Site icon Conservation news

Scientists warn of global warming threat to temperate rainforests


Redwoods in Big Basin State Park, California. Photo by Rhett A. Butler.

Redwoods in Big Basin State Park, California. Photo by Rhett A. Butler.

If you Google “rainforest,” you’re almost assured to get a page of search results mostly about the tropics. Yet, another kind of rainforest also exists: temperate rainforests. Far less expansive than the tropical kind, temperate rainforests occur in isolated patches and strips around the world – from the coasts of western North America and eastern Siberia, to throughout much of New Zealand and Tasmania. In a new study published recently in Earth Systems and Environmental Sciences, researchers warn that temperate rainforests may be in for big changes in the face of global warming, and they recommend reducing greenhouse gas emissions before it’s too late.



Definitions vary per country as to what exactly defines a temperate rainforest, but generally, they comprise dense stands of forest with canopies covering most of the sky, occur in areas with high annual rates of rainfall, and are composed mainly of tree species that don’t need fire to reproduce. They are a highly biodiverse biome, supporting many different species – including many endemics. Research indicates 45 percent of the vertebrates in Chile’s temperate rainforests, for example, are found nowhere else on earth.



Human impacts have long affected temperate rainforests. Most of Europe’s were logged long ago, Chile’s declined significantly in the last century, and few redwoods remain on the U.S. west coast compared to the extensive forests that existed before Europeans entered the scene. Now, after logging pressures have somewhat subsided and protected areas have been established to preserve the remnants that remained, the world’s temperate rainforests are facing a new threat: global warming.



Atmospheric greenhouse gas levels are ramping up as fossil fuels are burned, trees are cut down, and methane leaches from the sea, the arctic, cows, and palm oil production plants (among many other sources). Carbon dioxide, the primary culprit, now hovers at 400 parts per million (ppm), a level not recorded at any other point in human history. These high levels of greenhouse gases are trapping heat energy in the atmosphere, which, in turn, is changing climates around the world.



The authors of the study used global climate models to predict what will happen to temperature and precipitation patterns along a 2,200-mile stretch of coastline in western North America if greenhouse gases continue to rise. They found coast redwoods may lose 23 percent of their current distribution, the range of Alaska yellow-cedar could shrink 21 percent, and rainforest communities in Oregon and northern California may contract. They also found most of the protected areas in the study region will not be immune from climatic changes.






Global Forest Watch shows extensive forest loss in the coastal forests of northern California and southern Oregon. Satellite imagery shows significant tree die-off in King’s Range National Conservation Area. In total, the conservation area lost more than 13 percent of its tree cover from 2001 through 2012. Click to enlarge.



However, there were a couple bits of “good” news. Because glaciers are melting, new real estate may open up for some northern temperate rainforests. And the authors say climatic conditions in Alaska may remain hospitable for rainforests.



“In the Pacific Northwest, the glass is half empty as the climate may no longer support rainforest communities like coast redwood, while on the Tongass National Forest in southeast Alaska the glass is half full as cooler, moister conditions may prevail as a refuge for rainforest communities that can migrate in time,” said lead author Dominick A. DellaSala, Chief Scientists of the Oregon-based Geos Institute.



The authors caution that as global warming restricts temperate rainforests to their northern reaches, protecting those areas from human disturbance will become all the more important.



“We know from studies around the world that if rainforests are stressed by the combined impacts of climate change and land-disturbances, there is little hope in maintaining their ecosystem benefits for people or wildlife over the long term,” said Patric Brandt a global warming researcher with the Research Program on Climate Change, Agriculture, and Food Security (CCAFS).



The researchers urge reductions in greenhouse gas emissions and protecting rainforests from logging and development. They write that areas of protection focus should include north-facing slopes and older forests – which will be less likely to be affected by a changing climate – and specifically underline the importance of preserving Tongass National Forest in Alaska, which they say may end up being the last best refuge for temperate rainforest ecosystems.



“The Tongass is our best hope for holding onto the verdant rainforest web-of-life that has sustained native peoples for millennia and supported the subsistence economy of southeast Alaska,” DellaSala said, “but only if the old-growth forests are protected for their climate and wildlife benefits.”







Citations:





}}


Related articles


When forests aren’t really forests: the high cost of Chile’s tree plantations

(08/18/2014) At first glance, the statistics tell a hopeful story: Chile’s forests are expanding. On the ground, however, a different scene plays out: monocultures have replaced diverse natural forests while Mapuche native protesters burn pine plantations, blockade roads and destroy logging equipment. At the crux of these two starkly contrasting narratives is the definition of a single word: “forest.”

World Heritage Committee takes ten minutes to reject Australia’s bid to strip forests of protection

(06/23/2014) The UNESCO World Heritage Committee today unanimously rejected a controversial proposal by the Australian government to strip 74,000 hectares of temperate rainforest from a World Heritage Site in Tasmania. In an embarrassing setback for the Australia government, it took the committee less than ten minutes to unanimously reject the proposal.

Australia proposes removing old-growth forests from World Heritage Site

(02/03/2014) Last year, after decades of fighting, environmentalists and the forestry industry reached a landmark agreement that added 170,000 hectares of old-growth forest in Tasmania as a part of a World Heritage Site. But less than a year later and that so-called peace agreement is in danger of unraveling. The new Australian government, under Prime Minister Tony Abbott, is going ahead with removing 74,000 hectares (43 percent) from the World Heritage site.

Decades-long fight leads to old-growth forest protection in Tasmania

(06/25/2013) Almost 200,000 hectares of Tasmania’s old growth forest have been world heritage listed, bringing hope that a three-decade fight between environmentalists, politicians and loggers is over. The World Heritage Committee has extended the heritage listed boundary of the Tasmanian Wilderness World Heritage Area by more than 170,000 hectares after accepting a proposal from the Australian government which will give the areas the highest level of environmental protection in the world.

Legislation leaves future of world’s largest temperate rainforest up in the air

(11/27/2012) Although unlikely to pass anytime in the near term, recurring legislation that would hand over 80,000 acres of the Tongass Rainforest to a Native-owned logging corporation has put local communities on guard in Southeast Alaska. “The legislation privatizes a public resource. It takes land that belongs to all of us, and that all of us have a say in the use and management of, and it gives that land to a private for-profit corporation,” Andrew Thoms, Executive Director of the Sitka Conservation Society, told mongabay.com in a recent interview.

Future of the Tongass forest lies in salmon, not clear-cut logging

(10/25/2012) The Parnell administration’s Timber Task Force recently unveiled a proposal to carve out two million acres of the Tongass National Forest for clear-cut logging under a state-managed “logging trust.” The stated goal is to revive Southeast Alaska’s timber industry that collapsed two decades ago amid changing market conditions, logging cutbacks and evolving public opinion about timber harvesting on national forests.

Exit mobile version