Majella Massif Research Articles

How petrophysical properties influence the seismic signature of carbonate fault damage zone: Insights from forward-seismic modelling

Seismic imaging is the most common tool to detect subsurface structures in continental and marine settings. Despite technological advancement, seismic analysis of carbonates is still challenging because they are strongly influenced by petrophysical heterogeneities, being this even more difficult when further heterogeneities are added by the presence of faults. In this work, unmigrated forward-seismic models are developed to understand the seismic response changes related to carbonate-bearing fault systems and their deformation behaviour. We focus on the carbonate ramp of the Majella Massif (central Italy), that is characterised by the presence of porous and faulted carbonate lithologies. This carbonate system represents an analogue of carbonate reservoirs worldwide. Field and laboratory data of fault rocks sampled at increasing distances from the slip planes highlight a damage zone/fault core architecture with a decreasing porosity approaching fault planes. This observation is also confirmed by the thin sections analysis and the calculation of the shear modulus. Seismic images of fault rocks presenting lower porosity than the host rock show weak diffraction hyperbolas while diffraction hyperbolas are more evident in the forward-seismic models of fault rocks with greater porosity than the host rock. Moreover, factors such as the variation in the dip angle of the fault or the thickness of the damage zone can enhance or reduce the hyperbolas. Performing the migration process to stacked sections would not provide evidence of increased porosity in the damage zone due to the suppression of the diffractive component. The presence of weak hyperbolas in unmigrated seismic images is thus interpreted as evidence of a lower porosity damage zone with respect to the host rock. This can be related to deformation mechanisms leading to porosity loss in the damage zone for porous rocks as observed in the study area. However, this could also be related to the confining stress or fracture filling that counteract the fracture-related porosity increase when faults are hosted by tight rocks.

Genesis and preservation of patterned ground in permafrost non-affected soils – Central Apennines, Italy

Several research have been focused on the polygenetic origin of patterned ground soils, ascribing to the freeze-thaw cycles the driving mechanism in the sorted features genesis. Therefore, this type of soils may be considered strictly associated with permafrost-affected areas because freezing and thawing of soil are generally related to the seasonal frost and/or the occurrence of the active layer. Since permafrost can reach mid-latitudes depending on local microclimatic conditions, the Majella Massif (central Apennines, Italy) gained interest because of the presence of periglacial landforms (rock glaciers, kettle holes, and patterned ground), although no direct observations and measurements indicating the occurrence of permafrost have been reported. This work was aimed to determine the genesis and preservation of patterned ground on the Majella Massif through monitoring of soil and air temperatures and derived parameters, and soil characteristics.Results suggested that permafrost was absent at a depth <2 m. However, this did not exclude the presence of deep and sporadic permafrost, as a relict form of a shallower permafrost present in ancient climatic phases. Although during these phases permafrost-driven processes were probably responsible for the formation of the patterned ground, nowadays the preservation and reorganization of this periglacial form is driven by phenomena including superficial freeze-thaw cycles and snow redistribution due to wind. Specifically, the preservation of the miniature patterned ground has been ascribed to shallower phenomena related to the water-holding capacity of the soil and to freeze-thaw cycles of the upper soil layers, which resulted in differential frost heave and segregation of coarse fragments and fines.

Investigating the feasibility of using precipitation measurements from weather RaDAR to estimate potential recharge in regional aquifers: the Majella massif case study in Central Italy

Rain gauge spatial sparsity and temporal discontinuity of data represent one of the major issues for reliable recharge estimations. In the past decades, the use of ground-based microwave weather RaDAR has dramatically improved quantitative rainfall estimation by providing spatially continuous estimates of rainfall over an area of more than 400 km2 every 10 minutes. Furthermore, weather RaDAR data have also proved relatively reliable in mountainous areas. These paramount features of RaDAR-derived precipitation data could improve the estimation of potential recharge of aquifers, which rely on geospatializations (e.g., Thiessen polygons) of rainfall data collected by a sparse rain gauge network which often shows lacking at high altitude (i.e., recharge areas), introducing additional uncertainty in the inflow volumes. Weather RaDAR rainfall estimation is also affected by various sources of error, which can be reduced by proper post-processing; however, uncertainties remain, especially for surface rain rate estimations. Despite the currently necessary complex numerical processing, the purpose of the study is to evaluate the use of the weather RaDAR data as an alternative or in addition to meteorological data. Based on the above considerations, the feasibility of using RaDAR-based precipitation data to estimate aquifer potential recharge and calculate a detailed water budget in the areas characterized by high elevations, such as the Majella massif in the central Apennines, has been evaluated. To address this objective, the water budget has been calculated in the 2017-2018 period using both RaDAR-based precipitation data and rain gauge data, as well as adopting different methods (i.e., Turc and Thornthwaite). Although intrinsically uncertain, the RaDAR-based precipitation data provided solid results, pointed out by comparing it with water budget obtained by rain gauge data, and especially with experimental literature data. This interdisciplinary work may pave the way for continuous monitoring of aquifer potential recharge at extremely high temporal and spatial resolution.

Investigating Population Genetic Diversity and Rhizosphere Microbiota of Central Apennines’ Artemisia eriantha

The present study aimed to characterize the genetic structure of Artemisia eriantha Ten. and the diversity of the rhizosphere microbiota. Plant leaves and rhizosphere soils were sampled from three areas of Central Italy, namely Monte Corvo, Monte Portella (both from the Gran Sasso massif), and Monte Focalone (Majella massif). The plant samples were subjected to genetic structure analysis by amplified fragment length polymorphism (AFLP) markers. The microbiota from the rhizosphere soils was investigated by 16S rRNA gene metabarcoding. The within and among population variability was typical of outbreeding species. The AFLP polymorphisms revealed a marked closeness among plant populations collected in Monte Focalone and Monte Corvo, despite the geographical proximity of the latter with Monte Portella, a result confirmed by cluster, STRUCTURE, and discriminant analyses. 16S rRNA gene metabarcoding showed higher values of diversity for Monte Corvo (H, 5.7; Chao1, 445) and Monte Focalone (H′, 5.57; Chao1, 446) than Monte Portella (H′, 5.3; Chao1, 275). At the phylum level, the communities were mainly represented by Proteobacteria, Actinobacteria, and Acidobacteria (&gt;10%). At the genus level, the Monte Focalone and Monte Corvo microbiotas were closer than Monte Portella, thus confirming the results from the plant communities. The findings provided evidence for the first time of an association between the Artemisia eriantha plant and microbiota communities. The relevance of the results in terms of biodiversity and the conservation strategies of plant and microbiota communities in the Central Apennines are discussed.

From petrophysical properties to forward-seismic modeling of facies heterogeneity in the carbonate realm (Majella Massif, central Italy)

Forward modeling is a fundamental support to study the seismic response of reservoirs structure and subsurface architectures. Carbonate reservoirs result in non-univocal seismic response caused by the facies heterogeneity and due to the possible presence of infilling fluids. The carbonate ramp outcropping in the Majella Massif (Central Italy) is an excellent surface analogue of buried heterogeneous structures. It offers the opportunity to directly analyze a carbonate reservoir which clearly shows facies variations and natural hydrocarbon-impregnations allowing to quantify the induced petrophysical changes. In this study, we integrated original field and laboratory measurements with 3D facies modeling to carry out 1D and 2D forward seismic models of a carbonate reservoir following a structured workflow. A careful petrophysical characterization measuring density porosity and seismic wave velocities has been performed in all the sampled facies and then used as input for the 3D velocity model. The “Sequential Gaussian Simulation Co-Kriging” (SGS-CK) results to be the best algorithm to build the seismic velocity model, consequently a low-frequency (40 Hz) synthetic 1D seismogram was carried out simulating facies and hydrocarbon-saturation variations. Thus, a 9 km long synthetic profile from the platform top to the basin, SE-NW oriented, was carried out simulating the outcropping architecture and spatial distribution of the facies.The obtained synthetic seismic outputs are closer to real geophysical surveys with respect to classical forward modeling. Perturbations of the seismic signal derived from the modeled facies heterogeneity without introducing artificial noises made the synthetic results more realistic preserving the horizons architecture. We also quantitatively show that variations in the signal related to the hydrocarbon saturation can result in an increase or decrease in reflectivity depending on the seismic properties of the surrounding layers.The presented results give new insights about reservoir architectures and can be useful to better process as well as to interpret the field seismic data and the resulting seismic sections acquired in carbonate realms.

Lichens as monitors of the atmospheric deposition of potentially toxic elements in high elevation Mediterranean ecosystems

In this study we used a terricolous lichen (Cetraria islandica) as bioaccumulator of potentially toxic elements (PTEs) to explore spatial patterns of air pollutant deposition along elevational gradients in the Majella Massif (Italy). Samples of C. islandica were collected at 200 m intervals along 6 transects from 1600 to 2600 m, both along the eastern and the western slope of the Majella massif, and analyzed for their PTE content. The results supported the hypothesis that the deposition of PTEs to the Majella massif is largely influenced by elevation and slope. Two main patterns emerged connected either with local soil erosion and long-range atmospheric transport. For some PTEs, namely Al, Cr, Li, Mg, in the absence of any other data, it is supposed that the anthropogenic input is very small compared to the natural input from weathering processes. In contrast, the group of air pollutants subjected to long-range transport, as in the case of Cd, Hg, and Pb, has very limited local input and the main sources responsible for the higher concentrations on the eastern slope are probably to be searched in the Balkan area.

Structurally controlled development of a sulfuric hypogene karst system in a fold-and-thrust belt (Majella Massif, Italy)

We documented the deformation in the southeastern domain of the Majella anticline (Central Apennines, Italy) to highlight timing and structural characteristics of different fracture sets affecting the outcropping Cretaceous-Miocene ramp carbonates. An isolated and inactive hypogene karst system produced by sulfuric acid (Cavallone-Bove cave system) was studied following a multidisciplinary approach. Our findings suggest that deep-rooted, sub-vertical strike-slip fault zones reaching the H2S source rocks were the main vehicle for ascending acidic fluid flow. Linkage and intersection of these faults by splays in extensional stepovers and pre-orogenic normal faults permitted ascending fluids to reach multiple recharge points (feeders) near the paleo water-table. In proximity to the oxygenated groundwater, where H2SO4 was produced, lateral dissolution focused along bedding planes and zones of localized deformation (fracture clusters) characterizing the hinge of the anticline. We conclude that structural position in the anticline and large-offset, vertically extended strike-slip fault zones control the localization of efficient permeability pathways and represent first order controlling features for fluid flow in the fold-and-thrust belt. This study provides insights into the understanding of time-space evolution, geometry, and pattern of sulfuric hypogene karst systems in folded carbonates, whose prediction is critical for fractured and karstified reservoirs.

Santonian (Upper Cretaceous) rudists bearing conglomeratic site on the Majella Massif (Pennapiedimonte, Central Apennines, Italy)

Santonian (Upper Cretaceous) rudists bearing conglomeratic site on the Majella Massif (Pennapiedimonte, Central Apennines, Italy)

The Majella National Park: a case study for the conservation of plant biodiversity in the Italian Apennines

The Majella National Park (MNP) is a tangible example of the interaction between ex-situ and in-situ conservation of endemic, rare, or endangered species at a Regional level in the context of the Italian national parks. The MNP has the facilities and carries out activities for the conservation of plant biodiversity: it includes botanical gardens, a seed bank, a nursery, and a network of “guardian farmers”, an authentic “granary” in which to protect and conserve biodiversity in and around the Majella massif (central Italy).

Climate–growth relationships at the transition between Fagus sylvatica and Pinus mugo forest communities in a Mediterranean mountain

Species interactions implicate a complex balance of facilitation and competition, which may shift during community development, thus structuring the subalpine ecotone of Mediterranean mountain ranges through time and space. This study highlights that encroachment of grasslands and simultaneous downward/upward movement of forest tree species involve species interferences and environmental feedbacks, with differential effects on mountain pine and European beech, and the grassland communities of the Majella Massif. The transitional ecotone from the European beech closed forest to the mountain pine krummholz vegetation in the Majella Massif (Apennines, Italy) is a sensitive area to climate and land-use changes. Vegetation shifts in these ecotonal zones may cause a negative impact on the spatial distribution and survival of rare or endemic herbaceous species, thus influencing the appearance, structure, and productivity of the subalpine ecotone of the Majella National Park. We focused on determining the structures and dynamics of this Mediterranean tree line, and the climate–growth relationships of European beech and mountain pine. We investigated the upward and downward movement of pine into areas potentially suitable for beech expansion, and the concurrent beech encroachment upward. Growth dynamics and canopy cover of European beech closed forest and mountain pine krummholz vegetation were analyzed in relation to disturbances at four different sites. Spring and summer temperatures and summer precipitation affected stem radial growth of both species. In details, spring and summer temperatures negatively affected tree ring width (TRW) of European beech, except for the highest site, whereas spring temperatures affected positively and summer temperatures negatively TRW of mountain pine. Mountain pine expanded upward, encroaching formerly grazed pastures and harvested areas, especially where the soil is shallow and rocky; downward expansion is also occurring, following progressive abandonment of forest management practices. At the same time, European beech recruitment is moving upward, interspersed within mountain pine krummholz, taking advantage from canopy shelter and higher temperature. Climate and land-cover simultaneous changes induce species interactions and a complex balance of facilitation and competition, which may shift during community development and structure the subalpine European beech-mountain pine ecotone of the Majella Massif through time and space.

Le dauphin à dents de requin Squalodon (Cetacea: Odontoceti) du remarquable assemblage de vertébrés marins de Montagna della Majella (Formation de Bolognano, Italie centrale).

The extinct family Squalodontidae consists of heterodont, medium-sized odontocetes, featuring a long rostrum that houses large, procumbent incisors and heavily ornamented postcanine teeth carrying accessory denticles, hence their vernacular name, dolphins. These longirostrine toothed whales are often seen as bridging the anatomical gap between archaic Oligocene odontocetes and their late Miocene to Holocene relatives. Possibly among the major marine predators of their time, the shark-toothed dolphins are important components of several lower Miocene marine-mammal assemblages from the North Atlantic and Mediterranean/Paratethysian realms. In the present work, a partial skull of Squalodontidae is described from the strata of the Bolognano Formation cropping out in the northeastern sector of the Montagna della Majella massif (Abruzzo, central Italy), which has previously yielded a rich lower Miocene marine-vertebrate assemblage, including eleven taxa of elasmobranchs as well as subordinate teleosts and very fragmentary remains of marine reptiles and mammals. The specimen consists of the anterodorsal portion of a rostrum, preserving parts of both premaxillae and left maxilla, and the anteriormost seven upper left teeth. This partial skull is here identified as belonging to the genus Squalodon, whose presence in the Montagna della Majella vertebrate assemblage had already been tentatively proposed on the basis of two fragmentary teeth. The paleontological significance of this find is discussed in the broader framework of the Euromediterranean record of Squalodon.

Petrophysical properties of heavy oil-bearing carbonate rocks and their implications on petroleum system evolution: Insights from the Majella Massif

Abstract In this work, we investigate the role of hydrocarbons in changing the petrophysical properties of rocks by merging laboratory measurements, outcrops characterization, and subsurface data focusing on a carbonate-bearing reservoir (Bolognano Formation) of the Majella massif. This reservoir represents an interesting analogue for subsurface carbonate reservoirs and is made of high porosity (up to 32%) ramp calcarenites saturated by hydrocarbon in form of bitumen. We have characterized in the laboratory density, porosity, compressive strength, Young's modulus and Poisson's ratio of both clean and heavy oil-bearing carbonate rocks of the Bolognano Formation. At ambient pressure the Vp are in the range of 3.49 km/s to 5.06 km/s for clean samples with an inverse relation with porosity, whilst the Vp range for HHC-bearing rocks are from 3.56 km/s to 4.56 km/s without any relation with measured porosity. These data show that porosity and presence of HHCs within the samples both affects seismic waves velocity. In particular, Vp and the derived dynamic Young's modulus generally strongly decrease with increasing porosity for clean samples and, for a fixed porosity, tends to increase with the presence of heavy-oil. This is confirmed also at higher (up to 100 MPa) confining pressure that has not a significant effect on Vp and Vs. Cyclic loading-unloading experiments show that the average compressive strength is 25 MPa and 38 MPa and average static Young's modulus are 5.7 GPa and 9.9 GPa, for clean and HHC-bearing samples respectively. Additionally, the permanent strain is always larger for clean samples. Field work, consisting in measuring fracture orientation in 11 outcrops of the same lithology, shows that both heavy oil-bearing and clean outcrops are characterized by two main trends NW-SE and NNE-SSW. However, the spacing data show that heavy-oil-bearing outcrops are much less fractured respect to clean outcrops. This suggests, assuming that the deformation occurred under the same stress state, that heavy oil-bearing outcrops are stiffer respect to clean outcrops, as supported by the laboratory measurements. We thus infer that in the study area hydrocarbons migration predates the last stage of deformation, limiting the fracturing in bitumen-bearing portions of the Bolognano Formation. At regional scale, the presence of buried oil fields located few kilometres away from the heavy-oil-bearing outcrops and pertaining to the same petroleum system, suggests a good lateral continuity of the reservoir giving clues about the key role played by primary porosity in the secondary migration that acted in this area.

Sulfuric acid speleogenesis in the Majella Massif (Abruzzo, Central Apennines, Italy)

Many active and inactive hypogene sulfuric acid cave systems are known along the Apennines, Italy. The Cavallone-Bove cave system is located in the external part of the central Apennine Chain, in the Majella Massif, and opens at 1470 m asl along the Taranta Gorge (South of Chieti). The presence in these caves of peculiar geomorphological features, such as feeders, rising channels, megacusps, cupolas, and replacement pockets, offers evidence of rising acidic fluids. The secondary mineral deposits, including meter-size white gypsum deposits, alunite, jarosite, black layers of iron‑manganese oxides and hydroxides, along with a rare association of authigenic rutile-ilmenite minerals indicate a sulfuric acid origin. Stable isotope analyses of sulfates further confirm a sulfuric acid speleogenetic (SAS) origin of these minerals and, in general, of the whole cave system, with H2S coming from the bacterial sulfate reduction of deep-seated Triassic evaporites interacting with hydrocarbons. Alunite dating demonstrates this water table SAS cave to have been active at least until 1.52 ± 0.28 Ma. All the evidence suggests that Cavallone-Bove is an ancient sulfuric acid karst system that was uplifted <1 km above pre-existing base level. The age of speleogenesis further suggests that tectonic uplift of this area was as high as 670 m My−1 over the last 1.5 Ma.

Xylogenesis of compression and opposite wood in mountain pine at a Mediterranean treeline

Comparisons between compression and opposite wood formation in prostrating Pinus mugo indicate that the secondary meristem can produce more tracheids with thicker walls by also increasing the number of contemporaneously differentiating cells, rather than only increasing the duration or the rate of cell formation. Although cambium tissues within a stem experience the same climatic conditions, the resulting wood structure and properties can strongly differ. Assessing how meristem differently regulates wood formation to achieve different anatomical properties can help understanding the mechanisms of response and their plasticity. We monitored the formation of compression (CW) and opposite (OW) wood within the same stems to understand whether achieved differences in wood structure are caused by modifications in the process of cell formation. We collected weekly microcores of compression and opposite wood from the curved stem of ten treeline prostrating mountain pines (Pinus mugo Turra ssp. mugo) at the Majella massif in Central Italy. Results indicate that cambium formed approximately 1.5 times more cells in CW than OW, despite that CW cell differentiation only extended 2 weeks longer and the residence time of CW cells in the wall-thickening phase was only 20% longer. Differences in their formation were thus mainly related to both the rates and the width of the enlarging and wall-thickening zones (i.e., the number of cells simultaneously under differentiation) and less to duration of cell formation. We conclude that to achieve such a different wood structures, the efficiency of the secondary meristem, in addition of altered rate of cell division and differentiation, can also modify the width of the developing zones. Thus, deciphering what rules this width is important to link environmental conditions with productivity.

The Majella National Park: An Aspiring UNESCO Geopark

Majella National Park is located in the central Apennines (Italy), in a vast mountainous area of about 740 km2. Owing to the complex geological history of the Majella Massif and surrounding areas, it features many different landforms. Woodlands rich in water characterize the wide tectonic depression of Caramanico, which separates the rounded gentle profile of the Majella to the east from the impervious steep slope of the Morrone Mt. to the west. Bare pitted highlands, like lunar landforms, characterize the top of the Majella (i.e., Femmina Morta Valley) shaped by flowing ice that long ago covered the higher parts of the massif. Sedimentary structures and fossil content recovered in carbonates attest to a long period of sedimentation in warm, shallow-marine environments, revealing that the Majella and the surrounding carbonate mountains looked, approximately from 140 to 7 Ma, like the present-day Bahamas and Persian Gulf. The Park hosts at least 95 geosites, some of which (22) are well-known in the international literature because of their scientific relevance. In addition, its natural and cultural wealth, deeply fused together with geoheritage, preserves several features of national and world rarity. Therefore, the Park Authority decided to put forward its territory as a candidate to become part of the United Nations Educational, Scientific and Cultural Organization (UNESCO) Global Geoparks Network.

Ecophysiology of Adonis distorta, a high-mountain species endemic of the Central Apennines

Morphological, anatomical and physiological plant and leaf traits of A. distorta , an endemic species of the Central Apennines on the Majella Massif, growing at 2,675 m a.s.l, were analyzed. The length of the phenological cycle starts immediately after the snowmelt at the end of May, lasting 128 ± 10 days. The low A. distorta height (H max = 64 ± 4 mm) and total leaf area (TLA= 38 ± 9 cm 2 ) associated to a high leaf mass area (LMA =11.8±0.6 mg cm −2 ) and a relatively high leaf tissue density (LTD = 124.6±14.3 mg cm −3 ) seem to be adaptive traits to the stress factors of the environment where it grows. From a physiological point of view, the high A. distorta photosynthetic rates ( P N =19.6 ± 2.3 µmol m −2 s −1 ) and total chlorophyll content (Chl a + b = 0.88 ± 0.13 mg g −1 ) in July are justified by the favorable temperature. P N decreases by 87% in September at the beginning of plant senescence. Photosynthesis and leaf respiration ( R D ) variations allow A. distorta to maintain a positive carbon balance during the growing season becoming indicative of the efficiency of plant carbon use. The results could be an important tool for conservation programmes of the A. distorta wild populations.

A MIS 15-MIS 12 record of environmental changes and Lower Palaeolithic occupation from Valle Giumentina, central Italy

An integrated geological study, including sedimentology, stable isotope analysis (δ18O, δ13C), geochemistry, micromorphology, biomarker analysis, 40Ar/39Ar geochronology and tephrochronology, was undertaken on the Quaternary infill of the Valle Giumentina basin in Central Italy, which also includes an outstanding archaeological succession, composed of nine human occupation levels ascribed to the Lower and Middle Palaeolithic. 40Ar/39Ar dating, and other palaeoenvironmental and tephrochronological data, constrain the sedimentary history of the whole succession to the MIS 15-MIS 12 interval, between 618 ± 13 ka and 456 ± 2 ka. Palaeoenvironmental proxies suggest that over this time interval of about 150 ka, sedimentary and pedogenic processes were mainly influenced by climatic changes, in particular by the pulsing of local mountain glaciers of the Majella massif. Specifically, the Valle Giumentina succession records glacio-fluvial and lacustrine sedimentation during the colder glacial periods and pedogenesis and/or alluvial sedimentation during the warmer interglacial and/or interstadial periods. During this interval, tectonics played a negligible role as a driving factor of local morphogenesis and sedimentation, whereas the general regional uplift experienced in the Middle Pleistocene led to capture of the basin and its definitive extinction after MIS 12. These data substantially improve previous knowledge of the chronology and sedimentary evolution of the succession, providing for the first time, a well constrained chronological and palaeoenvironmental framework for the archaeological and human palaeoecological record of Valle Giumentina.

Snow vole (Chionomys nivalis Martins) affects the redistribution of soil organic matter and hormone-like activity in the alpine ecosystem: ecological implications.

In alpine environments, colonies of snow vole (Chionomys nivalis Martins) cause strong pedoturbation, which may affect humification process and soil organic matter (SOM) cycling, with repercussions on the hormone-like activity of organics. We investigated the effect of snow vole pedoturbation on the chemical and spectroscopic features of soil organic fractions, and the potential hormone-like activity of humic and fulvic acids (HA, FA). The study site was located on the high-mountain environment of the Majella massif (central Italy). Pedoturbated and regular soils were morphologically described and characterized for pH and content of total organic carbon, total extractable carbon, HA, and FA. Both HA and FA were extracted and investigated using attenuated total reflectance/Fourier transform infrared (ATR/FTIR), nuclear magnetic resonance with high-resolution magic angle spinning (HRMAS-NMR), and (1)H-(13)C heteronuclear single quantum coherence (HSQC). HA and FA were also tested for their auxin-like and gibberellin-like activities. Results provide evidences that bioturbated and regular soils contain a poorly decomposed SOM, but HA and FA with a well-defined molecular structure. The HA and FA from both bioturbated and regular soils show a hormone-like activity with a different allocation along the soil profile. In the regular soil, the highest auxin-like activity was shown by HA and FA from Oe1 horizon, while gibberellin-like activity was expressed by FA from Oe2 horizon. Burrowing activity determines a redistribution of organics throughout the profile with a relatively high auxin-like activity in the FA from straw tunnel wall (STW) and gibberellin-like activity in the HA from vole feces (VF). The relative high presence of carboxylic acids, amides, proteins, and amino acids in the FA from STW and the aromatic moieties in the HA from VF put evidences for their different behavior. The fact that snow vole activity has modified the chemical and biological properties of SOM in these soils otherwise considered governed only by low temperature has important ecological implications such as the preservation of soil fertility and vegetal biodiversity.

Changes in composition, ecology and structure of high-mountain vegetation: a re-visitation study over 42 years.

High-mountain ecosystems are increasingly threatened by climate change, causing biodiversity loss, habitat degradation and landscape modifications. However, very few detailed studies have focussed on plant biodiversity in the high mountains of the Mediterranean. In this study, we investigated the long-term changes that have occurred in the composition, structure and ecology of high-mountain vegetation in the central Apennines (Majella) over the last 42 years. We performed a re-visitation study, using historical and newly collected vegetation data to explore which ecological and structural features have been the most successful in coping with climatic changes. Vegetation changes were analysed by comparing geo-referenced phytosociological relevés collected in high-mountain habitats (dolines, gentle slopes and ridges) on the Majella massif in 1972 and in 2014. Composition analysis was performed by detrended correspondence analysis, followed by an analysis of similarities for statistical significance assessment and by similarity percentage procedure (SIMPER) for identifying which species indicate temporal changes. Changes in ecological and structural indicators were analysed by a permutational multivariate analysis of variance, followed by a post hoc comparison. Over the last 42 years, clear floristic changes and significant ecological and structural variations occurred. We observed a significant increase in the thermophilic and mesonitrophilic plant species and an increment in the frequencies of hemicryptophytes. This re-visitation study in the Apennines agrees with observations in other alpine ecosystems, providing new insights for a better understanding of the effects of global change on Mediterranean high-mountain biodiversity. The observed changes in floristic composition, the thermophilization process and the shift towards a more nutrient-demanding vegetation are likely attributable to the combined effect of higher temperatures and the increase in soil nutrients triggered by global change. The re-visitation approach adopted herein represents a powerful tool for studying climate-related changes in sensitive high-mountain habitats.

Rhizosphere effect of three plant species of environment under periglacial conditions (Majella Massif, central Italy)

The chemical, physical and biological processes occurring in the rhizosphere can influence plant growth by modifying root associated microorganisms and nutrient cycles. Although rhizosphere has been widely investigated, little is known about the rhizosphere effect of pioneer plants in soils of periglacial environments. The knowledge of the processes controlling soil–plant relationships in these severe environments may help understanding the ecological evolution of newly deglaciated surfaces. We selected three plants [Helianthemum nummularium (L.) Mill. subsp. grandiflorum (Scop.), Dryas octopetala (L.), and Silene acaulis (L.) Jacq. subsp. cenisia (Vierh.) P. Fourn.] that sparsely occupy deglaciated areas of central Apennines (Italy), with the aim to assess changes between rhizosphere and bulk soil in terms of physical, chemical, and biological properties. The three plants considered showed to have different rhizosphere effect. Helianthemum induced a strong rhizosphere effect through a synergistic effect between root activity and a well adapted rhizosphere microbial community. Dryas did not foster a microbial community structure specifically designed for its rhizosphere, but consumes most of the energetic resources supplied by the plant to make nutrients available. Conversely to the other two species, Silene produced slight soil changes in the rhizosphere, where the microbial community had a structure, abundance and activity similar to those of the bulk soil. The ability to colonize harsh environments of Silene is probably linked to the shape and functions of its canopy rather than to a functional rhizosphere effect.This study showed that the rhizosphere effect differed by species also under high environmental pressure (periglacial conditions, poorly developed soil), and the activity of roots and associated microbial community is decisive in modifying the soil properties, so to create a suitable environment where plants are able to grow.