Antonietta Fioretto

Lignin decomposition in decaying leaves of Fagus sylvatica L. and needles of Abies alba Mill

Abstract Lignin decomposition in litter of beech leaves and fir needles as related to litter N concentration and litter mass loss was studied for 7 y in two forests at Mount Taburno (41°05′N., 12°07′E.; Campania Apennines). Both types of litter showed a pattern of decomposition characterized by two stages with significantly decreasing decomposition rates. Litter N concentration did not appear to influence the rate of litter decomposition in either the early or the late stage of the process. On the contrary mass loss rates of litter were influenced by lignin concentrations at the beginning of the late stage: the lower the lignin concentration the higher was mass loss rate. Both in beech and fir litter lignin degradation started immediately during incubation. Lignin degradation throughout the study was less in fir needles than in beech leaves with lignin losses of 60–67% and 73–87% of initial amount, respectively. Both in beech and fir litter, lignin loss rate was negatively correlated to the initial N concentration. Lignin loss rate of both beech and fir litter was correlated to litter mass loss rate during the early as well as during the late phase of decomposition. Different dynamics of lignin decomposition between the two species were observed with a higher lignin decomposition rate in the early stage than in the late stage in beech litter, and rates of lignin decomposition increasing from early to late phase in fir litter.

Soil microbial activity in three evergreen oak (Quercus ilex) woods in a Mediterranean area.

Publisher Summary This chapter reviews the study on soil respiration and enzyme activities—cellulase, xylanase, invertase, protease, and trealase—in three evergreen oak woods in Southern Italy (Campania). The experimental sites differed in chemical and physical characteristics and microclimatic conditions. The chapter evaluates whether differences in chemical and physical soil characteristics and in microclimatic conditions promote differences in the biological activity of microbial communities. The microbial activity was tested every three months for one year. Microbial respiration showed seasonal variations, with minimum levels in summer and maximum levels in wet seasons, and this pattern closely followed seasonal changes in moisture content. In absolute terms, the highest levels of microbial respiration were found in the Vesuvius soil, which also had the highest organic C content, whereas the lowest levels were found in the Castel Volturno soil. Seasonal variations in enzyme activities were also found with good correlation with soil moisture content. No significant differences in enzyme activity were found among the three studied woods.

Soil organic matter, nutrient distribution, fungal and microbial biomass and enzyme activities in a forest beech stand on the Apennines of southern Italy

The aim of this study was to analyse the amount and qualitative characteristics of organic matter (OM) in the litter horizon (considering leaf litter at different decomposition stages) and underlying soil to a 30-cm depth in a beech stand on the Apennines in southern Italy. Distribution of major nutrients as well as fungal and microbial biomass were also evaluated, in addition to beech leaf nutrient content monitor from full expansion to abscission in order to estimate annual nutrient input to soil from litterfall and nutrient retranslocation before abscission. OM was significantly higher in leaf litter. C/N ratio and the Na, Mn, Fe levels also decreased along the decomposition continuum, whereas N and S contents slowly decreased with soil depth. Generally, leaf nutrient content was also significantly lower in dead leaves, indicating efficient retranslocation to persistent organs. Fungal biomass was the highest in leaf layers, with no significant changes between spring and autumn samplings. Enzyme activities did not differ significantly along the decomposition continuum but marked decreases were found in the upper soil layer; these remained relatively constant, with the exception of laccase, at deeper soil depths. No seasonal effect on enzyme activities and OM content was found.

Spectrophotometric methods for lignin and cellulose in forest soils as predictors for humic substances

The origin and fate of humus, a soil organic matter fraction that is most resistant to decomposition, are not yet completely understood. Humus derives mainly from plant structural components; that is, lignin and cellulose, together with several other primary and secondary compounds. There are several methods to estimate lignin and cellulose in plant material; however, the applications to soil are limited and usually complicated and expensive. Conversely, humus can be estimated in soil by chemical titration methods, which estimate the carbon linked to humic and fulvic acids (HAC and FAC). Therefore, we carried out analyses that aimed to compare, within beech forest soils, spectrophotometric data for lignin and cellulose with those of HAC and FAC. We used soil samples from six different beech woods in Italy, sampling in four layers from 0–5 to 30–40 cm. The relations between spectrophotometric cellulose and lignin and HAC and FAC were tested by linear mixed models. Our results showed that both lignin and cellulose were significant predictors for HAC and FAC, even if cellulose had a larger conditional coefficient of determination (Rc). The best fit was between cellulose and the sum of HAC and FAC (Rc = 0.675). Our novel approach proved that spectrophotometric lignin and cellulose provide reliable results in both organic and mineral beech forest soils, even though lignin had a greater random variation than cellulose. Thus, spectrophotometric lignin and cellulose provide reliable and rapidly obtained predictors of humic substances in beech forest soils, with appropriate conversion factors to estimate HAC and FAC.

Analysis of 11 trace elements in flight feathers of Italian Sparrows in southern Italy: A study of bioaccumulation through age classes, variability in three years of sampling, and relations with body condition

Trace elements have been acknowledged as one of the subtlest environmental hazards in all compartments of the total environment. Enhanced by activities in the anthroposphere, they accumulate in the atmosphere, lithosphere, and hydrosphere. Eventually, trace elements can bioaccumulate or biomagnifiy in the biosphere, with harmful effects on animals occupying higher trophic levels, including humans. Accordingly, there is great interest in assessing and monitoring trace element concentrations in the biosphere, and birds, especially passerines, have been commonly chosen as biomonitors. In this study, the concentration of 11 trace elements was measured (i.e. aluminum, chromium, manganese, iron, nickel, copper, zinc, arsenic, cadmium, barium, and lead) in flight feathers of Italian Sparrows, a common bird species hitherto not analysed in this respect. Samples were collected in an agricultural area in southern Italy, where a mosaic of natural environments, urbanized areas and industrial facilities can be found. Linear mixed modelling was applied to the analysis of flight feathers in juveniles, juvenile birds moulting to adulthood, and adults in three sampling years on 184 birds. Results are timely as they add new data to the scarce available information on Ba and As in bird feathers and showed clear bioaccumulation patterns from juveniles to adults for As, Cr, and Cd. Moreover, the modelling approach showed that the concentration of elements such as As, Cd and Cr can be variable across the years and that some elements, notably Cd and Ba, were inversely correlated with body mass and wing length, respectively, suggesting potential negative effects on bird health. Finally, when modelling bird body condition and trace elements, results showed that Cd and Ba negatively affect birds regardless of age or sampling year. Thus, the Italian Sparrow could be considered as a valuable biomonitor for trace elements in the total environment, especially for Cd and Ba.