Back to the Future: Building resilience in Colorado Front Range forests using research findings and a new guide for restoration of ponderosa and dry-mixed conifer landscapes

Paired historical and current photographs of the Cheesman Reservoir landscape (near Denver CO) illustrating the general increase in forest density and loss of openings that occurred from the late 1890’s to 2000. These types of paired photos can help us to give scientists a broad idea of how forests have changed over time (photos from 2000 by M. Kaufmann) via the Rocky Mountain Research Station.

Click here to read the January/February Bulletin from the Rocky Mountain Research Station. Here’s the summary:

Historically, the ponderosa and dry mixed-conifer forests of the Colorado Front Range were more open and grassy, and trees of all size classes were found in a grouped arrangement
with sizable openings between the clumps. As a legacy of re suppression, today’s forests are denser, with smaller trees. Proactive restoration of this forest type will help to reduce fuel loads and the risk of large and severe wild res in the Colorado Front Range. Using the best-available information on the historical conditions of these forests to develop “desired conditions” for restoration, the Rocky Mountain Research Station has published Principles and Practices for the Restoration of Ponderosa Pine and Dry Mixed-Conifer Forests of the Colorado Front Range (RMRS-GTR-373).

This guide was produced and reviewed by a range of scientists and managers from federal agencies, environmental non-pro ts, and academia to address the unique forest structure and re regime of this area as well as synthesize current Front Range forest science. It aims to help the management community understand the desired conditions for these forests, the principles behind the restoration recommendations made, and steps for implementing the principles. The guide is being released with a companion document, Visualization of Heterogeneous Forest Structures Following Treatment in the Southern Rocky Mountains, (RMRS-GTR-365) which allows users to “see” what the recommended treatments may look like at the stand level.

“Bergen Park” was painted by John Frederick Kensett circa 1870. The painting illustrates the open, spatially-variable structure of a ponderosa pine stand with an open understory typical of some Front Range forests at that time. (Bergen Park, at an elevation of 7800 ft., is located near Evergreen, CO, 25 miles west of Denver.) via Rocky Mountain Research Station

From Colorado Public Radio (Grace Hood):

Take a moment to picture Colorado in your imagination. You’re probably seeing mountain vistas with postcard-perfect evergreen forests. There’s a good chance what you’re imagining looks like Hall Ranch — a 220-acre carpet of pointy green trees flooding the landscape in Boulder County.
Ecologists who know the state’s forest history say it wasn’t always this way. Colorado’s lower elevation vistas have become too crowded.

“The first thing I see is we’re missing the meadows. Where are the meadows?” asked Tony Cheng, director of the Colorado Forest Restoration Institute at Colorado State University.

Euro-American settlement in the 1860s dramatically changed Colorado’s lower elevation forests. Before 1860, there would have been plenty of large open meadows. Small stands of ponderosa pines of various ages would have broken up the negative space. And low intensity wildfires would have moved through the stands of trees far more regularly.

Compare that to today where some crowded forests haven’t seen wildfire in more than a century. When fire comes it’s more likely to burn hot and intense, killing off all the trees.

Researchers care about this historical range because they want to make landscapes like Hall Ranch more wildfire friendly. Workers who manage forests now have specific guidelines on how to manage trees based on this framework. A new paper, published in April in Forest Ecology and Management, gives metrics to help guide and evaluate restoration projects.

“We’re not trying to exclude fire,” Cheng said. “We’re actually trying to set the landscape up to receive fire.”

Cheng, along with Peter Brown of the Rocky Mountain Tree-Ring Research organization, looked into the ranch’s historical forests and found that it’s pretty crowded today. Brown said, “there’s 10 times as many trees in these stands as there were historically.”

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