Why Protecting Mature Trees Matters

Part 1: Protecting Mature Trees on Private Forestlands in Whatcom County: Why It’s So Crucial

“Instead of being primarily concerned with the effects of habitat on the plants, the influences are the effects of the plants on the habitat.”

-Joseph Kittredge, 1948

Across the United States, smaller forests, in the hands of private citizens, have been little studied. Yet these forests are endangered. Endangered by the continual pressure to convert them to other uses, endangered by the lack of rules to protect them. Our local forests are not spared this jeopardy.

What is our status?

Of 19.6 million acres of forestland in Washington State, 42% is federally owned, 39% private, 10% WA DNR, 7% tribal, and 2% county or city owned. Whatcom County has a similar distribution but with a higher percentage (63%) of federal ownership, most of which is in the eastern half of the county. The county is 60% forested, but it is slowly losing precious tree cover. Between 2007 and 2019, 823 acres of forestland were lost to home-building, 349 to development, 474 to agriculture.

protecting mature trees

“An old stand of trees with its closed crown area differs from all other types of vegetation … as is known by anyone entering a wood from the blistering summer heat, a howling gale, or biting winter cold of the open country.”

– Rudolf Geiger, 1966.
All trees, all ages, are valuable, but mature mixed stands are especially important.

This is because larger trees in an undisturbed forest setting provide innumerable ecological benefits. These include:

Climate amelioration

Forests bring water. In any given biome, forested watersheds receive 25% more rain than unforested watersheds, mitigating drought and replenishing aquifers. Additionally, depending on the duration and volume of rain, forests may intercept up to 90% of rainfall within their canopies and understory vegetation, thereby helping to prevent flooding or limit its impact.

Carbon storage

As trees age, they absorb increasing amounts of carbon dioxide, removing it from the atmosphere and helping to cool the planet. A tree’s carbon storage rises steadily between the age of 20-175, making these years critical for maximum climate impact.

Clean air and water

The enormous surface area of leaves, stems, and other plant matter found in a mixed forest adhere pollutants such as hydrocarbons and soot and prevent them from entering streams or reentering the atmosphere. For example, urban forests remove as much as 16% of the ozone generated by cars, air conditioners, and other major polluters.

Supporting biodiversity

Whatcom County has 433 non-fish vertebrate species, most of which are associated with forested habitats. Local floral diversity includes 1,100 higher plants, not to mention countless insects and other invertebrates. Mixed forests (with both deciduous and coniferous trees) support the greatest suite of organisms and the richest diversity. 

“The forest is a place of miracles, often filled with serenity and an unfathomable sense of peace.”

– Bill Thomas, 1992
Small forest landowners are key.

Small forest landowners (owning 2-100 acres) are in a prime position to protect and enhance their woodlots and, for the most part, do so enthusiastically. Surveys conducted by the University of Washington have shown that landowners’ top reason for retaining woodlands is the “enjoyment of natural beauty”, with the protection of nature, water, and wildlife also a top priority. My Masters research in Skagit County showed that even the smallest woodlots (2-10 acres) provided protection from songbird nest predation. Riparian areas within larger tracts (10- 40+ acres) were most protected and highly species-rich.

Even solitary trees have great value, particularly in urban or cleared agricultural settings. A shade tree near a house can reduce heating and cooling costs by 50% or more, and reducing heating and cooling costs reduces the impact on the global climate. Solitary trees are also appealing to wildlife. For example, in the middle of Sedro-Woolley, a tall fir tree cradles the nest of a merlin hawk and is used year after year.

Happily, virtually all of the forests I studied in the mid-1990’s are still in existence and unchanged today, demonstrating the reluctance of landowners to give up their plots, and thus maintain their critical role in woodland preservation.

The lesson 

Trees take a long time to grow. Protecting mature trees in individual woodlots is essential whenever possible, at the same time allowing for judicious uses deemed important to landowners, such as for firewood. Because Whatcom County continues to lose forested habitat, it is more important than ever to act now.

Part 2 will explore current efforts of protecting mature trees by Whatcom Million Trees Project and other local organizations.

“Every part of the earth is sacred to my people.  Every shiny pine needle, every sandy shore, every mist in the dark woods, every clearing and humming insect is holy in the memory and experience of my people.”

– Chief Sealth of the Duwamish Tribe, 1855

 Campbell, Sally et al. 2008. Washington’s Forest Resources, 2002-2007: 5 year forest inventory. fs.fed.us/pnw/pubs/pnw_gtr800.pdf

Geiger, Rudolf. 1966. The climate near the ground. Harvard University Press. Cambridge. Pp 298-299.

Kittredge, Joseph. 1948. Forest influences: the effects of woody vegetation on  climate, water, and soil. Dover Publications. New York. Pp 4.

Naef, Virginia. 1996.  Susceptibility of forest avifauna to nest predation in varying Northwestern Washington landscapes. MS thesis. Huxley College, Bellingham.

Rabotyegov, Sergey et al. 2021. Washington’s small forest landowners in 2020. University of Washington, School of Environmental and Forest Sciences.

Thomas, Bill. 1992. Wild woodlands: the old-growth forests of America.  Taylor Publishing Company, Dallas.

Whatcom County 2017 ecosystem report. Wildlife Advisory Committee for the Whatcom County Council.


Please help us achieve our mission. Donate to Whatcom Million Trees Project today to help us meet our ambitious five-year goal! Or join us as a volunteer. We’d love to have you on our team!

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Virginia Naef is a contributing writer for Whatcom Million Trees Project. She has worn many hats, from construction laborer to wildlife biologist to laboratory technologist. But her greatest love is conservation biology. She has completed field studies on dam mitigation and river restoration for the Washington Department of Fish & Wildlife, and hatchery mitigation and fish habitat relationships in the South Fork Nooksack for the Lummi Tribe. Her Master’s Thesis through Huxley College is on the susceptibility of forest avifauna to nest predation in varying Northwestern landscapes.

Although retired, Virginia stays very busy on her 15 acre farm in Acme, as well as participating on the Boards of the Deming Friends of the Library and the Northwest All-Breed Goat Club. By helping the Whatcom Million Trees Project, she looks forward to bringing more trees to our beautiful region and to protecting the ones that are already here.

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