Biology subjects

D'Andrea, E.

Publications and source records attributed to D'Andrea, E..

5 recordsLinked to original sources

bioRxiv2025

Cerebrovascular response dynamics to hypercapnia in healthy aging

Cerebrovascular dysfunction is an early and underrecognized contributor to cognitive decline. Standard measures such as cerebrovascular reactivity (CVR) during hypercapnia capture only the amplitude of flow responses, providing limited insight into the timing of vascular adaptation. Temporal features, such as delay (onset latency) and time constant (rate of adjustment), together with gain (response amplitude) may serve as more sensitive indicators of vascular health, but cannot be directly obtained from conventional imaging. Here, we investigated cerebral blood flow (CBF), cerebral blood volume (CBV), and blood oxygenation level dependent (BOLD) signal dynamics during hypercapnic challenge in healthy aging. Using a physiologically validated computational model, we estimated delay, time constant, and gain by optimizing the mapping of end-tidal gases to their arterial counterparts in a region-of-interest framework. Once parametrized using CBF, the model successfully predicted CBV and BOLD responses in independent experimental sessions. Across subjects, aging was associated with widespread heterogeneous region-specific changes in delay and substantial reductions in gain and time constant, indicating that cerebrovascular responses become weaker and less adaptable with age. These results demonstrate that calibrated simulations have the ability to track vascular aging, allowing the extraction of parameters that may represent novel biomarkers of cerebrovascular dysfunction. Unlike conventional CVR, temporal hemodynamic parameters capture the dynamics of vascular adaptation, providing a complementary dimension for early detection and therapeutic monitoring in aging and disease.

neuroscience↗

bioRxiv2024

Assessing the combined effects of forest management and climate change on carbon and water fluxes in European beech forests

The consequences of climate change continue to threaten European forests, particularly for species located at the edges of their latitudinal and altitudinal ranges. While extensively studied in Central Europe, European beech forests require further investigation to understand how climate change will affect these ecosystems in Mediterranean areas. Proposed silvicultural options increasingly aim at sustainable management to reduce biotic and abiotic stresses and enhance these forest ecosystems resistance and resilience mechanisms. Process-based models (PBMs) can help us to simulate such phenomena and capture early stress signals while considering the effect of different management approaches. In this study, we focus on estimating sensitivity of two state-of-the-art PBMs forest models by simulating carbon and water fluxes at the stand level to assess productivity changes and feedback resulting from different climatic forcings as well as different management regimes. We applied the 3D-CMCC-FEM and MEDFATE forest models for carbon (C) and water (H2O) fluxes in in two sites of the Italian peninsula, Cansiglio in the north and Mongiana in the south, under managed vs. unmanaged scenarios and under current climate and different climatic scenarios (RCP4.5 and RCP8.5). To ensure confidence in the models results, we preliminary evaluated their performance in simulating C and H2O flux in three additional beech forests of the FLUXNET network along a latitudinal gradient spanning from Denmark to central Italy. The 3D-CMCC-FEM model achieved R{superscript 2} values of 0.83 and 0.86 with RMSEs of 2.53 and 2.05 for C and H2O fluxes, respectively. MEDFATE showed R{superscript 2} values of 0.76 and 0.69 with RMSEs of 2.54 and 3.01. At the Cansiglio site in northern Italy, both models simulated a general increase in C and H2O fluxes under the RCP8.5 climate scenario compared to the current climate. Still, no benefit in managed plots compared to unmanaged ones, as the site does not have water availability limitations, and thus, competition for water is low. At the Mongiana site in southern Italy, both models predict a decrease in C and H2O fluxes and sensitivity to the different climatic forcing compared to the current climate; and an increase in C and H2O fluxes when considering specific management regimes compared to unmanaged scenarios. Conversely, under unmanaged scenarios plots are simulated to experience first signals of mortality prematurely due to water stress (MEDFATE) and carbon starvation (3D-CMCC-FEM) scenarios. In conclusion, while management interventions may be considered a viable solution for the conservation of beech forests under future climate conditions at moister sites like Cansiglio, in drier sites like Mongiana conservation may not lie in management interventions alone.

ecology↗

bioRxiv2022

Simulating alternative forest management in a changing climate on a Pinus nigra subsp. laricio plantation in Southern Italy

Mediterranean pine plantations provide several ecosystem services but are particularly sensitive to climate change. Forest management practices might play a strategic role in the long-term adaptation of Mediterranean forests, but the joint effect of climate change and alternative management options in the near and far future have seldom been investigated together. Here, we developed a portfolio of management options and 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 change scenarios corresponding to increasing levels of atmospheric CO2 concentration, and seven management options with different goals, including post-disturbance management, wood production and renaturalization purposes. We analyzed the effect of climate change on annual carbon fluxes (i.e., gross and net primary production) and stocks (i.e., basal area and potential carbon woody stocks), as well as the impact of different management options compared to no management. Results show that, while climate change (i.e., warming and enriched atmospheric CO2 concentration) seems to increase carbon fluxes and stocks in the first half of the century, both show a substantial decrease in the second half, along with higher temperatures (+3 to +5 {degrees}C) and lower precipitation (-20% to -22%). When compared to no management, alternative options had a moderate effect on carbon fluxes over the whole simulation (between -6% and +7%) but overall carbon stocks were maximized by thinning interventions and the shelterwood system (+54% to +55%). We demonstrate that the choice of management exerts greater effects on the features of Laricio pine plantations than climate change alone. Therefore, silvicultural strategies might enhance potential stocks and improve forest conditions, with cascading positive effects on the provision of ecosystem services in Mediterranean pine plantations. HighlightsO_LIWe simulated the development of a Laricio pine stand over 137 years under three different climatic scenarios and seven management options. C_LIO_LICarbon fluxes and stocks benefit from climate change (i.e., warming and enriched atmospheric CO2 concentration) in the first half of the century but show a marked decrease in the longer-term. C_LIO_LIForest management exerts a much stronger effect on these features than climate change alone. C_LIO_LISilvicultural options aimed at reducing stand density preserve and enhance carbon fluxes and stocks over the simulated time period. C_LI

ecology↗

bioRxiv2020

Unravelling resilience mechanisms in forests: role of non-structural carbohydrates in responding to extreme weather events

O_LIExtreme weather events are increasing in frequency and intensity due to global climate change. We hypothesized that these have a strong impact on the stem radial growth and the dynamic of non-structural carbohydrates (NSCs). C_LIO_LIIn order to assess the effects on mature trees of a late frost occurred in spring 2016 and a drought event characterizing the summer 2017, we monitored the phenology, the radial growth and the dynamic of starch and soluble sugars in a Mediterranean beech forest. C_LIO_LIGrowth was much more reduced by spring late frost than by summer drought, while NSCs dynamic was deeply involved in counteracting the negative effects of both events, supporting plant survival and buffering source-sink imbalances under such stressful conditions, resulting in a strong trade-off between growth and NSCs dynamic in trees. C_LIO_LIOverall, our results highlight the key role of NSCs on trees resilience to extreme weather events, confirming the relevant adaptability to stressful conditions. Such an insight is useful to assess how forests may respond to the potential impacts of climate change on ecosystem processes and to define how future management strategies can help adaptation of beech forests in the Mediterranean area. C_LI

ecology↗

bioRxiv2019

The cold and the drought: effects of extreme weather events on Stem Carbon dynamic in a Mediterranean beech forest

The effects of short-term extreme events on tree functioning and physiology are still rather elusive. European beech is one of the most sensitive species to late frost and water shortage. We investigated the intra-annual C dynamics in stems under such conditions. Wood formation and stem CO2 efflux were monitored in a Mediterranean beech forest for three years (2015-2017), including a late frost (2016) and a summer drought (2017). The late frost reduced radial growth and, consequently, the amount of carbon fixed in the stem biomass by 80%. Stem carbon efflux in 2016 was reduced by 25%, which can be attributed to the reduction of effluxes due to growth respiration. Counter to our expectations, we found no effects of the 2017 summer drought on radial growth and stem carbon efflux. The studied extreme weather events had various effects on tree growth. Even though late spring frost had a devastating impact on beech radial growth in the current year, trees fully recovered in the following growing season, indicating high resilience of beech to this stressful event.

physiology↗