area and connectivity and act to increase aquifer recharge and spring flow compared to surrounding areas, landscape fragmentation is increasing. Increasing water demand and impervious cover are straining the local hydrology. The study area exhibits several elements that contribute to adaptive capacity (i.e. diversity, social capital, support), while other elements (i.e. flexibility in management) are present to a lesser degree or not at all.
