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Geomorphological characteristics of avalanche tracks on Babia Góra Mt., Western Carpathians

Łajczak A., Spyt B.

Studia Geomorphologica Carpatho-Balcanica

2016

Vol. 50

65--88

Distribution and parameters of avalanche tracks on the slopes of asymmetric ridge of Babia Góra Mt. (1725 m a.s.l. – the highest massif in the flysch Western Carpathians) were studied in relation to slope relief, prevailing wind directions, snow cover thickness, treeline and timberline locations. The following sections of avalanche tracks were distinguished: starting zone, track zone and runout zone. The entire course of each track was described using the following parameters: the elevation [m a.s.l.], vertical drop Δh [m], maximum and mean inclination α [°], length on slope L [m]. The relationships between these parameters were analyzed on slopes of straight, concave, step-like and convex profiles. The character of starting zone (from a point or a line) and the form of avalanche track (confined or unconfined) were determined. Values of sinuosity index [%] were calculated. The longest avalanche tracks (>300 m, locally >800 m) occur on convergent slopes of different profiles with domination of straight once. 75% of avalanche tracks exceed the treeline causing lowering of the timberline by over 200 m. On divergent slopes, avalanches are not present. The most frequent are avalanche tracks of mean slope inclination in the range 26–40°. The application of LiDAR data and their linkage with field work investigations made it possible to reveal that the number of avalanche tracks on Babia Góra Mt. and their dimensions are greater than it was so far assumed. Their main concentration was determined on the steep northern slope of straight, concave or step-like profiles.

Seedling survival and dynamics of upper timberline in Central Apennines

Catorci A., Scapin W., Tardella F., Vitanzi A.

Polish Journal of Ecology

2012

Vol. 60, nr 1

79-94

Despite several studies on the timberline dynamics in Europe were carried out in the last decades, very few papers refer to mountain areas where the timberline is composed of broadleaved trees, and no research was conducted on the dynamics of Apennine beech timberline in relation to seedling survival. The research aim was to analyse the beech wood timberline dynamics in the central Apennines, with reference to seedling survival. Furthermore, factors affecting seedling survival were identified. To assess the forest ecotone dynamics, vegetation layer cover, rock fragment cover and information about forest management and krummholz occurrence were collected in sampling plots placed over 1,600 m a.s.l., on north-facing slopes. The beech seedlings occurring in Brachypodium genuense-dominated stands above the timberline were counted and monitored along two growing seasons. Soil temperature, soil moisture, and photosynthetically active radiation available for seedlings (PHAR) in grasslands above timberline were measured. The research outputs indicate that timberline is not a natural boundary and that there is no evidence of its extension upwards. The greatest number of beech seedlings was recorded in late spring. The one-year mortality rate ranged from 71 to 100%. None of the seedlings still alive in the early autumn of the first year were recorded in the following spring. The competitive exclusion by Brachypodium genuense individuals, which limit the incident PHAR, and the low soil moisture during summer, were identified as the main factors that account for the high mortality of seedlings and affect beech regeneration above timberline. The effect of competition is probably intensified by the lack of pioneer shrubs which could otherwise serve as nurse plants for beech seedlings and protect them from browsing by wild ungulates. Thus, both the current and the past land use may be considered as driving forces in timberline dynamics. Probably, also the trend of global warming, that in the Mediterranean and sub-Mediterranean climatic context would determine the increase of summer drought stress, could worsen the effect of competitive exclusion of beech seedlings, so that it can be hypothesized that the expansion upwards of the upper timberline in the Apennines could be totally blocked.