Biology subjects

Tognetti, R.

Publications and source records attributed to Tognetti, R..

4 recordsLinked to original sources

bioRxiv2024

From calamity to infestation: linking windstorm tree damage to bark beetle outbreak through forest structure and meteorological analysis

In recent years, we have witnessed worldwide, an increase in natural forest disturbances, particularly windstorms, which have caused significant direct and indirect forest damages, often triggering largescale bark beetle outbreaks. In this study, we investigated the interaction between windstorm-induced tree damage and subsequent bark beetle outbreaks in the northeastern Italian Alps (Province of Belluno and Bolzano), focusing on the 2018 Vaia windstorm and the successive bark beetle infestation started in 2021. Additionally, we aimed to determine whether this potential correlation is influenced by forest structural characteristics such as forest height heterogeneity (HH), forest density, and forest mean height using LiDAR data, or by meteorological factors (mean temperature and cumulative precipitation) through in-situ spatialized information. Our research findings, based on a methodology centered on spatial interactions, indicate a potential link between the bark beetle outbreaks and the windstorm event Vaia occurred three years before. Our results suggest that forest structural variables are, in most of the cases, significantly similar across all areas affected by the bark beetle. This similarity is observed both in forests impacted by the Vaia windstorm and in other Picea abies forests not affected by the windstorm, indicating that these forest structural variables may not be a trigger for the bark beetle outbreak. Our findings do not show a clear and consistently significant difference in meteorological conditions. This variability can be attributed to the specific areas affected by the Vaia windstorm, which are predominantly mountainous regions characterized by distinct temperatures and precipitation compared to the rest of the provinces. When analyzing the combined influence of structural and meteorological variables in both study areas, our results indicate that none of these factors were ultimately significant predictors of the interaction between bark beetle infestations and areas affected by the Vaia windstorm. Our study suggests that, as climate change increases the frequency and severity of these disturbances, adaptable forest management framework to enhance forest resilience and sustainability are needed, helping forests to better withstand and recover from future natural disturbances.

ecology↗

bioRxiv2023

Integrating annual radial growth analyses and carbon isotope discrimination to forecast early warning of beech forest dieback across the Italian Peninsula

Tree mortality and forest dieback episodes are increasing due to drought and heat stress. Nevertheless, a comprehensive understanding of mechanisms enabling trees to withstand and survive droughts remains lacking. Our study investigated basal area increment (BAI), and {delta}13C- derived intrinsic water-use-efficiency (iWUE), to elucidate beech resilience across four healthy stands in Italy with varying climates and water availability. Additionally, fist-order autocorrelation (AR1) analysis was performed to detect early warning signals for potential tree dieback risks during extreme drought events. Results reveal a negative link between BAI and vapour pressure deficit (VPD), especially in southern latitudes. After the 2003 drought, BAI decreased at the northern site, with an increase in {delta}13C and iWUE, indicating conservative water-use. Conversely, the southern sites showed increased BAI and iWUE, likely influenced by rising CO2 and improved water availability. In contrast, the central site sustained higher transpiration rates due to higher soil water holding capacity (SWHC). Despite varied responses, most sites exhibited reduced resilience to future extreme events, indicated by increased AR1. Temperature significantly affected beech iWUE and BAI in northern Italy, while VPD strongly influenced the southern latitudes. The observed increase in BAI and iWUE in southern regions might be attributed to an acclimation response.

plant biology↗

bioRxiv2020

A meta-analysis of mesophyll conductance to CO2 in relation to major abiotic stresses in poplar species

Mesophyll conductance (gm) determines the diffusion of CO2 from the substomatal cavities to the site of carboxylation in the chloroplasts and represents a critical limiting factor to photosynthesis. In this study, we evaluated the average effect sizes of different environmental constraints on gm in Populus spp., a forest tree model. We collected raw data of 815 A-Ci response curves from 26 datasets to estimate gm, using a single curve-fitting method to alleviate method-related bias. We performed a meta-analysis to assess the effects of different abiotic stresses on gm. We found a significant increase in gm from the bottom to the top of the canopy that was concomitant with the increase of maximum rate of carboxylation and light-saturated photosynthetic rate (Amax). gm was positively associated with increases in soil moisture and nutrient availability, but insensitive to increasing soil copper concentration, and did not vary with atmospheric CO2 concentration. Our results showed that gm was strongly related to Amax and to a lesser extent to stomatal conductance (gs). Also, a negative linear relation was obtained between gm and specific leaf area, which may be used to scale-up gm within the canopy.

plant biology↗

bioRxiv2018

Impact of high phosphorous and sodium on productivity and stress tolerance of Arundo donax plants

Arundo donax L. is an invasive species recently employed for biomass production that emits large amounts of isoprene, a volatile compound having important defensive role. Here, the potential of A. donax to grow in degraded soils, characterized by poor fertility, eutrophication and/or salinization, has been evaluated at morphological, biochemical and transcriptional level. Our results highlight sensitivity of A. donax to P deficiency. Moreover, we show that A. donax response to salt stress (high sodium, Na+), which impaired plant performance causing detrimental effects on leaf cells ultrastructure, is characterized by enhanced biosynthesis of antioxidant carotenoids and sucrose. Differently from Na+, high phosphorous (P) supply did not hamper photosynthesis although it affected carbon metabolism through reduction of starch content and by lowering isoprene emission. In particular, we revealed on salt-stress leaves that high P enhanced the expression of genes involved in abiotic stress tolerance, but further increased diffusive limitations to photosynthesis and slowed-down sugar turnover without modifying isoprene emission. Therefore, despite limiting productivity, high P improved A. donax tolerance to salinity by favouring the accumulation of carbohydrates that protect cells and increase osmotic potential, and by stimulating the synthesis of antioxidants that improves photo-protection and avoids excessive accumulation of reactive oxygen species.\n\nHighlightsArundo donax is sensitive to elevated salinity. High phosphorous supply to salt-stressed A. donax enhances transcriptomic changesthat induce the onset of physiological mechanisms of stress tolerance but limits productivity.

physiology↗