Ecophysiological Responses to Rainfall Variability in Grassland and Forests Along a Latitudinal Gradient in Italy

Abstract

In the Mediterranean region, ecosystems are severely affected by climate variability. The Italian Peninsula is a hot spot for biodiversity thanks to its heterogeneous landscape and the Mediterranean, Continental, and Alpine climates hosting a broad range of plant functional types along a limited latitudinal range from 40 ′ to 46 ′ N. In this study we applied a comparative approach integrating descriptive statistics, time series analysis, and multivariate techniques to answer the following questions: (i) do the climatic variables affect Gross Primary Productivity (GPP), Reco, Water Use Efficiency (WUE), and ET to a similar extent among different sites? (ii) Does a common response pattern exist among ecosystems along a latitudinal gradient in Italy? And, finally (iii) do these ecosystems respond synchronically to meteorological conditions or does a delayed response exist? Six sites along a latitudinal, altitudinal, and vegetational gradient from semi-arid (southern Italy), to a mountainous Mediterranean site (central Italy), and sub-humid wet Alpine sites (northern Italy) were considered. For each site, carbon and water fluxes, and meteorological data collected during two hydrologically-contrasting years (i.e., a dry and a wet year) were analyzed. Principal Component Analysis (PCA) was adopted to identify temporal and spatial variations in GPP, Ecosystem Respiration (Reco), WUE, and Evapotranspiration (ET). The model outlined differences among Mediterranean semi-arid, Mediterranean mountainous, and Alpine sites in response to contrasting precipitation regimes. GPP, Reco, WUE, and ET increased up to 16, 19, 25, and 28%, respectively in semi-arid Mediterranean sites and up to 15, 32, 15, and 11%, respectively in Alpine sites in the wet year compared to the dry year. Air temperature was revealed to be one of the most important variables affecting GPP, Reco, WUE, and ET in all the study sites. While relative air humidity was more important in southern Mediterranean sites, Conte et al. Forest Responses to Rainfall Variability global radiation was more significant in northern Italy. Our work suggests that a realistic prediction of the main responses of Italian forests under climate change should also take in account delayed responses due to acclimation to abiotic stress or changing environmental conditions.

In-between Environmental Sustainability and Economic Viability: An Analysis of the State, Regulations, and Future of Italian Forestry Sector

“…The damage from climate change to Italian forests can be ascribed to the increase in the frequency and intensity of extreme events (heatwaves, late frost events, and reduction and/or asymmetrical distribution of rainfall, see, e.g., [108][109][110][111][112], which create a favorable context for parasitic and/or phytopathological attacks [113][114][115]. These have long-term repercussions also on employment levels, as well as on the supply chains and on the productive and sociocultural sectors associated with forests [116,117]. The storm "Vaia", in 2018, which struck a district of the Veneto region with a high forestry vocation [118][119][120], is a concrete example of the role of climate change in reducing the economic value of forested land in Italy [121][122][123].…”

Climate Change Impacts on the Water Resources and Vegetation Dynamics of a Forested Sardinian Basin through a Distributed Ecohydrological Model

“…The soil is a sandy-loam with a mean depth of 45 cm. Vegetation is mainly composed of Quercus ilex with a percentage cover ~60% [111,112]. This site is equipped with an eddy covariance tower for measuring evapotranspiration, CO 2 , and energy fluxes (e.g., [113]).…”

Exploring new strategies for ozone-risk assessment: A dynamic-threshold case study

“…In this study GPP was calculated from ecosystem scale fluxes of CO2 (NEE) by adding the ecosystem respiration term (Reco) to NEE, since NEE represents the balance between CO2 sequestrated and emitted by the photosynthetic (GPP) and respiratory (Reco) processes of the ecosystem. For more details on the site and meteorology, see Fares et al (2014) and Conte et al (2019).…”

“…Quercus ilex is an evergreen broadleaf forest species with a vegetative period which can last all year long in particularly warm years (Conte et al 2019). Exposure of leaves to ozone is therefore continuous and the turn-over of leaves, on average, is three years.…”