Paola Iovieno

Effect of drying and rewetting on bacterial growth rates in soil

The effect of soil moisture on bacterial growth was investigated, and the effects of rewetting were compared with glucose addition because both treatments increase substrate availability. Bacterial growth was estimated as thymidine and leucine incorporation, and was compared with respiration. Low growth rates were found in air-dried soil, increasing rapidly to high stable values in moist soils. Respiration and bacterial growth at different soil moisture contents were correlated. Rewetting air-dried soil resulted in a linear increase in bacterial growth with time, reaching the levels in moist soil (10 times higher) after about 7 h. Respiration rates increased within 1 h to a level >10 times higher than that in moist soil. After the initial flush, there was a gradual decrease in respiration rate, while bacterial growth increased to levels twice that of moist soil 24 h after rewetting, and decreased to levels similar to those in moist soil after 2 days. Adding glucose resulted in no positive effect on bacterial growth during the first 9 h, despite resulting in more than five times higher respiration. This indicated that the initial increase in bacterial growth after rewetting was not due to increased substrate availability.

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.

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.

Effects of soil pollutants, biogeochemistry and microbiology on the distribution and composition of enchytraeid communities in urban and suburban holm oak stands

Holm oaks form typical urban woodlands in the Mediterranean region. We aimed at characterizing the enchytraeid communities in these environments and searching for possible correlations with soil parameters, including the traffic contamination. Samples of litter and topsoil were collected at different spatial scales and seasons in Naples and Siena cities and in two suburban stands. Only the co-variation between pollution and other soil chemico-physical factors showed significant effects, whereas no direct effect of soil microbiology was detected. Some thermophilous Fridericia and Achaeta tolerate high concentrations of heavy metals and PAHs and their abundance was mainly determined by Ca bioavailability. Central-European mesophilous species increased significantly under more temperate environmental conditions. Different combinations of soil cohesiveness, grain size composition and moisture regime seem to select species of certain body sizes.

Genetically biodiverse potato cultivars grown on a suitable agricultural soil under compost amendment or mineral fertilization: yield, quality, genetic and epigenetic variations, soil properties

The use of compost for soil amendment is a promising agricultural practice environmentally and economically viable. In the framework of a wide research project designed to evaluate the effects of soil amendment with municipal solid waste compost in comparison with traditional mineral fertilization practices, 54 different cultivars (Cvs) of potatoes were AFLP (amplified fragment length polymorphism) molecularly fingerprinted. The seven most genetically biodiverse potato Cvs were used to establish an experimental field in southern Italy. The field area was divided into two portions fertilized with compost (20 Mg ha(-1)) or with ammonium sulphate (200 kg ha(-1)). No significant differences in productivity, organoleptic characteristics and element concentrations were observed between the potato tubers obtained with both kinds of soil fertilization, while the tubers grown on compost amended soil showed, on average, higher K concentrations with respect to those grown on mineral fertilised soil. cDNA-AFLP (complementary DNA-AFLP) and MSAP (methylation sensitive amplified polymorphism) analyses were carried out on both leaves and tubers of one selected Cv to estimate if any transcriptome alterations or epigenetic modifications were induced by the two kinds of fertilization, however no variations were detected. Chemical and biological soil qualities (i.e., microbial respiration, FDA hydrolysis, alkaline and acid phosphatase) were assessed on soil samples at the start of the experiment and at the end of potato crop cycle. No significant differences in soil pH and limited ones, in the available fraction of some trace elements, were observed; while conductivity was much higher for the compost amended portion of the experimental field. Microbial respiration, FDA hydrolysis and acid phosphatase activities were significantly increased by compost amendment, in comparison with mineral fertilization. Finally, a sensory panel of potato Cvs detected no significant differences among qualitative descriptors and among potatoes coming from the two differently fertilized soils.