Search results for "cession"
showing 10 items of 864 documents
Soil carbon dynamics during secondary succession in a semi-arid Mediterranean environment
2018
Clarifying which factors cause an increase or decrease in soil organic carbon (SOC) after agricultural abandonment requires integration of data on the temporal dynamics of the plant community and SOC. A chronosequence of abandoned vineyards was studied on a volcanic island (Pantelleria, Italy). Vegetation in the abandoned fields was initially dominated by annual and perennial herbs, then by Hyparrhenia hirta (L.) Stapf, and finally by woody communities. As a consequence, the dominant photosynthetic pathway changed from C3 to C4 and then back to C3. Conversion of a plant community dominated by one photosynthetic pathway to another changes the 13C/12C ratio of inputs to soil organic carbon (S…
Carbon dynamics of soil organic matter in bulk soil and aggregate fraction during secondary succession in a Mediterranean environment.
2013
Clarifying which factors cause an increase or decrease in soil organic carbon (SOC) after agricultural abandonment requires integration of data on the temporal dynamics of the plant community and SOC. A chronosequence of abandoned vineyards was studied on a volcanic island (Pantelleria, Italy). Vegetation in the abandoned fields was initially dominated by annual and perennial herbs, then by Hyparrhenia hirta (L.) Stapf, and finally by woody communities. As a consequence, the dominant photosynthetic pathway changed from C3 to C4 and then back to C3. Conversion of a plant community dominated by one photosynthetic pathway to another changes the 13C/12C ratio of inputs to SOC. Using the time si…
Litter contribution to soil organic carbon in the processes of agriculture abandon
2015
The mechanisms of litter decomposition, translocation and stabilization into soil layers are fundamental processes in the functioning of the ecosystem, as they regulate the cycle of soil organic matter (SOM) and CO2 emission into the atmosphere. In this study the contribution of litters of different stages of Mediterranean secondary succession on carbon sequestration was investigated, analyzing the role of earthworms in the translocation of SOM into the soil profile. For this purpose the δ13C difference between meadow C4-C soil and C3-C litter was used in a field experiment. Four undisturbed litters of different stages of succession (45, 70, 100 and 120 since agriculture abandon) were colle…
The effects of land abandonment and long-term afforestation practices on the organic carbon stock and lignin content of Mediterranean humid mountain …
2019
Afforestation is an important strategy that can decrease atmospheric carbon by sequestering carbon in biomass and soil. In Spain, an active afforestation programme was adopted in the 1950s when the soil was severely eroded after widespread abandonment of arable land. The Araguás catchment (Central Spanish Pyrenees) is a good example of this programme because it was afforested with both Pinus sylvestris L. (PS) and Pinus nigra J.F.Arnold (PN). The soil organic carbon (SOC) stock and lignin content (based on the vanillyl, syringyl and cinnamyl contents) of these afforested soils were examined and compared to those of bare soil, secondary succession and meadow soils. Both the SOC stock and lig…
Middle Eocene calcareous nannofossils in the Jaca transect (South-central Pyrenees Eocene Basin, Aragón river valley, Huesca)
2020
The calcareous nanoplankton is studied from the base of the turbidite systems of the Upper Hecho Group (Jaca Basin, middle Eocene of the South-central Pyrenean Basin) up to the Gracionepel instabilities, within the Larres slope Marls. This new chronostratigraphic contribution is of crucial importance for the improvement of the detailed temporal and spatial correlation framework of the genetically related depositional systems at basin scale. The calcareous nanofossil assemblage is largely dominated by Coccolithus pelagicus , C. formous as well as different species of Reticulofenestra , accompanied by occasional specimens of several species of Sphenolithus and Chiasmolithus . The results obt…
Succession et remplacements de communautés à brachiopodes en régime de sédimentation discontinue (Jurassique Moyen, Bourgogne, France)
1993
Abstract Sequence stratigraphy throws a new and seminal light on the fossil record and helps in determining the respective role played by external control (community replacement) and internal control (paleoecological succession) in the temporal “train” of marine benthic paleocommunities. Five brachiopod-dominated communities (C1–C5) are recognized and their temporal “train” described, during the uppermost Bathonian-lower Callovian interval in Burgundy. The first series (C1–C3) exhibits a trend interpreted as a paleoecological succession and the next two (C3–C4, C4–C5) as community replacements. Within the scope of sequence stratigraphy, the paleoecological succession comes at the end of a t…
Per una storia della Settimana Santa a Malta. I gruppi processionali del Venerdì Santo di Valletta
2013
L’articolo ricostruisce la storia dei riti della Settimana Santa e delle processioni per il Venerdì Santo a Malta, in relazione al più ampio contesto mediterraneo e, pertanto, alla tradizione dei pasos in Spagna e dei “misteri” di Trapani ed Erice. Viene evidenziato il ruolo cruciale svolto a partire dalla fine del XVI secolo dai frati Francescani, la cui presenza si rivelò determinante per la nascita e, in seguito, per la diffusione e la fortuna di tali rappresentazioni processionali, anche grazie al fatto che nel corso dei secoli la devozione per la Passione di Cristo a Malta fu alimentata dalla presenza di ben due crocefissi lignei dello scultore siciliano frate Innocenzo da Petralia. In…
Melo
2015
Il Progetto Nazionale, “Liste di Orientamento Varietale dei Fruttiferi - Melo”, ha ormai abbondantemente superato i vent’anni. Ultimamente sta attraversando diverse peripezie, anche se mantiene invariato lo spirito originario, proponendosi come obiettivo la verifica del comportamento vegetativo e produttivo di numerose nuove varietà introdotte in Italia e divulgazione dei risultati ottenuti. Basti pensare che dal 1980 al 2014 sono state registrate al mondo quasi 1700 nuove varietà, il Progetto nazionale ne ha valutate più di 300 a partire dal 1993. Il lavoro di valutazione, riguardante l’”adattabilità”, agronomica e merceologica, del nuovo materiale genetico è affidato a 16 Unità Operative,…