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Question: Do low or high intensity fires affect micro-organism activity in the upper soil layer of Mediterranean maquis? Location: 600 m from the sea in the Nature Reserve of Castel Volturno (Campania, southern Italy, 40°57' N; 13°55' E). Methods: Soil respiration was measured in situ on intact soil; enzyme activity (cellulase, xylanase, invertase, trehalase and protease) and ATP content were measured on soil samples collected under three species of maquis vegetation: Phillyrea angustifolia L., Myrtus communis L. and Cistus incanus L. Results: Soil microbial respiration showed no significant differences in CO 2 flux in treated and untreated plots, but the ATP content in the soil under C. incanus and M. communis was lower in the treated plots for most of the study period. In the soil under Ph. angustifolia, ATP content was low only for one week after fire. The reduction was more marked in the samples from 'high fire intensity' than from 'low fire intensity' plots. Soil respiration and ATP content exhibited seasonal variations linked to soil water content. Among the enzyme activity measured in the soil under the three plant covers, only invertase declined in burned plots throughout the study period, particularly in the 'high fire intensity' plots. Activity of the enzymes cellulase, xylanase, trehalase and protease had a different sensitivity depending on the respective shrub cover. Conclusions: Impact of fire on soil microbial activity is largely dependent on vegetation mosaic and species identity. © IAVS; Opulus Press.

Forests are among the most important land ecosystems both in term of their contribution to the global carbon cycle and for their prominence in hosting large biodiversity. Under a changing world, both in terms of land use and climate scenarios, it is pivotal to understand the matter and energy flows in complex ecosystems such as forests, in order to infer potential relationships at different levels, i.e. from soil to bird community within the forest stands. In this context, soil organic matter is main source of carbon and energy for heterotrophic soil organisms, which are a main component of the whole food web all the way up to bird communities. Even though many studies have investigated factors affecting C cycle and bird communities in forest ecosystems separately, an integrated approach that links soil to bird community was never attempted. Accordingly, we have used an innovative Two-block Partial Least Squares analysis to investigate patterns of covariance between soil and nesting bird communities in a relatively small wooded area surrounded by the urban area of Naples (southern Italy). Our research revealed that, in spite of the small extent and the surrounding urban context, the area of the Astroni hosts a substantial C stock and has a diversified bird nesting community. The abundance of species such as blue tit, jay, green woodpecker and great tit had a direct covariance with C stock in litter, while sampling sites that were characterized by greater C stocks in the soil and higher microbial activity were correlated with abundance of other bird species, most noticeably short-toed treecreeper and blackbird. Despite the limited extent of our research area, our study showed, for the first time, patterns of covariance between some forest species and different soil variables, linking forest ecological compartments whose connections are not immediately detectable and that could open new perspectives in land use management, both in terms of C stock and biodiversity evaluations.

Agricultural soils generally have a low content of organic matter, which affects soil fertility and hence crop yields. The use of olive pomace as an organic amendment could enhance soil properties due to its high content of organic matter and exchangeable cations as well as its extensive availability. However, little is known about the potentially detrimental effects of salts and high content of phenolic substances that might occur over time with the use of pomace amendment in agricultural soils. Similarly, its impact on microbial communities and enzyme activities is largely unknown. To ascertain these effects, we tested the response of soil enzyme activities (β-glucosidase, urease, acid phosphomonoesterase and dehydrogenase) starting from a long-term (8-year) previously amended soil and a control (non-amended) soil and exposing these soils to a short-term (12-week) laboratory experiment. We also focused on soil organic matter and mineral N, on relating enzymatic data to bacterial and fungal biomasses, and on an index for soil functional quality based on enzyme activities (AI3). Our results show that organic matter, enzyme activities and the soil quality index were improved by long-term treatment with olive pomace, contrasting with scant effects from short-term laboratory incubation. In spite of its high content in salts and phenolic substances, no detectable negative impact emerged from the use of this amendment. Overall, olive pomace clearly increased soil organic matter and improved soil biological activity and quality, without any detectable negative effects.

Litter decomposition is an ecosystem process that is regulated by a multitude of factors and by their complex interactions. Current decomposition paradigms do not always offer a coherent view of the process because it can be hardly understood without a thorough analysis of interacting factors. Thus, there is a need to further understand the mechanics of litter decay with a comprehensive approach, especially in temperate forest ecosystems where decomposition plays a crucial role in regulating them as source or sink of CO2. Therefore, the aim of this work was to identify the interactions between chemical, biological and soil fauna variables in order to discern driving variables and the changes in their interactions during long-time (1300 days) beech leaf litter decomposition. In order to investigate patterns of variation and co-variation within and between datasets, we used Two-block Partial Least Squares, helping us to interpret the decomposition process with a systemic approach. Our key findings showed that the decomposition process of beech litter in two Mediterranean forests was driven by litter quality at the beginning and in the later stages of decomposition, while edaphic and climatic factors were implied in the central steps, with a dramatic change of scenario around 2.5 years. Simultaneous and interacting changes in chemical variables, extracellular enzyme activities, and soil fauna were shown, with a significant role of lignocellulosic components and enzymes involved in their degradation, Mn residual weight, and abundance of Collembola.

Forests are the most important land ecosystems that can mitigate the earth’s ongoing climate change through their ability to sequester CO2 as C stock in forest biomass and soil. Short-rotation deciduous hardwoods or N2-fixing species are ideal candidates for afforestation and reforestation, given that most of the carbon accumulates in the first 30 years. Alders match both of the above-mentioned features, and Italian alder, which is less dependent on riparian habitats and more drought tolerant, is an ideal candidate. Despite this, few studies exist of this tree species and its effect on soil organic matter. In this study, we focused on litter input and leaf litter decomposition dynamics, forest floor leaf litter and topsoil (0–5 cm) organic matter, and patterns of covariation from litter to topsoil. The leaf litter was rich in nitrogen and decomposed quickly (k = 0.002 day−1). There was a large organic carbon stock, which varied in the leaf litter (from 1.7 ± 0.3 Mg/ha in January to 0.4 ± 0.1 Mg/ha in July) and was stable in the topsoil (on average 28.6 ± 1.5 Mg/ha). Stocks for total nitrogen, cellulose, lignin, water and ethanol extractables, and total phenols were also evaluated. In order to investigate patterns of covariation in these stocks from litter to soil, we used two-block partial least squares. The first axis showed that from January to July there was a reduction of total nitrogen, lignin and cellulose in the forest floor leaf litter, while in the topsoil there was a decrease in water extractables and total organic carbon. The second axis showed minor phenomena involving phenols, water and ethanol extractables, and total N. The fast turnover of dissolved organic matter fractions (water and ethanol extractables), linked with cellulose and lignin dynamics, might suggest that within the Italian alder ecosystem there is a reasonably fast formation of stable C compounds in the soil. Thus, Italian alder is an ideal species for afforestation and reforestation, which could be particularly interesting for land-use policies.

This study reports a comparative analysis of soil enzyme activities (β-glucosidase, protease, urease, arylsulphatase, phosphatase and fluorescein diacetate hydrolase), ATP, total N and organic matter contents in three vegetal successional stages (meadow, low shrubland and high maquis) of a Mediterranean ecosystem in the Natural Reserve of Castel Volturno (Campania, Italy). Because water availability is a major limiting factor of soil microbial activity in Mediterranean ecosystems, the analysis was performed in late spring (May), after the rainy period, and in early autumn (October), after the long dry summer. A significant decrease in protease, arylsulphatase, urease and β-glucosidase activities was observed in meadow soil in the autumn sampling, probably due to the prolonged summer drought. Combining the values measured in the two sampling dates, the high maquis tended to have higher levels of enzymes activities than shrubland and meadow. Notably, high maquis had significantly higher phosphatase and arylsulphatase activities than shrubland and meadow and, in addition, a higher ATP content compared to meadow. Drastic changes were observed in EA/ATP ratios between the sampling periods in the meadow and shrubland, suggesting changes in the efficiency of microbial community more likely linked to climatic fluctuations than to the successional stage. The more stable EA/ATP ratio in the maquis probably reflects a constant contribution of microbial biomass to enzyme secretion. In conclusion, our results point to an increase in soil microbial activity accompanying the succession from meadow to high maquis that probably reflects a parallel increase in soil functions. Nevertheless, spatial heterogeneity and, more important, temporal variations in soil activities often may obscure differences related to the plant cover type. © 2009 Elsevier Ltd. All rights reserved.

Soil microbial activities and chemical properties related to the N cycle were investigated in function of variations in plant cover type in a Mediterranean area of Southern Italy. Several biological (microbial biomass, soil respiration, protease activity, degradation of 7 amino acids, net N mineralization, net nitrification, potential net nitrification and denitrification) and chemical properties (water content, pH, organic C, total and mineral N, C/N ratio) were determined in soil samples collected in spring and early autumn under three plant cover types (high maquis, low shrub community and meadow) epitomizing distinct successional stages following disturbance. Water content, organic C and C/N ratio were higher in soil from high maquis than in soils from the other plant cover types; in contrast, no difference was generally observed between the three soil types as for total and mineral N content. Likewise, no clear-cut difference was recorded for most of the tested biological parameters if these were expressed per unit of soil dry weight, with the exception of protease activity and soil respiration, which were significantly higher in the high maquis. However, when biological data were expressed per unit of organic C, meadow soil showed higher values of microbial biomass, asparagine degradation (only in spring), net mineralization and net nitrification (only in autumn) compared to the other soils. Statistical analysis pointed to seasonal fluctuation of water availability as an important limiting factor for microbial biomass and activity, with the exceptions of net N mineralization, net nitrification, glutamine and glutamic acid degradation activities which appeared to be mainly driven by organic matter content in soils. Overall, the results suggest that, in the investigated Mediterranean environment, variations in plant community ranging from meadow to high maquis produce little changes in soil biological activities linked to the N cycle, these being primarily affected by the availability of water and soil organic matter during the annual cycle. © 2009 Elsevier B.V. All rights reserved.

The patterns of microbial respiration and enzyme activity (cellulase, xylanase, laccase and peroxidase) in the leaf litter of two evergreen sclerophyll species, Myrtus communis and Quercus ilex, were compared during decay in a low shrubland and in a coppice wood in a Natural Reserve in the Mediterranean area. The two litter types had similar initial amounts of lignin, cellulose and acid-detergent-soluble substances, but the litter from M. communis had a lower N content and higher C/N ratio. In spite of this, the decomposition rate of M. communis litter was higher than for Q. ilex. Whilst no seasonal variation was observed in the rate of organic matter degradation, respiration and extractable cellulase and xylanase activities showed seasonal variation in both litter types with the highest values in winter-early spring and the lowest in summer, and showed positive correlations with water content. Peroxidase activity exhibited a seasonal pattern and was higher in Q. ilex than in M. communis, while laccase activity was higher in M. communis and increased with fungal biomass as degradation progressed. Nevertheless, no relationship was found between laccase and peroxidase activity and lignin degradation. The results obtained indicate that the seasonal alternation of moist and dry periods is the major factor influencing soil biological activity in the Mediterranean area. The occurrence of pronounced seasonal variation in litter enzyme activity prevents the determination of possible correlations with litter mass loss. © 2006 Elsevier B.V. All rights reserved.

Leaf litter decomposition is one of the key phenomena in forest ecology. The patterns and trends of decomposition are related to the complex interaction of climate, soil biota and litter quality. The decay dynamics for the European beech are well-known for middle Europe, but lesser investigated in the Mediterranean area. In this study, we investigated mass loss and nutrient dynamics, especially nitrogen and manganese, in two Mediterranean beech forest located in northern and southern Italy. We used a litterbag experiment with leaves of each forest incubated in their own area of origin and vice versa. Moreover, we also used microcosms to follow early stages of decomposition under controlled conditions. The aims of this study were to investigate the role of climate and soil/litter quality at the different stages of decomposition and assess the response of diverse soils to changes in temperature and humidity. The results showed a faster field decomposition for the southern (warmer) site compared to the northern (colder) site, whereas under stable conditions in microcosms this trend reversed, implying different microbial adaptations to climate. Moreover, changes in temperature and humidity triggered complex microbial response during litter decay. Additionally, whereas our results showed trends of nitrogen concentration comparable to previous studies, the role of manganese in decomposition was very relevant even from the early stages. Noticeably, manganese was generally lower in both sites compared to middle Europe, but it was higher in the northern site than in the southern one. Manganese concentration, however, strongly increased for those leaves that had a lower initial content in all conditions, giving evidence of a strong mobilization of this nutrient and its essential role for decomposition in Mediterranean beech forests. Leaf litter decomposition is one of the key phenomena in forest ecology. The patterns and trends of decomposition are related to the complex interaction of climate, soil biota and litter quality. The decay dynamics for the European beech are well-known for middle Europe, but lesser investigated in the Mediterranean area. In this study, we investigated mass loss and nutrient dynamics, especially nitrogen and manganese, in two Mediterranean beech forest located in northern and southern Italy. We used a litterbag experiment with leaves of each forest incubated in their own area of origin and vice versa. Moreover, we also used microcosms to follow early stages of decomposition under controlled conditions. The aims of this study were to investigate the role of climate and soil/litter quality at the different stages of decomposition and assess the response of diverse soils to changes in temperature and humidity. The results showed a faster field decomposition for the southern (warmer) site compared to the northern (colder) site, whereas under stable conditions in microcosms this trend reversed, implying different microbial adaptations to climate. Moreover, changes in temperature and humidity triggered complex microbial response during litter decay. Additionally, whereas our results showed trends of nitrogen concentration comparable to previous studies, the role of manganese in decomposition was very relevant even from the early stages. Noticeably, manganese was generally lower in both sites compared to middle Europe, but it was higher in the northern site than in the southern one. Manganese concentration, however, strongly increased for those leaves that had a lower initial content in all conditions, giving evidence of a strong mobilization of this nutrient and its essential role for decomposition in Mediterranean beech forests. (C) 2015 Elsevier B.V. All rights reserved.

The decomposition dynamics of the litters of Corsican pine ( Pinus laricio Poiret), Stone pine ( P. pinea L.) and Scots pine ( P. sylvestris L.) exposed in a Corsican pine forest in the South Italy Apennines were followed for 2.5 y. Litter decomposition was very slow for all three species and appeared to be limited mainly by the low water availability throughout the study. The microbial activity, expressed as respiration, and the fungal biomass were also low due to the low moisture content of the litters, as suggested by the high increase of the potential respiration, after their hydration. A highly significant and positive relationship between potential CO 2 evolution rates and litter moisture content was found. The decomposition dynamics were also affected by the initial chemical composition of the three litter types. A delay in starting decomposition and the lowest initial rate were observed in Stone pine litter, that had the highest initial N, but also the highest lignin content and the lowest initial Mn content.

Concentrations of commonly used organochlorine pesticides (OCPs) were determined in tissues of 23 adult and 24 larval water frogs of two coexisting species (Rana lessonae and the hemiclonal hybrid R. esculenta) and in the water of their breeding pond in an agricultural zone in Umbria, central Italy, where increased occurrence of infectious diseases and distinctly oversized tadpoles were recently observed. The concentrations of OCP in tissues of both species were lower than those in the water of their breeding pond, except for DDT, which was more concentrated in adult frogs than in pond water (bioaccumulation factor 7 for R. lessonae, 15 for R. esculenta). Total OCP concentration and adult body weight were positively correlated for both species, which is consistent with bioaccumulation. In accord, adults contained higher OCP concentrations than tadpoles. Oversized tadpoles had higher OCP concentrations than normal tadpoles. Mean OCP concentrations in individual organs were about an order of magnitude higher than those in whole-frog homogenates. They were highest in brain, higher in ventral than in dorsal skin, and moderately high in ovaries; transmission of bioaccumulation loads to the next generation is therefore possible. The observed OCP concentrations appear too low to directly cause mortality in water frogs, but effects of cumulative exposure to low-level pollutants and their synergistic interactions with the effects of other natural and anthropogenic environmental stressors are unknown.

The fungal mycelium ingrowth and the rates of mass loss and respiration of needle litter of Pinus pinea, Pinus laricio, Pinus sylvestris, and Abies alba were investigated, in three coniferous forests, over a 3-year period by means of a composite set of incubations. In the early stages, the fungal flora of the decomposing needles was dominated by dematiaceous hyphomycetes and coelomycetes. Basidiomycetes reached a peak after 6 months on pine needles, but were absent from the N-rich needles of A. alba. Soil fungi (Penicillium, Trichoderma, Absidia, Mucor sp. pl.) became most frequent in later stages. At the end of the study period, the total mycelium amount showed the lowest values in all pine needles incubated in the P. laricio forest and the highest ones in P. pinea needles incubated in the P. pinea forest. In all data sets, as in data for boreal forests examined for comparison, the concentration of litter fungal mycelium versus litter mass loss followed a common exponential model. However, in later stages, the amount of litter fungal mycelium was very close to that of the humus at the incubation site, thus supporting the hypothesis of a logistic growth pattern. Respiration rates of decomposing litters varied with season and decreased with litter age to values close to those of the humus at the incubation site. Respiration of water-saturated litter was negatively correlated with the total mycelium concentration, and this was consistent with the observation that in far-decomposed litter only a minor fraction of the total mycelium is alive. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.

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.