Changing Canopies

Climate change is affecting ecosystems across the globe, negatively impacting human communities and the natural world. Here in Central Oregon, we’re seeing impacts to our natural areas including rising temperatures, increasing drought conditions, and expanding wildfire seasons. A major cause of climate change is the release of greenhouse gasses like carbon dioxide that trap heat in the atmosphere, so finding ways to remove carbon from the air is an important part of addressing the problem.Climate change is affecting ecosystems across the globe, negatively impacting human communities and the natural world.

At the Deschutes Land Trust, we think about ways that our conserved lands can store carbon, how restoration techniques can make carbon storage more effective, and how we can improve the ability of our protected lands to resist future changes. At the Metolius Preserve, management techniques are helping to keep our forests resistant to wildfire while promoting the growth of large trees that absorb carbon from the atmosphere. This is considered a 'natural climate solution', since it can both help to address greenhouse gas emissions and improve the health of natural areas.

Let’s dig deeper into the Metolius Preserve. The Metolius Preserve is almost entirely covered in forest, so it has the potential to store a lot of carbon, but when the Land Trust acquired the property in 2003, portions of the forest were dense and unhealthy. This also meant it had a high risk of wildfire, so one of the Land Trust’s first management priorities was reducing fire risk in the forest.

One way to decrease fire risk is to reduce the amount of fuel available to burn, which can reduce the intensity of a wildfire and the likelihood of tree mortality. This can be accomplished in several ways, including clearing underbrush (shrubs and small plants that form a dense layer near the ground) and tree thinning (selectively cutting down trees to reduce the overall number of trees in an area). The Land Trust chose to do both over many years of forest restoration efforts. Tree thinning is particularly effective at protecting stored carbon, since the Land Trust can retain larger, older trees that are more fire-resistant and also store more carbon than younger trees.

In addition to reducing fire risk and improving forest health, another goal of the Land Trust's forest management work is to increase long-term carbon storage. We can track stored carbon in the Preserve by looking at satellite-derived data that estimates the amount of aboveground carbon over time.

The graph above shows the total amount of aboveground carbon stored on the Preserve from 2013 to 2021. You can see the amount of carbon steadily increasing from 2013-2017, with a sharp drop during 2017-2018, and then a rapid recovery from 2018-2020. We would expect stored carbon to increase over time as trees grow and accumulate biomass (the total weight of plant material such as wood and leaves). So what happened in 2017 that resulted in a sharp decline in stored carbon?

Between 2017 and 2018, the carbon stored within tree biomass on the Preserve dropped significantly. You can see this in the large dark patches that appear over that time period. This drop in carbon storage is because of the forest restoration work carried out by the Land Trust, which thinned trees and removed biomass, and by extension stored carbon, from the Preserve. While this short-term loss is to be expected, selective thinning protects long-term carbon storage potential by reducing the risk of loss to wildfire and concentrating carbon in larger, mature trees.

However, from 2018 to 2020, forest carbon returned to similar levels as those observed prior to thinning. You can see this as the dark purple patches begin to disappear. This shift in carbon storage from small trees and underbrush that were removed, to the remaining larger trees is a good sign. The data shows that the forest was able to respond quickly to thinning treatments, absorbing nearly as much carbon as it originally stored within a much shorter time frame. The roughly 1,400 tons of carbon stored by the forest during this time period is the equivalent of 1,100 gasoline powered passenger cars being driven for one year!

The Land Trust's management efforts in the Metolius Preserve are far from over. In 2023 we completed mowing of overgrown shrubs in preparation for a prescribed burn. This fall we are planning a prescribed burn at the Preserve with our partners at the Nature Conservancy and Deschutes National Forest. The prescribed fire will further reduce fuels, improve habitat for plants and animals, and continue to help the Preserve adapt to the impacts of climate change.