نتایج جستجو برای: dendrochronology

تعداد نتایج: 264  

2013
Jian-Guo Huang Kenneth J. Stadt Andria Dawson Philip G. Comeau

We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA), the sum of stem diameter at brea...

2012
Philip J. Aston

Radioactive decay of an unstable isotope is widely believed to be exponential. This view is supported by experiments on rapidly decaying isotopes but is more difficult to verify for slowly decaying isotopes. The decay of 14C can be calibrated over a period of 12,550 years by comparing radiocarbon dates with dates obtained from dendrochronology. It is well known that this approach shows that rad...

2004

Northern and high-latitude alpine treelines are generally thought to be limited by available warmth. Most studies of tree-growth–climate interaction at treeline as well as climate reconstructions using dendrochronology report positive growth response of treeline trees to warmer temperatures. However, population-wide responses of treeline trees to climate remain largely unexamined. We systematic...

Journal: :Tree physiology 2015
Marco Carrer Georg von Arx Daniele Castagneri Giai Petit

Trees are among the best natural archives of past environmental information. Xylem anatomy preserves information related to tree allometry and ecophysiological performance, which is not available from the more customary ring-width or wood-density proxy parameters. Recent technological advances make tree-ring anatomy very attractive because time frames of many centuries can now be covered. This ...

2001
Veli Mäkinen

Edit distance is a powerful measure of similarity in string matching, measuring the minimum amount of insertions, deletions, and substitutions to convert a string into another string. This measure is often contrasted with time warping in speech processing, that measures how close two trajectories are by allowing compression and expansion operations on time scale. Time warping can be easily gene...

Journal: :Rapid communications in mass spectrometry : RCM 2016
M Isaac-Renton L Schneider K Treydte

RATIONALE Isotope analysis of wood is an important tool in dendrochronology and ecophysiology. Prior to mass spectrometry analysis, wood must be homogenized, and a convenient method involves a ball mill capable of milling samples directly in sample tubes. However, sample-tube plastic can contaminate wood during milling, which could lead to biological misinterpretations. METHODS We tested poss...

2014
Monik G Richard Colin P Laroque Thomas B Herman

This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 ...

2017
E. F. Baxter B. Dragovic

Garnet could be the ultimate petrochronometer. Not only can you date it directly (with an accuracy and precision that may surprise some), but it is also a common rock-forming and porphyroblast-forming mineral, with wide ranging—yet thermodynamically well understood— solid solution that provides direct and quantitative petrologic context. While accessory phase petrochronology is based largely up...

Journal: :Ecology 2008
Franco Biondi Fares Qeadan

Paleorecords provide information on past environmental variability, and help define ecological reference conditions by means of changes in their characteristics (accumulation rate, geochemical composition, density, etc.). A measure of temporal dissimilarity, which has traditionally been used in dendrochronology and is called "mean sensitivity," only focuses on first-order time-series lags. In t...

2004
Benoît St-Onge Udayalakshmi Vepakomma

Research on lidar change detection is at its inception with a few studies to monitor coastal erosion and almost none for forest dynamics. While long-term installations and dendrochronology are cost and time intensive, this study highlights potential use of multi-temporal medium density lidar data for studying forest dynamics in a spatially explicit manner, particularly in identifying new canopy...

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