Forest Carbon Storage in the Issaquah Alps
This month, the Issaquah Alps Trails Club hosted a guided hike about the importance of Forest Carbon. We started our Forest Carbon Hike at the Harvey Manning Park (919 Bear Ridge Ct NW) with a small but inquisitive group led by Kathleen Farley-Wolf, Program Manager with the King County Forestry Program. Kathleen is a wealth of knowledge and we felt lucky to have her share with us as we walked through the green wet forest.
We learned that carbon is sequestered from Earth's atmosphere through photosynthesis and stored in forest biomass and soils. 50% of a tree is made up of carbon which means mature forests, with bigger trees, are much better at storing carbon. Forests in the Pacific Northwest play an important role in sequestering and storing carbon due to their ability to accumulate large quantities of biomass in long-lived tree species that can sustain growth in both diameter and height over long time periods. These tree species characteristics combine with abundant moisture and mild winter temperatures to create some of the highest levels of carbon sequestration and storage in the world. However, due to past management, the forests in King County likely still have potential for greater carbon storage.
To kick off the King County Forest Carbon Program in 2019, King County sold some rural carbon credits from a small piece of the Cougar Mountain Regional Wildland Park, the property which we hiked on, to Microsoft. This program is the first in the nation to offer certified credits to protect local forests. Before putting the carbon credits on the market there was a lot of measurement and verification involved. Lidar, a method to measure distance using radar, was used to help measure tree height. Tree circumferences were measured by hand and ground logs were counted and measured all in a defined area. Although carbon is also stored in soil, it is difficult to measure in pacific northwest forests and was not included in this project.
This property was chosen because it is a very healthy forest that escaped the logging boom over a century ago and has thrived with diversity which made it the perfect piece of land for the King County Forest Carbon Program. Microsoft buys carbon credits from this piece of property to offset some of their carbon footprint. King County then uses the money to purchase more land to conserve through the Land Conservation Initiative. The initial purchase of carbon credits is much larger than the credits from the following years because it is a guarantee to keep forests safe from logging and housing developments. Later payments are for the accrued carbon as time goes on.
When purchasing property for conservation King County’s offer is based on the appraised value and it is difficult to pay over market value no matter how perfect the property is. IATC is hoping to help bridge this gap on some future parcels with the opportunity fund in which all donations will go to filling these gaps.
As Issaquah creates our Climate Action Plan (comments are welcomed) and changes land use codes, we are wise to follow the good advice and research of the KC 30-Year Forest Plan which Kathleen helped create. The plan covers 7 important topics:
Climate
Forest Health
Urban Forest Canopy
Human Health
Salmon Habitat
Water Quality and Quantity
Sustainable Timber
With the help of IATC, Issaquah has conserved 51% of its tree canopy. The more intact forests we can continue to save the better as we look to reduce and sequester carbon emissions to help reduce the effects of climate change and increase our resiliency. Healthy mature forests sequester tons more carbon than freshly planted trees. But planting trees is important too especially in disturbed or bare areas and to create greater diversity and resilience.
We can be very grateful to King County for purchasing this well intact forest on Cougar Mountain. Without the work of IATC and King County, many of the trees in this important carbon sink would most likely have been cut for development.