Climatic and anthropogenic factors explain the variability of Fagus sylvatica treeline elevation in fifteen mountain groups across the Apennines

Abstract Background Fagus sylvatica forms the treeline across the Apennines mountain range, with an average elevation of 1589 m a.s.l. Previous studies evidenced that the current position of the treeline in the Apennines is heavily depressed as a result of a complex interaction between climatic factors and the past human pressure. In this study we correlated treeline elevation in the fifteen major mountain groups in the Apennines with selected climatic, geomorphological, and human disturbance variables in order to investigate in detail the site-specific features affecting the current treeline distribution. Results Treeline elevation was lowest in the North Italy (Apuan Alps), while the highest treeline was found in Central Italy (Simbruini). An absolute maximum treeline elevation of F. sylvatica exceeding 2000 m a.s.l. was found on 13 mountain peaks in Central and Southern Italy. Noteworthy, treeline elevation was largely lower on warmer south-facing slopes compared to northern slopes, with values several hundred meters lower in the Gran Sasso and Velino-Sirente. Although the causes of this pattern are still unknown, we argue that treeline elevation on south-facing slopes may be limited by the combination of climatic constraints (i.e. summer drought) and human disturbance. Evidence of a pervasive anthropogenic effect depressing treeline elevation was found in the North (Apuan Alps) Central (Gran Sasso, Velino-Sirente, Sibillini) and Southern part of Apennines (Pollino). By contrast, treeline elevation of the Laga, Simbruini, and Orsomarso mountain groups appears less affected by past anthropogenic disturbance. Finally, we recorded in the several mountain groups (i.e. Majella, Marsicani and Pollino) the coexistence of very depressed treelines just a few kilometers away from much higher treelines, among the highest ever recorded for F. sylvatica. Conclusions Finally, we argue that F. sylvatica treeline across the Apennines is locally shaped both by the interaction of low temperatures experienced by the species in its earliest life stages in snow-free open spaces with summer soil water depletion and human disturbance

Bevacizumab plus XELOX as first-line treatment of metastatic colorectal cancer: The OBELIX study

AIM: To confirm the efficacy and safety of bevacizumab/XELOX combination for the treatment of locally advanced or metastatic colorectal cancer (CRC) in Italy. METHODS: This multicentric, prospective, open-label study included patients with CRC previously untreated with chemotherapy. Patients were administered bevacizumab in combination with XELOX. The primary efficacy end-point was progression-free survival (PFS). Secondary end-points included time to overall response (TOR), duration of response (DOR), time to treatment failure (TTF) and overall survival (OS). The incidence and type of adverse events AEs and severe AEs were evaluated. Also, the mutational status of BRAF and KRAS was assessed by high resolution melting and direct sequencing, and quality of life (QoL) was measured by the EuroQoL EQ-5D questionnaire at baseline and at the last visit. RESULTS: The intention-to-treat population included 197 patients (mean age: 62.3 ± 9.9 years, 56.4% males). At baseline, 16/34 evaluable subjects (47.1%) harbored a KRAS and/or a BRAF mutation; the mean QoL index was 80.2 ± 14.3. First-line therapy was given for 223.7 ± 175.9 d, and after a mean follow-up of 387.7 ± 238.8 d all patients discontinued from the study mainly for disease progression (PD, 45.4%) and AEs (25.4%). Median PFS was 9.7 mo (95%CI: 8.4-10.5) and the median values for secondary end-points were: TOR = 3.9 mo (95%CI: 2.6-4.7), DOR = 8.5 mo (95%CI: 7.3-10.3), TTF = 6.7 mo (95%CI: 6.0-7.7) and OS = 23.2 mo (95%CI: 20.1-27.2). Patients carrying at least one lesion had a lower overall response rate (66.7% vs 88.9%) and a lower probability of achieving complete or partial response than those without mutations, but the difference in relative risk was not statistically significant (P = 0.2). Mean EQ-5D-3L raw index score significantly decreased to 74.9 ± 19.1 at the last visit (signed-rank test, P = 0.0076), but in general the evaluation on QoL perceived by patients was good. CONCLUSION: The efficacy of bevacizumab in combination with XELOX in terms of PFS in patients with aCRC or mCRC in Italy was confirmed, with acceptable toxicity

Treeline dynamics and local microclimate of Fagus sylvatica forests along the Apennine Mountains range

L'obiettivo di questo progetto di ricerca era quello di indagare i fattori climatici, topografici, geografici e antropici che determinano il limite superiore delle foreste di Fagus sylvatica (treeline) negli Appennini. Lo studio delle risposte delle treeline al clima è fortemente influenzato dalla scala spaziale e temporale dell'analisi. Sono stati condotti tre studi su diversa scala spaziale, vale a dire regionale, paesaggistica e locale. A livello regionale, sono state misurate le treeline su immagini satellitari in quindici grandi gruppi montuosi dell'Appennino, e poi in seguito correlate a variabili climatiche, geomorfologiche e antropiche. A livello paesaggistico è stato condotto uno studio su otto catene appenniniche al fine di valutare l'avanzamento della treeline e i meccanismi di reclutamento del faggio sopra la linea del suolo attuale. A livello locale, lo studio è stato condotto al limite latitudinale meridionale di F. sylvatica ed è stato studiato il ruolo della copertura della chioma di faggio nella modulazione del microclima vicino al suolo. Il risultato su scala regionale ha mostrato che le treeline di faggio sull'Appennino sono modellate dalle interazioni sfaccettate tra vincoli climatici (basse temperature invernali e basse precipitazioni estive) e disturbi umani, a seconda del gruppo montuoso e del picco considerato. Lo studio su scala paesaggistica evidenzia che la treeline avanzerà verso l'alto grazie agli effetti di facilitazione degli arbusti che agevolano F. sylvatica al di sopra dell'attuale posizione altitudinale della treeline. La presenza di una copertura arbustiva è una condizione indispensabile sia per il reclutamento che per l'insediamento del faggio al di sopra del limite superiore delle foreste chiuse, indipendentemente dalle specie di arbusti e dall'elevazione. Su scala locale abbiamo affermato che la copertura del baldacchino di F. sylvatica ad alta quota è in grado di modulare il microclima in contesti topografici contrastanti della montagna. Le treeline oggetto di studio ricadono all'interno delle aree protette regionali o nei parchi nazionali, dove la conservazione di questi ecotoni è una priorità

Relazione tra indice di resistenza renale e severità dell’aterosclerosi carotidea in soggetti con ipertensione arteriosa.

RAZIONALE. L’indice di resistenza intraparenchimale renale (IR), valutato mediante eco-color-Doppler, è stato classicamente considerato mera espressione di resistenza vascolare distrettuale renale. Studi più recenti, tuttavia, hanno mostrato come tale indice sia anche influenzato da fattori a tergo, compliance vasale in primis, a prova di un suo possibile ruolo quale marker di alterazioni vascolari sistemiche. Diversi studi hanno dimostrato, inoltre, come lo spessore intimale (IMTc) e la placca a livello carotideo, valutati mediante ultrasonografia, siano documentati marcatori di danno d'organo subclinico nonché espressioni progressive di malattia aterosclerotica. Scopo del nostro studio è quello di valutare, in soggetti ipertesi, la relazione esistente tra IR intrarenale e severità della malattia aterosclerotica carotidea subclinica. CASISTICA E METODI. Sono stati reclutati consecutivamente 263 soggetti ipertesi, di età compresa tra i 30 ed i 70 anni, con o senza ridotta funzionalità renale. Sono stati esclusi dallo studio tutti i pazienti con ipertensione renovascolare ed endocrina, così come i soggetti con stenosi carotidea >50% (European Carotid Surgery Trial - ECST). I pazienti sono stati divisi in 3 diversi gruppi: pazienti con IMTc≤0.9 mme senza placche; pazienti con IMTc >0.9mme senza placche; pazienti con placche. Tutti sono stati sottoposti ad eco-color-Doppler del distretto carotideo e renale. RISULTATI. I valori di IR nel I, II e III gruppo sono stati rispettivamente di 0.61±0.07, 0.65±0.06 e 0.68±0.06 (p<0.001). Una forte correlazione positiva è stata osservata tra IR e IMTc nell'intera popolazione (r=0.43; p<0.001) e nei sottogruppi con (r=0.42; p<0.001) e senza (r=0.39; p<0.001) alterazione della funzione renale. Queste correlazioni sono rimaste statisticamente significative anche dopo aggiustamento per vari fattori confondenti all'analisi multivariata. CONCLUSIONI. I nostri risultati sembrano confermare una stretta associazione tra IR e severità della patologia aterosclerotica carotidea in pazienti ipertesi con e senza ridotta funzionalità renale, a controprova di un probabile ruolo dell’IR quale marker di alterazioni morfofunzionali vascolari sistemiche

Clonality drives structural patterns and shapes the community assemblage of the Mediterranean Fagus sylvatica subalpine belt

Past anthropogenic disturbances lowered the altitudinal distribution of the Mediterranean Fagus sylvatica forests below 2,000 m a.s.l. Accordingly, our current understanding of the southern distribution range of F. sylvatica forests is restricted to managed stands below this elevation, neglecting relic forests growing above. This study has shed light on the structure and species assemblage of an unmanaged relict subalpine F. sylvatica stand growing within the core of its southernmost glacial refugia and at its highest species range elevation limit (2,140 m a.s.l.) in southern Apennines (Italy). Here, tree biometric attributes and understory species abundances were assessed in eight permanent plots systematically positioned from 1,650 to 2,130 m a.s.l. In the subalpine belt, F. sylvatica had formed a dense clonal stem population that was layered downward on the steepest slopes. The density and spatial aggregation of the stems were increased, while their stature and crown size were decreased. Above 2,000 m, changes in tree growth patterns, from upright single-stemmed to procumbent multi-stemmed, and canopy layer architecture, with crowns packed and closer to the floor, were allowed for the persistence of understory herbaceous species of biogeographic interest. Clonal layering represents an adaptive regeneration strategy for the subalpine belt environmental constraints not previously recognized in managed Mediterranean F. sylvatica forests. The clonal structure and unique species assemblage of this relic forest highlight the value of its inclusion in the priority areas networks, representing a long-term management strategy of emblematic glacial and microclimatic refugia

Data_Sheet_1_Clonality drives structural patterns and shapes the community assemblage of the Mediterranean Fagus sylvatica subalpine belt.docx

Past anthropogenic disturbances lowered the altitudinal distribution of the Mediterranean Fagus sylvatica forests below 2,000 m a.s.l. Accordingly, our current understanding of the southern distribution range of F. sylvatica forests is restricted to managed stands below this elevation, neglecting relic forests growing above. This study has shed light on the structure and species assemblage of an unmanaged relict subalpine F. sylvatica stand growing within the core of its southernmost glacial refugia and at its highest species range elevation limit (2,140 m a.s.l.) in southern Apennines (Italy). Here, tree biometric attributes and understory species abundances were assessed in eight permanent plots systematically positioned from 1,650 to 2,130 m a.s.l. In the subalpine belt, F. sylvatica had formed a dense clonal stem population that was layered downward on the steepest slopes. The density and spatial aggregation of the stems were increased, while their stature and crown size were decreased. Above 2,000 m, changes in tree growth patterns, from upright single-stemmed to procumbent multi-stemmed, and canopy layer architecture, with crowns packed and closer to the floor, were allowed for the persistence of understory herbaceous species of biogeographic interest. Clonal layering represents an adaptive regeneration strategy for the subalpine belt environmental constraints not previously recognized in managed Mediterranean F. sylvatica forests. The clonal structure and unique species assemblage of this relic forest highlight the value of its inclusion in the priority areas networks, representing a long-term management strategy of emblematic glacial and microclimatic refugia.</p

Table_1_Clonality drives structural patterns and shapes the community assemblage of the Mediterranean Fagus sylvatica subalpine belt.XLSX

Past anthropogenic disturbances lowered the altitudinal distribution of the Mediterranean Fagus sylvatica forests below 2,000 m a.s.l. Accordingly, our current understanding of the southern distribution range of F. sylvatica forests is restricted to managed stands below this elevation, neglecting relic forests growing above. This study has shed light on the structure and species assemblage of an unmanaged relict subalpine F. sylvatica stand growing within the core of its southernmost glacial refugia and at its highest species range elevation limit (2,140 m a.s.l.) in southern Apennines (Italy). Here, tree biometric attributes and understory species abundances were assessed in eight permanent plots systematically positioned from 1,650 to 2,130 m a.s.l. In the subalpine belt, F. sylvatica had formed a dense clonal stem population that was layered downward on the steepest slopes. The density and spatial aggregation of the stems were increased, while their stature and crown size were decreased. Above 2,000 m, changes in tree growth patterns, from upright single-stemmed to procumbent multi-stemmed, and canopy layer architecture, with crowns packed and closer to the floor, were allowed for the persistence of understory herbaceous species of biogeographic interest. Clonal layering represents an adaptive regeneration strategy for the subalpine belt environmental constraints not previously recognized in managed Mediterranean F. sylvatica forests. The clonal structure and unique species assemblage of this relic forest highlight the value of its inclusion in the priority areas networks, representing a long-term management strategy of emblematic glacial and microclimatic refugia.</p