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

Background:Fagus sylvatica forms the treeline across the Apennines mountain range,with an average elevation of 1589 ma.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 2000ma.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 southfacing 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.

Frequent Applications of Organic Matter to Agricultural Soil Increase Fungistasis

Soil-borne plant pathogens are among the most important limiting factors for the productivity of agro-ecosystems.Fungistasis is the natural capability of soils to inhibit the germination and growth of soil-borne fungi in the presence of optimal abiotic conditions.The objective of this study was to assess the effects of different soil managements,in terms of soil amendment types and frequency of application,on fungistasis.For this purpose,a microcosm experiment was performed by conditioning a soil with frequent applications of organic matter with contrasting biochemical quality(i.e.,glucose,alfalfa straw and wheat straw).Thereafter,the fungistasis response was assessed on four fungi(Aspergillus niger,Botrytis cinerea,Pyrenochaeta lycopersici and Trichoderma harzianum).Conditioned soils were characterized by measuring microbial activity(soil respiration) and functional diversity using the BIOLOG EcoPlates^(?)method.Results showed that irrespective of the fungal species and amendment types,frequent applications of organic matter reduced fungistasis relief and shortened the time required for fungistasis restoration.The frequent addition of easily decomposable organic compounds enhanced soil respiration and its specific catabolic capabilities.This study demonstrated that frequent applications of organic matter affected soil fungistasis likely as a result of higher microbial activity and functional diversity.