From: David A Gabel, ENN
Published November 21, 2012 09:43 AM

Climate Change Complexities in the Northern Hardwood Forests

For residents of the northeastern United States, the abundant woodlands of the northern Appalachians provide an excellent getaway from the congested coasts. These woods are composed typically of hardwood trees like Oak, Ash, Maple, and Birch, changing to evergreen varieties at the higher elevations. Climatologists predict that the northeast will experience warmer and wetter conditions as the climate continues to alter. However, until now, there has been no exhaustive study conducted to see how the climate change will affect the biosphere of the northern hardwoods. A recent study found that this region will be susceptible to major disruptions to forest health, its maple syrup industry, the spread of wildlife diseases and tree pests, as well as changing timber resources.

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The study was conducted at the Hubbard Brook Experimental Forest, located in the White Mountains of New Hampshire. It was led by Dr. Peter Groffman, microbial ecologist at the Cary Institute of Ecosystem Studies. His team looked at more than 50 years of long term data on environmental conditions, concluding that current climate change models do not take account for the surprises that take place in forests.

"Climate change plays out on a stage that is influenced by land-use patterns and ecosystem dynamics," said Groffman. "We found that global climate models omit factors critical to understanding forest response, such as hydrology, soil conditions, and plant-animal interactions."

The most noticeable change is the arrival of spring earlier in the year, and fall later in the year. There has been more rainfall and less snowfall, and the remaining snowpack is melting two weeks earlier than usual. This means that the snowpack melting in no longer in sync with the spring plant growth. This transitional period is critical, because the melting snow also takes away important soil nutrients for plants awakening from their slumber.

Also, the lack of snowpack exposes the soils to more freezing, potentially damaging tree roots. This hits the sugar maples very hard. Not only is the soil frost linked to tree mortality, but warmer winters also reduce the sap yield. On top of that, mild winters also encourage the spread of pests and diseases, which were once held in check by more frigid winter temperatures.

The lack of snow depth allows deer to forage more throughout the forest, damaging young trees and the forest understory. The deer also carry a certain parasite that is lethal to moose, threatening the northern moose populations.

For human activities, climate change in the northern hardwoods will also have a great impact. Ski resorts, which already rely heavily on manmade snow, will be challenged even more with the lack of snowpack. Logging operations will also become more difficult with the loss of snow-packed roads.

"Managing the forests of the future will require moving beyond climate models based on temperature and precipitation, and embracing coordinated long-term studies that account for real-world complexities," concludes Groffman. "These studies can be scaled up, to give a more accurate big picture of climate change challenges—while also providing more realistic approaches for tackling problems at the regional scale."

The study has been published in the journal BioScience

New Hampshire White Mountains image via Shutterstock

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