Contributo Allo Studio Dei Limiti Altimetrici Del Faggio in Garfagnana

Summary

The Valley of Garfagnana runs North of the town of Lucca in Tuscany, in a North-West South-East direction, and is limited by the ridge-line of both the “Alpi Apuane” and the “Appennino tosco-emiliano”.

These two ranges of mountains have a different origin and geological constitution. As a matter of fact the “Apuane” are mostly composed of calcareous formations of the Secundary age, while the “Appennino tosco-emiliano” is essentially constituted of schisto-argillous dregs of the Terziary age.

The altimetric limits of beech have been studied in two different valleys: that of the “Turrite Secca” on the Apuan slope, and that of the “Fegana” on the side of the “Appennino”.

The Valley of the Turrite Secca is rather rainy; hydric action, however, is greatly attenuated by the steepness of its sides and the splits of its calcareous rocks.

Distribution of beech greatly varies on the two slopes of this valley. Beechwoods are widely spread on its prevailingly North exposed right side, when on its left side, exposed to the South, beech is sporadically present and only at rather high cotes. The upper part of this valley is extremely degraded and most of its majestic southern slopes are almost bare and show but a poor vegetation of xerophilous plants. It is presumable that some time ago these sides were covered by a much richer vegetation of forests. This is proved by small portions of beechwood and bushy samples of Taxus baccata that are still to be found there.

This extreme stage of degradation is probably due to the action of man and is helped by the peculiar morfological and topographical features and by the southern exposition of the ground.

The inferior limit of beech is very low in this valley. As a matter of fact a great dispersion of colonies of Fagus silvatica, at low cotes, is noticeable along the flow of the Turrite Secca. (See “Casa Zuppini” — m. 310 —, “Riccio” — m. 340 —, “Piastricoli” — m. 370 —).

The probable origin of these etherotopic submontane colonies goes back to the climatic crises of the post-Quaternary period when beech, in a continental phasis, started retiring towards the mountain belt of vegetation. It first had come down to the plains in the oceanic period. To the high raininess of the Valley of the Turrite Secca and to its oceanic climate, we owe if these colonies are still noticeable. The “shelter” characteristic of these stations of Fagus silvatica is confirmed by the high affinity of their flora with that of the upper beechwoods, especially in the most rapresentative species of such communities.

The distribution of beech in the Valley of the Fegana is much more uniform. Here it spreads along all the head of the valley without exceeding the limits of the region of mountain vegetation. It never goes under height of 700 m., not even sporadically. The prevailing southern exposition of the Valley of the Fegana and its raininess, that is lesser than that of the Valley of the Turrite Secca, do not permit the eventual subsistence of etherotopic colonies of beech at low cotes.

Studies of the flora have been made either in the typical beechwoods of both the valleys, or, in the Valley of the Turrite Secca, in the small groups of beech trees that extend along the flow of the river.

The total biological spectrum is the following:

Ph = 19,3% Ch = 7,3% H = 50% G = 18,5% Th = 4,9%

From the examination of the surveys, the remarkable heterogeneousness of the flora of the beechwoods of Garfagnana is evident. The meso-hygrophilous and exacting species, that are common in the good beechwoods, join with the xerophilous ones, or with those that are characteristic of poor or semidegraded woods. This happens especially on the Apuan side. These are coppices woods of beech, however, greatly alterated by man, always of a limited extension; they are often discontinued by rocky surfaces and by other kinds of forestal communities. Transgressions of the most plastic species from the limitrophe cenosis are, for the just mentioned reasons, rather frequent, especially after the periodical cuttings.

Comparing the surveys of the flora of Garfagnana with those related by variois Authors, and specifically with the ones of Vierhapper on the Austrian beechwoods, a high number of species can be remarked that are common to the type indicated by this Author, as the normal and most mature one. This confirms that the beechwoods of the “Appennino” can be considered as belonging to the great megacenosis of the European Fagetum, although they constitute regional facies. Nevertheless beechwoods of Garfagnana can not be considered as exactly belonging to any of the types indicated by Vierhapper, because of the above mentioned heterogeneousness of their flora, that is their mark.

Lastly we observe that the remarkable heterogeneousness of the flora, essentially due to human factors, is not an exclusive feature of the beechwoods of Garfagnana, as it can be found in various other types of like cenosis, also in natural conditions of vegetation. As a matter of fact, at any variation of some of the multiform ecological factors that rule the aspect of the vegetal covering, a continous alternative of microstational facies is usually noted in pluristratified and hence not coetanean woods, if considered in their whole.