Long serving heroes of the snow

Normally these blogs feature recent papers from our lab group - this one features a dataset that Gabrielle Boisrame has just published on HydroShare - six years of data measured at weather stations in Illilouette Creek Basin. These stations endured fire, freeze, drought and very wet years. They survived visits from curious bears with ... only minor injuries. They didn't just measure weather, but also soil water and soil temperature, and made time lapse photographic recordings of the area around them.  At the end of their service, Gabrielle retrieved them, ending our measurements in the basin.

PhD Students Katya Rakhmatulina and Emily Gonthier making measurements at one of the weather stations.

Illilouette Creek is an exciting place for those interested in fire ecology and hydrology. Unlike most of California's Sierra Nevada, a frequent wildfire regime has been allowed to operate in this part of Yosemite National Park for nearly 60 years. Frequent fires have altered the structure and composition of vegetation in the basin, and have also changed its hydrology.

Fire remains and Half Dome - Illilouette Creek Basin is an extraordinary and rapidly changing landscape.

This came to our attention when Scott Stephens, fire ecologist extraordinaire, noticed that areas that had been pine forest burned and regenerated with wetland plants. Spatial analysis and hydrological modeling confirmed that as the frequent fire regime established, the basin was storing more water and generating more flow. To better understand these changes, we installed the weather stations in 3 locations, within 200m of each other. These locations had all originally been pine forest, had burned, and then variously regenerated as wetland, shrubs or pines.

Although these 3 areas received the same large-scale weather conditions, they varied in their snow dynamics and in their water storage. Wetland locations typically retained snow for longer than other locations, mostly because they stayed cooler at night - presumably from greater radiative cooling. They were wetter at the end of snowmelt, and stayed wetter through summer.

Gabrielle Boisrame enjoying the beauty of mountain meadows restored by fire.

There is more to learn from of these datasets - for example are the wetland sites like they are because soils and slopes make them wetter - or did the wetter, colder conditions suppress growth of other types of plants, allowing them to stay wetter and colder than areas with pines?

To make things even more interesting, in 2017 the Empire fire burned through the area, allowing pre- and post-burn comparisons to be made.

We're pleased to make the data available publically, and hope that you will find exciting new ways to use them. Fire and water management in the Sierra Nevada and elsewhere remain urgently important, and we hope that these heroic weather stations will keep contributing to our collective learning.

This work was funded by NSF CAREER grant, the Critical Zone Collaborative Research Network, and the Joint Fire Science Program. Gabrielle Boisrame is the mule-train and hiking with heavy batteries in a backpack queen of Yosemite. Thanks to all the many scientists and friends involved in producing these data.