Science of dating trees
The great houses, once covered by timbered roofs and ceilings made from thousands of large pine beams, took nearly three centuries to build.Scientists have explored Chaco Canyon for more than 100 years, making it one of the best-known archaeological sites in the world. Lekson, “Its ruins represent a decisive time and place in the history of ‘Anasazi,’ or Ancestral Pueblo peoples.”* Who these ancestral peoples were and what they accomplished has been the subject of much study, including research sponsored by Western National Parks Association.Results of carbon-14 dating are reported in radiocarbon years, and calibration is needed to convert radiocarbon years into calendar years.Uncalibrated radiocarbon measurements are usually reported in years BP where 0 (zero) BP is defined as AD 1950.Our results indicate that dissolved organic carbon and phosphorus fluxes increase temporarily downstream after development, and that silt management measures may be an effective mitigation measure Bruce Osborne – University College Dublin“Impact of Drying and Re-Wetting Events on Greenhouse Gas Emissions in Forests and Grasslands in a Drier Future: The ‘Birch Effect’ Revisited” It is well known that short rainfall/re-wetting events can induce a pulse of mineralisation and associated emissions of carbon dioxide, often termed the ‘Birch-Effect’, after its discoverer, Harry Birch.Although this is believed to have a potentially significant impact on annual greenhouse gas budgets, this has rarely been quantified and the focus has generally been on its significance in arid or semi-arid ecosystems.It is also worth noting that the half-life used in carbon dating calculations is 5568 years, the value worked out by chemist Willard Libby, and not the more accurate value of 5730 years, which is known as the Cambridge half-life.Although it is less accurate, the Libby half-life was retained to avoid inconsistencies or errors when comparing carbon-14 test results that were produced before and after the Cambridge half-life was derived.
The rate of decay of radioactive substances is one way to determine the age of an object, but attempts using this method to date Chaco Canyon’s Great Houses produced vague results.
Dendrochronology is the study of climate change as recorded by tree growth rings.
Each year, trees add a layer of growth between the older wood and the bark.
28th April 2017 - CANCELLEDJulia Urquhart – Imperial College London“Are the public concerned about tree health risks?
A Q Methodology study of lay perceptions of Ash dieback and Oak processionary moth” 23rd May 2017 CANCELLEDJohn Healey/Andy Smith – Bangor University “Multi-Land: Enhancing Productivity and Ecosystem Service Resilience in Multifunctional Landscapes”.