Wednesday, November 15, 2006
293-3
Non-Destructive Estimation of Net Primary Production in Urban Rain Gardens.
Marie R. Johnston, Sara E. Rouse, and Nick J. Balster. Dept of Soil Science, Univ of WI, 1525 Observatory Dr, Madison, WI 53706-1299
As residential use of rain gardens continues to outpace scientific understanding, the necessity to evaluate their performance quantitatively has grown. The type of vegetation is fundamental to the construction and performance of rain gardens, and varies from turf grass to wet-mesic prairie to conventional shrubs. Biomass production (NPP) and changes in carbon allocation and cycling must be estimated as part of this evaluation without altering the inherent function of the biophysical system. Many studies, particularly in forested landscapes, relate NPP to leaf area index (LAI) as a means to indirectly quantify changes in NPP. To the best of our knowledge, this relationship has not yet been established within urban rain gardens, particularly with perennial vegetation. We developed allometric equations using a combination of direct and indirect methods over a growing season (i.e., May through October). Specifically, we combined dimensional analysis with measured changes in LAI and aboveground biomass for 19 species of prairie plants and six species of shrubs. These equations will provide estimates of NPP in larger experimental rain gardens and thus facilitate critical assessment of performance where destructive sampling is prohibitive.
Handout (.ppt format, 15292.0 kb)