At the Southern Sierra CZO: Tracking soil erosion & its impacts in Sierra Nevada forests
Erin Stacy
Sierra Nevada Research Institute
UC Merced
What does the CZO do?
Cover background on Sierra Nevada & water resources, goals of the CZO, who works there and what we
study.
Quickly: define the critical zone, the conceptual design of the study & what the instruments
there do
Implications for managing natural resources of Sierra Nevada, water resources in California
Why it's important: climate change & the need to better predict resources as they become more
variable.
When and why does soil erosion occur in undisturbed forests?
Erosion impacts ecosystem health, soil fertility & our water resources, even under minimal disturbance.
Increasing intensity and variability of storms will affect sediment transfer rates - but we don't have good
numbers for background rates in the Sierra (interannual variability, spatial variability among
watersheds).
In forests and other undisturbed environments, it can be hard to tell whether erosion is occurring at all.
But, rainstorms and snowmelt continuously lead to transport of soil across the landscape to streams,
where it can travel far from the source.
This transfer of soil and organic matter is a major component of the Critical Zone - the zone between
rock and air that is critical for life. Erosion impacts soil fertility and the carbon balance. For example,
intense fall storms or sudden snow melt can radically increase the amount of transported soil material
for any given year. However, knowledge is sparse for erosion at different scales of time and space in the
Sierra Nevada.
Researchers at the Kings River Experimental Watershed (KREW) and the Southern Sierra Critical Zone
Observatory (CZO) have been filling in this gap by tracking erosion in several small watersheds to
examine the amount and composition of sediment produced each year. This project is part of a multiinvestigator study of the Sierra Nevada critical zone for an elevational transect stretching between valley
floor to ridgeline.
As this study goes forward, it will help resource managers with how prescribed burns, tree thinning, and
other land management decisions impact erosion.