Anna Alfani

Effects of urban heavy metal pollution on organic matter decomposition in quercus ilex L. woods

Decomposition of oak (Quercus ilex) leaves containing different concentrations of Fe, Zn, Cu, Cr, Ni and Pb was measured in laboratory microcosms. The leaves were collected from a polluted site inside the city of Naples and from a control site away from the city. Soil was sampled from the upper A horizon (0–5 cm) at both sites and analyzed for respiration, microbial biomass and abundance of fungal mycelia. The soils from the two sites differed significantly in heavy metals concentrations. The accumulated mass loss reached an asymptotic value after four months both for the control and polluted litters. However, control and polluted litters significantly differed in accumulated mass loss, that was respectively 40 % and 29 % of the initial weight, after 10 months. Moreover decomposition rates appeared to be strongly influenced by metal contamination in the early stages, while in later stages, they did not differ significantly. Litter respiration appeared to be inhibited by metal contamination and showed pattern and rates consistent with those found for litter decomposition. Fungal mycelia were significantly less abundant both in litter and soil from the polluted site than from the control site. Metabolic activity (both as soil respiration and degree of mineralization) was lower in the polluted soil. Soil respiration and amount of soil mycelia correlated negatively with soil Pb, Zn and Cr concentration.

Factors regulating early-stage decomposition of needle litters in five different coniferous forests

The decomposition dynamics of needle litter of Stone pine (Pinus pinea), Corsican pine (Pinus laricio), Scots pine (Pinus sylvestris) and Silver fir (Abies alba) were investigated in a comparative study including five coniferous forest sites. Initial chemical composition, mass-loss rates, and the water-holding capacities of the litters were determined in the early stages of decomposition. Water-holding capacity differed among the fresh litters but increased in linear proportion to litter mass both over each species and over all species combined in a linear regression (r = 0.708; n = 45; P < 0.001). At the early decomposition stages the daily mass-loss rate of Scots pine needles in two dry sites was positively related to (1) the measured litter water content at sampling (r = 0.727; n = 16; P < 0.0025), (2) mean daily precipitation in the period of measurement (r =0.909; n = 16; P < 0.0001). These models could explain water as a rate-limiting factor to the extent of 49 and 81% respectively. A significant linear relationship was also found between decay rate during a moist period and accumulated mass loss (r = 0.771; n = 8; P < 0.05) which has been suggested to be due to the increase of litter water-holding capacity with increasing accumulated mass loss. Three types of decay curve are described and the pattern of decomposition at dry sites has been found to be influenced by moisture variations more than by litter quality.

Leaves of Quercus ilex L. as biomonitors of PAHs in the air of Naples (Italy)

Polycyclic aromatic hydrocarbons (PAHs) were determined by the GC-MS chromatography in the leaves of Quercus ilex L., an evergreen Mediterranean oak, to monitor the degree of pollution in the urban area of Naples compared to remote areas. Leaf samples were collected in July 1998 from four urban parks, six roadsides and two sites in remote areas. The total PAH contents in Q. ilex leaves ranged from 106.6 in a control site to 4607.5 ng/g d.w. along a road with a high traffic flow. The mean concentration factors (urban/control) were 3.8 for the parks and 15 for the roads. The contribution of carcinogenic PAHs (benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, indeno[1,2,3-c,d]pyrene) was higher in urban area and differed according to the site, ranging from 6.7% to 21.3%. The total PAH burden in control sites was dominated by the low molecular weight PAHs, whilst along the urban roads fluoranthene, pyrene and benz[a]anthracene among the measured PAHs showed the highest values. PAHs were positively correlated (P<0.01) to trace metals measured in a previous study.

Ecological portrayal of old‐growth forests and persistent woodlands in the Cilento and Vallo di Diano National Park (southern Italy)

Abstract The maintenance of certain levels of old forest represents a cornerstone of the EU’s biodiversity management strategy. A consensus on a single general ecological definition of old‐growth is particularly difficult in Mediterranean Europe. The present paper deals with old‐growth forests and persistent woodlands in the Cilento and Vallo di Diano National Park (PNCVD) to give an ecological understanding of forest complexity and dynamics under a multiscale and multidisciplinary perspective. The multiscale approach ranged from the identification and mapping of potential old‐growth stands at landscape scale to a two‐level field review of forest stand features. Field sampling involved a multidisciplinary team of researchers in forest structure, pedologic environment, soil microbial activity, flora and vegetation and deadwood components. The research provided sound knowledge about old‐growthness features in the PNCVD that constitutes a unique case study in the whole Mediterranean basin. The integration of results allowed to: identify main ecosystem functions and the related services of the old‐growth forests in the study area; distinguish persistent woodlands, multi‐aged stands with old trees deriving from nineteenth‐century management practices, from old‐growth forests sensu strictu; recognize indicators of direct and indirect impacts of human activities; suggest effective practices for sustainable management in the Mediterranean context.

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.

Leaf contamination by atmospheric pollutants as assessed by elemental analysis of leaf tissue, leaf surface deposit and soil

In order to evaluate the influence of air pollutants influx on leaf elemental composition, the concentration of N, S, Cu, Fe and Pb were analyzed in the surface deposit and tissue of Quercus ilex L. leaves from 8 sites of the urban area of Naples. The soil from the trunk base area of Q. ilex trees in the same sites was also analyzed for total contents of N and S and for available contents of Cu, Fe and Pb. In the leaf surface deposit S content was high though significantly (P <0.001) lower than in the leaf tissue, whilst N was not detectable. Cu, Pb and Fe contents in leaf surface deposit were conspicuous. The Pb content was higher in the leaf surface deposit than in the leaf tissue. No correlation between leaf tissue and surface deposit contents was found for S or for Fe. By contrast, positive and significant correlations (P<0.01) were found between leaf deposit and leaf tissue for both Cu and Pb. N and S contents in the leaves were not correlated to the respective contents in the soil and the same was also found for Cu and Fe. In contrast with the presence of limiting concentrations in the soil, N, S and Fe leaf contents were significantly higher than in the leaves from remote sites. The data suggest that direct uptake of airborne pollutants, in addition to root absorption, may influence leaf elemental composition of Q. ilex L. leaves.

TRACE METAL BIOMONITORING IN THE SOIL AND THE LEAVES OF QUERCUS ILEX IN THE URBAN AREA OF NAPLES

The concentrations of Pb, Cu, Fe, and Mn were analyzed in surface deposit and tissue ofQuercus ilex leaves from several sites of the urban area of Naples, exposed to different degrees of air pollution. These included some major roads with heavy traffic loads, squares, and three urban parks. The soil from the trunk base area ofQ. ilex trees in the same sites was also analyzed for total and available metal contents. Pb, Cu, and Fe contents in the surface deposit and leaf tissue were significantly higher (p<0.01) in leaves from roadside sites than in leaves from parks; significant correlations were found between deposit- and tissue-contents of Pb, Cu, and Fe. Mn content in leaves from roadside sites and in leaves from parks were similar and Mn content in the leaf deposit was irrelevant. Significant differences (p<0.001) in both total and available Pb and Cu soil content were found between sampling sites. Also for available Fe and Mn soil content differences among sites were relevant, although the highest values were measured in soil from urban parks. A positive correlation between leaf and soil metal content was found only for Pb, thus suggesting that trace metal contents of leaves directly depend on atmospheric depositions. Seasonal variations of Pb, Cu, and Fe were pronounced at a polluted site, whereas no relevant seasonal variation was observed at a control site; moreover, metal accumulation was high at the polluted site. Mn content and seasonal dynamics were comparable at control and polluted sites.

Assessment of nutritional status and trace element contamination of holm oak woodlands through analyses of leaves and surrounding soils

The nutritional status and trace element contamination of holm oak woodlands in Vesuvius National Park were assessed by analyses of Quercus ilex L. leaves and surrounding soils. The concentrations of Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn were measured in 1-year-old leaves, and in the soils at 0-5 and 15-20 cm depths. The potentially available concentrations were also measured for the soils. The leaf element concentrations were similar to the Q. ilex chemical fingerprint, thus indicating a good nutritional status and the absence of short-term trace element depositions. Total K and V were more abundant in the deep soil layers than in the surface ones, whereas Cd and Pb showed higher values in the surface soils. This suggests that long-term soil accumulations of Cd and Pb are due to atmospheric input. The soil availabilities of Cd, Pb and Zn were high, and Cr availability was very low. A correlation between the available concentrations in the deep soil layers and leaf concentrations was found only for Zn.

Assessment of the effects of soil PAH accumulation by a battery of ecotoxicological tests

Surface soils were collected at remote, urban and industrial sites in the Southern of Italy in order to evaluate PAH concentrations and assess the toxic effects by a battery of ecotoxicological tests. The tests were performed on whole soils and on both organic and aqueous extracts. Further goal of this study was to integrate the results coming from each test and matrix in a synthetic toxicity index. The highest summation sigmaPAH concentrations were measured at the industrial soil, although this one did not show an high ecotoxicological risk. Among the performed tests, the phytotoxicity tests showed the highest sensitivity. For whole soil, the worst case always has been represented by test through bacteria. Our results could represent the first step toward the selection of a proper battery to characterize the soil ecotoxicological risk.

Improved biomonitoring of airborne contaminants by combined use of holm oak leaves and epiphytic moss

Concentrations of 12 elements (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn) and 16 EPA-listed PAHs were detected in Quercus ilex leaves and the epiphytic moss Leptodon smithii collected at urban, periurban and extraurban holm oak stands, in two Italian Regions (Campania and Tuscany). Levels of environmental contaminants were generally higher in leaves and moss from urban areas than periurban and extraurban ones and samples from Campania had the highest PAH content. The epiphytic moss accumulated higher concentrations of trace elements than leaves and the latter showed a higher accumulation capability for PAHs, especially for those with low molecular weight. The different bioaccumulation in leaves and moss were explained in terms of their distinctive morphological and ecophysiological characteristics. The combined approach seems a promising tool for the monitoring of a wide range of pollutants in Mediterranean urban and extraurban environments.