Our research efforts focus broadly on applied conservation biology, as our projects range from monitoring vulnerable species in the Coachella Valley's desert ecosystem to investigating vegetation fire resilience in the Mojave National Park. Learn more about our ongoing projects below.
Several parks within the Mojave Desert Inventory & Monitoring Network (MOJN), contain either or both Western and Eastern Joshua tree forests (Yucca brevifolia and Yucca jaegeriana, respectively), which are already demonstrating impacts from climate change (e.g. increased intensity and frequency of fire, mortality, lowered recruitment). Information is needed to understand ongoing threats to develop management actions in response to preserve these iconic species within NPS units. response to preserve these iconic species within NPS units. Overall goals are to (1) analyze climate change-induced vulnerabilities to Joshua trees, (2) investigate recruitment niche patterns and vulnerabilities, (3) determine demographic trends of Joshua tree populations, and (4) produce fine-scale future suitable habitat models that will inform management actions for maintaining Joshua tree persistence under climate change.
The Coachella Valley Multiple Species Habitat Conservation Plan and Natural Community Conservation Plan (CVMSHCP) was established in 2008 to ensure the regional conservation of plant and animal species, natural communities, and ecological processes across the Coachella Valley. This multi-agency plan provides for the long-term conservation of Coachella Valley's ecological diversity.
We are actively involved in implementing the CVMSHCP using scientific oversight. We have developed methods to monitor many of the covered species protected under the plan and understand the potential drivers and stressors of their population dynamics. These methods are scientific method-based, meaning that they begin with hypotheses for the causes of population increases or declines and then test those hypotheses. From these data, we can compare the differences in species occurrences and abundance between years, plots, and habitat types.
Our goal is to continue to test, demonstrate, and produce applied scientific research on the efficiency and efficacy of this approach and to guide management decisions that are made to sustain these species and landscapes. We are committed to supporting the well-being of Riverside County's communities through our participation in the CVMSHCP.
Stabilized sand field at the Coachella Valley National Wildlife Refuge
Flat tailed horned lizard (Phrynosoma mcallii) camouflaged on inland desert dunes
Palm Springs Pocket Mouse (Perognathus longimembris bangsi) tracks on desert dunes
Coachella Valley Milkvetch (Astragalus lentiginosus var. coachellae)
Vegetation, defined as the patterns of plant cover over the landscape, is the best biological indicator of wildlife habitat quality and ecosystem function. It synthesizes much of what ecologists and conservation biologists require to understand the terrestrial landscape.
Fine-scale vegetation maps are used by the California Department of Fish and Wildlife (CDFW), other state and federal agencies, non-governmental agencies, and the public for conservation planning, and many other purposes. The Survey of California Vegetation (SCV) is the CDFW’s standard for classifying and mapping California’s vegetation, set forth by the Vegetation Classification and Mapping Program (VegCAMP). The SCV starts with the collection of plant data in the field that are analyzed to develop a classification of vegetation types, which is then used to create fine-scale digital vegetation maps.
Our objective is to characterize and map vegetation for this region to contribute to the SCV’s goal to develop a state-wide digital vegetation layer that is uniform in resolution and supported by field data, using a repeatable methodology. Using the SCV’s methodology, we will create a fine-scale vegetation map of the Colorado Desert ecoregion. The vegetation map will provide critical information that can assist in monitoring habitat suitability in conservation areas, and help researchers understand the effects of environmental variability, including drought and climate change.
Scientists performing a reconnaissance survey in the Coachella Valley
Algodones Dunes
Researchers reviewing data at a field site
Reference photo for habitat type
The goals of the Desert Climate Resilience Initiative | Iniciativa de Resiliencia Climática del Desierto project are to improve overall scientific expertise and community engagement around several key themes: native plant communities; climate change and carbon sequestration potential in the desert, and building equity within the Coachella Valley.
The Desert Climate Resilience Initiative (DCRI) | Iniciativa de Resiliencia Climática del Desierto (IRCD) aims to build the state of knowledge and capacity for coordinating climate change adaptation. Deserts are rich in biodiversity and have important economic, recreational, and cultural benefits. In spite of this, these areas have been overlooked as being important to the carbon economy beyond their utility for solar energy. There is a lack of understanding of the extent to which deserts, especially those in the Coachella Valley, store carbon and act as ongoing carbon sinks. In order to promote climate resilience, the DCRI | IRCD integrates scientific research into land management and decision-making.
For Latino Conservation Week, we partnered with Friends of the Desert Mountains and led Latinx families on a guided nature hike within the Coachella Valley.
We tabled at Morongo Tribe's Earth Day, where we engaged with the community to share ideas regarding local climate change
Burrobush (Ambrosia dumosa) stem that was collected for water stable isotope analysis
Caliche, a soil accumulation of soluble calcium carbonate that has long-term carbon storage potential
Joshua trees are likely to be highly vulnerable according to predictive modeling studies. There are areas that look to be suitable future habitat for the Joshua Trees, known as habitat refugia, but these are threatened by invasive grass fueled wildfires. NPS plans to expand efforts to protect these high-elevation stands through strategically placed fuel reduction treatments and to engage in efforts to restore burned refugia through novel restoration techniques. These treatments are costly and must be guided by the best available science.
This project provides the opportunity for collaboration and science for the holistic management of refugia not only for Joshua trees but for other species, including bringing together scientists from across agencies and disciplines. Project work examines Joshua tree reproduction and mortality across the landscape, information crucial to designing and implementing management actions geared toward preserving Joshua trees for future generations in the context of climate change.
Joshua Tree National Park
Volunteer measures the size of a Joshua tree
Joshua tree (Yucca brevifolila) blossom
Volunteers and scientists surveying plant species abundance
Wildfire is a significant force influencing vegetation worldwide; and where its frequency or intensity departs from natural or culturally-imposed historical intervals, it represents a real and present environmental threat.
The Mojave National Preserve (MOJA) protects a rich diversity of plant species, including Eastern Joshua trees (Yucca jaegeriana) and banana yucca (Yucca baccata). Both these species were found in great numbers within the Joshua tree woodland before the area burned in the 2020 Dome Fire on Cima Dome. Generally, this vegetation does not readily recover from large and intense wildfires. While the Preserve’s fire history is still being investigated, wildfire occurrence is likely influenced by various factors including the frequency of summer monsoonal storms, pre- and post-Euro-settlement human practices, the historically recent invasion of non-native grasses, and the structure and phenology of the vegetation.
Fires like the 2020 Dome Fire provide opportunities to understand how wildfire influences the distribution and composition of vegetation at the Preserve today. By establishing study plots within the perimeter of this recent fire, we can address specific questions regarding passive recovery (the process of natural recruitment and population growth) of vegetation as well as document the survivorship of two dominant Yucca species in the region.
Cima Dome burn area in Mojave National Preserve
Dr. Lynn Sweet measuring the height of a burned Joshua tree (Yucca jaegeriana)
The burned stump of a banana yucca (Yucca baccata) with sprouts
Scientist measuring the height of a Joshua tree sprout
The Mojave desert tortoise (Gopherus agassizii) is a charismatic, large, terrestrial, herbivorous species found primarily in the Mojave and Colorado deserts. These tortoises have experienced significant declines across most of their range and have been the focus of conservation efforts for decades, being listed as federally threatened in 1990. Despite these conservation efforts declines are continuing, with densities falling over 50% in large parts of their range between 2004 and 2014.
One strategy for mitigating these declines is head-starting, the ‘practice of protecting especially vulnerable life stages of a species to increase the likelihood of survivorship for conservation purposes’ (Burke 2015). We are helping analyze what determines the survival and movement of head-started tortoises at the 29 Palms Marine Corps Air Ground Combat Center, or MCAGCC.
Our post-doctoral researcher, Clay Noss, holding a Mojave desert tortoise (Gopherus agassizii) (also shown left)