Sessions in which Michael Stambaugh participates
Tuesday 28 June, 2022
The most frequent fire regimes in the world exist in environments that balance maximum fuel production and maximum fire occurrence potential. Often these environments exist at low elevations, correspond to subtropical climates, and have long growing seasons that push the limits of reliable annual ring formation. Historical fire regimes in ecosystems with these conditions are poorly studied. We investigated fire scarring in such conditions in southwestern Georgia, USA and successfully const...
Wednesday 29 June, 2022
Session reescheduled from June 28th to June 29th
The most frequent fire regimes in the world exist in environments that balance maximum fuel production and maximum fire occurrence potential. Often these environments exist at low elevations, correspond to subtropical climates, and have long growing seasons that push the limits of reliable annual ring formation. Historical fire regimes in ecosystems with these conditions are poorly studied. We investigated fire scarring in such conditions in southwestern Georgia, USA and successfully const...
Sessions in which Michael Stambaugh attends
Monday 27 June, 2022
Free, in person and onlineWe will hold a practical, skills-based workshop introducing openDendro -- an open-source framework of the base analytic software tools used in dendrochronology in both the R and Python programming languages. openDendro is a new unified set of tree-ring analysis tools in open-source environments that provides the necessary baseline for dendro...
Meet colleagues and friends in an informal settingFree drinks for all!
Tuesday 28 June, 2022
Climate change poses an existential threat to trees, given our understanding of the importance of climate in shaping their geographic distributions. Climate envelope models are commonly used to predict how species will respond to climate change. These models give rise to the leading edge-trailing edge paradigm for range change: populations at the cool edge of a species’ distribution are expected to benefit from warming, whereas populations at the warm edge are expected to decline. We chall...
Maritime forests are extremely important for coastal protection as they buffer storm surge and wind, conserve nutrients, and store groundwater. They grow several 100 meters behind primary beach dunes or along intertidal marsh-forest ecotones and within range of salt spray, near shoreline estuaries, where they support large amounts of biodiversity and migratory birds. Trees in these forests typically handle small concentrations of salt spray, strong winds, and slight flooding, but prolonged...
Evidence of volcanic cooling and its human impacts has been described for various regions of the globe over the past several centuries to millennia, derived from paleoclimatic and historical data. Due to its remote location, detailed accounts of such impacts over Northwestern North America (NWNA) are still quite limited. Here we use a newly expanded tree-ring density network (derived from blue intensity as well as maximum latewood density parameters) to assess the climatic and human impact...
Forest disturbances and tree growth are major drivers of dynamics and long-term carbon storage in forests. Combining forest inventory data and tree-ring analysis allows for a retrospective estimate of aboveground forest biomass (AGB) and disturbance dynamics at decadal to centennial scales, both being directly related to net primary productivity (NPP). We used this combined approach to estimate precisely-dated ages of aboveground carbon in over 20 temperate old-growth forests in Western Eu...
Growing concerns about vulnerabilities of boreal forests to climate change and disturbances warrants additional information about their impacts on the growth of dominant tree species in different surrounding environments. To address these concerns, we investigated how the surrounding environment influences the growth of such trees and their responses to climate and insect epidemics in stands of eastern Canada’s boreal forest. For this, we focused on 96 black spruce, jack pine, and tremblin...
Indigenous land stewardship and mixed-severity fire regimes both encourage landscape heterogeneity and the relationship between them is an emerging area of research. To contribute to this exploration, we reconstructed the historical fire regime of Ne Sextsine, a 6000-ha dry, Douglas-fir-dominated forest in the traditional territory of the T’exelc (Williams Lake First Nation) in British Columbia. Between 1550 and 1982 CE, we found median fire intervals of 15 years at the plot-level and 4 ye...
Wednesday 29 June, 2022
Dendrochronology is considered one the most precise of all the scientific dating techniques. However, it requires long sequences of tree rings and a master record for both the species and region in question. At the University of Groningen, we have been pioneering a new approach to dating that combines the precision of dendrochronology with the versatility of radiocarbon dating. It relies on the detection of spikes in the annual radiocarbon record, thought to b...
The main objective of this study was to develop a universal response function to integrate climatic and genetic effects on the diameter growth of 13 eastern white pine (Pinus strobus L.) provenances planted at seven test sites throughout the part of the species’ native distribution in eastern North America. The test sites (i.e., Wabeno, Wisconsin, USA; Manistique, Michigan, USA; Pine River, Michigan, USA; Newaygo, Michigan, USA; Turkey Point, Ontario, Canada; Ganaraska, Ontario, Canad...
In the 1970s, forest geneticists with the British Columbia Forest Service established a number of long-term provenance trials throughout the province. The Trinity Valley (TV) provenance trial was established in 1975 in the southern interior to evaluate interior Douglas-fir (Pseudotsuga menziesii var. glauca) across the species’ range. TV is a factorial experiment, where 64 populations of 4 year-old Douglas-fir seedlings were planted in a randomized complete-block design with three replicat...
The Mid-Ohio River Valley’s (USA) rich cultural fabric is preserved in the extant 19th century buildings that dot the landscape. Extensive tree-ring analysis 3has provided construction and modification dates for regional buildings (n > 200) such as barns, houses, mills, churches, and various outbuildings. In addition to determining construction dates, the goals of this long-term study include identifying the various timber types used in construction, determining potential bias and cause...
Carbon-14 (14C) is produced via a nuclear reaction between the atmosphere and cosmic rays. Although the main source of 14C is galactic cosmic rays, solar energetic particles (SEPs) also contributes in producing 14C. Extreme SEP events are considered to produce 14C spikes that considerably exceed the 14C amount produced by galactic cosmic rays. Thus far, several signatures of 14C spikes originates by extreme SEP events have been reported, such as the 774 CE, 992 CE, and ~660 BCE events. In ...
Forty years ago Dr. Tom Yanosky, a research botanist with the US Geological Survey, reported that ash trees growing along the Potomac River contained rings with abnormal wood anatomy caused by flood damage. Dr. Yanosky recommended these rings — which he dubbed “flood rings” — could be used to estimate the date, seasonal timing, and (most importantly) peak stage of past floods. Since that discovery, flood rings have been identified for forested river systems in eastern France, central Canad...
Fluctuations in water resources is one of the main factors modulating ecosystem dynamics, human population changes and culture in semiarid regions. One of the largest high-altitude semiarid regions of South America is the Altiplano in the Central Andes. With an elevation of 4.000 m this region has been the environment for the settlement of many communities who have inhabited the region for thousands of years. Tree-ring research has been developed in this region allowing the reconstruction ...
Dendrochronology in eastern New York State, USA, was established from timbers used in European settlement and development of the Hudson and Mohawk River Valleys starting in the mid-17th century. The abundant primary forests were the source, and timbers were used locally and exported via the rivers. West of the Hudson River Valley, successful settlement was more precarious from human conflict until the late 18th - early 19th century, and the oldest dated buildings are located al...
Dendroclimatological reconstructions are often extended into the past with wood from historical buildings. However, the varying, though frequently unknown origin of timbers not only affects the growth rate but also the climate response of individual tree-ring samples. We tested nine supervised machine learning algorithms for the geographical provenancing of 99 historical tree-ring samples. We sampled 143 living larch (Larix decidua Mill) trees at seven sites along an elevational gradient f...
"Drought legacy effects (DLE) in radial tree growth (RTG) have been extensively studied over the last decade and are found to critically influence carbon sequestration in woody biomass. However, the statistical significance of DLE depends on our definition of expected vs. unexpected growth variability, a definition that has not received sufficient scrutiny.Here, we revisit popular DLE analyses using the ITRDB and employ a synthetic data simulation to disentangle four key factors influe...
Anthropogenic climate warming is altering the ecosystem function of temperate and boreal forests. A number of studies have indicated a rise in overall ecological productivity due to a lengthening growing season, particularly into early spring. However, interactions between temperature and precipitation remain understudied with respect to their combined impacts on the responses of trees to warming in spring. Here, I examine the sensitivity of common Midwestern conifers to multiple dimension...
Western Ukraine are largely forested, especially Transcarpatia with more than 50% of the land covered by forests. Despite this fact, Transcarpathian Ukraine belongs to the last European regions without a long and well replicated oak TRW chronology. The first step in compiling a new tree-ring width (TRW) chronology is to start with living trees; therefore, a new recent oak TRW chronology was assembled.In this study, totally 336 oak samples from 16 oak forest stands and 1 sawmill from th...
Oxygen isotope ratios in tree rings (δ18OTR) from Amazon forests have been shown to provide historical records of rainfall amounts at a large scale, due to the rainout of heavy isotopes during moisture transport. Here, we present a 110-year oxygen isotope record obtained from tree ring-cellulose of six Cedrela odorata trees (rbar = 0.57, EPS = 0.89) from the region of Tapajos River, Eastern Amazon. Our analysis indicates that δ18OTR series reflects inter-annual variability of wet season (J...
Trees do not grow during winter where freezing temperatures occur regularly. Therefore, much of what has been learned from tree-ring data about variability in Earth’s climate is driven by summer conditions. To investigate winter climate and atmospheric circulation over North America, we employ a multi-proxy approach. First, we use earlywood carbon and oxygen stable isotopes of trees growing adjacent to Lake Superior to capture the climate memory embodied by this inland sea. Indeed, previou...
We reconstructed wildfire history from fire-scars to detect the influences of climatic variability and land-use change on wildfire dynamics in the lodgepole pine (Pinus contorta var. latifolia Engelm.) forests of Jasper National Park in the Canadian Rocky Mountains. New original analyses were performed on 170 cross-section samples collected in the 1970s from 52 sites around Jasper, Alberta. The updated fire record reveals that fire occurrence was highly variable: site-lev...
Presentation of all Ameridendro2022 posters.FREE LUNCH FOR ALL ATTENDEES!
Fire-dependent red pine (Pinus resinosa Ait.) vegetation communities in the central Appalac...
It has been shown that trees get older in the wet tropics, but the mechanisms behind this observation are still not clear. Literature shows that moisture could directly affect longevity by modulating physiological processes of trees. Other studies point to the potential role of water on tree size, which could indirectly affect longevity if one reconciles to the fact that the growth rate of tropical trees doesn’t differ significantly between wet and dry sites. The third group points to the ...
This is a mandatory (!) .... and FREE (!!) cocktail & award ceremony (!!!)(in replacement of the Banquet formula)->->->->->->->->->->->->->->->->->->After a great summer day of scientific and urban discoveries in our beloved MTL, we wish to bring together all the AmeriDendro community in one place and congratulate the TRS awardees for their remarkable achievements! -Bonsinsegna award-Fr...
Thursday 30 June, 2022
The assessment of pre-instrumental climate variability during the Common Era (CE) has been a key element of IPCC reports and was recently emphasized by showing a single temperature reconstruction as the first figure in the 2021 Summary for Policymakers (SPM). This reconstruction is derived from dozens of proxy records including tree-rings, corals, ice cores and sediments, and displays the course of global temperatures over the past 2000 years. Show casing a single study for paleoclimate co...
Tree-ring records have been used extensively to reconstruct past streamflow variability. Annually resolved estimates for several centuries prior to observations, and in some cases millennia, have been produced from dendroclimatic proxies. However, despite an often strong hydroclimatic signal embedded in the rings, some factors limit the skill of such reconstructions, including human interference with the hydrological cycle. We examine the relationship between local output...
The state of fragmented populations of tree Polylepis genus heavily impact by human activities leads to the need to conduct ecological studies to better understand their vulnerability. We evaluated the newly identified tree species Polylepis rodolfo-vasquezii, endemic to central Peruvian Andes, distributed from 3700 to 4750 m a.s.l. and suitable for dendrochronological studies. Our objectives were twofold: (1) to determinate age population in both forests and developed linear models that c...
Given the short span of instrumental hydroclimatic records in the South American Altiplano, longer time records are needed to understand the nature of climate variability and to improve the predictability of precipitation, a key factor modulating the socio-economic development in the Altiplano and adjacent arid lowlands. In this region growths P. tarapacana, a long-lived tree species being very sensitive to hydroclimatic changes and widely used for tree-ring studies in central and southern...
Polylepis tarapacana is the longest paleoclimatic tree-ring archive in the South American southern tropics. It grows up to 5200 m a.s.l. in the South American Altiplano, a semiarid-high elevation Andean Plateau. P. tarapacana ring-widths (RW) have provided centuries of past hydroclimate information, but the potential use of tree-ring stable isotopes for paleoclimatic or ecophysiological studies remained understudied for this species. Here, we developed a network of four RW, oxygen (δ18O) a...
The occurrence of annual growth rings in tropical trees—the result of the seasonal activity of vascular cambium—has been explained either by seasonal periods of water deficit or flooding. However, little is known about the drivers of annual tree-ring formation under tropical hyper-humid conditions without evident seasonal dry periods or flooding (ever-wet conditions). Shelford's law states that both the deficit and the excess of environmental resources limit plant growth. Accordingly, we h...
The use of multiple data from tree-rings, including isotopic ratios and xylogenesis monitoring, can enhance our interpretations on tree functioning and on tree-environment relations. Here, we explored whether understanding of carbon deposition to tree-rings could be improved using: (1) monitoring of wood cell formation during the growing season, (2) intra-annual data of d13C in tree-ring cellulose and (3) ecophysiological modelling. We collected wood micro-cores to monitor wood cell format...
A gap of millennial tree-ring data suitable for dendroclimatology has long been evident in the North American boreal forest. In my talk, I will describe the adaptive approach we have developed to build and improve a data network for millennial dendroclimatology in the eastern Canadian taiga. Recurrence of stand replacing wildfires is the most important constrain to the elaboration of long tree ring chronologies, which can only be developed away from regions ...
Climate change across the western US has increased air temperature, resulting in decreased snow and lengthening of the summer drought. Recent studies have also highlighted the positive feedback loops between soil moisture and vapor pressure deficit (VPD), which can exacerbates aridity in water limited ecosystems. These interactions can make it difficult to untangle the influences of soil moisture and VPD on tree growth, and yet our ability to untangle these parameters is important for buil...