PLACES | 01.23.18
Quiver trees thrive in arid conditions, but as climate change makes the Namib Desert hotter and drier, can these immobile icons find a way to beat the heat?
As the full moon rises over the Namib Desert, the region’s titans are revealed, their bifurcated branches silhouetted against the night sky. Quiver trees (Aloidendron dichotomum
) are a unique and quintessential part of this seemingly inhospitable landscape in southern Namibia and northern South Africa. These giants reach heights of 10 meters (33 feet) and can live up to 350 years. Their succulent leaves, branches, and trunks are well-adapted for conserving the desert’s precious water, while their shallow root systems have evolved to allow the trees to absorb rainfall quickly, before it evaporates or percolates through the porous soil and out of reach.
Quiver trees support a wide variety of creatures in the desert. Birds, insects, and mammals, including baboons, rely on the nectar in their flowers for moisture and sustenance. As some of the few elements on the landscape with any height, the trees act as nesting sites for sociable weaver birds (Philetarius socius
) and perches for raptors. The trees provide resources for humans, too; indigenous San hunters hollowed out the branches to construct quivers to carry their poisonous arrows, which is what gives the tree its common name.
While the trees have carved out an impressive niche in this extreme environment, they don’t have a lot of wiggle room within it. Quiver trees are surprisingly sensitive to changing conditions—especially high temperatures and drought, which is exactly the trend predicted for this part of the world as the global climate changes.
While the quiver tree is still quite prevalent today, it is on the International Union for Conservation of Nature (IUCN) hit list of the top ten species expected to be most heavily impacted by climate change. As is the case with many species, climate change is causing the quiver trees’ niche conditions to move, toward both higher latitudes and higher elevations. Models predict that the trees’ geographic range is likely to shift south in latitude by 23 kilometers (14 miles) and up in altitude by 16 meters (53 feet) every decade, should current climate trends continue. But some scientists see hope on the dry, desert horizon. Although individual trees can’t relocate, their populations can, as seeds are carried by wind to habitats that might be more suitable under predicted climate conditions.
In addition, some populations of quiver trees may be able to adapt to changing conditions where they currently stand. Researchers have found a high degree of genetic diversity among some quiver trees, especially those nearer the equator. These populations tend to be both older and better adapted to relatively hot, dry conditions than those farther south. Scientists think this may be evidence of a previous range shift, perhaps following the last ice age. This gives them reason to hope that the trees may, again, be able to adapt, if we can collectively slow the rate of change.
Namib Desert, Namibia
ABOUT THE Photographer
Pulitzer Prize winning photographer Jack Dykinga’s images tell the story of the land. He is a regular contributor toArizona Highways
Magazines. He has produced more than a dozen wilderness photography books, and his work has been recognized among the best Nature Photographs of all time by the International League of Conservation Photographers. In 2017, he received the North American Nature Photography Association’s Lifetime Achievement Award. He and his wife Margaret live in Tucson, Arizona.
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