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Purposes: The aim of this paper was to characterize elements dynamics, including resorption before leaf shedding and accumulation/release during decompo sition, of two functionally diferent tree species, the N-fxing, broadleaf, deciduous black locust (Robinia pseudoacacia L.), and the Mediterranean black pine (Pinus nigra Arn.), planted on recent unconsolidated volcanic deposits. Methods: In two paired, 40 years old stands, we investigated the stoichiometry of thirteen elements in green leaves, newly shed leaf litter, stable litter resi due and soil. Results: Black locust leaves were richer in N, P, K, Mg and Mn; black pine needles were richer in Na, Fe, Zn, Cr, and Pb. Resorption efciency was Pb>Zn>Fe~N~Mn~Mg>Cd~K>P in black locust, and Pb~Cu>Zn~Na>Mn>K~Cr in black pine. Com pared to black pine, black locust newly shed litter was richer in K, Na, Mn, Cu, and Ni. During decomposi tion, black locust leaf litter released N, K, Mg, Na, Mn, Zn, Cu and Cd, and accumulated Fe, Ni, Cr and Pb, whilst black pine needles released N, Zn and Cd, and accumulated all the other elements. Compared to black locust black pine had a stable needle litter resi due richer in all elements but N, whilst the mineral soil was poorer in all elements but Pb. Conclusions: The two functionally diferent tree species have distinct element dynamics from leaf to far decomposed litter. Element sequestration in the stable residue of black pine litter, likely prevents their release in the mineral soil that is thus poorer in nutrients and minor elements compared to the soil of black locust.

Aims In Mediterranean ecosystems fire and drought are two natural disturbances that affect plant traits and generate a highly heterogeneous landscape. The objective of this research was to analyze leaf chemistry, one important driver of carbon and nutrients cycles, and decomposition of Phillyrea angustifolia L. in a landscape affected by recurrent fire disturbance. Methods We investigated leaf litter collected in a low-maquis at sites burned by a wildfire 10 years before the current study, at sites burned by an experimental fire 1 year before and at sites located at the edge low-maquis/gaps. Results The three litters differed in chemical composition, mass loss and dynamics of lignin/AUR (Acid-Unhydrolizable-Residue), nitrogen and manganese. During the early decomposition phase lignin/AUR increased in litters from sites burned 1 year before and from sites located at the edge low-maquis/gaps and decreased in litter from sites burned 10 years before. Nitrogen and manganese were immobilized in litter during the early and the middle phase of decomposition. (13) C NMR spectroscopy revealed that all the litters were rich in Alkyl-C, the fraction including waxes and cutin that are effective barriers to water loss from the leaves. Litter from sites burned 1 year before had the highest hydrophobicity and aromaticity indexes and the highest alkyl ratio, and decomposed at the lowest rate. Conclusions Differences of leaf chemical composition within the same plant species across an uneven landscape affect decomposition. The traditional approach and (13) C NMR spectroscopy complementarily explain decomposition pattern and give a comprehensive view of the individual drivers of litter decomposition.

Afforestation of new unconsolidated volcanic deposits is a practice used to stabilize barren areas and enhance the accumulation of organic matter in the developing soil. Changes in soil carbon (C) and nitrogen (N) pools, including the soluble and microbial fractions, within the first decades since afforestation have been poorly investigated. Therefore the objective of the present study was to investigate how key C and N pools vary in litter and soil of four forests planted on barren volcanic deposits from recent Mount Vesuvius eruptions. We examined three forest stands (40, 70 and 100 years old) afforested with Stone pine (Pinus pinea L.) and a 40-year old forest of Black pine (Pinus nigra Arn.). As a baseline of C and N pools prior to afforestation, data from treeless sites were included in the study. Both the inputs with litter fall and soil C and N stocks increased with forest age in the Stone pine stands. In the mineral soil, C concentration per gram soil dry weight and C:N ratio increased with age from treeless sites to the oldest forest. Microbial biomass C and fungal biomass as a fraction of organic carbon (OC) and respiration per unit OC (an index of organic matter mineralization potential) decreased significantly with stand age. The results suggest that a main driver of C accumulation in the mineral soil is the decline with increasing stand age of the microbial fraction of organic matter and its activity. The comparison between the two pine species revealed that litter production was more abundant in the Black pine than in the even-aged, 40-year-old, Stone pine stand; moreover Black pine litter was more acidic and had a higher stable residue than Stone pine litter. Therefore a different pattern of C sequestration occurs with a higher C stock in the organic layers and a lower C stock in the mineral soil of Black pine compared to Stone pine.

Background and aims Invasion by N2-fixing species may alter biogeochemical processes. We hypothesized that the grade of invasion by the N2-fixer black locust (Robinia pseudoacacia L.) could be related to the distribution and pools of carbon (C) and nitrogen (N) along the profile of two Mediterranean mixed forests of stone pine (Pinus pinea L.) and holm oak (Quercus ilex L.). Methods A low-invaded (LIN) and a high-invaded (HIN) mixed forest were studied. We assessed: N concentration in green and in senescent leaves; C and N pools along the soil profile; seasonal changes of soluble C and N fractions, and microbial activity. Results Compared to coexisting holm oak and stone pine, black locust had higher N content in green and in senescent leaves. In the mineral soil: N stocks were similar in LIN and HIN; water soluble C and microbial activity, were lower in HIN compared to LIN; water soluble N showed seasonal changes consistent with tree growth activity in both HIN and LIN. In the organic layer of HIN, C and N stocks were about twofold larger than expected on the basis of stand density. Conclusion Black locust increased C and N stocks in the upper organic layers that are more vulnerable to disturbance. However, it did not increase N stocks in the mineral soil.

Many studies across a range of ecosystems have shown that decomposition in mixed litter is not predictable from single-species results due to synergistic or antagonistic interactions. Some studies also reveal that species composition and relative abundance may be more important than just richness in driving non-additive effects. Most studies on litter decomposition in Mediterranean maquis, an high-diversity shrubby ecosystem, have dealt exclusively with single species. In this study we investigated, at the individual-litter level, as well as at the litter-mixture level, the effect of litter mixing on decomposition of 3-species litter assemblages with different relative abundance of the component litters; we set up two types of litter assemblages that reflected the heterogeneity of bush cover in the inner maquis and at the edge maquis/gaps, as related to the leaf traits, i. e. sclerophylly vs mesophylly. We measured mass loss, decay of lignin, cellulose and ADSS (acid detergent soluble substances) and fungal mycelium ingrowth. The results show that over a 403-day incubation period, the decomposition of individual litters in mixtures deviated from that of monospecific litters and had different directions. In litter mixtures of the sclerophylls Phillyrea angustifolia and Pistacea lentiscus with the mesophyll Cistus, decomposition was lower than expected (antagonistic effect); in the mixtures of litters with similar physical structure (Ph. angustifolia and P. lentiscus with Quercus ilex) decomposition was faster than expected (synergistic effect). When considering the different decomposition phases, both negative and positive effects occurred in Quercus mixtures depending on the phase of decomposition. In both types of 3-species litter assemblages the greatest effect occurred in uneven mixtures rather than in even mixtures. Our results show that species composition drives the direction whilst the decomposability and the relative abundance drive the magnitude of non-additive effects of litter mixing on decomposition.

In natural conditions, litters shed from different species become mixed with each other, and decompose together. Most studies deal with decomposition of individual species; few studies investigate the influence of litter mixing on decomposition and nutrient dynamics; the results are contradictory as positive, negative, or no effect, of litter mixing have been observed. In this study we test the hypothesis: i) that litter mixing in the Mediterranean maquis, a nutrient poor, high diversity ecosystem, produces non-additive effects on nutrient dynamics; ii) that the effects vary with the composition in species of the mixture and with the relative amount of the species component the mixture. Two types of 3-species mixtures were set up; one contained three sclerophylls, Phillyrea angustifolia, Pistacia lentiscus and Quercus ilex; the other contained the first two species with the mesophyll Cistus. Litterbags, containing monospecific litters and even and uneven mixtures, were incubated under natural condition in situ; even mixtures had the 3 species in equal proportion, whereas uneven mixtures had one of the species as dominant (50%) and the other two species in equal proportion (25%:25%). Litterbags were retrieved after 92, 188 and 403 days; litters from the mixtures were separately analyzed for mass loss and content of nitrogen (N), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn). Results indicate that mixing influences the dynamics of N, Mn, Ca, Mg, Fe, Cu and Zn, but scarcely affects the dynamics of K and Na. The comparison of observed to expected values for changes of nutrients in litterbags indicates the occurrence of non-additive effects of litter mixing on movements of N, Fe, Cu, and Zn to or from the litterbags containing the mixtures. The effects depend on the composition in species of the mixture, whereas the relative amount of the species component the mixture is not relevant.

The Mediterranean area of Southern Italy is characterized by different natural plant covers that mainly reflect different successional stages (i.e. low maquis, high maquis, Quercus ilex wood) and managed areas with introduced plant species (such as Pinus species). Soil properties could be affected by plant cover types as well as by plant species. Our objective was to determine the relationships of plant cover types and plant species with the chemical and biological characteristics of the soil. In four neighbouring areas with different plant cover types (low maquis, pure high maquis, high maquis with pines and pinewood, with pines planted by foresters in both cases), soil samples were collected under different plant species in order to evaluate the effect of plant cover types and plant species on soil properties. Soil samples were analyzed for nutrient content, microbial biomass, soil potential respiration and enzymatic activity (phosphatase, arylsulphatase, β-glucosidase and hydrolase activities) as well as for pH, water holding capacity (WHC) and cation exchange capacity (CEC). Application of cluster analysis and principal component analysis to the data revealed that the plant cover type was the key factor influencing soil properties more than plant species. In fact, the largest differences were observed between pure high maquis soils and all other soils, with pure high maquis soils generally showing the highest values of WHC, CEC, nutrient content, organic and microbial C, soil respiration, phosphatase, arylsulphatase and β-glucosidase activities. The significantly lower values of these variables in the low maquis relative to the pure high maquis probably reflect the effect of ecological succession on soil. The high maquis with pine, differing from the pure high maquis only for the presence or absence of pine, showed values of soil physical, chemical and biological characteristics similar to those found in the low maquis, thus suggesting that the presence of pine retards soil development. © 2004 Elsevier Ltd. All rights reserved.

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 1 year after the incubation when the highest amount of lignin had been detected; the study extended over the following 2 year 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. © 2008 Springer Science+Business Media B.V.

The dynamics of nutrients (N, P, K, Ca, Mg) in decomposing beech and fir litters was studied. N, P, Mg and Ca content increased in all litters, whereas K content decreased. Nutrient content correlated to mass loss with a few exceptions for K and P. Final N, K, Mg and Ca content was higher the lower the initial content and the higher the initial C/nutrient ratio was. Final P content correlated neither with initial P content nor with initial C/P ratio. All litters lost K very quickly, mainly by leaching. P was lost initially by leaching, although at a lower rate than K, and later by mineralization. Mg, Ca and N showed alternate phases of accumulation and release. Mg losses by leaching occurred only in litters with high initial Mg content; in litters with low initial Mg content, Mg losses occurred by mineralization. Ca and N were lost only by mineralization. A mobility series K>P>Mg>Ca=N is suggested.

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.

Litter quality is an important determinant of soil organic matter formation. Changes of organic components were investigated along decomposition of black locust (Robinia pseudoacacia L.) leaf litter and black pine (Pinus nigra Arn.) needle litter in the native adjacent coeval forest stands. To this purpose, data from proximate analyses were compared with those from CPMAS 13C NMR. Newly shed leaf litter of black locust had significantly higher concentrations of ADSS (acid detergent soluble substances) as well as lower concentrations of cellulose and AUR (acid unhydrolyzable residues that include lignin) and higher AUR-to-Cellulose ratio than that of black pine. The 13C CPMAS NMR spectra of newly shed leaf litter of black locust and black pine revealed that O-Alkyl-C components (including cellulose and hemicelluloses) accounted, respectively, for 53.8% and 61.4% of the total area of the spectra. All other C fractions were relatively more abundant in black locust than in black pine. Within individual sampling periods, relationships between residual litter mass and concentrations of ADSS, cellulose and AUR were examined, as were relationships between residual litter C and NMR fractions. Four periods were defined based on the slopes of the decomposition curve, with the length of period I defined by the start of a net decrease of AUR. Proximate analyses and NMR data showed changes in chemical composition over the decomposition process, as well as changes in decay rates of the residues, following different paths in the two litters. ADSS decayed faster in black locust litter; in contrast cellulose and AUR decayed faster in that of black pine. AUR concentration increased in both litters during decomposition; however, compared to black pine, the remaining litter of black locust was richer in AUR, despite the lower initial concentration, and had a higher AUR-to-Cellulose ratio. Phenol-C and Aryl-C decayed faster in black locust litter, while Alkyl-C decayed faster in that of black pine. In both litters, mass loss in periods was negatively correlated to concentration of AUR at the start of the periods. C loss in periods was negatively correlated to the concentration at the start of the periods of MC-to-PC (an index of lignin content) in black locust litter and positively correlated to Alkyl-C and O-Alkyl-C in that of black pine. Phenol-C, O-Alkyl-C and Aryl-C were the most decomposable C fractions in black locust. O-Alkyl-C and Alkyl-C were the most decomposable C fractions in black pine. Limit value was lower in black pine than in black locust. Consequently the different pattern of litter decomposition can affect the size of C sequestration in the forest floor and the quality of accumulated organic carbon.

The concentrations of Cd, Cr, Cu and Pb were measured in leaves of Quercus ilex L. and in the soils collected from 15 sites of the Campania Region of Italy of two different typologies (anthropic and remote), in order to evaluate: (1) the effect of translocation and/or direct deposition from air on leaf element concentrations; and (2) the suitability of the studied matrices as pollution monitors. The available fractions of the studied elements in the soils were also measured. The accumulation factor (anthropic/remote sites) was calculated to evaluate the element accumulation, both in leaves and soils, at the anthropic sites compared to the remote sites. The concentration factor (leaf/soil) was used to investigate the translocation of the element from soil to leaves. Cd and Cr soil contents at the remote sites were higher than at the anthropic ones; in contrast, at the latter, Cd and Cr leaf concentrations were higher than at the remote sites. Cu and Pb concentrations were greater both in the soils and in the leaves of the anthropic sites as compared to the remote ones. The differences between the two site typologies were statistically different with the exception of Cu soil contents. The concentrations of Cu and Pb in the leaves and in the soils were significantly correlated. Available Cd, Cu and Pb fractions were significantly correlated to the total soil contents. Moreover, available Cu in the soil was significantly correlated to Cu leaf concentrations. All the studied elements appear to be taken up in relevant measure directly from the air at the anthropic sites. The translocation from roots to leaves could be relevant only for Cu. Q. ilex leaves appear better biomonitors than soil in the investigated area. The soil background contents of all the studied elements hid the input of trace elements from the air. In addition, soil contents reflect a mixture of past and recent inputs, whereas leaf contents reflect the element inputs for a known exposure time.

The objective of this investigation was to assess the changes in chemical composition (lignin, cellulose, hemicelluloses, non-structural compounds, N, and ash) of decomposing litter. Standard Pinus sylvestris needle litter, originating from southern Sweden, was incubated in litterbags at 15 sites selected from the Netherlands to south Spain. The changes in chemical composition of this litter were determined using near infrared reflectance spectroscopy. The hypothesis was that standard (chemically uniform) litter decomposing under a range of climates would show different dynamics of accumulation and loss of C-fractions, N, and ash, relative to mass loss. It was shown that, for a given mass-loss value (10, 20, 30, 40, or 50%), the proportion of lignin, cellulose, hemicelluloses, non-structural compounds, N, and ash in the decomposing pine needles differed between sites. Lignin concentration in the litter residue at 50% mass loss ranged from approximately 26 to 43%, cellulose from 19 to 27%, hemicelluloses from 7 to 11%, non-structural compounds from 19 to 25%, N from 0.7 to 1.3%, and ash content from 1.4 to 10.1%. Lignin concentrations showed the highest range of variation. Lignin concentrations during decomposition were positively related to moisture factors as significant correlations were found with actual evapotranspiration and were improved in multiple regressions by the mean annual precipitation or the water surplus. Cellulose was degraded further at sites with high precipitation whereas hemicellulose degradation was related to temperature. This leads to the conclusion that the remaining organic matter produced by standard litter decomposition within the studied climatic range of variations tended to be more recalcitrant under wet and warm climatic conditions than under cold or dry climate.

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.

The present study investigates the impact of fire (low and high severity) on soil fungal abundance and microbial efficiency in C assimilation and mineralisation in a Mediterranean maquis area of Southern Italy over 2 years after fire. In burned and control soils total and active fungal mycelium, microbial biomass C, percentage of microbial biomass C present as fungal C, metabolic quotient (qCO2) and coefficient of endogenous mineralisation (CEM) were assayed together with several chemical properties of soil (i.e. pH and contents of organic C, total and mineral N, available K, Mg, Mn and water). Fire significantly decreased the fungal mycelium, whereas it stimulated microbial growth probably through the enhancement of bacterial growth because of the increase in organic C and nutrient contents in burned plots. This shift in microbial community composition might explain the observed reduction in soil microbial efficiency of C assimilation (high qCO2) and the increase in C mineralisation rate (CEM) in the first 84 days after fire. Therefore, fire might increase CO2 input to the atmosphere not only during combustion phase but also in the post-fire period. © 2007 Springer-Verlag.

This synthesis paper presents a model for estimating the buildup of soil organic matter in various types of coniferous forests. The knowledge used was obtained from a well‐studied forest with good Iitterfall data, decomposition information and validation measurements of the soil organic matter layer. By constructing a simple model for litterfall, and the information on maximum decomposition levels for litter, we could estimate the annual increase in soil organic matter and extend this to encompass stand age. The validation measurement and the estimated amount of soil organic matter differed by about 8 or 26% over a 120‐yr period, depending on the litterfall model. The estimated increased storage of soil organic matter as a consequence of climate change was found to be drastic. We thus found that the soil organic matter layer would grow about four times as fast as a result of the needle component only. This estimate was based on a comparison between latitudes with a difference of 17°.

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. Copyright © 1996 Elsevier Science Ltd. All rights reserved.

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. © 1993.

Interest in investigating denitrification in forest soils is steadily increasing in order to quantify its role in the N budget and its contribution to N2O flux to the atmosphere. Existing estimates of actual rates are very few; potential denitnfication is inconsistently defined and between-forest comparison is critical. Within-forest variability of denitrification is very high owing to microscale gradients of nitrification, C availability and oxygen. Denitrification also exhibits a strong temporal variability, with brief periods of high activity associated to wetting-drying and freezing-thawing. Denitrification in forest soils may be higher at field capacity than at saturation moisture. The successional state of the community appears to control denitrification mainly through nitrate availability. Denitrification may increase substantially following deforestation, but the effect is dependent on post-harvest treatments. Forest denitrification can act as a sink of nitrate in groundwater and counteract N deposition to some degree. To deal with the high variability of the process, soil texture and drainage and the ratio denitrifying enzyme activity/biomass C would seem to be appropriate parameters for denitrification modelling.

Experimental fires were performed during the summer-drought period in a Mediterranean maquis in the Castel Volturno Nature Reserve in south-western Italy. The two different fuel loads applied (4 kg m−2 and 2 kg m−2) resulted in complete and partial combustion of the vegetation, respectively. Soil organic matter content (SOM), total and available element concentrations (K, Mg, Na, Mn, Fe, Cu, Pb, Cd), microbial carbon, respiration, metabolic quotient (qCO2), and the coefficient of endogenous mineralization (CEM) were measured at intervals in the dry and wet seasons over a period of about 3 years, in burned and adjacent unburned soils. Soil samples (0–5 cm depth) were collected under the cover of Phillyrea angustifolia L., a dominant species in the study area. Both fires induced long-lasting increases in SOM. As indicated by the increase in CEM, part of the accumulated SOM was mineralized in the first 3 months after fire whereas part of the accumulated SOM was instead stable. Both fires increased the total and available fractions of nutrients and trace elements. During the first 3 months after fire, microbial biomass and qCO2 were higher in the burned soils, which were richer in nutrients, but were characterized by harsher environmental conditions compared to unburned soils.

The potential for nitrification is appreciable throughout the whole seasonal cycle, but nitrate is depleted at different rates during the year. The highest values of nitrate depletion occurred in late spring, early summer and at leaf-fall when readily available carbon substrates are released from root exudates or from litter decomposition. -from Authors

Nitrogen mineralization has been studied in the slightly acidic brown earth on limestone of a beech stand and a beech-fir stand, in the forests of Monte Taburno (Campania Apennines). NH4 is the predominant form of the mineral N in the soil of both stands. Yearly NO3- production is 42.4 kg ha-1 in the beech stand and 47.0 kg ha-1 in the beech-fir stand.-from Authors