Fire scar analysis, dendrochronology, forest history
Overview description: Measuring the age of trees: The trees in the Boreal forest grow during the summer months and stop growing during the winter months. In the spring, trees grow most quickly because of all the moisture coming from melting winter snows and warm early summer temperatures. Trees grow most quickly at this time. In the Fall, trees grow more slowly because of little moisture and cool evening temperatures. During the winter, the water freezes and trees do not grow at all. The early season growth shows as a larger, whiter band of cells in the rings of the tree. The later season growth shows as a darker band of smaller cells. As the tree grows a layer of wood around the trunk, it also grows in height. A shoot or leader grows from the top of the tree adding new height to the tree. The seasonal rings tell the age of the tree, how well the tree grew in each year and provides a record of the conditions that result in tree growth. Method: Samples of tree growth are taken in two ways. A tree “cookie” is a section cut across the trunk. This gives us a clear picture of the trees growth around the entire tree, but the tree is killed when taking this type of sample. We can take a sample through the tree by using an increment bore to drill a sample from the outside edge to the middle of the tree. We try to take this sample as close to the base of the tree as possible so we do not miss many years of growth. When we drill a core sample, we glue the sample into a block of wood, sand it smooth then count the year of each rings beginning at the outside ring as the year we took the sample. You should be able to date each growth ring starting with the year the sample was taken. Date the years in which the tree has the poorest growth (the ring is the smallest) and plot these dates on the “skeleton plot”. Use lines to plot the date with the smallest ring having the longest line. (Hint, begin counting down by year starting at the outside edge of the tree, starting with the year the sample was taken.) any events will happen In the life of a tree which may be recorded in its wood either at the ring level or as more obvious scars or deformations in the tree itself. Frost, insect epidemics, and droughts are a few examples of events that will be recorded in the rings at the precise year in which they occurred. Fire, and other cambium- destroying accidents will stop the production of wood where the cambium was damaged, leaving a scar which might eventually close with time. This scar. can also be dated. More positive events in the life of a tree will usually be recorded as a wide ring, pointing to an increase in growth rate; for example, an opening in the forest canopy following the death of a tree will allow the understory saplings to grow better due to an increase in the availability of light and water.
Community interest or concern
Duration of study and numbers involved Dendrochronology studies have been conducted for more that 20 years by ES 11 students.
Protocols followed and resources. Standard methods for creating skelton plots and master chronologies. See Coorecorder.
Contact person and more detailed information Chris Marion, (Yukon dendrochonoligist), Shawn Frances, Bob Sharp, Alain Dalaire and Kevin O’Connor
Overview description: Measuring the age of trees: The trees in the Boreal forest grow during the summer months and stop growing during the winter months. In the spring, trees grow most quickly because of all the moisture coming from melting winter snows and warm early summer temperatures. Trees grow most quickly at this time. In the Fall, trees grow more slowly because of little moisture and cool evening temperatures. During the winter, the water freezes and trees do not grow at all. The early season growth shows as a larger, whiter band of cells in the rings of the tree. The later season growth shows as a darker band of smaller cells. As the tree grows a layer of wood around the trunk, it also grows in height. A shoot or leader grows from the top of the tree adding new height to the tree. The seasonal rings tell the age of the tree, how well the tree grew in each year and provides a record of the conditions that result in tree growth. Method: Samples of tree growth are taken in two ways. A tree “cookie” is a section cut across the trunk. This gives us a clear picture of the trees growth around the entire tree, but the tree is killed when taking this type of sample. We can take a sample through the tree by using an increment bore to drill a sample from the outside edge to the middle of the tree. We try to take this sample as close to the base of the tree as possible so we do not miss many years of growth. When we drill a core sample, we glue the sample into a block of wood, sand it smooth then count the year of each rings beginning at the outside ring as the year we took the sample. You should be able to date each growth ring starting with the year the sample was taken. Date the years in which the tree has the poorest growth (the ring is the smallest) and plot these dates on the “skeleton plot”. Use lines to plot the date with the smallest ring having the longest line. (Hint, begin counting down by year starting at the outside edge of the tree, starting with the year the sample was taken.) any events will happen In the life of a tree which may be recorded in its wood either at the ring level or as more obvious scars or deformations in the tree itself. Frost, insect epidemics, and droughts are a few examples of events that will be recorded in the rings at the precise year in which they occurred. Fire, and other cambium- destroying accidents will stop the production of wood where the cambium was damaged, leaving a scar which might eventually close with time. This scar. can also be dated. More positive events in the life of a tree will usually be recorded as a wide ring, pointing to an increase in growth rate; for example, an opening in the forest canopy following the death of a tree will allow the understory saplings to grow better due to an increase in the availability of light and water.
Community interest or concern
Duration of study and numbers involved Dendrochronology studies have been conducted for more that 20 years by ES 11 students.
Protocols followed and resources. Standard methods for creating skelton plots and master chronologies. See Coorecorder.
Contact person and more detailed information Chris Marion, (Yukon dendrochonoligist), Shawn Frances, Bob Sharp, Alain Dalaire and Kevin O’Connor