Grow Zones: Function over form in restoration of urban Creeks in Austin, TX
Decades of mowing and recreational use and a waning urban forest have led to bank erosion, poor water quality, and limited habitat in riparian buffers in parks around Austin, TX. Through a joint program between parks managers and stream ecologists these degraded areas are being reclaimed as “Grow Zones”, where a passive restoration approach is restoring a range of basic ecological functions. Due to the “rambunctious” aesthetic of this approach, and it’s potential to be unacceptable to a wide range of stakeholders, a robust and quantifiable measurement tool was need to clearly document the potential benefits it provided. In an effort to measure and demonstrate restoration progress, a monitoring program was initiated that compared 15 measures of ecological function between reference and degraded urban riparian zone locations.
We compared 14 degraded and 14 paired reference sites in the Austin metropolitan area in the spring of 2012, in order to select the most efficient and effective measures that would assess riparian function. Considering primarily discriminatory power, but also redundancy and sampling effort, we selected seven metrics for the final assessment tool: Soil compaction, soil moisture, buffer width, canopy cover, structural diversity, hardwood demography, and seedling recruitment. Each of these metrics is indexed using regionally appropriate ranges and the result represents a robust and easily measured assessment of riparian function that can be compared spatially, at a range of restoration sites, and temporally, as these locations mature. This tool, in conjunction with buy-in and active engagement from local stakeholders, has allowed managers to confidently replicate this approach in degraded riparian areas citywide with minimal resource investment.