Analyzing a phenological anomaly in Yucca of the southwestern United States

Yucca in the American desert Southwest typically flowers in early spring, but a well-documented anomalous bloom event occurred during an unusually cold and wet late fall and early winter 2018–2019. We used community science photographs to generate flowering presence and absence data. We fit phenoclimatic models to determine which climate variables are explanatory for normal flowering, and then we tested if the same conditions that drive normal blooming also drove the anomalous blooming event. Flowering for Yucca brevifolia (Joshua tree) and Yucca schidigera (Mojave yucca) is driven by complex, nonlinear interactions between daylength, temperature, and precipitation. To our surprise, early-season flowering odds are highest in colder and drier conditions, especially for Joshua trees, but increase with precipitation late-season. However, the models used to fit normal blooming overpredicted the number of anomalous blooms compared to what was actually observed. Thus, predicting anomalous flowering events remains a challenge for quantitative phenological models. Because our model overpredicted the number of anomalous blooms, there are likely other factors, such as biotic interactions or other seasonal factors, which may be especially important in controlling what is presumed to be rare, out-of-season flowering in desert-adapted Yucca.

Parasitism to mutualism continuum for Joshua trees inoculated with different communities of arbuscular mycorrhizal fungi from a desert elevation gradient

Most desert plants form symbiotic relationships with arbuscular mycorrhizal fungi (AMF), yet fungal identity and impacts on host plants remain largely unknown. Despite widespread recognition of the importance of AMF relationships for plant functioning, we do not know how fungal community structure changes across a desert climate gradient, nor the impacts of different fungal communities on host plant species. Because climate change can shape the distribution of species through effects on species interactions, knowing how the ranges of symbiotic partners are geographically structured and the outcomes of those species interactions informs theory and improves management recommendations. Here we used high throughput sequencing to examine the AMF community of Joshua trees along a climate gradient in Joshua Tree National Park. We then used a range of performance measures and abiotic factors to evaluate how different AMF communities may affect Joshua tree fitness. We found that fungal communities change with elevation resulting in a spectrum of interaction outcomes from mutualism to parasitism that changed with the developmental stage of the plant. Nutrient accumulation and the mycorrhizal growth response of Joshua tree seedlings inoculated with fungi from the lowest (warmest) elevations was first negative, but after 9 months had surpassed that of plants with other fungal treatments. This indicates that low elevation fungi are costly for the plant to initiate symbiosis, yet confer benefits over time. The strong relationship between AMF community and plant growth suggests that variation in AMF community may have long term consequences for plant populations along an elevation gradient.

Predicting Phenological Anomaly: a Case Study of Yucca in the Southwestern United States

Yucca in the American desert Southwest typically flowers in early spring, but a well-documented anomalous bloom event occurred during an unusually cold and wet late fall and early winter 2018–2019. We used citizen science photographs as a means to generate flowering presence and absence data. We fit phenoclimatic models to determine which climate variables are explanatory for normal flowering, and then we tested if the same conditions that drive normal blooming also drove the anomalous blooming event. Flowering for Y. brevifolia and Y. schidigera is driven by complex, nonlinear interactions between daylength, temperature, and precipitation. To our surprise, early-season flowering odds are highest in colder and drier conditions, especially for Joshua trees, but increase with precipitation late-season. However, the models used to fit normal blooming overpredicted the number of anomalous blooms compared to what was actually observed. Thus, predicting anomalous flowering events remains a challenge for quantitative phenological models. Because our model overpredicted the number of anomalous blooms, there are likely other factors, such as biotic interactions or other seasonal factors, which may be especially important in controlling what is presumed to be rare, out-of-season flowering in desert-adapted Yucca.

Leveraging Stakeholders to Cover Budgetary Shortfalls in U.S. National Parks: Lessons from the 2018/2019 Government Shutdown and Joshua Tree National Park

Joshua Tree National Park is a remarkable desert ecosystem made iconic by the famed Joshua trees that dot the landscape. In 1994, a majority of Joshua Tree’s holdings were designated as “wilderness” (a legal status in the U.S.). Subsequently, Joshua Tree was buffeted by deleterious anthropogenic forces and suffered from severe budgetary constraints. In 2018/2019, a U.S. Government shutdown forced the Joshua Tree staff into furlough, while the park remained open to visitors. The response of local volunteers, who took responsibility for educating visitors about park policies and ecosystem conservation in the midst of the shutdown, shows the extent to which networks of local and community volunteers can be mobilized to mitigate at least some of the effects of budgetary constraints that affect the wilderness and national park lands.

Merging Art, Science and Motherhood to Save Joshua Trees

Human behaviors have driven us into a planetwide species extinction crisis that is linked to the rapidly changing climate. To move forward we need interdisciplinary research approaches that protect our resources and a variety of outreach strategies to educate and inspire the public toward sustainable living. We need a public identity shift into the role of environmental caretaker to continue living on this planet and to improve the environmental conditions for ourselves and others. In her current doctoral ecological and arts research, the author draws on themes of motherhood to connect people to these ecological issues on a deep and tangible level. Her hope is to better communicate the complexity surrounding species loss and to motivate sustainable actions.