Arboriculture & Urban Forestry 40(5): September 2014 the 0.85 cm per year reported for the same size trees in Chicago, Illinois, U.S., in part because of a lon- ger growing season in Los Angeles (Nowak 1994b). It is comparable with the mean growth of larger trees (7.7 to 15.2 cm) in Houston (1.01 cm) and Gainesville (1.11 cm) (Staudhammer et al. 2011). Mean DBH for two of the most frequently sam- pled street tree species, Platanus spp. and Pyrus calleryana, were 9.1 cm (S.E. = 2.03 cm) and 7.6 cm (S.E. = 1.09 cm), respectively. These sizes fall within the 95% prediction intervals (α = 0.05) for the same species at four to five years aſter planting in Claremont, California, U.S., which has a storied municipal forest program (Wright 1999) (Figure 3). Overall, MTLA trees are growing vigorously and on track to achieve the stature predicted by this study’s tree growth models (McPherson et al. 2008a). 297 130% greater than sequestration. However, annual values per tree planted from the preliminary study are about 50% of those reported in this study. One expla- nation for the discrepancy is that this study assumed planting of relatively more, larger-stature trees. Kovacs et al. (2013) estimated net CO2 reductions emissions avoided per tree per year varied by species, ranging from 13.2 to 52.1 kg and 25.7 to 52.1 kg per year, respectively. Sequestered CO2 values are similar to the 20.1 kg value reported here. The avoided emis- sions values are somewhat higher than reported here, in part because trees were projected to provide sub- stantial heating savings from wind speed reductions. McHale et al. (2007) estimated the amounts sequestered and emissions avoided over of CO2 40 years for plantings in the Denver, Colorado, U.S., region. Sequestered and avoided CO2 ranged from 7.2 to 11.2 kg and 5.3 to 11.5 kg per tree per year, respectively. These values are somewhat less than the 20.1 kg and 27.7 kg per year per tree planted as reported here. The Denver region’s shorter growing season is partially responsible. Estimates from this study can be compared to Figure 3. DBH (means and standard errors) for four- to five- year-old Platanus spp. and Pyrus calleryana. Dashed lines are 95% prediction intervals (α = 0.05) from growth equa- tions for street trees of the same species measured in Claremont, California, U.S. Note that the quadratic growth equation appears linear for the first eight years. Carbon Dioxide Stored and Avoided Emissions MTLA trees were projected to store CO2 results from urban forest inventories, although the two are fundamentally different. This study mod- eled biomass accumulated throughout the 40-year project lifetime, while inventories are a snapshot in time that reflect the current mix of tree species and sizes. The amounts reported here are over twice the amounts reported for Los Angeles’s existing urban forest, which were 9.6 kg and 9.1 kg of CO2 , respec- and avoid emissions in the amounts of 20.1 kg and 27.7 kg per tree planted per year, respectively. These values are best compared to the three stud- ies that simulated biomass accumulation from tree plantings over a 30- to 50-year period. In the initial study of the MTLA program, plant- ing one million trees was estimated to sequester and reduce emissions by 10.1 kg and 12.9 kg per year per tree planted, respectively. In both this study and the preliminary study, avoided emissions are 120% to tree per year by urban forests in Miami-Dade (28.0 kg) and Gainesville, Florida, U.S. (21.2 kg) are slightly greater than the 20.1 kg reported here for MTLA, but avoided emissions are substan- tially less than 27.7 kg (2.3 and 6.4 kg per tree per year) (Escobedo et al. 2010). Existing trees in these urban forests are not achieving emission reduc- tions comparable to CO2 stored. MTLA trees are cally selected and placed to achieve energy savings. projected to achieve emission reductions in excess of CO2 stored, suggesting that trees are strategi- ©2014 International Society of Arboriculture tively (McPherson et al. 2013). The higher values reported here reflect differences in the mix of spe- cies and their wood densities, as well as their sizes and locations relative to the buildings they shade. The average amount of CO2 sequestered per from planting 182,736 street trees in New York City over 50 years. The amounts of CO2 sequestered and
September 2014
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
