Sessions in which Milagros Rodriguez-Caton participates
Monday 27 June, 2022
Free, in person and onlineThe stable isotopic compositions of carbon and oxygen (d13C and d18O) measured in tree rings are valuable proxies for reconstructing paleoclimate and are increasingly used as paleophysiological proxies. Applying these proxies in ecophysiology and paleoclimate can be challenging as they rely on complex process-based models and poorly constrained input data. In recent years, h...
Wednesday 29 June, 2022
Hydroclimate variability in tropical South America is strongly regulated by the South American Summer Monsoon (SASM). However, past precipitation changes are poorly constrained due to limited observations and high-resolution paleoproxies. We found that summer precipitation and the El Niño-Southern Oscillation tarapacana (ENSO) in the Chilean variability and Bolivian are well registered Altiplano in in tree-ring the Central stable Andes oxygen (18–22°S, isotopes ∼4,500 (δ18OTR) m a.s.l.) of...
Thursday 30 June, 2022
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...
Sessions in which Milagros Rodriguez-Caton attends
Tuesday 28 June, 2022
Tree-ring research has given generations of scientists a long memory of what is acceptable for a tree to be included for data analysis. The established criteria, however, were set through purposeful goals to maximize the response for climatic reconstructions. Ecology is different. Tree-rings are increasingly being used to study a wide swath of ecology, including the carbon cycle or the response of ecosystems to global changes. A fundamental aspect of ecology is to understand the range of r...
Climate extremes are driven by a combination of thermodynamical and dynamical factors. In Europe, the primary dynamical driver of summer climate extremes is the position of the jet stream over the Europe-North Atlantic (EU) region. To study long-term variability in the position of the EU jet, as well as its potential impact on past climate extremes and human systems, we have reconstructed EU jet variability over the past 800+ years (1200-2005 CE). To accomplish this, we have combined five ...
Our understanding of climate change impacts on boreal forest net primary productivity (NPP) largely rely on terrestrial biosphere models (TBMs). TBMs characterize forest NPP through predictions of plant carbon fluxes and allocation from climatic data, physiological parameters and process logic. TBMs’ outcomes may be highly variable, a major source of uncertainty being the formulation of ecophysiological processes and their parameterization. In our study, we compared patterns of growth resp...
In this work we show the application of dendrochronology as an educational resource for schoolchildren and as a mean to disseminate science to society. Tree rings are popularly known in Chile due to the massive use of wood for construction, handicrafts and firewood. The visible tree rings generate a distinct, tangible and familiar curiosity in many people. “Tree-Rings as a Natural Encyclopedia of Environmental Archives” is an exhibition built as an educational project for schoolchildren, w...
It is generally assumed that tree-rings, and their vessel diameters, are wider in warmer and wetter years. To maintain constant conductance per unit leaf area as trees grow taller, stem vessels should widen from tip to base. But wider vessels are more susceptible to embolism, so taller plants are progressively becoming more vulnerable to drought or cold as they grow. The traditional theory of vessel hydraulic adaptation postulates that vessel diameter is affected by climate, with cold envi...
Historical accounts in the Brazilian Digital Library provide independent support for most of the tree-ring reconstructed wet season rainfall extremes in the eastern Amazon during the late-18th and 19th centuries. Newspapers, government reports, and other documents describe crop failure, livestock mortality, water shortages, and ship groundings on the Amazon River during many of the tree-ring reconstructed drought extremes. Heavy rains and flooding are described during some of the wet extre...
Half of the tributaries of the Amazon River originate in the tropical Andes; however, it is difficult to assess hydroclimatic conditions due to the scarcity of long, high-quality instrumental records. Data from the Global Precipitation Climatology Project (GPCP) provides a complete record since 1979 and offers a good representation of rainfall over the tropical Andes. Longer records are needed to improve our understanding of rainfall variability and summer monsoon behavior at various scale...
In the context of climate change, more research is needed to better understand the impact of short-term environmental stressors on forest productivity. Intra-annual data provide crucial information to achieve this objective. Our project aims to determine the responses of tree growth and water status of boreal tree species (jack pine, black spruce and quaking aspen) under variable meteorological conditions and on contrasted soil surficial deposits using intra-annual measurements from dendro...
Intra-annual tree-ring δ13C record has the potential to provide deep insights into past plant performance and environmental conditions. With concomitant high temporal resolution δ13C analysis of non-structural carbohydrates, the processes behind observed low- and high-frequency δ13C changes in tree-ring record could be interpreted more reliably. This is essential for predicting forest response to impacts of climate change, such as more frequent and severe drought episodes.To better ...
Regional teleconnections permit cross-continental modeling of hydroclimate throughout the world. Tree-rings are a good hydroclimatic proxy used to reconstruct drought and streamflow in regions that respond to common global forcings. We used a multi-species dataset of 32 tree-ring width chronologies from Chile and Uruguay as a climate proxy to infer annual streamflow (Q) variability in the Negro River basin, a grassland-dominated watershed of lowland Southeastern South America. A positive l...
Improving our understanding of the carbon cycle is key to addressing the challenges of climate change. In this study, we investigated the relationships between intra and inter-annual climate variations, carbon fluxes, and the xylem biomass in an 80-year plantation of Pinus strobus at Turkey Point, Ontario, Canada. From eddy covariance tower, we obtained daily Gross Primary Production (GPP), precipitation and air temperature for the period 2003-2018. To determine inter-and intra-annual xyle...
Leaf water isotopic enrichment (ΔD[LW]) is the original source of climatic information stored in tree-ring δ¹⁸O and δD. Tree-ring δ¹⁸O temporal variability has been correlated to environmental variables such as temperature, precipitation, relative humidity (RH), and phenomena such as tropical cyclones and drought. Meanwhile, more development is needed to use tree-ring δD temporal variability as a paleoclimatic bioindicator. An increased understanding of the climatic signal of ΔD[LW] could ...
In the context of climate and environmental change, the boreal forest is subject to potential changes in structure and function. Stand-level physiological models can be used to predict these responses over time and to understand the interaction between tree ecophysiological processes and climate variability. We present here a project that aims to develop potential growth scenarios for Canadian boreal forest stands based on the characterization of their ecosystem fluxes using the MAIDEN mod...
The impacts of inland flooding caused by tropical cyclones (TCs), including loss of life, infrastructure disruption, and alteration of natural landscapes, have increased over recent decades. While these impacts are well documented, changes in TC precipitation extremes—the proximate cause of such inland flooding—have been more difficult to detect. Here, we present a latewood tree-ring–based record of seasonal (June 1 through October 15) TC precipitation sums (ΣTCP) from the region in North ...
The representation of snow processes in forest growth models is necessary to accurately predict the hydrological cycle in boreal ecosystems and the isotopic signature of soil water extracted by trees, photosynthates and tree-ring cellulose. Yet, most process-based models do not include a snow module, consequently their simulations may be biased in cold environments. Here, we modified the MAIDENiso model to incorporate a new snow module that simulates snow accumulation, melting and sublimat...
The ongoing North American megadrought has persisted since the year 2000, and has been characterized by anomalously low amounts of winter and summer precipitation. The climate systems providing these seasonal precipitation regimes are distinct in their origins but overlapping in their geographic ranges. However, our understanding is still incomplete in how alternation in water resources influences forest growth and physiology during extreme and persistent drought, including whether replete...
"Little is known about the impact of volcanoes on trees from the Southern Hemisphere. In this study, we investigated whether volcanic signals could be identified in ring widths from eight dendrochronological species from New Zealand, using superposed epoch analysis. We found that most species are good recorders of volcanic dimming and that the magnitude and persistence of the post-event response can be broadly linked to plant life history traits - whether the species responds as a 'stress ...
The current climate warming is unique in terms of its ubiquity and synchrony on a global scale. Over the last millennium, pre-industrial periods with warmer and colder temperatures occurred at different times in different locations around the globe (Neukom et al., 2019). Long-term temperature reconstructions in the Southern Hemisphere remain sparse and not always consistent among them (Lara et al., 2020). Therefore, to understand the temporal and spatial patterns of global-scale temperatur...
Wednesday 29 June, 2022
Ring-width (RW) and Blue Intensity (BI) parameters (earlywood - EWB, inverted latewood – LWBinv, and delta - DB) were measured from samples of Araucaria araucana from six sites in northern Patagonia, Argentina. The distance between the most southerly and northerly sites is ca. 130 kms. Despite a much weaker between-tree signal for the BI parameters than RW, principal component analysis identifies a much stronger regional between-site signal for the BI parameters. Split period correlation r...
The representation of snow processes in forest growth models is necessary to accurately predict the hydrological cycle in boreal ecosystems and the isotopic signature of soil water extracted by trees, photosynthates and tree-ring cellulose. Yet, most process-based models do not include a snow module, consequently their simulations may be biased in cold environments. Here, we modified the MAIDENiso model to incorporate a new snow module that simulates snow accumulation, melting and sublimat...
The ongoing North American megadrought has persisted since the year 2000, and has been characterized by anomalously low amounts of winter and summer precipitation. The climate systems providing these seasonal precipitation regimes are distinct in their origins but overlapping in their geographic ranges. However, our understanding is still incomplete in how alternation in water resources influences forest growth and physiology during extreme and persistent drought, including whether replete...
Dendroprovenance is a discipline usually linked to dendroacheology or wood commercialization; however, other purposes as inferring the origin of wood in rivers (i.e., instream large wood, LW) are often overlooked. LW in fluvial ecosystems enhances its geomorphology and biodiversity, but also increases potential risk during floods. Thus, knowledge about its source is crucial for understanding LW dynamics and optimizing river and riparian forest management. This project aims at deve...
Thursday 30 June, 2022
Hydrogen isotope ratios in tree ring cellulose (δ2HC) have been recognized as a potential proxy for plant-climate interactions, plant physiology, and carbon metabolism. This goes along with recent studies showing species-specific δ2HC differences that cannot be explained by climatic conditions. However, systematic investigations on the phylogenetic impact on 2H-fractionations in carbohydrates of woody plant species are missing.Here, we sampled leaves and twigs of 152 trees and ...
The ability of forests to continue absorbing atmospheric CO2, and hence mitigating climate change, depends on the extent to which their productivity is limited by nutrients, with nitrogen (N) being particularly important in temperate and boreal regions. Fertilisation experiments offer an opportunity to directly determine whether atmospheric N input can contribute to alleviating N limitation. However, the majority of the experiments have normally considered soil N applications, which do not...
In mixed forests, diffuse-porous and ring-porous species represent two distinct functional groups undergoing similar environmental variations, but allegedly displaying different growth responses due to their anatomical features. We hypothesized that in sympatric species, functional groups-specific carbon allocation strategies result in different relationships between wood traits and canopy architecture, mirroring contrasting sensitivity to drought.We selected 2 diffuse-porous species (...
Under elevated CO2, photosynthetic carbon isotope discrimination is expected to increase in response to photosynthesis stimulation. While this response is widely documented in laboratory and field experiments, long-term proxies indicate that such response is not universally observed in response to the growth of atmospheric CO2. We investigated historical trends of photosynthetic carbon isotope discrimination derived from carbon isotope measurements of tree rings (Δ13C) from 147 chron...
The boreal forest located in high northern latitudes stores about a third of the world’s carbon and covers almost a quarter of the Earth’s land surface. This region is experiencing one of the fastest temperatures increases on the planet. Yet it is unclear how global warming affects carbon sequestration and storage in this biome. Here, we explore how white spruce (Picea glauca [Moench] Voss) growing in North America responded to climate change during the 20th century using tree-ring width a...