Paleoecology grand challenge

Exactly 50 years ago, in 1964, a landmark article whose two-word title, “Strong inference,” revealed little and evoked plenty, appeared in the hallowed pages of Science (Platt, 1964). Simply stated, Platt's view of scientific research in its highest form proceeds through three steps: development of alternative hypotheses; design of crucial experiments to exclude one or more hypotheses; execution of careful studies to obtain clear-cut results. It was a powerful reminder of how problem solving can be performed, written in a style both informal and authoritative. In those days it was not unusual for the most prestigious scientific outlets to publish articles whose language seems to nowadays have been relegated to blog posts. Just seven years earlier, another Science paper had appeared with a whimsical title, “Biological clock in the unicorn” (Cole, 1957), addressing the excessive reliance on statistical analysis of cycles and correlations that was plaguing the biologists of the time. Among the many citable passages in either one of those articles, one may dwell on a segment in Platt's text: “Whether it is hand-waving or number-waving or equation-waving, a theory is not a theory unless it can be disproved. That is, unless it can be falsified by some possible experimental outcome.” Literal interpretations of such statements, especially when translated to all possible scientific research, are problematic, and Platt's impact is best described as “more an inspirational tract than the development of a formal scientific methodology” (Davis, 2006). It is in that vein that I decided to open this Grand Challenge editorial by evoking a paper from half a century earlier

Hierarchical modeling of space-time dendroclimatic fields: Comparing a frequentist and a Bayesian approach

Environmental processes, including climatic impacts in cold regions, are typically acting at multiple spatial and temporal scales. Hierarchical models are a flexible statistical tool that allows for decomposing spatiotemporal processes in simpler components connected by conditional probabilistic relationships. This article reviews two hierarchical models that have been applied to treering proxy records of climate to model their space?time structure: STEM (Spatio-Temporal Expectation Maximization) and BARCAST (Bayesian Algorithm for Reconstructing Climate Anomalies in Space and Time). Both models account for spatial and temporal autocorrelation by including latent spatiotemporal processes, and they both take into consideration measurement and model errors, while they differ in their inferential approach. STEM adopts the frequentist perspective, and its parameters are estimated through the expectation-maximization (EM) algorithm, with uncertainty assessed through bootstrap resampling. BARCAST is developed in the Bayesian framework, and relies on Markov chain Monte Carlo (MCMC) algorithms for sampling values from posterior probability distributions of interest. STEM also explicitly includes covariates in the process model definition. As hierarchical modeling keeps contributing to the analysis of complex ecological and environmental processes, proxy reconstructions are likely to improve, thereby providing better constraints on future climate change scenarios and their impacts over cold regions

Research poster: Eco-hydrological pathways inferred from stable isotopes in a Pinus ponderosa and Pinus monophylla woodland of the Sheep Range, southern Great Basin, USA

Research poste

Dendroecological testing of the pyroclimatic hypothesis in the central Great Basin, Nevada, USA

In the Great Basin region of western North America, records of past climate and wildfire variability are needed not only for fire use, but also for understanding the mechanisms behind the century‐long expansion of piñon‐juniper woodlands. The Mt. Irish area (Lincoln County, south‐eastern Nevada) is a remote mountain ecosystem on the hydrographic boundary between the Great Basin and the Colorado River Basin. Non‐scarred ponderosa pines (Pinus ponderosa C. Lawson var. scopulorum Engelm.) and single‐needle pinyons (Pinus monophylla Torr. & Frém.) were used to develop a tree‐ring reconstruction of drought (mean PDSI for May–July from NV Climate Division 3) from 1396 to 2003. A hypothetical fire regime was obtained from the PDSI reconstruction and from explicitly assumed relationships between climate and wildfire occurrence. A census of fire‐scarred trees was then sampled at the study area, and crossdated fire‐scar records were used to generate the fire history, independently of the pre‐existing pyroclimatic model. Out of 250 collected fire‐scar wood sections, 197 could be crossdated (about 89% from ponderosa pines), covered the period from 1146 to 2006, and contained 485 fire scars, 390 of which could be dated to a single year. Numerical summaries were computed for the period 1550–2006, when recorder trees ranged from 16 to 169, using a total of 360 fire scars on 176 sections. Up to 1860, the time of Euro‐American settlement, fires that scarred at least two trees were very frequent (minimum fire interval: 1 year, mean: 4, median: 2, Weibull median: 3, maximum: 19), while fires that scarred at least 10% of the recorder trees were relatively rare (minimum fire interval: 40 years, mean: 66, median: 50, Weibull median: 63, maximum: 123). Fire frequency remained high during the 1780–1840 period, when fire was reduced or absent in other areas of the western United States. Both the “expected” and the “observed” fire history showed lower fire frequency after Euro‐American settlement, which most likely displaced Native people and any deliberate use of fire, but did not introduce publicly organized suppression in the area. Therefore, less favorable climatic conditions, not post‐settlement fire management, were responsible for reduced wildfire occurrence in the modern era

Virtual and Augmented Reality Therapy Framework for Phobia Treatment

Phobias are a common type of anxiety disorder that affects a great number of people. Treating phobias is not always straightforward and require a significant effort from both the patient and the therapist. In recent years, Virtual Reality Exposure Therapy and Augmented Reality Exposure Therapy have emerged to help in phobia treatments by using virtual content. However, most available systems are not free and require expensive hardware. In this paper, we present a free and open-source framework for phobia treatment, designed for both the therapist and the patient. A Virtual Reality scenario for acrophobia (fear of heights) and an Augmented Reality scenario for arachnophobia were developed for validation.XVI Workshop Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI

Virtual and Augmented Reality Therapy Framework for Phobia Treatment

Phobias are a common type of anxiety disorder that affects a great number of people. Treating phobias is not always straightforward and require a significant effort from both the patient and the therapist. In recent years, Virtual Reality Exposure Therapy and Augmented Reality Exposure Therapy have emerged to help in phobia treatments by using virtual content. However, most available systems are not free and require expensive hardware. In this paper, we present a free and open-source framework for phobia treatment, designed for both the therapist and the patient. A Virtual Reality scenario for acrophobia (fear of heights) and an Augmented Reality scenario for arachnophobia were developed for validation.XVI Workshop Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI

Long-term response of Torrey pine to coastal climate: precipitation, temperature, and fog

EXTRACT (SEE PDF FOR FULL ABSTRACT): Torrey pine (Pinus torreyana Parry ex Carr.) has one of the most limited geographical ranges and population size in the Pinus genus; it is present only on Santa Rosa Island and on the coast between San Diego and Del Mar, where our research was conducted. A 168-year chronology (1827-1994) was developed using 28 increment cores extracted from 15 living and 2 dead stranding trees at Torrey Pines State Reserve, San Diego, California. ... The spatial correlation with western North America winter and spring precipitation, as well as with published tree-ring chronologies, indicates a connection with the American Southwest. Global correlation maps with winter sea level pressure and sea surface temperature are consistent with the hypothesis that San Diego precipitation is affected by a southerly displaced North Pacific storm track and by warmer water farther south, both leading to higher transport of lower latitude moisture

Using Automated Point Dendrometers to Analyze Tropical Treeline Stem Growth at Nevado de Colima, Mexico

The relationship between wood growth and environmental variability at the tropical treeline of North America was investigated using automated, solar-powered sensors (a meteorological station and two dendrometer clusters) installed on Nevado de Colima, Mexico (19° 35′ N, 103° 37′ W, 3,760 m a.s.l.). Pure stands of Pinus hartwegii Lindl. (Mexican mountain pine) were targeted because of their suitability for tree-ring analysis in low-latitude, high-elevation, North American Monsoon environments. Stem size and hydroclimatic variables recorded at half-hour intervals were summarized on a daily timescale. Power outages, insect outbreaks, and sensor failures limited the analysis to non-consecutive months during 2001–2003 at one dendrometer site, and during 2002–2005 at the other. Combined data from the two sites showed that maximum radial growth rates occur in late spring (May), as soil temperature increases, and incoming short-wave radiation reaches its highest values. Early season (April–May) radial increment correlated directly with temperature, especially of the soil, and with solar radiation. Stem expansion at the start of the summer monsoon (June–July) was mostly influenced by moisture, and revealed a drought signal, while late season relationships were more varied

Integrating varve and tree-ring time series for southern California climate reconstruction: a 20th century outlook [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Our objective is to combine terrestrial and oceanic records for reconstructing West Coast climate. Tree rings and marine laminated sediments provide high-resolution, accurately dated proxy data on the variability of climate and on the productivity of the ocean and have been used to reconstruct precipitation, temperature, sea level pressure, primary productivity, and other large-scale parameters. We present here the latest Santa Barbara basin varve chronology for the twentieth century as well as a newly developed tree-ring chronology for Torrey pine