When people think of the Endangered Species Act their minds drift to the conservation of charismatic animals such as wolves, grizzly bears and spotted owls. Mention this Act and people also start to ponder discussions concerning the ecological and economic trade-off that are a part of this law’s protections. What is overlooked, is that unless Congress gets involved, species’ listing under this Act are based on science alone. That is why it is interesting that one recently listed species is a tree: the whitebark pine.
This pine is not found in Utah but does occur in Idaho, Wyoming and Nevada. It is primarily encountered at high elevations in the Northern Rockies, the Cascade Mountains, and the Sierra Nevada Range. Whitebark pine grows slowly, going from a sprout to a cone producing tree in around 60 years. This is a timeframe that encompasses more than three human generations. This slow growth is partly due to being found in areas with poor soils. Despite adaptions that have allowed this species to survive in the harshest of environments, their populations are in decline. Recent data has found that approximately half of the standing trees are dead and half of these deaths occurred over the last couple decades. This is an alarmingly high mortality rate given this species is primarily found on public land, with many populations overlapping protected lands like National Parks and wilderness areas.
The principal mechanism of these rapid declines is a pathogen that was accidentally introduced from Europe to the western United States in the early 1900s. The movement of white pine blister rust through whitebark pine has been slow due to this rust’s complex life cycle. This pathogen does not spread from tree to tree but instead must move through an intermediated host, woody shrubs such as currants and gooseberries. Whitebark pine populations are also negatively affected by mountain pine beetles, fire and climate change.
This would not be the first tree species in the US to have succumbed to a botanical disease. Another is the American chestnut. In this species’ case, the spores from the pathogenic fungus can spread tree-to-tree, so it rapidly all but eliminated this species. Prior to the oblivion caused by this pathogen, the American chestnut was the dominant tree species across much of the mountainous eastern United States. Thankfully the need for an intermediate host has given us a bit more time to protect whitebark pine.
The ability to colonize harsh environments makes whitebark pine the organizing species of these ecosystems. For example, their seeds are primarily dispersed by the Clark’s Nutcracker. During late summer and fall these birds collect the tree’s seeds and cache them in the ground close to and up to 20 miles from where they were collected. The rest of the year these nutcrackers feed on the seeds they cached. While many seed caches are found and eaten, others are overlooked and eventually their seeds sprout to become the next generation of trees. These seeds provide an important food source for other species ranging from red squirrels to grizzly bears that inhabit these sparse high elevation forests.
Whitebark pine can be found across the West in locations ranging from the relatively dry and warm habitats of California to the wet and cold climates of Northern Idaho. This may be the key to their future. This broad distribution suggests considerable genetic diversity within this species. Hopefully within this diversity there are local populations that are naturally resistant to white pine blister rust. If such trees can be found, with a bit of work and a little luck, the negative population trajectory of this species may be altered. While the endangerment of a tree species will never get the same newspaper coverage a large mammal might receive, the loss of whitebark pine would likely have greater consequences and play out over decades.
Why should whitebark pine be protected under the Endangered Species Act if human management plays such a small role in their decline? Because even though this plant plays an important role in national parks such as Yellowstone, Crater Lake, and Yosemite, it might be overlooked without this protection. Furthermore, listing leads to identifying core areas and research that may help maintain or restore this species. Finally, it’s appropriate that society spend some time and money trying to protect an organism on which some of the most iconic landscapes in this country depend on.
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We welcome comments, however there are some guidelines:
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