Sand Dunes on the Loose Due to Climate Change

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Jessica Robertson:  Hello and welcome to the USGS CoreCast.  I'm Jessica Robertson.

Climate change is affecting several landscapes, altering the basic building blocks of ecosystems and threatening their viability. One example of a changing landscape is the sand dunes of Northern Arizona, where work is being conducted by USGS scientist Margaret Hiza and USGS intern Leanna Begay.  Leanna is a student who receives support from the USGS Science in Support of Native American Relations.  She is also a native of the Navajo Nation in Arizona and is a master’s student at Purdue University.

Today I'd like to welcome and introduce you to our guests, Leanna and Margaret, who will be joining us on the phone and discussing their research.  Thank you both for joining us today.

First, Margaret, can you provide us some background information and an overview of your research with Leanna?

Margaret Hiza:  I'm working to study sand dunes on the Navajo Nation because they are a predominant surface feature of this region and they are very sensitive to climate change, especially here in the Southwest where climate change is bringing warmer and drier conditions.  As the climate warms, less vegetation can grow on sand dunes and they become more mobile.  Once sand has become mobile, the character of the ecosystem changes.  What plants can live and grow here has changed, and the animals and people that use these plants for sustenance can no longer find them.

Leanna is helping me to understand what plants grow where, which plants can tolerate moving sand, and which plants can’t.By studying climate change impacts on sand dunes, we can identify strategies for keeping sand dunes more stable.  We can identify which plants need to be protected and what kind of plants may tolerate dune mobility enough to be used in a revegetation program.

Jessica Robertson:  Margaret, can you provide us some examples of the impacts of climate change and sand dune mobility to the surrounding region?

Margaret Hiza:Sure.  One of the big impacts is to Navajo rangeland.  Rangeland and forage is very important to a lot of Navajo people.  Few plants can grow on mobile dune fields and only a few plants can keep pace with moving sand and tolerate abrasion from moving sand.  Once the rangeland becomes altered and there's a lot of moving sand dunes, invasive plants have an opportunity to move in, so that even when wetter periods come back, the native plants have often permanently lost their niche in the ecosystem.

Another thing that happens is that with mobile sand and dust, travel becomes hazardous.  Often on windy days, the highways will become closed around the Navajo nation because of decreased visibility, and mobilized sand and dust impacts human health and damages infrastructure.

Jessica Robertson:  And Leanna, can you tell us about your role in the research?

Leanna Begay:  My roles in this research are two-fold.  First is that I am a community member bringing my personal observations, which has helped me understand and know the timing of changes which are occurring on the landscape.  This allows me to assess how much activity is occurring or has occurred since my previous field site visit.

Secondly is that I'm a graduate student leading my own research in my home community of Tuba City, Arizona, on the Navajo Nation.  I'm applying the tools and methods of scientific inquiry to a local issue which is to learn more about the plant communities which are impacted by mobilized sand dunes.  Throughout the years, I have seen significant changes occurring especially when driving by sand dunes, which I have selected as my field sites.  Not only do roads become impassable by actively mobile dunes, but the plant communities on the leeward face of the dune gradually get covered by the approaching dune.

From these observations, this is a cause of concern especially since my grandparents and neighboring residents travel these roads on a daily basis.  When roads become impassable, they have to rely on their four-wheel drive vehicle or just become really good at driving in sand and just hope that their car makes it over the dunes.  That's all you can do in a situation like this.

Jessica Robertson:  Leanna, I think it's wonderful you’re able to give back to your community through your research.  Can you discuss the impacts of climate change on sand dunes and plant communities as well as the main outcomes of your research?

Leanna Begay:  Climate change is having a significant impact on plant communities and sand dunes, which is evident by the visible changes on the landscape.  The plant communities essentially don't have enough time to move. As a dune progresses, so does the deposition of the sand on the leeward face of the dune, also the front edge of the dune.

In the most recent decade, we've noticed a rise in temperature and also a decrease in precipitation, which seem to be simultaneously occurring.  And with these kinds of conditions, the vegetation which stabilizes the sand dunes is not as successful in acquiring the needed water to maintain its growth on these sand dunes.  And so with some of the preliminary observations, it has become apparent that some species tend to be found at certain zones or distances on a sand dune.

And also we noticed that the difference in the physical appearance of flora on the leeward and windward face of the dune are different.  It allowed me to see the diversity and the density of the species across the dunes.  With that diversity and being able to see that rich flora, it doesn’t seem obvious when you first come out to the field site, so you just have to take a closer look to visually see what type of plants are within the larger shrubs.

I see that there is a benefit for the plant community because among them, we could learn more about these individual plants who are specialized at being colonizers or facilitators and eventually becoming the stabilizers of these sand dune plant communities.  So we won’t know until we've looked deeper into the diversity of the flora to truly understand what benefits they offer the sand dunes and how these plants benefit from living on the sand dunes.

Jessica Robertson:  Leanna, how are these plants, which you mentioned are on or near the sand dunes, used by the Navajo Nation and others?  What cultural significances exist?

Leanna Begay:  This is an open-range land management area.  The most popular use is the forage value that these plants provide for the grazing livestock which we have out here, which include the cattle, the sheep, and the horses.  And aside from that is the domestic purposes which we use some of these plants for, such as for brushes, weaving, dyes to make the weaving, making baskets, and also collecting teas.

The other benefits would be the medicinal purposes, where the traditional medicine men would go out and gather particular plants for particular ceremonies.  The other aspect which isn’t really included is looking at how these plants provide shade and food for other mammals such as lizards, jack rabbits, foxes, and birds.

Jessica Robertson:  Leanna, is there anything else you want to share with us regarding this project?

Leanna Begay:  For my master’s thesis, I just want to continue to analyze my data that I've collected and also just to get a complete understanding of why these plants exist where they do. And stemming from my research here, I'd also like to publish this information so that it's available to other readers and scientists who are interested not only in the Navajo Nation but perhaps the Colorado Plateau.  Also, another aspect is to continue this research through my education continuing onto a PhD program and learning about both the plant communities again and then also incorporating more sand dune mobility information into, into the research.

Jessica Robertson:  Thank you, Leanna. Margaret, is there anything else you would like to share with us?

Margaret Hiza:  Sure.  I think it's really special when somebody like Leanna can go back to the community where she is from and do her research in a way that benefits the community.  And it's really a great way for our research project to build a connection to the community that she's from.

We have a project website, http://geomaps.wr.usgs.gov/navajo/, where we will have a link to an open file report that is going to be compiled from Leanna's species checklist.  And people from the Navajo Nation who are interested in learning more about dune plants or just anybody in general who is interested in dune ecosystems can come and look at our work.

Jessica Robertson:  Well, thank you both for joining us today.  And thank you to all of our listeners who joined us for this episode of CoreCast.

As always, CoreCast is a product of the US Geological Survey, Department of the Interior.

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Mentioned in this episode:

• USGS Navajo Nations Studies