The Fate of Sky Islands in a Rapidly Changing World
Forests cover 30% of the world’s terrestrial landscapes and have major influences on ecological systems, but increasing numbers of studies are reporting that many trees species are experiencing substantial declines due to global change. Understanding the extent of such declines as well as their drivers is a major focus of the Cushman lab.
We have recently initiated a new project that explores the health of forests on sky islands, isolated high-elevation environments that differ greatly from surrounding arid landscapes. Such environments have been shown by Jim Brown and others to have island-like properties, with the number of species occupying them typically increasing with sky island size. How are sky islands faring during a period of unprecedented human-caused climate change? Are they decreasing in size, with possible reductions in the number of species that they can support? Or are the forests on sky islands shifting upwards in elevation or becoming more prominent on the cooler, more mesic northern slopes? What is happening to the highest parts of sky islands that are above tree line? Are these areas – the ‘donut holes’ of sky islands – becoming colonized by trees as their climates become more hospitable or are they shifting in position?
We are using satellite imagery from the past 35 years to address these and other related questions in the Great Basin Archipelago of Nevada and western Utah, a complex of ~200 forested mountain ranges surrounded by Great Basin Desert. We also hope to expand our analyses to include the Madrean Archipelago found in New Mexico, Arizona and the Mexican states of Chihuahua and Sonora.
This project is being conducted in collaboration with our colleague Jonathan Greenberg at UNR (https://naes.unr.edu/gears/).
We have recently initiated a new project that explores the health of forests on sky islands, isolated high-elevation environments that differ greatly from surrounding arid landscapes. Such environments have been shown by Jim Brown and others to have island-like properties, with the number of species occupying them typically increasing with sky island size. How are sky islands faring during a period of unprecedented human-caused climate change? Are they decreasing in size, with possible reductions in the number of species that they can support? Or are the forests on sky islands shifting upwards in elevation or becoming more prominent on the cooler, more mesic northern slopes? What is happening to the highest parts of sky islands that are above tree line? Are these areas – the ‘donut holes’ of sky islands – becoming colonized by trees as their climates become more hospitable or are they shifting in position?
We are using satellite imagery from the past 35 years to address these and other related questions in the Great Basin Archipelago of Nevada and western Utah, a complex of ~200 forested mountain ranges surrounded by Great Basin Desert. We also hope to expand our analyses to include the Madrean Archipelago found in New Mexico, Arizona and the Mexican states of Chihuahua and Sonora.
This project is being conducted in collaboration with our colleague Jonathan Greenberg at UNR (https://naes.unr.edu/gears/).