Greasewood ecosystem in Pine Valley, Nevada with the Roberts Mountains in the background.
Greasewood Greasewood ecosystem near Pine Valley, Nevada © Louis Provencher/TNC


New Paper Defends Greasewood and Other Undervalued Ecosystems

Scientists from The Nature Conservancy in Nevada introduce the concept of biodiversity potential to assess the value of these ecosystems

  • Sara Cobble
    Marketing and Communications Manager
    The Nature Conservancy in Nevada

Who cares about greasewood? We should, as it’s an undervalued and extreme ecosystem that has economic value and policy implications, scientists from The Nature Conservancy in Nevada argue in a new paper published this month.

In “All Systems Are Equal: In Defense of Undervalued Ecosystems,” author Louis Provencher and co-authors Laurel Saito, Kevin Badik, and Sarah Byer write that it’s time to recognize the biodiversity potential of greasewood and other misunderstood ecosystems that are not considered biodiversity hotspots. Biodiversity potential questions whether the degradation of ecosystems like greasewood with seemingly low number of species compared to more species-rich or socially valued ecosystems is acceptable. According to the authors, it’s important to recognize the biodiversity potential of these undervalued systems, as their soils, hydrology, and climates create unique assortments of adapted species that cannot be replaced by other or more species from other ecosystems. In other words, undervalued systems are more significant than they appear.

The Nature Conservancy in Nevada mapped Nevada’s indicators of groundwater-dependent ecosystems (iGDEs) last year, which cover at least one-tenth of the state, and found that greasewood was the largest iGDE type and makes up almost a third of iGDEs in Nevada. It is also found in California, Idaho, Oregon, Utah, and other western states. Phreatophytic (plants with roots that can tap into groundwater) systems like greasewood are often indicator species for groundwater located near the ground surface. But if groundwater is pumped to the point where the water table drops and taproots cannot reach it, the plants will become stressed, wilt and eventually might disappear. GDEs like greasewood may be disregarded in favor of economic uses for water, but this has policy implications: they could be subject to groundwater withdrawals that could be litigated, subject to NEPA decision-making or other regulatory mechanisms, or reviewed by a state engineer for approval or denial of water right applications.

“As surface water supplies become scarce, pressures to develop and use groundwater can lead to water table declines that can affect greasewood ecosystems,” Provencher said. “Understanding the groundwater needs to sustain greasewood ecosystems and being able to model ecosystem transitions of these systems will help us to consider how to maintain groundwater sustainability that supports social, economic and environmental needs for water.”

Greasewood ecosystems may also be disregarded in favor of a transition to another ecosystem with more biodiversity, but they aren’t easily replaced. Few species other than those present in greasewood ecosystems can survive the saline to sodic (salty or containing sodium chloride) soils they grow in. Instead, the loss of greasewood ecosystems, which are a naturally effective fuel break, could encourage the spread of invasive non-native plants like cheatgrass, which creates a wildfire risk.

Greasewood covers 2.2. million acres of Nevada and is typically found in elevations of 3,800-5,800 feet in valley bottoms where summer temperatures reach into the hundreds. Pronghorn, mule deer, black-tailed jackrabbits, golden eagles and more than 100 invertebrate, reptile, and small mammal species depend on these ecosystems. The loss of these ecosystems not only increases fire risk, but also drops the biodiversity potential, as species such as golden eagle would lose habitat and have to travel further for their preferred prey, jackrabbit.

“Greasewood ecosystems in Nevada have historically been deemed ‘less valuable’ than other ecosystems based on species richness and past cultural values,” the authors write. “However, some greasewood ecosystems may be near or at their biodiversity potential (that cannot be replaced by another ecosystem) and therefore worth conservation protection.” 

Some greasewood ecosystems may be near or at their biodiversity potential (that cannot be replaced by another ecosystem) and therefore worth conservation protection.

Director of Conservation Ecology, The Nature Conservancy in Nevada

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world’s toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. Working in 76 countries and territories—37 by direct conservation impact and 39 through partners—we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit or follow @nature_press on Twitter.