1. Monthly archive

December 2013

Dendro Workshop Organization Meeting

Pinus nigra encroachment at high altitude in the Central Apennines (Italy)

In the central Apennines the treeline is usually composed by Fagus sylvatica L. forests located between 1500-1800 m a.s.l., whereas on some other sites it is replaced by extensive black pine plantations to reduce slope-erosion. On one hand the upward shift of beech forests is a very slow or blocked process, on the other black pine natural expansion has been documented well above its altitudinal range of 800 - 1500 m a.s.l.

LTRR seminar

Dendro & Egypt

The Egyptology Workgroup of the LTRR/Egyptian Expedition will present a series of brief illustrated lectures intended to update colleagues and interested members of the community on our current projects and research. Presentations have three related foci: graduate student thesis research (Egyptology), postdoctoral research (regarding artistic and linguistic trends with important chronological considerations), and collaborative research projects in progress and preparation (dendrochronology/dendroarchaeology).

Dendrochronological Sourcing of Timbers from the Great Houses of Chaco Canyon, New Mexico

The cultural history of Chaco Canyon is characterized by connections with distant landscapes. From utilitarian ceramics to prestige items, goods arrived in Chaco from all directions, and from great distances. Wood beams, necessary for the construction of the Great Houses, are no exception. Strontium isotopes have revealed that spruce and fir timbers were likely carried to Chaco from forested mountains ranges over 50 km away. Ponderosa pine is the predominant architectural timber species at Chaco, and presently grows at many upland areas and mountain ranges surrounding Chaco Canyon.

Quantitative reflectance of modern wildfire charcoals: Implications for the origin of sedimentary charcoal assemblages and inference of past wildfire regime shifts

To what degree are crown fires part of the meta-fire regime of Southwestern ponderosa pine forests over millennial timescales? Fire-scar records and calibrated fire-climate reconstructions suggest the role of crown fires may have been limited over the last 1500 years but high energy alluvial fan records may indicate elevated crown fire activity during severe droughts, peaking during the Mid-Holocene Altithermal and, perhaps, during the Medieval Climate Period.

Tree-ring δ13C tracks flux tower ecosystem productivity estimates in a NE temperate forest

We investigated relationships between tree-ring δ13C and growth, and flux tower estimates of gross primary productivity (GPP) at Harvard Forest from 1992 to 2010.  Seasonal variations of derived photosynthetic isotope discrimination (D13C) and leaf intercellular CO2 concentration (ci) showed significant increasing trends for the dominant deciduous and coniferous species.

The East-West Mediterranean Moisture Gradient: Multi-Decadal Phasing Changes from Mediterranean Tree Rings

Diagnosing the causes of the Mediterranean drying trend now being observed requires a temporal perspective that is not possible through relatively short instrumental climate records. In the simplest case, it is possible to take long tree-ring chronologies from the east-west poles of Mediterranean Basin and evaluate these records for changing patterns of variability since medieval times.

Tree Ring Isotopes (¹³C and ¹⁸O), Intrinsic Water Use Efficiency and Tree Growth of Mexican Forest Species: Trends in the last century.

Tree rings are useful to study changes if forest productivity, human-induced changes in atmospheric composition and physiological responses of trees to climate variability. This presentation will show particular experiences about the response of some Mexican forest species to changes in the chemistry of the atmosphere. We used isotopic measurements (¹³C, ¹⁸O, and ¹⁵N) and dendrochronological techniques to deduce these responses.

Dendroclimatology in Taiwan: from the cloud forest to the tree line

Are you tired of the same old environmental recipes controlling tree growth in your research area? Consider making a Taiwan! It’s easier than you think! Simply choose an island with tall jagged mountains, and place it in the ocean next to a very large continent. Now turn on a fast seasonally stable jet stream just to the north, and bathe the east coast in a massive fast moving warm ocean current. Oh, and make sure it straddles the boundary between the tropics and subtropics.