Roger Bales

University of California, Merced | UCM · Sierra Nevada Research Institute (SNRI)

Across the western United States and elsewhere, the frequency and intensity of wildland fires are projected to increase, posing a challenge to natural‐resource management. While collaborative, multi‐benefit partnerships can provide opportunities to overcome barriers to effective management, in many cases these collaborations have been slow to form....

Recent drought, wildfires and rising temperatures in the western US highlight the urgency of increasing resiliency in overstocked forests. However, limited valuation information hinders the broader participation of beneficiaries in forest management. We assessed how historical disturbances in California's Central Sierra Nevada affected live biomass...

The Mediterranean montane catchments of the Sierra Nevada region of California are vital for the western US’s water resources. The granitic landscape, high elevation, rugged topography, and changing precipitation phase create a complex coupling between water and energy cycling, influencing the vegetation, soil water, and snow dynamics. The interact...

Increasing drought frequency and severity in a warming climate threaten forest ecosystems with widespread tree deaths. Canopy structure is important in regulating tree mortality during drought, but how it functions remains controversial. Here, we show that the interplay between tree size and forest structure explains drought-induced tree mortality...

Extreme droughts are a major determinant of ecosystem disturbance that impacts plant communities and feeds back into climate change through changes in plant functioning. However, the complex relationships between aboveground and belowground plant hydraulic traits and their role in governing plant responses to drought are not fully understood. In th...

The social impacts of natural resource management are challenging to evaluate because their perceived benefits and costs vary across stakeholder groups. Nevertheless, ensuring social acceptance is essential to building public support for adaptive measures required for the sustainable management of ecosystems in a warming climate. Based on surveys w...

Forests across the Western U.S. face unprecedented risk due to historic fire exclusion, environmental degradation, and climate change. Forest management activities like ecological thinning, prescribed burning, and meadow restoration can improve landscape resilience. Resilient forests are at a lower risk of high-intensity wildfires, drought, insects...

Forest restoration through mechanical thinning, prescribed burning, and other management actions is vital to improving forest resilience to fire and drought across the Western United States, and yields benefits that can be monetized, including improvements in water supply and hydropower. Using California's Sierra Nevada as a study area, we assess t...

Extreme droughts are a major determinant of ecosystem disturbance, which impact plant communities and feed back to climate change through changes in plant functioning. However, the complex relationships between above- and belowground plant hydraulic traits, and their role in governing plant responses to drought, are not fully understood. In this st...

The interactions among soil water dynamics, vegetation, and topography are the base of ecohydrological processes in the water-limited system. Topographic factors like slope and aspect can influence the diurnal and seasonal microclimatic conditions of the landscape by regulating the duration and angle of the incoming solar energy. In the northern he...

Understanding potential response of forest carbon (C) and nutrient storage to warming is important for climate mitigation policies. Unfortunately, those responses are difficult to predict in seasonally dry forests, in part, because ecosystem processes are highly sensitive to both changes in temperature and precipitation. We investigated how warming...

To estimate snowpack water storage in mountain basins, this study presents a framework that couples a deep-learning long short-term memory (LSTM) model and a zonal bias-correction approach for assimilating ground snow observations. We explored the framework’s ability for snow water equivalent (SWE) mapping and forecasting in a domain, including the...

Watershed managers require accurate, high-spatial-resolution evapotranspiration (ET) data to evaluate forest susceptibility to drought or catastrophic wildfire, and to determine opportunities for enhancing streamflow or forest resilience under climate warming. We evaluate an easily calculated product by using annual gridded precipitation (P) and me...

This study reports on a blending approach using snowpack measurements from a wireless‐sensor network, gauge precipitation, and atmospheric‐moisture data to estimate mountain precipitation amount and phase. We applied the approach in California's American River basin, using dense measurements from a network consisting of over 130 sensor nodes distri...

Feedbacks between the intertwined water and carbon cycles in semi‐arid mountain ecosystems can introduce large uncertainties into projections of carbon storage. In this study, we sought to understand the influence of key mechanisms on carbon balances, focusing on an ecosystem whose complex terrain and large interannual variability in precipitation...

An inconsistent relationship between precipitation and runoff has been observed between drought and non-drought periods, with less runoff usually observed during droughts than would be expected based solely on precipitation deficit. Predictability of these shifts in the precipitation–runoff relationship is still challenging, largely because the und...

Elucidating climatic impacts on stream nutrient export and stoichiometry will improve the understanding of forest carbon (C) storage in a warmer world. We analyzed C, nitrogen (N), and phosphorus (P) cycles in four watersheds within a rain-snow transition site and another four within a higher-elevation, snow-dominated site, in California's mixed-co...