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Climate Change Threatens Unique West Coast Forest Region

May 09 2018 | 03:09:57
The Klamath is a unique region in Northern California and Southwest Oregon. In addition to being a haven for biodiversity— hosting plants that only live in its mountainous landscape and 29 different species of conifers—it also stores carbon in its diverse array of tall trees.But those iconic trees, and their carbon-storing power, are under threat from climate change, a study published Monday in Scientific Reports found.Using a landscape simulation model, researchers at Harvard University, Portland State University and the Smithsonian Conservation Biology Institute looked at five different potential climate change scenarios and found that, even under a continuation of current climate conditions, up to one third of the conifer landscape could be replaced by less-carbon-absorbing shrubs and hardwood this century.This change in vegetation is largely driven by the impact of climate change on wildfires. Conifers are adapted to withstand fires, but climate change reduces the time between fires, called the "fire rotation period," and increases their size and severity.Researchers found that every climate change scenario also increased drought in the summers, which made it harder for all plant species to re-establish themselves after fires. This effect was worse for conifers, whose ability to regrow decreased from 26 to 39 percent depending on the climate scenario, while shrubs declined by 7 to 20 percent."If the fire-free interval is too short or if the growing conditions are too dry, the shrubs can persist indefinitely, and the iconic conifers are squeezed out," study co-author and Harvard senior ecologist Jonathan Thompson said in a Harvard press release published by Phys.org.While the conifer-dominated area was reduced even under current climate conditions, that area further decreased in the climate change scenarios.