Dendroecology and age dating

ETH Zurich - Course Catalogue

dendroecology and age dating

Abstract, The course dendroecology offers theoretical and practical aspects The students learn various methods to date tree rings and they understand Age and size structures, forest dynamics (regeneration, growth, competition, mortality). 9 Dendroecology Dendroecology uses dated tree rings to study ecological events such as Exact age dating is important to provide a complete picture of the. Example: dating the inside rings of trees on moraines to establish the from a statistically derived equation that relates tree growth over time to tree age. Usually.

The largest mountain-range fire scar network in North America: We are expanding the network using a spatially systematic sampling approach with a main goal of reconstructing area burned since CE over aacre area.

Quaternary paleoenvironments - methods

Colored symbols represent individual fire-scarred trees from different collections over 30 years. The large spatial foot print of fire in the Jemez Mountains in the yearas recorded by tree-ring fire scars.

The circles are individual trees that were scarred inwith the colors indicating the fire-scar position, or fire seasonality. The grey x's indicate trees that were not scarred.

New Mexico Dendroecology Lab

The histogram in the upper right indicates the relative elevation of the fire-scarred trees. Dual-season climate reconstructions and fire-climate relationships in the southwestern United States Working in collaboration with Connie Woodhouse and Tom Swetnam from the University of Arizona on an NSF Macrosystems project, we are quantifying the effects of winter and summer monsoon moisture on fire occurrence and fire seasonality in two regions of the Southwest - the Jemez Mountains of northern New Mexico and the Sky Islands of southern Arizona.

Variability in winter moisture is a primary driver of large spring and early-summer fire occurrence, but weak or failed monsoons in the past e. Large mid-summer fires are unprecedented in the last century in the Southwest.

dendroecology and age dating

In addition, we found that extended droughts historically did not promote continued fire occurrence, due to fuel limitations. This suggests that although fuels are not currently limiting for fire occurrence in dry conifer forests due to a century of fire suppressionthese forests will likely return to being fuel limited in future decades. Prior wet conditions followed by drought in the cool- and monsoon-seasons affect fire occurrence and fire seasonality e.

Abundant old trees on the Navajo Nation provide centuries-long records to study ecosystem responses to disturbances and climate variability.

dendroecology and age dating

Fire history, old-growth forests, and climate change on the Navajo Nation Working in collaboration with Chris Guiterman University of ArizonaNavajo Forestry, and the BIA, we are using tree rings to identify and assess the vulnerabilities of Navajo forests to climate change.

The age of a tree can be determined by counting the tree rings, and if the year of the death of the tree is known, the year in which each ring was formed can be dated in calendar years. If you have a living tree with tree rings and you analyse the tree rings, you can determine very recent events like climate variations or geomorphological events.

If you want to date events that occured many hundreds or thousand years ago, you have to establish extended tree-ring chronologies. This is only possible, if you have tree-ring series from a lot of trees with differnt ages from the same region and the same tree species.

Tropical Dendrochronology

The following figure shows, how to construct long tree ring-chronologies with the so called cross dating method. If the inner rings of the living trees of known ages match with the outer rings of beams from an old building, the rings of the beams of unknown age are dated. The chronology is now extended further back in time.

With this chronology you can date wood found in glacier forefields in the same way. Finally, wood that comes from peatbogs can be dated using the chronology constructed from the other sites.

Common methods of analysing tree rings Skeleton plot This method of tree-ring analyses was used from dendrochronologist before any actual measurements are made. The width of each ring is compared with the precedent rings.