Ecosystem Services in the RCESC
An analysis of iTree data and a breakdown of the value of trees and their ecosystem services in the RCESC habitats.
Satellite imagery of the PCC Rock Creek campus and RCESC with the five different habitats shown.
Carbon Storage and Sequestration
Carbon sequestration is the process in which carbon is captured from the atmosphere by plants and converted into compounds to be used as energy or stored within the soil or biomass of the organism. The reservoir of carbon being stored by any one plant is known as its carbon storage. Trees are especially important in this process as an entire forest can store and sequester vast amounts of carbon annually. If a tree is cut down or damaged in some other way, it will eventually release its vast carbon stores and instead add to carbon emissions. For example in California forests, “tree biomass loss due to wildfires and bark beetle damage generated around 10 Mt CO2 of total emissions from 2003 and 2012” (Sánchez et al. 2021). This points to an unfortunate positive feedback loop in which the increased ecosystem disturbances caused by rising CO2 levels in the atmosphere end up adding even more carbon back into the atmosphere. In order to empower decision-makers to make the best calls for these ecosystems, organizations like iTree work to assign a valuation to the different ecosystem services provided by these forests. The goal here is to prove that conservation of these ecosystems and their services is not only important for the planet, but is also economically valuable and essential for us to protect (Taye et al. 2021).
Gaia GPS data showing five different forest habitats in the RCESC and the GPS locations of the random stratified sampling plots.(RCESC Photos Val Brenneis)
Five Forest Blocks in the RCESC:
- Westside Forest (upland coniferous)
- Bottomland Forest
- Oak Woodland
- Bobcat Forest
- Eastside Forest (upland coniferous)
Figure 2 from the iTree report breaks down the number of trees per hectare across the different forest habitats within the RCESC. Both of the upland coniferous forests (westside and eastside) have the largest number of trees present.
Rachel and Savanah taking tree diameter measurements (RCESC Photos Val Brenneis)
Data Collection
The storage and sequestration capabilities of the RCESC forests were estimated through the use of stratified random sampling plots. Each plot is 0.04 hectares (400 m2) in area and within each plot, every tree over 2 cm in diameter was identified and the percentage of canopy die-back, as well as the diameter at breast height (DBH), was measured and recorded. Using this information, the iTree program outputs an estimated value of ecosystem services representing the entire RCESC forest area.
Figure 3 from the iTree report breaks down the percentage of trees in the RCESC that fall within the DBH ranges listed. We can see here that the majority (over 50%) of trees within the RCESC fall below a 7.6cm diameter.
Westside forest canopy (RCESC Photos Val Brenneis)
The Importance of a Biodiverse Forest.
Younger trees will tend to sequester carbon at a higher rate than older trees due to the faster rate of growth pulling more carbon from the atmosphere. However, older established trees will have a larger storage capacity for carbon. Different species will also prove to have different carbon storage and sequestration capabilities. For example, findings from a study published in October 2021, “indicate clear differences in the protection of SOC [soil carbon storage] between broadleaf and coniferous forests growing on the same soil type” (Su et al. 2021). This reinforces the need to protect a variety of forest types and the wide range of biodiversity within those forests.
Figure 1 from the iTree report breaks down the species composition within the RCESC. Maple dominates this chart (both bigleaf and vine maple) with beaked hazelnut and Douglas-fir following shortly behind.
Figure 8 from the iTree report shows annual carbon sequestration within the RSESC. Although the Douglas-firs are much larger on average, the bigleaf maple provides more annual sequestration due to having a more dominant presence.
Figure 9 from the iTree report shows the estimated carbon storage of each species of tree. Douglas-firs are estimated to have almost half the total storage compared to bigleaf maples and show the importance of them to store carbon.
Figure 11 from the iTree report summarizes the findings and gives a cost of replacement estimate. Due to their age, size, and valuable ecosystem services Douglas-firs are by far the most costly to replace.
Conclusion
The importance of bigleaf maples and Douglas-firs in the RCESC is clear when looking at the iTree report. While the bigleaf maple dominates the area and provides the most carbon sequestration, Douglas-fir, due to their size and age, store about 50% of all carbon. Not discussed are the added benefits of avoided runoff, pollution removal, and oxygen production, which all increase the importance of these habitats further. With a replacement value of $4.34 million and carbon storage estimated at a value of $360,000, the RCESC is very valuable and worth protecting.
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Sources:
Oak Woodlands (RCESC Photos Val Brenneis)
iTree. 2021. Ecosystem Analysis, RCESC forest stratified random sampling: Urban Forest Effects and Values.
Sánchez JJ, Marcos-Martinez R, Srivastava L, Soonsawad N. 2021. Valuing the impacts of forest disturbances on ecosystem services: An examination of recreation and climate regulation services in U.S. national forests. Trees, Forests and People. 5:100123. doi:10.1016/j.tfp.2021.100123.
Su F, Xu S, Sayer EJ, Chen W, Du Y, Lu X. 2021. Distinct storage mechanisms of soil organic carbon in coniferous forest and evergreen broadleaf forest in tropical China. Journal of Environmental Management. 295:113142. doi:10.1016/j.jenvman.2021.113142.
Taye FA, Folkersen MV, Fleming CM, Buckwell A, Mackey B, Diwakar KC, Le D, Hasan S, Ange CS. 2021. The economic values of global forest ecosystem services: A meta-analysis. Ecological Economics. 189:107145. doi:10.1016/j.ecolecon.2021.107145.
Yin S, Gong Z, Gu L, Deng Y, Niu Y. 2022. Driving forces of the efficiency of forest carbon sequestration production: Spatial panel data from the national forest inventory in China. Journal of Cleaner Production. 330:129776. doi:10.1016/j.jclepro.2021.129776.
Cover photo: The boreal forest in Quebec. Shutterstock.com, by Pat Lauzon.
