Study: Warming future means more fire, fewer trees in western biodiversity hotspot

Study: Warming future means more fire, fewer trees in western biodiversity hotspot
The 2002 Biscuit Fire reburns the area of the 1987 Silver fire. Credit: Thomas Link

Increasing fires and summer droughts caused by global warming are drastically changing a globally unique bio-region of northern California and southwestern Oregon, according to new research funded by the National Science Foundation and published today in the journal Scientific Reports.

The Klamath, as the region is known, is a pocket of the Pacific Northwest known for its rugged mountains, wild rivers, and Mediterranean climate. The area is a hotspot of biological diversity and a storehouse of carbon—home to an astonishing 29 species of conifers and many rare plants that exist only in this small region of the world.

These forests are well-adapted to wildfire, but more severe fires—like the region's record-breaking Biscuit Fire of 2002, which burned 500,000 acres—have a greater impact on the area's biodiversity. As plants recover, the iconic conifers must compete with a host of more -resilient shrubs and other species, which sweep through the understory and begin to grow quickly.

Jonathan Thompson, Senior Ecologist at the Harvard Forest and co-author on the study, explains, "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."

The research team, composed of scientists from the Harvard Forest, Smithsonian Conservation Biology Institute, and Portland State University, simulated the next 100 years of forest dynamics in the Klamath according to five potential climate futures. One climate future was simply a continuation of recent climate trends (1949-2010); the others projected shifts, from conservative to extreme, in warming and seasonal precipitation.

Study: Warming future means more fire, fewer trees in western biodiversity hotspot
The Bear Fire 1994 shows shrubs in the understory. Credit: Alan Tepley

Every scenario led to increased summer drought, which reduced plant survival overall. Climate change also increased the size, intensity, and frequency of wildfires, which can kill even the largest trees, reduce the survival rate of new tree seedlings, and pave the way for growth of those low-growing shrubs, which in turn create more fuel for future fires. Because of this shift in the plant population, the warmest climate simulations created fires that would break all records of burned area size for the region.

The most surprising result? Shrubs swept into the forest even in the absence of intensified climate change. Even with a continuation of recent climate, the region can expect at least 1/3 of the iconic cone-bearing trees to replaced by shrubs over the coming century.

The researchers believe that this is due in part to legacy of fire suppression that initially gave the conifers an edge over shrubs during the 20th century.

Looking to the future, Thompson adds, "As the continues to warm, big severe wildfires will be more frequent, and the dry conditions that follow will increasingly favor shrubs over conifers. The combination will mean less of the that make the Klamath so distinct."


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Scientists examine impact of high-severity fires on conifer forests

Journal information: Scientific Reports

Provided by Harvard University
Citation: Study: Warming future means more fire, fewer trees in western biodiversity hotspot (2018, April 30) retrieved 23 July 2019 from https://phys.org/news/2018-04-future-trees-western-biodiversity-hotspot.html
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Apr 30, 2018
They will have to plant their current bio-diversity further north if its to survive; just as it would migrate naturally in a warming climate.
Species that survive drought and fires ( the canary islands are full of them) must replace them as a new bio diversity.

Apr 30, 2018
More PATHOLOGICAL LIES from the AGW Cult and their PATHOLOGICAL "science", just to keep their ignorant and hungry Chicken Littles satiated.

Here's the truth. https://www.fs.fe...ds33.JPG

Apr 30, 2018
Try to keep up, antigoracle. Your graph shows exactly what they say in the article, "...this is due in part to legacy of fire suppression that initially gave the conifers an edge over shrubs during the 20th century." The issue is the severity of the fires that do occur.

May 12, 2018
Or they can stick their heads in the sand and pretend that the vested commercial interests in destroying the environment for gain will go away. Then their biodiversity can survive on their fantasy land.
Every time we dump plastic in the trash, jet off on holiday or eat our palm oil products we agree with and support those commercial interests.

Anyone wanting to be deep frozen and revived in 1000 years should anticipate facing criminal charges when revived.

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