Two articles have already been published regarding the same topic discussing the important attributes of Urban Green Spaces (UGSs). My intention was to introduce a few specific characteristics, ecosystem services, and importance of selected five blocks of “South Park Blocks (SPBs)” located between the SW market street and SW college street. This third and final article will further elaborate on the aspects such as carbon sequestration, air purification, storm-water management, and health benefits provided by the SPBs.
As we previously described, about 22 tree species have been recorded out of a total of 122 trees located within the study area. Out of all recorded tree species “American Elm” (Ulmus americana) is the most common tree species. The second article discussed some of the few species characteristics of Elms and a few other species characteristics as well. By using the geo-database provided in the park inventory web portal species distribution map has been plotted to demonstrate the location of different trees and each recorded species is symbolized as shown in the legend. Then the DBH and canopy width have also been symbolized according to the size by using graduated symbols. Species distribution, DBH, and Canopy width illustrations were placed in one layout, facilitating a rough comparison of how the DBH and Canopy width related.
Statistics provided in the park inventory web portal were further utilized to demonstrate the amount of carbon sequestrated by each tree and contribution of each tree to air pollution control. These figures were also displayed by using graduated symbols and arranged in one layout. This layout facilitates the comparison of the amounts of two different ecosystems services provided by each tree. Since both layouts were generated on a similar scale (1:4000) ecosystem services can be compared even with the DBH and canopy width to some extent.
Hence, the importance of pollution control and carbon sequestration for human health should not be needed to discuss deeply. As we all know, trees act as a physical barrier and as well as an air regulator through evapo-transpiration, respiration, and photosynthesis. Since the heavy number of traffic and industries in urban setups always emitting hazardous gasses to the atmosphere including dust particles. Therefore, the mechanism of trees to control air pollution is important and the park inventory web portal has quantified to $1463.49 per annum. Similarly, the value of carbon sequestration has been quantified to $ 347.87 per annum. These values can be further useful for future planning of UGSs since it helps to select the most useful tree species. On the other hand, it still can be noticed through the two given layouts that there is a significantly wider range of tree sizes in terms of DBH, canopy width, and tree height. The dominance of deciduous species within the park blocks makes it more off-colored during the winter and replacing some small deciduous species with confers will maintain the green out-fit throughout the year without making noticeable visual and ecological disturbances.
Reshaping Concepts
Emerald arrow concept, Braided Districts Concept, and Mirrored Chain Concepts are the three main concepts that Portland Park and Recreations has used to develop three future scenarios for SPBs. Since they are more concentrating on new tracks for bikers and walkers, while enhancing the welcome feeling, most of the vegetation including large trees, native plants, and colorful roses is planned to remain unchanged. However, I believe that this is a good opportunity to change the existing plant architecture to some extent. As we discussed previously, the dominance of deciduous is significant and DBH, and canopy width distribution shows that there are a lot of replaceable opportunities. Two possible approaches can be suggested and the first one is to replace some of the most available tree species with few different tree species including confers. The second option is replacing some older tree species with other species including conifers. However, the first option would be more helpful to enhance the species diversity and as well as to maintain the visual attraction, because the removal of larger trees will significantly spoil the scenic value of the park for a greater time. On the other hand, the first option would be more economical since we have enough room to deal with smaller trees. However, it will take several years to display the modification although the ecosystem services are ensured. Confer stands will create beautiful architecture and experience for the public during the future winter seasons.
Finally, these beautiful trees of SPBs will serve us for generations even without expecting anything from humans. As this beautiful landscape welcomes me and makes me comfortable, future visitors will also welcome without any difference.
List of References
https://www.portlandoregon.gov/parks/78629
https://pdx.maps.arcgis.com/apps/webappviewer/index.html?id=763ccdb78fc04181b79a0bdee8834ed7
Seeing Trees PDX 