Search results for "forest"
showing 10 items of 3780 documents
A new approach to analysis of relationships between 137Cs activity concentrations in forest soil horizons
2013
The measurements results of 137Cs activity concentrations in forest soil profiles are discussed. In studies some simplifications were considered. First of them concerns disregarding of soil subtype in data analysis. However initially this parameter was considered in data analysis, it was finally ignored. The second assumption drops information about specific soil horizon. Description of 137Cs accumulation is based on relationships between its relative activity concentrations in soil layers. The model formulation was based on the results of exploratory data analysis of the relative 137Cs activity concentrations. In studies the methods designed for compositional data analysis were used. The r…
A salt-induced mechanism for the swelling of black liquor droplet during devolatilization
2017
Abstract Black liquor (BL) from the pulp and paper industry is a significant bioenergy source. Swelling of BL droplet during the pyrolysis stage of combustion and gasification is a profound phenomenon affecting various boiler processes. However, the mechanism for droplet swelling has remains a puzzle due to an insufficient understanding of the formation of the plastic droplet at the pyrolysis stage of the thermal conversion. Thermogravimetric studies with model aliphatic carboxylates unraveled the melting and decomposition behavior of the complex mixture of BL salts during pyrolysis, indicating that the melting of salts forming a liquid state may be the primary cause for the development of …
“The tale of the three little tits”: Different nest building solutions under the same environmental pressures
2020
Evolutionary selection pressures, and species-specific ecology and behavior, promote a great variability in the size and composition of nests. However, it would be expected that phylogenetically close species, with similar ecological needs, breeding at the same time in the same place, would also build similar nests. In contrast with this, previous studies have found differences in nest mass and composition among closely related sympatric species. These differences have been attributed to small differences in body size (smaller species building larger and/or more insulated nests), or to the different ways in which species perceive the environment (e.g. perceived predation risk). In this stud…
Differences of raw cork quality in productive cork oak woods in Sicily in relation to stand density
2010
Differences of raw cork quality, in terms of thickness and porosity, were observed in productive cork oak (Quercus suber L.) stands in the Nebrodi and Iblei mountains of Sicily in relation to stand density. Five study areas were chosen across a range of different stand density satisfying specific sampling requirements among two managed cork oak stands. Analysis of variance using Fisher-Snedecor's F test (p<0,05) were used to identify statistically significant differences of cork quality and sylvicultural, dendrometric and cork stripping parameters between study areas within each stand and also between stands. Relationships between cork quality and sylvicultural and dendrometric parameters w…
The Preservation of Sicilian Forests with Poorly Mechanized Logging Processes
1997
Abstract In the province of Agrigento (Sicily), owing to lack of funds, machinery and permanently employed workers, it is necessary to forecast costs and time required for thinning out about 1500 ha of artificial forest using only chain saws and temporarily employed manpower. This study was made to find out how costs and labour productivity vary with tree species, age, size, forest density, land orography and ground uneveness, in order to decide in which areas the change from artificial to natural forest, by gradually thinning out the non-autochthonous trees, could be done at the least cost. Logging processes have been monitored at nine different test sites of about 1 ha each. The results s…
Improved Beerkan run methodology to assess water impact effects on infiltration and hydraulic properties of a loam soil under conventional- and no-ti…
2021
Beerkan infiltration experiments with three water pouring heights (low, L = 3 cm; intermediate, M = 100 cm; high, H = 200 cm) were performed on both a no-tilled (NT) and a conventionally tilled (CT) bare loam soil to determine the surface soil hydraulic properties by the BEST-steady algorithm. Saturated soil hydraulic conductivity, Ks, significantly and monotonically decreased from the L to the H runs (from 236 to 37 mm h‒1) and lower Ks values were detected under CT (163–23 mm h‒1) than NT (346–51 mm h‒1) for each water pouring height. For both soil management practices, the gravitational potential energy, Ep, of the water used for the infiltration runs, explained most of the variance in t…
Popolamenti marginali di faggio e cambiamenti climatici: criticità dell’applicazione di pratiche colturali classici in ambiente mediterraneo (Sicilia)
2013
Il faggio (Fagus sylvatica) è tra le specie forestali più importanti d’Europa per distribuzione, selvicoltura, rilevanza paesaggistica. Il faggio in Sicilia raggiunge il limite meridionale del proprio areale, nonché le quote altitudinali più elevate in Europa (timberline intorno a 2000 s.l.m.), localizzandosi sui Monti Nebrodi, Madonie ed Etna. La maggior parte di questi soprassuoli è stata tradizionalmente governata a ceduo semplice matricinato, seppur raramente all’interno di un quadro di interventi pianificati di lungo periodo, e molti popolamenti recentemente hanno subito primi interventi di avviamento alla conversione a fustaia. L’assetto attuale di questi soprassuoli è tuttavia destin…
Determining Probability Distribution of Hillslope Peak Discharge by Using an Analytical Solution of Kinematic Wave Time of Concentration.
2016
Hillslope hydrology is fundamental for understanding the flood phenomenon and for evaluating the time of concentration. The latter is a key variable for predicting peak discharge at the basin outlet and for designing urban infrastructure facilities. There have been a multitude of studies on the hydrologic response at the hillslope scale, and the time of concentration has been derived for different approaches. One approach for deriving hillslope response utilizes, in a distributed form, the differential equations of unsteady overland flow, specifically developed at the hydrodynamic scale, in order to account for the spatial heterogeneity of soil characteristics, topography, roughness and veg…
A time domain triangle method approach to estimate actual evapotranspiration: Application in a Mediterranean region using MODIS and MSG-SEVIRI produc…
2016
Abstract In this study, spatially distributed estimates of regional actual evapotranspiration (ET) were obtained using a revised procedure of the so called “triangle method” to parameterize the Priestley–Taylor ϕ coefficient. In the procedure herein proposed, named Time-Domain Triangle Method (TDTM), the triangular feature space was parameterized considering pairs of T s –VI values obtained by exploring, for each pixel, only their temporal dynamics. This new method was developed using time series products provided by MODIS and MSG-SEVIRI sensors. Moreover the proposed procedure does not depend on ancillary data, and it is only based on remotely sensed vegetation indices and day–night time l…
Strumenti conoscitivi per la gestione delle risorse forestali della Sicilia. Tipi Forestali.
2011
Con l’affermarsi di una impostazione selvicolturale basata sulla conoscenza e l’imitazione delle tendenze dinamiche naturali dei boschi e il parallelo consolidarsi della pianificazione forestale polifunzionale, è diventata sempre più sentita la necessità di avere a disposizione idonei metodi di inquadramento della vegetazione forestale per fondare su presupposti ecologici la gestione del bosco, al fine di valorizzare il ruolo multifunzionale delle foreste. Le carte fitosociologiche da un lato e quelle fisionomiche dall’altro, tradizionalmente utilizzate nella pianificazione forestale e normalmente allegate ai Piani d’Assestamento forestale, infatti, si sono rilevate poco adatte a soddisfare…