Preserving tree canopy in Washington state in face of a warming climate

King County foresters planted 5,700 native tree seedlings acquired from warmer, drier climates for a long-term study designed to promote healthy, resilient, and productive local forests.

Based on climate modeling that predicts conditions at the end of the century, the King County Department of Natural Resources and Parks secured tree seedlings from Southwest Washington, Oregon, and Northern California. 

Forest specialists selected four planting locations throughout King County that have different site conditions and will monitor the trees’ survival and health multiple times over the next decade.

The climate-adaptive tree planting trials are one of the strategies included in King County’s 30-Year Forest Plan launched by Executive Dow Constantine to promote urban and rural tree canopy and improve forest health and productivity for current and future generations.

"We are taking action to ensure that the forests of King County – recognized around the world for their ecological value and spectacular beauty – remain healthy and productive into the next century,” said Executive Constantine.

“The study conducted by our scientists today will inform tree planting for a more climate-resilient future.”

The goal of the study is to answer one primary question: Do seedlings grown from seed collected in regions with warmer, drier climates have a better chance of surviving and thriving in King County as the local climate changes?

Foresters at the Department of Natural Resources and Parks used a mapping program developed by the U.S. Forest Service that helps forest stewards find the right seeds for their planting sites based on climate predictions. 

They chose the 2071-2100 timeframe – the furthest timeframe available – and identified locations that currently have climates similar to what is predicted for King County by the end of this century.

The project team selected Douglas-fir, western red cedar, Sitka spruce, grand fir, western hemlock, and ponderosa pine species for the study.

They are trying to identify genotypes of native species that might be better adapted to a changing climate rather than assist with the migration of species that are not currently found in King County.

After preparing the designated sites, crews planted a combined 5,700 trees in early March at four locations stewarded by King County: Taylor Mountain Forest, Middle Issaquah Creek Natural Area, Neely Bridge Natural Area near Auburn, and Vashon-Maury Island. 

They will return to each location during the second, fifth, and 10th years of growth to monitor the trees’ health, and comparing the response of seedlings grown for seed collected in other regions to growth exhibited by seedlings sourced locally.

More information here