Save a Forest in Southworth, WA

Southworth Forest Update:

Mature Conifers Increasingly Need Summer Deep Watering

Posted August 9, 2024 by Southworth Forest

This grove of mature Western Red Cedar at the heart of the Southworth Forest experienced significant dieback in the summers of 2020 to 2022 after the neighboring forest's destruction. It now takes multiple days to deep water twice each summer.

Residents of the Pacific Northwest's temperate rainforest areas have felt the effects of hotter summers and particularly the occasional "heat dome" that brings periods of temperatures over 100 degrees. This consequence of climate change has stressed the native mature forest stands, particular conifers like the Western Red Cedar and Western Hemlock, two stalwarts of the region.

Younger trees of ten feet in height can expend 25 gallons of water per day, and mature ones can process over 100 gallons. It's tough to underestimate just how much water can be stored in the mostly sandy loams of this region and extracted by large trees. But even these reserves can be insufficient for mature trees that established themselves decades ago, prior to these hotter conditions.

At the Southworth Forest restoration project in Port Orchard, the summers of 2020 to 2022 exposed significant dieback of needles and whole branches on mature conifers starting as early as July. It's normal for such dieback to occur in the fall, but the cedars, hemlocks, and Grand firs were losing two to four years of needles in the matter of one summer season. This process suggests that the trees are so stressed that photosynthesis has shut down.

The spread of the tree stress has been most concentrated in the Southworth Forest areas exposed to the illegal 2019 forest destruction at the neighboring 11090 SE Southworth Dr. Mature trees in the southeast quadrant of the forest especially feel the impacts of increased heat and wind from the environmental violation. Trees in the path of these warmer winds across multiple acres have been impacted, causing significant summer dieback, particularly on the cedars. During the worst years, nearly an entire mature cedar can turn orange.

In 2023 and 2024, deep watering has been conducted in the largest groves of mature cedars and firs at the Southworth Forest, greatly reducing the dieback those years. Since the region no longer receives appreciate rainfall in the summers like it used to, the first deep watering of the trees occurs in late July while a second follows in late August. With a hose source running fully at a healthy rate of 80 PSI (and plenty of hose!), it takes three days to saturate the driplines of these groves of 60-year-old trees. This volume of watering can help resupply the trees with at least an additional two to four weeks of water expenditure, depending upon temperatures.

Mature trees immediately adjacent to the neighboring deforestation, including the more drought-resistant Douglas firs, are being deep-watered every two weeks to help them through the adjustment period of losing the adjacent canopy. This effort continues despite those neighboring violators, Meghan and Clint Edwards, declaring an intent to remove those mature trees in the Southworth Forest since an easement exists there. Edwards proposes developing a second driveway to a parking lot through that easement, an act Kitsap County has identified as merely retaliatory but has declined to prohibit despite its certain worsening of environmental impacts.

Meanwhile, the hundreds of young trees planted in the Southworth Forest over the past six years are watered once per week, with a concentration on establishing the hemlocks and coast redwoods. Some of the hemlocks perish in the first three years, which is typical. Aside from that, the only trees showing any stress in 2024 despite regular watering are a handful of younger Grand fir, which prematurely drop yellowing needles in irregular patterns on their branches. The Douglas firs and various pines have, not surprisingly, performed the best in the changing climate. Giant sequoias have also proven hearty, though they tend to grow more slowly in adverse conditions.

Preserving the long-term health of the Southworth Forest will require deep watering of its mature trees for the foreseeable future. While this effort affects the conifers more than everything else, the big leaf maples, madrone, and alders also appreciate the assistance. It's important to remember that the loss of mature canopy causes inevitable heat stress on neighboring forests, and Kitsap County must recognize and address these widespread impacts when bringing careless and dishonest forest violations into compliance.

Mature Grand fir and Western Red Cedar trees exhibit alarming stress during the summer of 2022. The fir tree eventually died but the cedar was nursed back to health with deep watering.

When highly stressed by heat, a Western Red Cedar can turn completely orange by September. While this act of self-preservation by the tree is not always fatal, it can become so if it doesn't receive assistance. Such browning can be avoided with watering in July and August.

The Western Red Cedars directly adjacent to the illegal neighboring deforestation are at the highest risk of death from exposure. Despite efforts to help the trees, the violators seek to eliminate them by overdeveloping an easement in which they stand.