Bark up the right tree: Which native species provide the most stormwater benefits?
Streaming Media
Presentation Abstract
For millennia, iconic arboreal giants have been the dominant landscape feature of upland environments surrounding the Salish Sea and were revered by the many indigenous communities that lived amongst them. Today, urban development - buildings, roads, and parking lots - replace forests and disrupt natural hydrologic processes, in turn, transporting toxic chemicals to sensitive aquatic ecosystems. Green stormwater infrastructure attempts to counter-act this harm, emphasizing the importance of trees and other elements of the pre-development landscape that manage large quantities of water. While cultivated “street trees” are often planted in dense urban centers, many residual stands of mature native trees face removal along the peri-urban fringe. These trees are exceptionally well adapted to the regional climate but have not yet been adequately assessed for their ability to mitigate stormwater runoff. In this study, a network of environmental sensors was deployed to measure individual tree water use over two years at two sites near Olympia, WA. Sixty-four individual trees belonging to two evergreen species (Douglas fir and western redcedar), and two deciduous species (red alder and bigleaf maple), were selected. Tree water use was quantified by measuring tree transpiration, interception, and stemflow. Sap flux, the water transported from the tree’s roots to its leaves, was measured to quantify transpiration. Interception or the precipitation captured by the tree’s canopy and stemflow were also measured. We evaluated the quantity of stormwater managed by each tree by analyzing seasonal and species-specific trends, thereby describing its stormwater value. In general, transpiration was relatively low during the winter months, with evergreen trees having slightly higher transpiration rates. Deciduous trees outpaced evergreen trees for transpiration during the summer. Interception rates were higher for evergreen species regardless of the season and were highest during short, low-intensity winter storms.
Session Title
Green Infrastructure
Conference Track
SSE10: Contaminants
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-traditionals-469
Start Date
26-4-2022 1:30 PM
End Date
26-4-2022 3:00 PM
Genre/Form
conference proceedings; presentations (communicative events)
Subjects – Topical (LCSH)
Stormwater infiltration; Runoff; Roots (Botany)
Geographic Coverage
Washington (State)
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Format
application/pdf
Bark up the right tree: Which native species provide the most stormwater benefits?
For millennia, iconic arboreal giants have been the dominant landscape feature of upland environments surrounding the Salish Sea and were revered by the many indigenous communities that lived amongst them. Today, urban development - buildings, roads, and parking lots - replace forests and disrupt natural hydrologic processes, in turn, transporting toxic chemicals to sensitive aquatic ecosystems. Green stormwater infrastructure attempts to counter-act this harm, emphasizing the importance of trees and other elements of the pre-development landscape that manage large quantities of water. While cultivated “street trees” are often planted in dense urban centers, many residual stands of mature native trees face removal along the peri-urban fringe. These trees are exceptionally well adapted to the regional climate but have not yet been adequately assessed for their ability to mitigate stormwater runoff. In this study, a network of environmental sensors was deployed to measure individual tree water use over two years at two sites near Olympia, WA. Sixty-four individual trees belonging to two evergreen species (Douglas fir and western redcedar), and two deciduous species (red alder and bigleaf maple), were selected. Tree water use was quantified by measuring tree transpiration, interception, and stemflow. Sap flux, the water transported from the tree’s roots to its leaves, was measured to quantify transpiration. Interception or the precipitation captured by the tree’s canopy and stemflow were also measured. We evaluated the quantity of stormwater managed by each tree by analyzing seasonal and species-specific trends, thereby describing its stormwater value. In general, transpiration was relatively low during the winter months, with evergreen trees having slightly higher transpiration rates. Deciduous trees outpaced evergreen trees for transpiration during the summer. Interception rates were higher for evergreen species regardless of the season and were highest during short, low-intensity winter storms.
