When most people think about species at risk in Alberta, wildlife like bull trout, caribou, or burrowing owls probably come to mind. What people usually forget is that Alberta has many plant species at risk too – mostly in the prairies. Alberta has two endangered tree species: whitebark pine and limber pine. Both of these species grow in the Rocky Mountains and limber pine also grows in the adjacent foothills, so working with these endangered species always involves spectacular scenery, starring these gnarled spreading trees, and hiking or helicopter access.
Climb every mountain!
Whitebark pine and limber pine have similar habitat, ecology and threats. The main threat causing a rapid range-wide decline of both species is an introduced fungus that causes white pine blister rust. This is a fatal disease that spread rapidly all across North America after its introduction from Eurasia about 100 years ago. Luckily, there are some special trees that are naturally disease resistant, and they can pass this resistance on to their seedlings.
Alberta’s recovery work is focused heavily on finding and protecting these rare and valuable trees, collecting their seeds, and using confirmed resistant seedlings for restoration so the natural resistance will become more widespread, allowing these high elevation ecosystems to sustain themselves over the long term.
But it’s more complicated than just conserving and restoring one (or two) tree species. Whitebark and limber pine both rely heavily on a bird in the jay family, the Clark’s nutcracker, for their seed germination. In fact, whitebark pine relies totally on this bird to peck open the cones as they no longer open on their own after thousands of generations of co-evolution (limber pine cones do open, but this species still relies on the birds to plant its seeds).
The nutcracker has a special pouch under its tongue where it can keep about 100 seeds as it works on the cones. It then flies to mostly open, warm-aspect or windswept sites that are snow-free for much of the winter, and caches groups of 1 to 15 seeds in the ground. It digs up seeds for a winter and spring food supply, and those it forgets about germinate and grow into these majestic trees, which often grow in clumps because of the groups of seeds cached together.
It may seem bizarre, but to collect whitebark and limber pine seeds for planting, we need to outwit a bunch of birds. Each tree needs to be surveyed early in summer when the snow melts to check for cones – they don’t produce cones each year, because it takes so much energy for these trees to produce cones full of very large, fat and protein-rich seeds. Each tree must be climbed and a wire mesh cage installed, or else when we return in the fall to collect the mature seeds, there won’t be a single one left – they really are the favourite food of birds, squirrels, bears, and other animals!
To restore whitebark and limber pine populations, there must be enough mature cone-producing trees on site to keep the nutcrackers coming back. As the rust kills these trees, they lose their reproductive ability and if there isn’t a reliable food source, the nutcrackers will leave the area so those populations will wink out. Alberta is mapping tree populations to determine which areas are the top priorities for restoration.
Because these trees grow in such extreme habitats, they grow very slowly and only start making a decent cone crop after age 80 to 100. Recovery actions are all the more urgent because each tree lost takes over a century to replace.
So far, Alberta has identified 136 limber pine trees and 54 whitebark pine trees that appear to be blister rust resistant, and Parks Canada has identified over 100 more in the Rocky Mountain National Parks. Seeds from 126 trees have been sent by Alberta to get tested to confirm if they are actually resistant, and crews will continue to search for as many of these special trees as they can find to ensure there is a diverse, well-adapted supply of seeds for restoration across the range of both species.
A major reason for the accomplishments of this recovery program is collaboration. Parks Canada, Alberta Agriculture and Forestry, Alberta Environment and Parks, Wildfire, USDA Forest Service, US National Forests, US National Parks Service, universities, NGOs such as the Whitebark Pine Ecosystem Foundation, and volunteers have all shared resources and information and worked together to study, conserve, and restore whitebark pine and limber pine habitat across boundaries.