## 5 Conclusions  
Replacing lawns or impervious surfaces with tree cover can be an important part of sustainable development in urban areas. However, a relatively large percentage of 10% of the area will have to be converted to see a noticeable change in carbon storage, although changes in some variables are evident with as little as 3% land use conversion. Due to the maximum amount of each land use type that could realistically be converted, to achieve more sustainable goals, multiple land use changes would need to occur in tandem, such as replacing large areas of both impervious surfaces and turf lawns with forests. Converting lawn to forest has a larger effect in this study than converting impervious surface to forest due to the higher nutrients in the soils of the lawn, but fertilizing converted impervious surfaces should increase their carbon storage capacity. While these transitions may be difficult, the replacement of parking lots or the inclusion of more trees in residential areas and lawns or even city parks will be crucial for reaching these goals. The South Side also has many parks that are solely abandoned fields, making these areas ideal candidates for reforestation efforts, although conversations with residents also reveal the importance of open space for children to play. Based on the modeling experiments, higher proportions of forest to impervious surface and lawn result in higher productivity and carbon sequestration, which agrees with other studies [1; 2; 9]. With urbanization expected to increase in the future due to increasing populations, there is a potential for a reduction in the amount of carbon storage due to the removal of trees. Even after increasing tree cover, the forests will not have the same carbon storage capacity as mature forests, which reduces the immediate impact, although younger forests sequester carbon at a faster rate than mature forests. Therefore, further deforestation will have a larger impact than planting new trees in the same size area. While the younger trees will not store as much carbon in the short term, the negative impacts of deforestation are felt immediately. With an overarching goal of producing more sustainable cities capable of sequestering more carbon and decreasing the effects of climate change, it is clear that increasing the number of trees within cities will be necessary. The sensitivity experiments show that even moderate changes to land use (10%) can have a positive impact on carbon sequestration within cities. In several scenarios with less than 10% change in total area, the results end up being significant, suggesting that even smaller changes can be impactful. Urban areas with high proportions of impervious surfaces or abandoned fields have the largest potential for change and should be prioritized when considering implementing land use changes with the goal of sustainability. In addition to enhanced carbon sequestration, added tree cover reduces crime rates and reduces the urban heat island, making cities more livable and reducing environmental inequities. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/environments11070133/s1](https://www.mdpi.com/article/10.3390/environments11070133/s1)]([https://www.mdpi.com/article/10.3390/environments11070133/s1](https://www.mdpi.com/article/10.3390/environments11070133/s1)). Table S1. Remote sensing data for the summer and winter images used. Data are provided by USGS Earth Explorer. Table S2. Total area converted from each experiment as shown by the percent change for the Lehigh Valley in km\({}^{2}\). Table S3. Percent of the total area of the Lehigh Valley changed by each LULCC. Table S4. The percentage of each land use type within the four regions of Bethlehem, PA. Table S5. Landsat Band wavelength and resolutions provided by USGS. Figure S1. Gridded, random-trees classification of the Lehigh Valley overlaid with a 4 km fishnet. Bethlehem is shown as the highlighted region. Classification based on Landsat 8 imagery from 30 July 2017. Figure S2.