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]

Formation[edit]

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]

References[edit]

  1. ^ http://www.statesind.com/page/veneer-grading Veneer Grading
  2. ^ http://www.forestry.gov.uk/pdf/fcpg13.pdf/$file/fcpg13.pdf Hazards From Trees
  3. ^ http://oilpeak.web.fc2.com/myenvironmentalism/science/treebark/satake.htm Tree "bark pocket" as pollution time capsule for historical monitoring.
  4. ^ http://vancouverdoorco.com/knots-burls-and-bark-pockets Knots, Burls, and Bark Pockets
  5. ^ http://oilpeak.web.fc2.com/myenvironmentalism/science/treebark/satake.htm Tree "bark pocket" as pollution time capsule for historical monitoring.
  6. ^ https://www.researchgate.net/publication/248404567_Monitoring_of_heavy_metals_in_airborne_particles_by_using_bark_samples_of_japanese_cedar_collected_from_the_metropolitan_region_of_Japan Monitoring of heavy metals in airborne particles by using bark samples of japanese cedar collected from the metropolitan region of Japan.
  7. ^ https://www.researchgate.net/publication/229195228_Utilization_of_bark_pockets_as_time_capsules_of_atmospheric-lead_pollution_in_Norway 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.