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The goal of this project is to provide real-time tree water content and other data from a mixed boreal forest stand near Fairbanks, Alaska, to help local residents decide when the optimal time is to harvest firewood. We also aim to provide drying schedules for trees harvested at different times of the year and different water contents at harvest time.

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The water content of a tree (or how much water a living tree is holding in its trunk) changes over the year and differs by species. The main boreal tree species this project focuses on are those that are often harvested by local people for firewood, including Birch, Aspen, and White Spruce. This project focuses on areas without permafrost, which is where these trees grow. Winters are cold in Interior Alaska, and many of us burn wood to stay warm.

Since 2016, research carried out by the Forest Soils Lab at UAF has focused on understanding boreal tree water use and growth in places with and without permafrost. By "boreal tree water use use", we mean understanding when, how much, and under what environmental conditions the trees take up water from the soil, store it in their trunks, and lose it to the air through their leaves.

 Water enters the soil from rainfall and snowmelt, and trees take up this water through their roots. They store the water in their trunks and use it when they photosynthesize (take up carbon dioxide from the air) and transpire (lose water vapor to the air). Tree water content changes over the year because the they are responding to changes in the environment. For example, they take up snowmelt water in the spring, store it in their trunks, and use it all summer, supplementing it with water from rainfall. So, a good snowpack is important for boreal trees because they use their stored trunk water when there is not enough rainfall to sustain them.


What does this have to do with harvesting firewood?

Harvesting firewood when the trees are are their lowest water content during the year can reduce the drying time of the woodpile. This means the wood reaches 20% water content a little faster, and you can burn it sooner, particularly if you split and stack it once you get it home. Also, wet wood is heavy, so you could save wear-and-tear on you back, your truck, or your four-wheeler if you harvest when the trees are drier. Watching the tree water content change over the year will help you decide when to harvest your firewood.

We are also producing drying schedules for trees we harvested at different times of year (and, therefore, different water contents). We will share these data with you once the drying is done. Click here to read about our drying experiment.

Other data collected at our site are: air temperature, relative humidity, wind speed and direction, incoming solar radiation, soil temperature and water content down to 20 inches or 50 cm.

optimal time to harvest
Mixed boreal forest stand
other data
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This project is funded by the U.S. Department of Agriculture McIntire-Stennis program (project # ALK19-08) which supports relevant forestry research that meets the needs of the public and State. 

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