Bark pocket

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A cross-section of a Scots Pine (Pinus sylvestris L.) containing a bark pocket. The two trunks have been inosculated.

Bark pockets are patches or inclusions of bark partially or fully embedded in the wood of a tree. They can also be used as biomonitors. Bark pockets are considered a nuisance in the lumber industry because they are considered a defect, and lower the grade of the wood.[1] Bark pockets can also weaken tree forks, and can result in damage to the junction under stress.[2]


A cut limb in the process of encapsulation.
A sign ingrown into a tree trunk.

Bark pockets can be formed by inosculation, formation of a tree fork, encapsulation of a branch, joining together of an uneven trunk, or encapsulation of another object.[3][4] During inosculation, the bark trapped between the two joining trunk becomes surrounded with wood once the trunks fuse. The resulting bark pocket formed during inosculation or in a tree fork is referred to as included bark.

When a branch is encapsulated, the outer bark on the branch may remain inside the wood of the tree, as the trunk widens and grows around the branch.

As biomonitors[edit]

Bark pockets can be used as an indicator of air pollutants during which the time they formed.[5] They can be used to monitor heavy metals such as lead and copper, as dust or other matter deposited on the bark at the time of formation is still present.[6][7] One study analysed the amount of polycyclic aromatic hydrocarbons (PAHs) present in bark pockets as a historical record of air quality, possible due to the interaction between PAHs and lipids in the bark.[8]


  1. ^ Veneer Grading
  2. ^$file/fcpg13.pdf Hazards From Trees
  3. ^ Tree "bark pocket" as pollution time capsule for historical monitoring.
  4. ^ Knots, Burls, and Bark Pockets
  5. ^ Tree "bark pocket" as pollution time capsule for historical monitoring.
  6. ^ Monitoring of heavy metals in airborne particles by using bark samples of japanese cedar collected from the metropolitan region of Japan.
  7. ^ Utilization of bark pockets as time capsules of atmospheric-lead pollution in Norway.
  8. ^ Wang, Qiuquan. "Historical Records of Airborne Polycyclic Aromatic Hydrocarbons by Analyzing Dated Corks of the Bark Pocket in a Longpetiole Beech Tree". Environmental Science & Technology. 38: 4739–4744. doi:10.1021/es049685j.