Tree-Ring Anomalies

Introduction In our region we have 1 growing period.

Each ring corresponds to a well-defined year of formation. Cambial activity is h/w not continuous in space or in time

Growth anomalies can be observed. Not talked about in this lecture: Blue Rings: stains blue instead of red, means there was no lignification due to climatic conditions. False Rings AKA density fluctuation. Looks like a complete growth zone with well-marked boundaries. Can only be identified by cross dating. False rings occur when there is a temporary stopping of cambial activity during environmental stress (low Auxin). Most often associated with drought. During drought tree growth stops – late wood starts forming (w/ thick secondary walls & small lumens), environmental conditions go back to normal and tree growth continues again. Problem: over estimation of tree age and dating error. **1947 & 1979 – false ring years in Jack Pine from Manitoba. 1933 – thin pale late wood. Hoffer & Tardif – aimed to quantify how well defined false rings are. They found that the more snow on the ground the higher proportion of false rings. They quantify how well defined false rings are in comparison to real latewood cells. Missing Rings (Absent) Incomplete (Discontinuous, Partial, Locally Absent Rings) Missing rings usually related to cambium dying at a given point. Or the cambium is dormant at one point. Delayed arrival or deficiency of growth regulators – if you hit a tree with a baseball bat you may disturb the cambium blocking growth regulators from moving down the entire tree length. Problems: underestimation of tree age and dating error. Found in: suppressed/old trees, heavily defoliated trees senescing branches and stems from tree with one-sided crown. Usually more frequent in cold/dry regions and at the base of the tree (growth regulators don’t make it to the base of the tree). Missing or partially absent rings are identified by careful cross-dating techniques. Discontinuous Ring – Two-latewood rings merge together into one. Depending on where you core you can have an extra or a missing ring.

Frost Rings Usually there is some normal early wood, then subfreezing temperature occur and cause ray cells to bend, and tracheids collapse and become crushed. Light Rings – White Rings Latewood zone with thin walled cells. Light rings in deciduous Larix. In conifers light rings are also called pale late wood. Have two main causes: Biotic origin (insect defoliation), or abiotic origin (climatic event). Larch get defoliated by Larch Sawfly – they need to produce new leaves – instead of using their stored sugar to form latewood they allocate it to produce new foliage. White rings in diffuse porous species. These trees sacrifice the mechanical integrity of the entire ring to reproduce leaves after a defoliation event. Biotic Origin: Model: low precipitation causes tree stress leads to high nitrogen in foliage which helps the insects reproduction, increased insect population causes increased defoliation and a narrow light ring is formed. Larch Sawfly was introduced around 1885-1900. This is postulated because if you go back into the 1700’s you do not see light/white rings/pale latewood. Thus Sawfly is not a native species. White rings have thin/absent secondary walls. Normal fibers/tracheids have much thicker secondary walls. May or may not be synchronous among all trees – depends on the dynamics of the insect. Climatic Origin: Should be synchronous among all trees in a stand. He observed light fall wood in many trees. Some of the trees were ~240 km apart. In a study – 1815- 1817 (volcanic eruption) 1900-2000 – there was high relative frequency of light rings.

There must be a common event that is causing these noticed patterns. Composite Map of 2004 Anomaly

Warm on the west coast, and cold towards central Canada. When we look at temp data we see that everywhere we have a light ring corresponds to a cool summer – 2004, and other dates.

People near the tree line (where growth season is short) were able to find light rings that correspond to major volcanic events. Are White EARLYwood rings seen in conifers?

Sometimes

Other Anomalies Traumatic Resin Ducts: can be formed by woodpeckers. In Porous Trees: in one ring for whatever reason they do not produce ANY vessels – we do not know why – it is a very rare event. A Pith Fleck: a little cavity/wound made by insects. In Ring Porous Species: In a certain species they make two rows of vessels in their early wood, sometimes this gets messed up and they only produce 1 row of vessels, or 5 row of vessels. Flood Rings: in ring porous species – Observed fall floods/flash flood systems – usually after the growing season – there is sprout of growth new leaves/new vessels. Ethylene builds up in trees and the vessels get smaller. Wounding