1,721,018 research outputs found
The role of respiration in estimation of net carbon cycle: Coupling soil carbon dynamics and canopy turnover in a novel version of 3D-CMCC forest ecosystem model
No full textUnderstanding the dynamics of organic carbon mineralization is fundamental in forecasting biosphere to atmosphere net carbon ecosystem exchange (NEE). With this perspective, we developed 3D-CMCC-PSM, a new version of the hybrid process based model 3D-CMCC FEM where also heterotrophic respiration (Rh) is explicitly simulated. The aim was to quantify NEE as a forward problem, by subtracting ecosystem respiration (Reco) to gross primary productivity (GPP). To do so, we developed a simplification of the soil carbon dynamics routine proposed in the DNDC (DeNitrification-DeComposition) computer simulation model. The method calculates decomposition as a function of soil moisture, temperature, state of the organic compartments, and relative abundance of microbial pools. Given the pulse dynamics of soil respiration, we introduced modifications in some of the principal constitutive relations involved in phenology and littering sub-routines. We quantified the model structure-related uncertainty in NEE, by running our training simulations over 1000 random parameter-sets extracted from parameter distributions expected from literature. 3D-CMCC-PSM predictability was tested on independent time series for 6 Fluxnet sites. The model resulted in daily and monthly estimations highly consistent with the observed time series. It showed lower predictability in Mediterranean ecosystems, suggesting that it may need further improvements in addressing evapotranspiration and water dynamics
Simulating diverse forest management options in a changing climate on a Pinus nigra subsp. laricio plantation in Southern Italy
Full text linkMediterranean pine plantations provide several ecosystem services but are vulnerable to climate change. Forest management might play a strategic role in the adaptation of Mediterranean forests, but the joint effect of climate change and diverse management options have seldom been investigated together. Here, we simulated the development of a Laricio pine (Pinus nigra subsp. laricio) stand in the Bonis watershed (southern Italy) from its establishment in 1958 up to 2095 using a state-of-the-science process-based forest model. The model was run under three climate scenarios corresponding to increasing levels of atmospheric CO2 concentration and warming, and six management options with different goals, including wood production and renaturalization. We analysed the effect of climate change on annual carbon fluxes (i.e., gross and net primary production) and stocks (i.e., basal area, standing and harvested carbon woody stocks) of the autotrophic compartment, as well as the impact of different management options compared to a no management baseline. Results show that higher temperatures (+3 to +5 °C) and lower precipitation (-20 % to -22 %) will trigger a decrease in net primary productivity in the second half of the century. Compared to no management, the other options had a moderate effect on carbon fluxes over the whole simulation (between -14 % and +11 %). While standing woody biomass was reduced by thinning interventions and the shelterwood system (between -5 % and -41 %), overall carbon stocks including the harvested wood were maximized (between +41 % and +56 %). Results highlight that management exerts greater effects on the carbon budget of Laricio pine plantations than climate change alone, and that climate change and management are largely independent (i.e., no strong interaction effects). Therefore, appropriate silvicultural strategies might enhance potential carbon stocks and improve forest conditions, with cascading positive effects on the provision of ecosystem services in Mediterranean pine plantations
Emissions of climate-altering species from open vegetation fires in the Mediterranean region - A review on methods and data
No full text: The climate change over the Mediterranean region poses serious concerns about the role of open vegetation fires in the emissions of climate-altering species. The aim of this work is to review the current methodologies for quantifying the emissions of greenhouse gases and black carbon from open vegetation fires, as well as the data provided by four state-of-the-art inventories of emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and black carbon (BC) in the Mediterranean region for the period 2003-2020. A limited number of studies specifically addressed the quantification of emissions from open fires in the Mediterranean region. Our data review of fire emissions in the Mediterranean region, where "top-down" methods have not yet implemented, reveals discrepancies across the four inventories examined (GFED v4.1s, GFAS v1.2, FINN v2.5, and EDGAR v8.0). Among these, FINN v2.5 consistently reported the highest emissions, while GFED v4.1s reported the lowest. We observed that the relative ranking of total emissions between the inventories varied for the species considered (e.g. CO2 vs. CH4) and that different proportions of emissions were attributed to the individual countries included in the Mediterranean domain. We argued that these differences were related to the different spatial resolutions of the input data used to detect the occurrence of fires, the different approaches to calculating the amount of fuel available, and the emission factors used. The three inventories reporting wildfire emissions were consistent in identifying the occurrence of peaks in the emissions for the years 2007, 2012 and 2017. We hypothesized that La Niña events could partially contribute to triggering the occurrence of these emission peaks. To increase the accuracy and consistency of climate-altering emission data related to open vegetation fires in the Mediterranean region, we recommend to integrate bottom-up approaches with top-down inversion methods based on satellite and in-situ atmospheric observations
Growth and Allocation of Woody Biomass in Forest Trees Based on Environmental Conditions
Full text linkTerrestrial ecosystems, and forests in particular, are important components of land processes because of their key role in reducing atmospheric greenhouse gas concentrations by storing a large amount of carbon in tree biomass and soils [...
Meteorological, chemical and biological evaluation of the coupled chemistry-climate WRF-Chem model from regional to urban scale. An impact-oriented application for human health
Full text linkExtreme climatic conditions, like heat waves or cold spells, associated to high concentrations of air pollutants are responsible for a broad range of effects on human health. Consequently, in the recent years, the question on how urban and peri-urban forests may improve both air quality and surface climate conditions at city-scale is receiving growing attention by scientists and policymakers, with previous studies demonstrating how nature-based solutions (NBS) may contribute to reduce the risk of population to be exposed to high pollutant levels and heat stress, preventing, thus, premature mortality. In this study we present a new modeling framework designed to simulate air quality and meteorological conditions from regional to urban scale, allowing thus to assess the impacts of both air pollution and heat stress on human health at urban level. To assess the model reliability, we evaluated the model's performances in reproducing several relevant meteorological, chemical, and biological variables. Results show how our modeling system can reliably reproduce the main meteorological, chemical, and biological variables over our study areas, thus this tool can be used to estimate the impact of air pollution and heat stress on human health. As an example of application, we show how common heat stress and air pollutant indices used for human health protection change when computed from regional to urban scale for the cities of Florence (Italy) and Aix en Provence (France)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On the Increasing Occurrence of a Green Christmas: A Perspective from Long-Term Eddy Covariance Observations on Winter Dormancy Interruptions in a Subalpine Forest
Full text linkSeasonal dormancy in temperate and boreal forests is an adaptive trait that guarantees tree survival during the winter season. This phenomenon is mainly affected by temperature and photoperiod (Heide 1974). However, increasing evidence suggests that winter dormancy is not a static state but rather a dynamic period influenced by intermittent warm spells that can temporarily reactivate ecosystem processes. These dormancy interruptions, particularly during "Green Christmas" events — characterized by reduced snow cover and anomalous winter temperatures — have the potential to alter seasonal carbon fluxes, shift forest phenology, and alter physiological cycles. As climate change intensifies, understanding the frequency and implications of these interruptions becomes crucial for predicting long-term shifts in ecosystem carbon dynamics and energy fluxes.Recent studies have reported that evergreen forests can initiate photosynthesis well before complete snowmelt (Bowling 2024), while deciduous forests exhibit a delayed response to warming trends. Additionally, Körner (2023) challenges conventional meteorological definitions of growing seasons, emphasizing that photosynthetic activity does not always align with temperature-based phenological markers. While there is strong evidence that climate warming influences seasonal carbon fluxes, long-term Eddy Covariance (EC) records reveal mixed trends in photosynthetic activity, suggesting that additional research is needed to uncover the underlying ecological and physiological mechanisms driving these shifts.As multiple EC flux tower sites established under the EUROFLUX project approach three decades of continuous observations, they offer a valuable opportunity to assess the long-term effects of climate variability on forest dormancy and carbon cycling. These extensive datasets allow for detailed trend analyses of winter dormancy interruptions, providing insights into their frequency, intensity, and potential impact on annual carbon sequestration.For this study, we selected the Renon-Selvaverde site (ICOS ID: IT-Ren, eLTER ID: BOL1), a subalpine forest with a long-term EC measurement record. To enhance the completeness of our dataset, we incorporated locally processed EC data, extending the NEE record from the Warm Winter Dataset (Gharun 2024) up to the present (1997-2024). Additionally, we ensured continuity in meteorological observations for the whole time span of our analysis.Leveraging this long-term dataset, we investigated how winter dormancy interruptions influence seasonal carbon dynamics. By integrating EC observations with environmental drivers, we aimed to refine our understanding of subalpine ecosystem responses to mid-winter warming events and evaluate their broader implications for carbon balance in the context of climate change.Winter dormancy interruptions were identified based on periods when NEE fluxes were significantly different from zero during the winter months. We then examined the relationships between NEE, shortwave radiation, soil temperature, and air temperature from the vertical profile during these interruptions. To quantify these interactions, we conducted a correlation analysis to assess the strength and significance of environmental drivers influencing ecosystem-level fluxes.Our analysis revealed an increase in the frequency of warm spells beginning in 2020. However, we did not detect a significant pattern in the duration of these events. Currently, warm spells appear to be isolated occurrences, allowing the forest stand to return to its dormant state after each event. Additionally, we observed that dormancy interruptions correspond to periods when soil temperatures remain above freezing and snow cover is absent, supporting the hypothesis that soil conditions play a critical role in determining ecosystem activity during winter. Anyhow, it is important to distinguish between warm spells characterized by non-freezing soil temperature (with or without snow cover) and photosynthetic activation driven by solar radiation but occurring under soil freezing conditions. In the latter case, photosynthesis may be initiated but remains constrained by water availability, with unclear effects on NEE.At present, these dormancy interruptions do not significantly impact the winter carbon budget of the observed ecosystem. However, we hypothesize that a continued increase in both the frequency and duration of warm spells could lead to fundamental shifts in seasonal or even annual carbon dynamics. An extended period of mid-winter photosynthetic reactivation could alter the seasonal carbon budget and potentially reduce the ability of subalpine forests to function as a long-term carbon sink, affecting their contribution to carbon neutrality.Future research should focus on mechanistic modelling approaches to predict long-term changes in carbon sequestration capacity under scenarios of increased winter warming and reduced snow cover
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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