A Spruce Cone-u-copia in the Pike-San Isabel National Forest

This article is part of a monthly environmental column for the Mountain Mail/Chaffee County Times. It first appeared Feb 1, 2025.

As you ride up Tumbleina, Panorama, or Breezeway at Monarch Mountain, check out the trees beside the lift. You’re likely to see a healthy line of Engelmann spruce, laden with bunches of brown and purple cones.

These clusters of cones triggered the curiosity of GARNA members at our biweekly Ski With a Naturalist Program. They suspected that there are more cones on the trees at Monarch this year than there have been in the past few years, and they wondered what could cause such an uptick in cone production.

In a conversation with GARNA, U.S. Forest Service silviculturist Eric Eden confirmed these folks’ suspicions that this year’s cone crop is particularly bountiful at Monarch and throughout the Pike-San Isabel National Forest.

Increased cone production has been observed primarily on Engelmann Spruce trees, which comprise 90% of the tree population at Monarch Mountain (lodgepole pines constitute the other 10%). Young Engelmann spruce trees can start producing cones and encased seeds when they reach 5 feet tall or are 15-45 years old. However, they produce the most viable seeds when they are 100-200 years old. Most spruces in the Pike-San Isabel forest are in this sweet spot; due to mass deforestation to support railroads and logging in the late 19th century, most Engelmann spruce trees in our neck of the woods are around 140 years old.

So the trees in question are in their prime reproductive years, but why might mature Engelmann spruce produce more seed cones in some years than others?

Eden could not give a definitive answer to this question given that a variety of factors- including climate, location, age, genetics, and environmental stressors- can impact seed production and dispersal. However, Eden offered several possible explanations for the widespread cone-u-copia we’re seeing right now.

Eden’s first possible explanation was that Engelmann Spruce are currently “masting.” Masting is an evolutionary adaptation which enables plants and trees to produce a large amount of seeds synchronously every several years. By producing a surplus of seeds, plants and trees overwhelm predators like mice, insects, and seedworms and promote the viability of their seeds. Masting occurs every 2-5 years for Engelmann spruce, which enables the tree to conserve energy in off-years for processes besides reproduction.

It could also be the case that this large crop of Engelmann spruce cones is being stimulated by stressors like drought, pests, disease, and air or soil pollution. All of these triggers can disrupt plant homeostasis and impact their development and reproduction. For instance, Eden mentioned that this year’s large cone crop could potentially be a long-term consequence of the significant beetle kill which ran through the Pike-San Isabel National Forest around 10 years ago. It is exceedingly difficult to map exactly what triggers cone production, so even unlikely triggers like drought or cold temperatures– neither of which Eden says are likely to be the cause of this year’s cone production– cannot be ruled out as possibilities.

Regardless of if this year’s cone bounty is stress-induced or not, Eden affirms that a large cone crop which occurs every few years is not of much concern. Increased cone production that carries on for multiple years in a row, however, would be indicative of a persistent stressor within the forest ecosystem.

Fortunately for all of us who care about the health of our beloved local forests, the USFS is keeping an eye on the well-being of the cone-crazy Engelmann spruce. Eden and other silviculturists monitor the regeneration of trees within 100-acre plots throughout the Pike-San Isabel National Forest every several years. You can support the USFS in their efforts by volunteering at stewardship events, led in collaboration with GARNA, this summer. Stay tuned for details on these volunteering opportunities as they become available in the coming months!

Until then, go explore the national forests in our area, see these magnificent clusters of spruce cones for yourself, and stay inquisitive about the eccentricities of our incredible natural environment.

Rose Nadelhoffer is Programs Development Coordinator at the Greater Arkansas River Nature Association. Have a burning environmental question? Send it to Rose@garna.org.