Changes in soil properties related to natural regeneration of silver fir (Abies alba, Mill.) in small (185 m 2 ) and medium (410 m 2 ) gaps, in the Calabria Apennines (Southern Italy), were studied 2 years after gap creation. The organic matter within the medium gaps decayed more rapidly than those in the small gaps. Among the microenvironmental variables and soil properties, soil temperature was most strongly positively related to organic matter decomposition rates. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance, and low soil moisture. Within medium gaps, we found a great amount of phenolic compounds and a low content of organic matter and humic acids. These results indicate that in the medium gaps mineralization of organic matter was more important than humification. In contrast, in small gaps, the great amount of organic matter, the high content of humic acid and the values of humification index suggested that in these gaps the humification process of organic matter prevailed. Within small gaps, we observed more silver fir regeneration than medium gaps. Difference in organic matter content, particularly in the amount of phenolic compounds, may account for differences observed in natural regeneration of silver fir between small and medium gaps.
In Mediterranean regions, climate change increasingly affect tree species distributions. Conifer forests under continuing disturbance show a more rapid shift to dominance by beech and other temperate broadleaves. Thus, there is an urgent need to conserve coniferous vegetation to avoid local extinction. Gap opening has profound effects on the structure and dynamics of most forests and may represent a sustainable way to restore coniferous ecosystems in Mediterranean habitats. What kind of artificial canopy opening is the most sustainable and effective means for restoring coniferous ecosystem functions? We explored the efficacy of artificial gaps in regeneration and dynamics of coniferous in Mediterranean environment. We examined how regeneration of different tree species is associated with soil environmental conditions and how gaps of different sizes influence the ecology and management of Mediterranean forest. Specifically, we analyzed gap disturbance in silver fir and black pine stands, as they dominate central and southern Italian forests. We demonstrated a specificity between gap size and coniferous species regeneration, indicating that small gaps (about 200 m 2 ) favor silver fir regeneration, while black pine, depending on its subspecies, regenerates both in small and medium gaps (about 500 m 2 ). Further, we found that gap characteristics (age and shape) and suitable substrate availability are the primary factors affecting seedling establishment. Our results provide functional information to design a silvicultural system useful to manage the natural regeneration of Mediterranean forest minimizing the environmental and visual impact.
The purpose of this paper is to highlight a case study of forest restoration in the Pomieri Wood area (Madonie regional park, Sicily), consisting of a relict population of sessile oak (Quercus petraea subsp. austrothyrrenica Brullo, Guarino & Siracusa). To assess the functionality of the stand some biological indicators were taken into consideration: dendrometric-structural, floristic-vegetation, ecological, fructification, natural regeneration, disturbances. They reveal a state of degradation after a long period of overexploitation of resources. Forest restoration would lead to the regaining of the cultural value of the Pomieri wood by management authorities and local populations. Then a series of measures are to be carried out providing for the removal of degradation factors (grazing, illegal cuttings) and restoring stand density, biodiversity and ecological functionality
In Italy since the beginning of the XXI century conifer afforestations, most of them of Pinus sp. species, were established over large areas for soil protection and/or wood production. Today, afterwards insufficient attention to the silvicultural practices, ageing processes, insects and fungi outbreaks lead to an unsteady biological equilibrium in many of these afforestations. The restoration of conifer afforestations into stands with a more complex structure and composition is a current challenge for the Italian silviculture and an opportunity to provide wood energy. A silvicultural system aiming to the natural regeneration by means of canopy gaps (gapbased approach, sensu coates and Burton, 1997) has been applied. Gap cutting mimics natural forest evolution and derives from the empirical experience that relates the
The present study was focused on how cardinal directions inside gaps of different sizes (small, 200 m2; medium, 400 m2; and large, 600 m2) can affect soil characteristics and tree regeneration. Additionally, the effects of gap size on the growth dynamics of trees outside the gaps were evaluated. The study was carried out in a European beech stand located in Aspromonte National Park (Southern Apennines, Calabria, Italy). Microclimatic variables, physical, chemical, and biochemical soil properties, natural regeneration density, and growth trees outside the gaps density of natural regeneration were assessed. This study provided evidence for an important effect of cardinal points on micro-environmental parameter variability, nutrient cycle, physic-chemical soil properties, water availability, and biological processes such as trees growth and regeneration. The European beech natural regeneration was most abundant in the south part of the gaps. Thus, we can state that cardinal points affect the trees natural regeneration in a species-specific manner. The new microclimatic conditions due to the gap opening had positive effects on the tree growth located along the gap edge, especially in the trees sampled on the edges of the medium gaps. On the contrary, the trees located in the forest recorded a productivity coherent with the period prior the gap opening. In medium-sized gaps, the combination and interaction of microclimatic and soil parameters (humification and mineralization process and microbial activity) created the best conditions for beech natural regeneration and favored an increase in the productivity of the trees at the edge of the gaps.
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