Conservation Training

Trees, Ponds, and Watersheds: Long-Term Ecological Research to Understand People and Water in Cities

May 16, 2024

10:00 am – 12:00 pm
Location: Online

The Minneapolis-St. Paul Urban Long Term Ecological Research project (MSP LTER) is an NSF-funded project exploring interactions between people and nature in the Twin Cities to understand how urban ecosystems respond to rapid environmental and social change and inform approaches to addressing environmental inequities. After introducing the broader suite of MSP LTER research questions related to pollinator communities, urban forests, and aquatic ecosystems, this presentation will highlight research focused on urban watersheds and surface waters. One of these projects addresses the role of urban trees in the water cycle. Specifically, by instrumenting trees across multiple St. Paul parks, we have quantified how trees take up water from the soil and send it back to the atmosphere via transpiration and how trees alter the amount and chemistry of precipitation as it falls through their canopy. This work shows that urban trees can export nutrients in throughfall at concentrations 2.7 times (for nitrate) and ~ 8-11 times higher (for soluble reactive phosphorus) compared to open precipitation, and that nutrient dynamics depend on season, canopy condition, and water use, with implications for management strategies to increase the net benefits of urban trees. A second project quantifies the essential functions provided by stormwater ponds to manage impacts of urban stormwater runoff. This work shows strong effects of vegetation, including trees, tiny free-floating plants, and submerged macrophytes, on the dynamics of pond systems. Integration of study of urban ponds into MSP’s long-term ecological research agenda is bringing ecological and biogeochemical perspectives into water quality research and yielding insights into how pond functions change over time and in response to diverse management approaches. We highlight MSP LTER’s role in organizing and disseminating data and information collected by diverse organizations to generate novel insights into the functioning of urban watersheds and surface waters.