NASA’s Down-to-Earth View of Drought Impacts


Above, dead pines in the Sierra Nevada and (inset) beetle-infested oak trees prompted a study to understand what happened in the Santa Monica Mountains.

Rosi Dagit tapped NASA and a formidable team of ecologists in a study that analyzed the impacts of drought and beetles on our woodlands throughout the local ecosystem.

When you look at the Santa Monica Mountains on Google Earth, bands of dark green oak canopies, sprinkled with sycamores and alders make it easy to follow the drainages to the creeks. So many shades of green, much of which faded to shades of gray during the drought, provide a key to understanding how much loss has occurred throughout the mountains.

But how can you really tell what is dead and what is alive?

Last fall, bad news about the millions of pines and oaks dying in the Sierra Nevada prompted a coalition led by the Resource Conservation District of the Santa Monica Mountains (RCDSMM) to solicit help from on high to figure out what happened in the Santa Monica Mountains.  

Oak woodlands and chaparral shrublands throughout the Santa Monica Mountains experienced extensive tree loss and shrub dieback. Yet, as ongoing drought and the proliferation of pests and pathogens impact the Santa Monica Mountains, it is difficult to understand the underlying causes and how these patterns are associated with landscape variables. Who better to bring a big-picture, landscape-level perspective from the sky than NASA?

NASA’s Earth Observations DEVELOP Program team, headquartered at the Jet Propulsion Lab in Pasadena, worked with the RCDSMM on a national program that selects a few projects each term to investigate a problem proposed by a community group that will “integrate NASA’s Earth Observation to help meet the challenges of environmental change and improve life on our planet.”  

The Santa Monica Mountains Ecological Forecasting project work started in January and the results were presented in April to the Technical Advisory Committee (TAC). The goal was to determine the extent of drought dieback in shrublands and oak woodlands, and examine the role of insect-related changes within the Santa Monica Mountains from 2010 (the baseline before the drought began) through 2016, before the rains returned.

Danielle LeFer from State Parks helped organize training and facilitated access for the incredible Malibu Creek and Topanga Creek Docents to provide assistance. The RCDSMM Stream Team contributed by making maps, establishing study plots, and assessing trees along with help from the docents, Topanga Elementary School and Manzanita School students.

“We have rarely worked with such a large group of collaborators, but it is so exciting to have so many partners,” said Natalie Queally, the team leader for DEVELOP.

Our team will be using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to classify land cover types for 2013–2016. This data has 200+ wavelength spectral resolution, which can discern different vegetation and substrate types using tree condition data from the study plots in Topanga. “

Tree health assessments were done in randomly selected 25-square-meter plots located throughout the mountains that provided on-the-ground verification to allow specific spectral signatures to be correlated with existing trees. Unmanned Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data for 2010-2013, was collected and integrated by team member Emil Chang. The goal was to show how cover of green vegetation, non-photosynthetic (i.e. dead) vegetation, and substrate (soil, pavement) has changed over these years.”

With assistance from mentors Nick Rousseau, Dr. Ben Holt, Christine Rains and Natasha Stavros, Queally and Chang explained their results to the TAC on April 13. Comparing maps based on 15-by-15m pixels over time, it was obvious how the drought progressed overall, with the most severe loss occurring in 2014, followed by slight recovery in 2015-16.

When the oak plots were teased out and examined independently, the decline we observed on the ground also showed up from the aerial imagery. Due to the short ten-week time window for the project and the complexity of compiling all the data, preliminary correlations were significant between rainfall and the number of days over 90o F, as was expected.

Further analysis will look at the role of variables like slope, wildland interface risks, and whether the data can be used to help predict the areas and species most at-risk of decline or beetle infestation.

The data generated so far is a great start, providing an important tool to help us respond to drought impacts, especially now that the rains are helping us out and we can plant more oaks!



Unfortunately, this is just the first step of the effort. The “bad beetles” started emerging and moving in March. To better understand how fast the Polyphagous Shothole Borer beetles are spreading, the RCDSMM is coordinating the Detection Detective Citizen Science Project. In addition to traps set in 14 sensitive sites located in creeks throughout the mountains, we hope that property owners who live near wildlands will help expand the study by building and setting up traps at home.  

Ken Wheeland, Marisa Wizenga, Teena Takita and Wendi Gladstone are already up and running. The traps are a fun DIY project, great for students who need a science fair project or community service hours.  

Built from recycled soda bottles and outfitted with a lure that the beetles cannot resist, the traps are hung just on the edge of the tree canopy. Once a week, the water and all the bugs collected get strained through a coffee filter, put in a labeled Ziploc bag and brought to the RCD office. We hope to have summer interns help our Watershed Steward Project member, Nina Trusso, examine the samples and look for the bad guys. If any are found, we will send them to UC Riverside for confirmation and DNA analysis. To participate:

This trapping program should help us see how fast these beetles are spreading, how long it takes to kill trees and, most important, figure out if they are spreading into our precious parklands.

Oaks are keystone species that provide food and shelter for literally thousands of local insects and animal species. Sycamores, willows and alders provide bank stabilization, shade and help provide food for frogs and fish. Losing our woodlands to drought and beetles could be a landscape-level change that will have serious ripple effects throughout the local ecosystem. We need to get a better understanding of this and soon!

“This study built an incredible foundation that will allow us to use spatial analysis to hone in on drought impacts to specific vegetation types, examine wildfire risk and correlate what we observe on the ground with the big picture,” noted NPS Fire Ecologist Marti Witter. “The TAC is excited to submit another study proposal to NASA with the hope to continue developing this resource.

Thanks to the baseline efforts from the NASA folks, this fall we will be able to integrate the bug information into the overall picture of woodland and chaparral health conditions, providing a critical perspective from above to better guide our actions here below on earth.



Funding for this effort was provided by Supervisor Sheila Kuehl, with additional grants from the Santa Monica Mountains Research Learning Center and the Los Angeles County Fish and Game Commission.

TAC included the resource team from National Park Service’s (NPS)  GIS specialists Denise Kamradt, Brendan Clarke, Lena Lee and Robert Taylor; restoration ecologists Irina Irvine and Joey Algiers; and fire ecologist Marti Witter; Kim Corelle from CalFire and Dr. Tom Scott from the UC Cooperative Extension staff assisting.

Providing important background data were Los Angeles County Forester Jay Lopez, County GIS specialist Nick Franchino and Regional Planning biologists Joe Decruyenaere and Jennifer Mongolo.


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