Leopold’s Arboretum Needs Upstream Water Treatment to Restore Wetlands Downstream
2014
Joy B. Zedler | James M. Doherty | Isabel M. Rojas
A case study has broad relevance for urban natural reserves. Aldo Leopold’s far-reaching vision to restore historical ecosystems at the UW-Madison Arboretum has been difficult to achieve despite ~80 years of restoration work. Wetlands (~1/4 of the 485-ha reserve) resist restoration, given urban watersheds and inflows of low quality water. Current conditions favor aggressive invasive plants (cattails, reed canary grass, and buckthorn)—species that do not fulfill the 1934 vision. Today, urban runoff flows into remnant natural wetlands, degraded wetlands, the iconic Curtis Prairie, and constructed wetlands. Regulations for total maximum daily loads (TMDLs) have led local municipalities to expand pre-existing sediment- and nutrient-trapping ponds from 5.67 ha (14 ac) of Arboretum land to 9.3 ha (23 ac) to protect downstream lakes. Both the runoff and the treatment facilities (with invasive plants) limit the Arboretum’s ability to achieve pre-settlement vegetation. Consistent with Leopold’s vision, we endorse Arboretum principles that urban runoff be restored to pre-settlement quality, and we recommend shifting efforts to reduce TMDLs to upstream lands in order to protect the Arboretum. Given that invasive species will persist, Leopold’s Arboretum should be rededicated to research, education, and restoration, plus sustainable management of its waters and wetlands.
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