By M. Martin Smith and Fiona Gow
High Country News
Two hundred and fifty miles southeast of San Francisco, new studies resulting from decades of research show that giant sequoia saplings are thriving less robustly in the warming central Sierra Nevada. So do officials in Sequoia National Park build sequoia sapling greenhouses? Do they install sprinkler systems around the great sequoia monarchs? Or do they prepare a new habitat farther north, removing other species to make space for sequoia saplings? Should such moves even be contemplated, given the still-fledgling nature of predictive climatology?
And what of the rest of the trees in the West — the ones doomed to die from drought, fire and beetle infestation?
Scientists studying forest diebacks say one response to the dying might be to thin forests, so that individual trees are hardier and more beetle-resistant. It remains to be seen how well this would go over with an environmental movement accustomed to opposing logging. Other controversial ideas include intensive breeding and genetic engineering to create insect-resistant tree species, combined with the aggressive use of herbicides and pesticides.
Wildlife managers have long believed that local plant species should be kept genetically pure. But climate change may ultimately call for a sophisticated type of wildlife gardening, in which heat-loving southern plant species are brought north and encouraged to crossbreed with cold-loving cousins.
Already, a massive die-off of pinon pine trees in the Southwest is being called a "global warming type event." Again, selective logging might be one answer, scientists say: If fewer trees share scarce water, they just might survive in the new climate.
But for plant species that simply can't survive in their old habitat, some scientists are floating the idea of a forced march north.
Animals whose habitat dwindles as the climate changes might just scurry elsewhere, explains Nathan Stephenson, a research ecologist at the Western Ecological Science Center at Sequoia and Kings Canyon National Parks. But trees cannot get up and walk away. "The National Park Service has to decide: Are we going to assist species migration?" says Stephenson.
Helping plants and animals migrate north isn't just a matter of leasing fleets of flatbed nursery trucks. Many species under threat aren't easy to dig up and put in a pot. Soil microorganisms, fungi, butterflies, and other small creatures critical to the functioning of ecosystems may also find their traditional homes unlivable. Assisting species migration would mean setting aside broad swaths of wild land to provide an uninterrupted pathway north for entire habitats.
"I've had a number of conversations with land managers, identifying all the land in California that could conceivably be used as refugia, and what would be the appropriate species to go where. The magnitude of the problem is mind-boggling," says David Graber, chief scientist for the Pacific West region of the U.S. National Park Service. "There is a vocal minority of people in the conservation community who believe that things should unfold on their own. The theory being, we don't know what we're doing, and we're bound to screw things up.
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