GEOBOTANICAL COMPARISON BETWEEN TWO JAPANESE VOLCANOES: MT. FUJI AND MT. ASAMA

Mt. Fuji and Mt. Asama are two of the highest Japanese volcanoes. reaching 3776 and 2542 m a.s.l. respectively. The former is dormant but the latter is an active volcano. This study is based on our own unpublished data, which inc1udes a total of 152 phytosociological relevés. and on previous studies of the vegetation of both volcanoes. On the basis of the data collected al different times a geobotanical comparison between the two vo1canoes as regards their high moutain regions was made. In this region the following belts may be distinguished on both volcanoes: - a subalpinc belt, characterized on its upper zone by shrub communities with some Ericaceae, larch (Larix leptolepis), Salix reinii and other dwarf woody species; - an alpine belt, where there is scattered herbaceous vegetation, mostly dominated by Polygonum weyrichii v. alpinum. In this belt on Mt. Fuji, the following communities may be distinguished: the Arabis serrata-Polygonum alpinum community on the lowest altitudes; the Stellaria nipponica-Polygonum alpinum community and at higher altitudes a very sparse poor community characterized by Cassiope lycopodioides. In the highest region up to the summit there are moss and lichen communities only. On the southeastern side on the 1707 ash and scoria there is pioneer vegetation dominated by Cirsium purpuratum and Campanula hondoensis. On Mt. Asama the high-mountain vegetation is dominated by the Polygonum alpinum community. It occupies a narrower belt. Here the volcanic activity doesn't allow the vegetation to reach the top. In the highest region of the volcano there is a bare sterile zone. The differences found in the altitudinal distribution of vegetation on the two volcanoes can partIy be attributed to the fact that one (Mt. Fuji) is dormant, while the other (Mt. Asama) is active. On active volcanoes the ecological factors related to the volcanic activity have a strong influence on the vegetation and its distribution

GEOBOTANICAL COMPARISON BETWEEN TWO JAPANESE VOLCANOES: MT. FUJI AND MT. ASAMA

Mt. Fuji and Mt. Asama are two of the highest Japanese volcanoes. reaching 3776 and 2542 m a.s.l. respectively. The former is dormant but the latter is an active volcano. This study is based on our own unpublished data, which inc1udes a total of 152 phytosociological relevés. and on previous studies of the vegetation of both volcanoes. On the basis of the data collected al different times a geobotanical comparison between the two vo1canoes as regards their high moutain regions was made. In this region the following belts may be distinguished on both volcanoes: - a subalpinc belt, characterized on its upper zone by shrub communities with some Ericaceae, larch (Larix leptolepis), Salix reinii and other dwarf woody species; - an alpine belt, where there is scattered herbaceous vegetation, mostly dominated by Polygonum weyrichii v. alpinum. In this belt on Mt. Fuji, the following communities may be distinguished: the Arabis serrata-Polygonum alpinum community on the lowest altitudes; the Stellaria nipponica-Polygonum alpinum community and at higher altitudes a very sparse poor community characterized by Cassiope lycopodioides. In the highest region up to the summit there are moss and lichen communities only. On the southeastern side on the 1707 ash and scoria there is pioneer vegetation dominated by Cirsium purpuratum and Campanula hondoensis. On Mt. Asama the high-mountain vegetation is dominated by the Polygonum alpinum community. It occupies a narrower belt. Here the volcanic activity doesn't allow the vegetation to reach the top. In the highest region of the volcano there is a bare sterile zone. The differences found in the altitudinal distribution of vegetation on the two volcanoes can partIy be attributed to the fact that one (Mt. Fuji) is dormant, while the other (Mt. Asama) is active. On active volcanoes the ecological factors related to the volcanic activity have a strong influence on the vegetation and its distribution

GRASSALAND VEGETATION ON THE ARCHAEOLOGICAL SITES OF THE CALTAGIRONE AREA (SOUTHERN ITALY)

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FLORISTIC COMPOSITION, PHY SIOGNOMIC AND STRUCTURAL ASPECTS OF THE FAGUS SYLVATICA L. FORESTS OF THE MT. ETNA NATURAL PARK (SOUTHERN ITALY)

This study was carried out on all the Etna beech distribution area and consists of a phytosociological analysis. Moreover data relating to various pysiognomical and structural aspects was collected from 12 sample areas selected on the different expositions of the volcano. From the phytosociological analysis it emerged that it is very difficult to define the Etna beech forests syntaxonomically: in most cases it can be seen that they belong to the class Querco-Fagetea, but it is not always possible to identify the association, the alliance and the order. Some communities seem to belong to the Quercetalia pubescentis rather than to the Fagetalia sylvaticae. Other communities do not even belong to the class Querco-Fagetea. These are in fact relict forests surviving in extreme life conditions. They are at the southern limit of its distribution area and are subject to unfavorable environmental conditions: a volcanic substrata, the Mediterranean climate, the high level of man&rsquo;s intervention. The study of the tree and stump density, stem diameter, basal area, litter cover and litter thickness and seedling density, carried out on 12 sample areas, shows that these forests have a very variable physiognomy and structure. The forests with a more balanced physiognomy and structure are made up of forests with high trunks of different ages. The seedling density, correlated with the litter thickness and cover, was found to be significant in areas located on the east side of Etna, where there are better light conditions and greater rainfall. This study brought to light the presence of a species: Monotropa hypopytis L. not previously reported as having been found on Mt. Etna

Charcoal and stable soil organic matter as indicators of fire frequency, climate and past vegetation in volcanic soils of Mt. Etna, Sicily

Charcoal fragments in soils are useful to reconstruct past vegetation because the level of preservation is often good enough to determine the tree genus. All forest ecosystems have the potential to burn as a result of naturally occurring or human-induced fires. Forest fires are coupled to climate and are a not-negligible factor of pedogenesis in Mediterranean areas, where they occur frequently. Furthermore, soil organic matter (SOM) is prone to undergo peculiar changes due to forest fires, both in terms of quantity and quality. A soil sequence along an elevational gradient ranging from Mediterranean to subalpine climate zones on slopes of Mt. Etna (Sicily, Italy) was investigated in respect of soil organic C and charcoal. The amount of charcoal and the identification of charred species gave an indication of the fire frequency and vegetation changes that have occurred in the past. The distribution into labile and stable organic fractions provided insight into the stabilisation and turnover mechanisms of SOM. The stable organic matter fraction was measured as the residue of a H2O2 treatment. The soils along the altitudinal sequence are variations of Vitric Andosols that developed on a single trachy-basaltic lava flow having an age of 10–15 ky BP. Maquis vegetation dominates at the lower sites of the toposequence, followed by oak- and chestnut-forests at mid elevations, and pine-forest at the highest-elevated sites. Charcoals are older at higher elevations (ages of up to 1.5 ky cal BP). Here, the vegetation type has not changed over the last > 1000 years, as all charcoal pieces were identified as Pinus nigra. Charred material at the lower sites could be identified as particles of deciduous shrubs, Quercus, Castanea sativa, Lonicera implexa and Cytisus spp. with mostly a modern age up to about 300 y cal BP. A similar finding was obtained for the stable (H2O2 resistant) SOM. Very high ages for this fraction were found at the highest elevations where it had an age of up to 8.2 ky BP — an age that is close to the start of soil formation. At the lower sites, where frequent bush fires often destroyed a part of the stable fraction, the stable SOM fraction had a maximum age of 1 ky. The studied soils have recorded the signals of the interrelated factors fire frequency, climatic effects and vegetation whose role cannot always be clearly distinguished. With decreasing altitude and with a warmer climate, vegetation changes and fire frequency, org. C and especially nitrogen abundance and the amount of labile SOM increases. At the lower sites, charcoal particles reflect the more recent vegetation probably because the repeated fires here hindered their preservation. Our findings hence suggest that a high fire frequency is a powerful rejuvenating factor for soil organic matter, removing part of the old SOM and promoting plant recolonisation that is a source of young SOM. Fire frequency and intensity on Mt. Etna is, however, moderate enough even at the lowest altitudes for the organic matter pool to be high and not depleted