Angelo Fierro

Soil-Atmosphere Methane Exchange in Undisturbed and Burned Mediterranean Shrubland of Southern Italy

Soils represent the primary biotic sink for atmospheric methane (CH4). Uncertainty is associated, however, with global soil CH4 consumption because of the few data available from many areas and, in particular, from Mediterranean-type ecosystems. In this study, soil-atmosphere CH4 exchange was measured for one year in a coastal Italian shrubland (maquis), from both undisturbed areas and areas treated with experimental fire. Although fire represents one of the most frequent disturbance factors in seasonally dry environments, very few studies in these ecosystems have focused on its effect on soil CH4 fluxes. Significant differences in soil ammonium content, water content, and temperature were measured between burned and unburned plots, however, no statistical differences were observed for CH4 fluxes. CH4 fluxes varied between −0.39 and −16.1xa0mg CH4 m−2 day−1 and temporal variations were mainly driven by variations in soil water content and temperature. The highest CH4 oxidation rates were measured during the driest and warmest period. Low gravimetric soil water content in the top 10xa0cm, as well as high NH4+ concentration, did not seem to reduce methanotrophic activity, suggesting that maximal CH4 oxidation activity might take place deeper in the soil profile, at least during part of the year.

Factors regulating litter mass loss and lignin degradation in late decomposition stages

We studied late-stages decomposition of four types of coniferous needle and three types of deciduous leaf litter at two sites, one nutrient-poor boreal and one nutrient-rich temperate. The late stage was identified by that reached by litters at the onset of net loss of lignin mass, i.e. at about 1xa0year after the incubation when the highest amount of lignin had been detected; the study extended over the following 2xa0year period. Decomposition rates were significantly lower at the boreal than at the temperate site and did not differ between needle litter and leaf litter. In the boreal forest: (1) mass-loss was positively correlated with N and Mn release, (2) Mn concentration at the start of the late stage was positively correlated with lignin decay, (3) Ca concentration was negatively correlated to litter mass loss and lignin decay. In the temperate forest neither lignin, N, Mn, and Ca concentration at the start of the late stage, nor their dynamics were related to litter decomposition rates and lignin decay. In leaf litter mass-loss and lignin decay were positively correlated with N and Ca release and with Ca concentration. In needle litter mass-loss was positively correlated to Mn release and N concentration negatively with lignin decay. We concluded that Ca, N and Mn have different roles in controlling lignin decay depending on type of litter and site conditions.

The influence of management and environmental variables on soil N2O emissions in a crop system in Southern Italy

Soil N2O emissions were monitored throughout a 3-year crop rotation including maize, fennel and a ryegrass-clover sward, at Borgo Cioffi NitroEurope site. N2O emission rates were highly variable in time and space and controlled by soil nitrogen and soil water content. The N2O effluxes were low for most of the monitored period. The highest N2O emissions were recorded throughout the 2007 maize cropping season, ranged form 15.2 to 196.2xa0μgxa0m−2xa0h−1 whereas the lowest ones ranged form −5 to 10xa0μgxa0m−2xa0h−1 during the 2007–2008 ryegrass-clover winter crop. For the maize crops, N2O peaks were detected after fertilization but with a delay of some weeks from applications, probably due to the presence of DMPP nitrification inhibitor in the applied fertilizer. A properly designed ANOVA model was developed to explain the influence of the main chemical-physical factors. This model also allowed the quantification of the delay time in peak emissions following fertilization, which resulted variable over the years and ranged between 2 and 21xa0days. A dependence of emissions from soil temperature and moisture was found, with significant interactions in some instances. Calculated Emission Factors (maize 2007: 0.48%; ryegrass-clover sward 2007–2008: 0.05%; maize 2008: 0.14%; fennel: 0.28% 2008–2009; maize 2009: 0.015%) resulted well below the values reported in the literature and the 1% reference value indicated by IPCC, probably due to a sub-optimal water regime inducing low Water Filled Pore Space (WFPS) values.

Comparative attributional life cycle assessment of annual and perennial lignocellulosic feedstocks production under Mediterranean climate for biorefinery framework

Annual fiber sorghum (FS) and perennial giant reed (GR) cultivated in the Mediterranean area are interesting due to their high productivity under drought conditions and their potential use as lignocellulosic feedstock for biorefinery purposes. This study compares environmental constraints related to FS and GR produced on experimental farms (in the Campania region) using an attributional life cycle assessment (LCA) approach through appropriate modeling of the perennial cultivation. For both crops, primary data were available for agricultural management. Direct field emissions (DFEs) were computed, including the potential soil carbon storage (SCS). Giant reed showed the lowest burdens for all impact categories analyzed (most were in the range of 40%-80% of FS values). More apparent were the differences for climate change and freshwater eutrophication (respectively 80% and 81% lower for GR compared to FS). These results are due to the short-term SCS, experimentally detected in the perennial GR crop (about 0.25 ton C ha(-1) yr(-1), with a global warming offsetting potential of about 0.03 ton CO2/ton(GR dry biomass)). The results are also due to the annual application of triple superphosphate at the sowing fertilization phase for FS, which occurs differently than it does for GR. Phosphorous fertilization was performed only when crops were being established and therefore properly spread along the overall crop lifetime. For both crops, after normalization, terrestrial acidification and particulate matter formation were relevant impact categories, as a consequence of the NH3 DFE by volatilization after urea were spread superficially. Therefore, the results suggest higher environmental benefits of the perennial crop than the annual crop.

Life Cycle Assessment of second generation bioethanol produced from low-input dedicated crops of Arundo donax L.

This work presents a Life Cycle Assessment (LCA) of bioethanol (EtOH) from perennial Arundo donax L. feedstock. A cradle-to-wheel approach was applied considering primary data for the cultivation of dedicated crops on hilly marginal lands and innovative second generation technologies for feedstock conversion into EtOH. The goals of the study were to: (i) quantify impacts of lignocellulosic EtOH production/use chain, (ii) identify hotspots and (iii) compare the environmental performance of different bioethanol-gasoline vehicles, E10 (10% EtOH and 90% gasoline) and E85 (85% EtOH and 15% gasoline), with a conventional gasoline passenger car. Results for E85 underlined that the feedstock production and the use phase were the prevailing contributors, whilst for E10 the gasoline production phase shared the largest part of impacts. The comparison showed that vehicles using lignocellulosic bioethanol have potentially significant benefits on global warming, ozone depletion, photochemical oxidant formation and fossil depletion in respect to conventional passenger car.

Effects of water stress on gas exchange of field grown Zea mays L. in Southern Italy: an analysis at canopy and leaf level

Zea mays is cultivated in the Mediterranean regions where summer drought may lead to photoinhibition when irrigation is not available. In this work the response of maize to water stress was evaluated by gas exchange measurements at the canopy and leaf level. Leaf gas exchange was assessed before, during and after water stress, while canopy turbulent fluxes of mass and energy were performed on a continuous basis. In the early growth period, a linear increment of net ecosystem photosynthetic rate (PNE) to incoming of photosynthetic photon flux density (PPFD) was found and net leaf photosynthetic rate (PNL) showed the tendency to saturate under high irradiance. During water stress, the relationship between PNE and PPFD became curvilinear and both PNE and PNL saturated in a range between 1,000 and 1,500xa0μmol (photons) m−2xa0s−1. Leaf water potential (ψl) dropped from −1.50 to −1.88xa0MPa during water stress, indicating that leaf and canopy gas exchanges were limited by stomatal conductance. With the restoration of irrigation, PNE, PNL and ψl showed a recovery, and PNE and PNL reached the highest values of whole study period. Leaf area index (LAI) reached a value of 3.0xa0m2xa0m−2. The relationship between PNE and PPFD remained curvilinear and PNE values were lower than those of a typical well-irrigated maize crop. The recovery in PNE and PNL after stress, and ψl values during stress indicate that the photosynthetic apparatus was not damaged while soil moisture stress after-effects resulted in a sub-optimal LAI values, which in turn depressed PNE.

Heavy metals and litter decomposition in coniferous forests

The dynamics of Mn, Zn, Fe, Cu, Pb, and Cd during litter decomposition was studied to understand how litter and soil metal concentrations influence the accumulation and/or the release of metals. Three types of leaf litters (green and brown leaves of Populus tremula L., green leaves of Betula pubescens Ehrh.) and four types of needle litters (green and brown needles of Pinus sylvestris L., brown needles of Pinus contorta L. and Pinus pinea L.), differing in heavy metal concentrations were incubated at two unpolluted coniferous forest sites: a temperate silver fir ( Abies alba Mill.) forest at site Monte Taburno, southern Italy, and a boreal Scots pine ( Pinus sylvestris L.) forest at site Jadras, Sweden. Compared to the Scots pine forest, the humic surface horizon of the silver fir forest had a higher pH, higher concentrations of available Cu and Cd, and lower Fe concentration. After a period of about 900 days, all litter types were more decomposed at M. Taburno than at Jadras. Zn, Fe, Pb and Cd concentrations in leaf and needle litters increased at both sites; Cu concentrations increased only in the silver fir forest; Mn concentration decreased in the litter richest in Mn and increased in the litters poorest in Mn. Litter decomposition in an early phase (0 up to 528/565 days) was significantly and positively correlated to initial Cu and Cd concentrations in litter. In a late phase (528/565 up to 918/929 days), decomposition was correlated significantly and negatively with litter Zn and Cu, and significantly and positively with litter Mn concentration at the start (528/565 days) of the period. At both sites, increases in absolute amounts of Fe, Cd, and Pb were observed in all litters; however, P. pinea , which showed the highest initial concentration of Pb, released Pb during decomposition. All litters released Cu at Jadras and accumulated Cu at M. Taburno. Zn was released at both sites from all leaf litters and from the needle litter of P. contorta . Mn was released at both sites from all litters, except the litter of P. tremula , which accumulated Mn at Jadras. The results indicate that heavy metal accumulation or release may depend on the gradient of metal concentration between litter and soil, on the pH of the soil, and on the capacity of litter to bind metal; atmospheric deposition could account at least partly for the increase of absolute amounts of Pb, Fe, and Cu at M. Taburno.

Post-fire stimulation of soil biogenic emission of CO2 in a sandy soil of a Mediterranean shrubland

Fire is a frequent perturbation in Mediterranean-type ecosystems, altering soil organic matter turnover. In a Mediterranean shrubland subjected to experimental fire, soil CO2 emissions were measured over an annual cycle in burned and unburned sites using static chambers. Some chemical-physical parameters affecting soil C turnover (soil nitrogen and organic carbon content, pH, soil temperature and water content) and some microbial indicators of soil C turnover, i.e. soil potential respiration, microbial carbon, metabolic quotient and coefficient of endogenous mineralisation, were also measured. A high spatial variability of CO2 effluxes was detected in control as well as in burned plots, with 8.9 and 16.6% respectively of hot spots of gas emission; the hot spots contributed 33% to the whole annual soil CO2 emission in control plots and 54.1% in the burned plots. No relationship between temperature and CO2 effluxes was found. In contrast, the data showed that soil water availability is the main climatic factor affecting field CO2 effluxes in the burned plots. Laboratory measurements under 55% of water-holding capacity showed a stimulating action of fire on soil organic matter mineralisation as indicated by coefficient of endogenous mineralisation, microbial carbon and metabolic quotient values. We concluded that fire could decrease the efficiency of soil microflora at conserving C.

Growth and gas exchange response to water shortage of a maize crop on different soil types

The effect of water shortage on growth and gas exchange of maize grown on sandy soil (SS) and clay soil was studied. The lower soil water content in the SS during vegetative growth stages did not affect plant height, above-ground biomass, and leaf area index (LAI). LAI reduction was observed on the SS during the reproductive stage due to early leaf senescence. Canopy and leaf gas exchanges, measured by eddy correlation technique and by a portable photosynthetic system, respectively, were affected by water stress and a greater reduction in net photosynthetic rate (AN) and stomatal conductance (gs) was observed on SS. Chlorophyll and carotenoids content was not affected by water shortage in either condition. Results support two main conclusions: (1) leaf photosynthetic capacity was unaffected by water stress, and (2) maize effectively endured water shortage during the vegetative growth stage.

Comparative life cycle assessment study on environmental impact of oil production from micro-algae and terrestrial oilseed crops

In this study the LCA methodology is applied in order to satisfy two goals: i) to evaluate the hot spots in site-specific production chain of biodiesel from terrestrial and micro-algae feedstock; ii) to compare quantitatively, utilizing primary data, the impacts of the first generation in respect to the third generation bio-fuels. Results show that micro-algae are neither competitive yet with traditional oil crops nor with fossil fuel. The use of renewable technologies as photovoltaics and biogas self production might increase the competitiveness of micro-algae oil. Further investigations are however necessary to optimize their production chain and to increase the added value of co-products.