Catch Up #2 - Firs on the Edge -
The short version of the story goes like this: From 2017 through 2023, Hyla Woods’ Mt. Richmond Forest continued to have ongoing die offs in Douglas fir in the 25 to 35 year range. Though we will never be certain, the die offs seem to be triggered by the abnormal heat is the summers of 2015-16.
The longer, more interesting story is more complex and uncertain. The best way to sum it up is through the stories of five, different sections of the forest each of which tells a unique story. To ward off depression, we’ll start with the most upbeat of the stories.
#1 – The Gate Patch - In the summer of 2011 we contracted with Randy Skeens and his crew to thin roughly half of the smaller and least vigorous trees from the area just inside the forest’s Lower Gate. One purpose of the logging was to help support forest health by reducing the trees’ net demand for the limited water during the increasingly hot summers. The work went smoothly, but by the end of the following summer the vigor and vital signs of many of the remaining trees were declining in troubling ways. Having never experienced a response like this in our forests, we feared for the worst and watched the fading trees closely. Over the subsequent years, we were pleased and somewhat surprised to see their vigor eventually return. Though the remaining die off of the top third of some of the trees remind us of this stressful time – for both the trees and us – a person visiting the grove today would be unlikely to know this recent episode of stress and eventual recovery.
#2 – Loop Road Die Off – That same summer of 2011, the same crew did a similar thinning of a 35 acre, 23 year old fir plantation. Knowing that the trees had grown to an age when their water demand grows increasingly large and knowing that some parts of the stand had shallower, more poorly drained soils than other area, we were on alert watching how the forest would respond. In the two years following the thinning, all of the remaining firs in two areas totaling three acres died.
#3 – Doctor Mutch’s Plantation – Meanwhile, in a distant corner of the 750 acre forest, an area planted by a former owner was growing well but had become dense enough that the weaker trees were losing the race for sunlight and beginning to die. In hopes of following nature’s lead and staying ahead of the risk of water stress in hot summers, 2016 we arranged for Brandon Epling and his crew to thin the stand as part of a larger project. Roughly half of the least vigorous trees were removed. Though the remaining trees appeared to be strong and were growing in deep, well-drained soils, we were shocked to have 95% of the remaining trees rapidly die within the next two years. Contrary to the Loop Road situation where the causes of die off seemed clear and understandable, this case caught us off guard and leaves us puzzled. Given that the thinning work was done at the beginning of the second of two abnormally hot summers, we wonder whether the impacts of normal thinning stress and extraordinary heat stress combined to cause the unexpected die off.
#4 – Lower Fawn Stand – Beginning in the summer of 2016, we were, once again, troubled to see a previously strong, 30 year old fir stand begin to fade. Assuming that the cause might be poor soils and water stress in hot summers, we thinned roughly half of the trees from the stand. Contrary to our hopes, this did not improve the situation. The trees continue their slow decline.
#5 – Apparent Success in “John’s Meadow” – Just a quarter mile north of the previously described site lies a former 22 acre farmed field that the previous owner and friend, John Mulholland, planted with fir in 2008. Being the good and determined farmer that he was, the young trees were thriving and beginning to crowd one another when we bought the land in 2015. Having wrestled with die offs in similar stands in other parts of the forest, in the summer of 2020 we turned our concern into proactive action by pre-commercially thinning the stand in hopes of maintaining vitality by reducing water stress during hot summers. By pre-commercial we mean cutting the trees before they have grown to a size that can be sold. The cut trees are left on the forest floor to help feed the soil. For reasons you can understand, we worried and closely watched to see how the thinned stand would respond. Would it die, as happened in stories 2 and 3 or would it continue its strong growth as we hoped it would? As of January 2025 the stand is growing strongly. Though John is no longer with us, we know that he’d be pleased.
Lessons Learned? – With each of these five situations, we humbly acknowledge that there are complex interactions between many factors that come together to determine which stands die and which grow well. While there is much that we do and can know and learn, there will always be much that remains unknown. Regardless, here are some the conclusions that we have tentative reached about these situations:
1 – Soils are Fundamental - Where soils are deep and well-drained, the fir tends to grow well – but not always! Where our forest’s ancient landslides cause shallow, poorly drained soils, the roots of young trees develop poorly in the winter saturated soils which increase their vulnerability to the water stress of hot summers. Stressed and weak trees become vulnerable to secondary killers such as Black stained root disease.
2 – Heat Appears to Play a Role – Over the past decade, the forests have been stressed by several forms of heat. In the summers of 2014-15, trees were stressed by relatively long periods of heat, which came at a time in the year when soils were already particularly dry. A second form of heat was the extraordinary spike in temperature when nearby stations recorded 113* on June 28th, 2021. The former appears to have had a significant impact on our die offs while the 2021 event seems to have had little, lasting impact. This may be because the spike was relatively short and came in a month when the soils were still relatively moist.
3 – Simplicity vs. Complexity – The die offs are concentrated in those parts of the forests that are least complex – even-aged, single-species plantations. Our investment in growing mixed aged, mixed species forests reduces our risks and chances of die off. The choice to impose plantations on sites better suited to a mix of native species, in hopes of increasing financial return, in many case, led to total loss of the trees. In contrast, the choice to follow nature’s lead takes us toward greater resilience and long term viability.
And Now What? Of these five stories, two remain alive and three resulted in total die off. Though uncertainties remain, the rapid spread of non-native, invasives (black berry and scotch broom), leave us no choice but to act. Sitting back and letting nature find its way is unfortunately not an option. In all cases, we have worked to correct past mistakes by planting a new, young forest made up of a mix of trees and shrubs that we feel have the best odds of thriving in both current and anticipated conditions. These include oak, ash, pine, maple, cedar and, yes, some fir. Our experimentation includes planting locally native trees from seed zones to our south as well as planting Incense cedar which is not native to this region, but is nearby. Ash is a workhorse restoration choice in our many wet areas, but the recent arrival of Emerald ash borer nearby, adds a new challenge and has caused us to stop planting one of our favorite species. Meanwhile, as the forests change and we do all that we can to increase its resilience and resistance to new stress, we watch the forests more closely than ever while we wonder “what next?”.
