Many open grasslands in the United States are at risk of conifer encroachment, an environmental phenomenon where conifer trees begin spreading into these grasslands, shrublands, or prairies. The conifers’ intrusion into these areas significantly changes the land, greatly affecting these unique habitats for various plant and animal species, which also benefit humans.
The rate of spread of native conifer trees, particularly pinyon pine and juniper, in the US over the past 150 years has been alarming, reflecting a global trend of conifer encroachment into other biomes. In most cases, trees found in higher areas are colonizing lower areas that previously did not have trees, turning them into forests. While forests are important native ecosystems, having too many of them can also have a negative effect on wildlife, watersheds, and productive grazing lands. The trees also use up a lot of moisture, outcompeting other plants that serve as food for both wildlife and livestock that are important to many rural agricultural communities.
The Big Hole Watershed Committee (BHWC) is a nonprofit that seeks to address the negative effects of conifer encroachment on the environment. Founded in 1995, BHWC coordinates various organizations and efforts, ensuring that their concerns are heard. It also develops practical solutions that aim to benefit all stakeholders and empower local communities.
According to Pedro Marques, BHWC Executive Director, water consumption is one of the often-unnoticed reasons behind conifer encroachment.
“You can think of each conifer as a straw; and through the process of evapotranspiration, they use up too much groundwater,” he says. “Because at least 70% of all precipitation is used by plants, this has serious implications for groundwater levels, which have a huge effect on rivers, wetlands, and the many species that depend on these bodies of water.”
According to Marques, because conifers are evergreen and have needles instead of regular leaves, they can photosynthesize even when it’s very cold. This means the conifers are drawing up groundwater, unlike deciduous plants that drop their leaves and become dormant, only beginning to use water later in spring. He adds that the trend of warmer winters makes this worse, as conifers are continuously drawing water.
“It’s very important to maintain the balance between conserving native ecosystems and the need for proper management of water resources,” Marques notes.
The causes of conifer encroachment are not fully understood, but the evidence points to climate change and less frequent fires. Experts theorize that the climate of the late 1800s and early 1900s was favorable for the spread of conifers into new habitats. Humans also began actively suppressing wildfires that historically kept conifer numbers in check.
Land management organizations employ different ways to counter conifer encroachment, including chainsaws, heavy equipment, and controlled burning.
Meanwhile, BHWC employs a different approach to addressing this persistent problem.
BHWC spearheads a project called the Eastern Pioneers Low-tech Process-based Restoration (LTPBR). It collaborates with the Southwest Montana Sagebrush Partnership (SMSP) and the Bureau of Land Management (BLM) in responding to the anthropogenic disturbances that have impacted streams in the region.
According to BHWC, streams in the region are facing several challenges, including the encroachment of conifers far beyond their historic borders. This diminishes forage for wildlife and livestock, intensifies wildfires, and causes habitat loss for species like sagebrush and mule deer. This project aims to enhance stream function and revitalize both instream and riparian habitat conditions. The committee is also designing diversions with measuring devices to enhance water control. It partners with new large landowners to deliver conservation projects and addresses Superfund sites.
Marques emphasizes that BHWC is facing multiple challenges in its ventures, such as severely depressed fish populations and institutional hurdles. However, the organization remains resilient and every donated private dollar is translated into projects and local cooperation. The Big Hole Watershed Committee invites continued support from the community and beyond to scale up its conservation efforts.
