Novel Use of Image Time-Series to Distinguish Dryland Vegetation Responses to Wet and Dry Years by Dawn Browning
New results from Emily Myers and her collaborators found that rain plays a crucial role in shaping the greenery patterns of semi-arid grasslands, with some surprising twists when it comes to places dominated by grasses versus those dominated by shrubs.
The team set out to address a significant challenge: how to effectively monitor these important but vulnerable ecosystems. Semi-arid grasslands are vital yet often overlooked components of our landscapes, providing essential resources for livestock, habitats for wildlife, and renewable energy. However, these areas face increasing threats from rising aridity and ill-timed livestock grazing, which can gradually transform them into less productive shrublands.
To track these changes and better understand how these ecosystems function, Myers and her team turned to unlikely pairs of eyes in the sky: near-ground cameras, called PhenoCams, and satellites. They focused on a site on the Jornada Basin LTER in southern New Mexico, watching how the landscape’s greenness ebbed and flowed over wet and dry years.
What they found was both expected and surprising. As you might guess, more rain meant greener landscapes across the board. But here’s the surprise:
grass-dominated areas were the real drama queens, showing the most extreme responses to rainfall. They burst into vibrant green during wet years and dialed it back when things got dry.
But the real magic happened when the researchers compared what the ground-based cameras saw versus the satellite view. These differences could be the key to telling apart areas dominated by grass from those overtaken by shrubs – a crucial distinction for land managers.
The team suggests that by combining the frequent, detailed observations from PhenoCams with the broad view of satellites, we can access a currently
underused line of data to monitor these intriguing and “flashy” landscapes. They’re particularly excited about using the timing and intensity of the grass’ peak greenness as a potential early warning system for ecosystem changes.
In a nutshell, this research gives us new tools to keep our eyes on these vital but threatened grasslands, helping ensure they continue to support both wildlife and human livelihoods for years to come.
Comparison of grass-dominated (top) and shrub-dominated (bottom) dryland ecological states, with differences in growing season phenology shown for dry and wet rainfall years. States are shown on the left using PhenoCam images.