Browsing by Author "Inkiläinen, Elina"

The conversion of vegetated land cover to impervious surfaces has made stormwater runoff into a major hydrological concern due to its capacity to deteriorate water quality and stream health in cities. Urban forests are capable of reducing the amount of potential stormwater runoff by regulating throughfall via canopy rainfall interception. The lack of stand-scale studies of urban throughfall hinders realistic estimates of the benefits of urban trees for stormwater regulation. Urban forests are extremely variable with regard to canopy cover and species composition and are to a large extent managed by private residents with varying landscape preferences. To quantify the amount of rainfall interception by vegetation in an urban forest we measured throughfall in Raleigh, North Carolina, USA between July and November 2010. We further analyzed 16 residential yards with varying levels of canopy cover to evaluate the relative importance of different descriptive measures of vegetation in influencing throughfall in an urban watershed. Throughfall comprised 89.7 % (StdErr=0.005) of gross precipitation in the study area. Canopy cover (p<0.0001) and the percentage of coniferous trees (p=0.0305) were the most influential vegetation variables explaining throughfall whereas leaf area index (LAI) was not found to be significant. Throughfall varied significantly among yards (p<0.0001) ranging from 84.0 % (80.2 % canopy cover) to 98.2 % (60.3 % canopy cover). Differences in vegetation between front and backyards resulted in 3.1 % less throughfall in backyards. Thus, residents‘ management choices at yard-level affect the amount of throughfall reduced at the landscape scale.