Microdistribution of macroinvertebrates in a temporary pond of Central Italy: Taxonomic and functional analyses

AbstractSpatial distribution of physical and chemical variables and macroinvertebrate composition, structure and functional aspects were investigated in five microhabitats available (Ranunculus acquatilis+Ranunculus sardous, Spirogyra sp., Juncus effusus, and unvegetated littoral sediments and central sediments) in a temporary pond near Rome during spring 2004. The central sediments were found to differ greatly from the other substrates. They were characterized by higher nutrient contents (total P, total N), organic matter and organic C, and silt and clay in the sediments, and lower dissolved oxygen content and lower pH in the water. Species richness and densities of total macrofauna showed the lowest values in central sediments and the highest ones in submerged macrophytes (Ranunculus spp.) and emergent vegetation (Juncus effusus). Oligochaeta Tubificidae, some Nematoda (Dorylaimus spp.), and Chironomidae Tanypodinae (Procladius sp. and Psectrotanypus varius) and Chironominae (Chironomus plumosus group) characterized the central sediments, whereas Ephemeroptera and most of the Odonata and Coleoptera species were commonly found in submerged macrophyte beds. Some species of Coleoptera and Hemiptera (Hygrobia hermanni, Helochares lividus, Berosus signaticollis and Gerris maculatus) were mainly found in the algal substratum, and some Nematoda species (Tobrilus spp. and Aporcelaimellus obtusicaudatus), Oligochaeta Enchytraeidae, young larvae of Sympetrum and Diptera Ceratopogonidae in littoral sediments. Juncus effusus appeared to be mainly colonized by Chironomidae Orthocladiinae (Psectrocladius sordidellus group and Corynoneura scutellata) and Tanytarsini (Paratanytarsus sp.). Central sediments also favoured high abundances of collector-gatherers, burrowers and drought resistant forms with passive dispersal, whereas Ranunculus spp. hosted mainly scrapers, shredders, swimmers+divers and active dispersal forms without any resistant stages to desiccation. Juncus plants were mostly colonized by collector-filterers and by organisms capable of both active dispersal and surviving desiccation. Littoral sediments and algae showed similar functional organization and intermediate features between central sediments and submerged macrophyte beds. All these results demonstrate that microhabitat characteristics play a crucial role in selecting macroinvertebrate taxa according to their environmental requirement, feeding mechanism, movement and resistance to drought. Moreover, our study confirms the role of submerged and emergent vegetation in maintaining high biodiversity and suggests that all microhabitats should be considered to provide both an exhaustive collection of species for pond management and conservation and basic insights into the functioning of pond communities

Preliminary researches on fungal population dinamic of natural and cultivate soils in tropical rainforest

Significant differences in the species composition of the mycoflora in tropical rainforest soils were compared between natural and cultivated areas. The last one's were prepared by cutting, burning and sowing natural areas. Community composition and structure were based upon statistical analyses of 6957 colonies from seven samplings collected from December 1978 to January 1980. Moreover pedological and vagetational analyses in every areas were carried out

Tolerance to vanadium as a response of agricultural soil fungi in the Valle Latina (Italy): which are the potentialities for mycoremediation?

The aim of this work was to investigate a soil fungal community of contaminated agricultural soils and to test the growth response of selected species to the toxic metal vanadium. Physico-chemical analysis was performed on contaminated soils that lay under maize and wheat crops in the Valle Latina (southern Lazio, Italy). The Valle Latina is one of the 57 sites of national interest (S.I.N.). It’s a high environmental risk area due to its industrial sites, waste landfills and agricultural activities and the environmental contamination of hexachlorocyclohexane, an anthropogenic pollutant. Moreover, natural background high level of potentially toxic elements due to volcanic rocks (pyroclastic deposits) occurs in this area in which several elements, including vanadium, thallium and beryllium exceed the threshold values established by Italian legislation, as well. The soil community of saprotrophic fungi of contaminated agricultural soils near the Sacco River have been studied. Contrary to expectations, the community was found to be rich in fungal species (150 species in total), although the typical Penicillium and Aspergillus species components were poorly represented. Species, reported to be tolerant/resistant to heavy metals in the literature and potentially useful in bioremediation, were found. The occurrence of these may be taken as a potential bioindicator of environmental pollution. Vanadium, one of the elements which exceed threshold values, was chosen as metal to test fungi tolerance. In the last decades, evidence in increasing of the environmental levels of vanadium, has raised concern over its release into the atmosphere from anthropogenic sources of which hydrocarbon fuel combustion is the most important. Burning of fossil fuels caused about 110000 t V/a to enter the atmosphere globally (Manfred, 2004). Vanadium is essential for several species of green algae, fungi and nitrogen-fixing microorganisms, as well. We selected six species : Aspergillus terreus Tiegh., Cladosporium cladosporioides (Fresen.) G.A. de Vries, Clonostachys rosea (Preuss) Mussat, Paecilomyces lilacinus (Thom) Samson, Penicillum citrinum Sopp and Rhizopus arrhizus Fischer, among isolated species, reported to be tolerant/resistant to heavy metals in the literature, and examined the growth response by inoculating them with malt extract agar amended with ammonium vanadate at concentrations of 1, 2, 3 and 6 mM to simulate potential environmental concentrations. Metal tolerance was assessed in all samples by means of growth measurements, tolerance index, scanning electron microscopy, electron dispersion spectroscopy and biomass metal concentrations. Results revealed that all the fungi tested tolerated 6 mM concentrations, Clonostachys rosea and Rhizopus arrhizus being the most tolerant. Soil fungi tolerance to natural metal occurrence may explain their tolerance to anthropogenic contamination. Therefore results of this research can contribute to enhance knowledge on the potential use of these fungal species for mycoremediation purposes in polluted sites

Multiscale heterogeneity of topsoil properties in southern European old-growth forests

Assessing the contribution of forest soils to carbon (C) and nutrient dynamics is extremely complex due to the high spatial variability of soil properties, at fine to very broad scales. Improving our understanding of soil variability is necessary to scale up sample-based inventory data for the estimation of regional contribution of forest soils to C dynamics. We analyzed the patterns of variation of soil properties in 11 southern European old-growth beech stands. We analyzed the topsoil spatial variability of organic carbon and matter, nitrogen (N), C/N ratio, texture and pH with the aim of assessing their within- and among-stand variability, and determining the drivers underlying this variation. For each stand we sampled the topsoil in 25 quadrats in a 1-ha regular grid, where we recorded overstorey structural and compositional attributes, deadwood quantity and quality, microtopography and site conditions. Soil parameters varied highly at both scales: when considering all the topsoil properties together through multivariate analysis, most of the variability occurred at the within-stand scale (mostly due to shifts in organic matter content, C/N and litter depth); the opposite was true when considering soil properties singularly, with pH, soil texture and N concentration varying greatly among stands. Most of the among-stand variability depended on climate and on the direct and indirect effects of parent material. Fine-scale variation, instead depended mainly on overstorey composition and microtopographical variation. Surprisingly, we found no direct influence of overstorey structure on topsoil parameters, likely because soil parameters respond to changes in stand structural features only after a substantial time lag

Correspondences between plants and soil/environmental factors in beech forests of Central Apennines: from homogeneity to complexity

Data have been collected in beech forests of central Apennines through 94 phytosociological relevSs and 37 soil profiles. The main edaphic factors have been analyzed. Environmental factors [light (L), temperature (T), continentality (K), soil moisture (F), reaction (R), nitrogen (N), hemeroby (H)] have been expressed by Ellenberg bioindication model and hemeroby index to estimate anthropogenic disturbance. Significant correlations have been found by Pearson correlation test: the distribution of beech forest typical species, such as Cephalanthera damasonium, Aquilegia vulgaris were positively correlated with carbon/nitrogen (C/N) ratio. Five factors (T and L indicator values, hemeroby index, CaCO(3), C/N ratio) explained almost the whole variability of data set in the canonical correspondence analysis. The relationships found between soil/environmental factors and species/communities allow to detect significant differences within an homogeneous habitat providing management indications at fine-scale

Fire effects on above-below ground system of Phillyrea angustifolia L. in a Mediterranean area (Central Italy)

Six plot of a Mediterranean maquis in Castel Volturno Nature Reserve were burned at two intensity level. During post-fire period four measurement campaigns were carried out on Phillyrea angustifolia, referring to stomatal conductance, net photosynthesis, intercellular CO2 concentration, percent mycorrhizal infection, soil microfungi, soil water content, total nitrogen, available phosphorous and exchangeable cations. The results of non parametric statistical analysis indicated a significant difference among fire treatments and temporal distribution

Ecophysiological response to water stress and heavy metals uptake in Salix alba L. cuttings

Heavy metals accumulation in soils as a result of human activities is constantly increasing. At this regard, phytoremediation (i.e. the use of plants to remove pollutants from the environment or to render them harmless) is attractive as it offers site restoration, partial decontamination, maintenance of the biological activity and physical structure of soils, and is potentially cheap. In a short-term experiment, cuttings of Salix alba L. were treated with a mix of heavy metal chlorides, consisting of copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb), in order to determine the physiological response and the uptake capacity of this species under different conditions of water availability. In fact, the willow tree is a typical species of riparian zones, and could be subjected to variable water supply due to the hydrological regime of the river (constant flow or torrential regime). The amount of absorbed metals allocated in biomass of roots, stems and leaves was determined by atomic absorption spectroscopy (ASS). Translocation (TF) and bioaccumulation (BAF) factors were also determined. Under non limiting water conditions, a phytotoxic effect of heavy metals was evident on gas exchanges, though a reduction of net photosynthesis mostly caused by metal-induced stomatal limitations similar to those induced by water stress. Moreover, at the end of the experiment, chlorophyll “a” fluorescence measurements (JIP-Test) highlighted a reduction of the number of active reaction centres per leaf cross section in the metal-stressed plants; this was followed by increase of the efficiency of the electron transport processes that, according to the the Lichtenthaler model of plant response to stress, can be interpreted as a response mechanism aimed at sustaining detoxification and repair processes. The analysis of heavy metals concentration in roots, stems and leaves of plants subjected to different water supply showed TF values < 1 in all sets; moreover, water shortage limited metal uptake and translocation to leaves. In conclusion, although this species cannot be considered an iperaccumulator due to its low TF, it could be used to limit heavy metals dispersion in the environment, and to restore riparian zones at polluted sites

Valle del fiume Sacco (Lazio): analisi dell'ecosistema a differente scala spazio-temporale in relazione all'inquinamento ed al disturbo antropico

Sul bacino idrografico del fiume Sacco insistono pressioni ambientali dovute essenzialmente alle attività dell'industria chimica, meccanica, elettronica ed alimentare. Nel corso degli anni si sono verificati episodi acuti di inquinamento da sostanze chimiche. A seguito di questi episodi l'area è stata dichiarata sito da bonificare di interesse nazionale. Lo scopo dello studio è quello di definire e quantificare il disturbo antropico nell'area e il suo impatto sull'ecosistema fluviale. A tal fine sono stati utilizzati bioindicatori a macrofite e a diatomee perifitiche; sono stati anche studiati i suoli dal punto di vista pedologico e con l'analisi delle specie fungine resistenti ai metalli pesanti