Search results for "FOREST"
showing 10 items of 3780 documents
AILANTHUS ALTISSIMA (MILL.) SWINGLE (Simaroubaceae) IN SICILIA E CENNI STORICI SULLA SUA INTRODUZIONE IN ITALIA
2012
Nonostante la diffusa presenza dell’ailanto in Sicilia, mancavano sino ad oggi studi specifici a carattere regionale su questa specie arborea esotica invasiva. Allo scopo di colmare alcune di queste lacune, il presente lavoro si è posto cinque obiettivi: 1) ripercorrere la storia della diffusione globale dell’ailanto, prestando particolare attenzione all’Italia ed alla Sicilia; 2) analizzare le cause (antropiche e biologiche) della sua spiccata invasività a livello globale e locale; 3) fornire un primo quadro della sua distribuzione e della sua auto- e sinecologia sul territorio regionale; 4) stabilire i metodi più idonei ed efficaci per contenerne la diffusione e ridurne l’impatto ecologic…
Rhizosphere soil indicators for carbon sequestration in a reclaimed coal mine spoil
2016
Abstract Re-vegetation of mine spoil enhances carbon storage in both above-ground plant biomass and mine soil. The current study was conducted at the coalmine overburden dumps of Jharia Coalfield (India), with the aim to evaluate the effect of different tree species on the rhizosphere soil properties and to identify key rhizosphere soil indicators that influence tree biomass and carbon density. Rhizosphere soil samples were collected from five tree species ( Acacia auriculiformis , Albizia lebbeck , Cassia siamea , Delonix regia , and Dalbergia sissoo ) of the same age. An area without ground vegetation was selected as a non-rhizosphere soil. The carbon density was higher for D. sissoo and …
The recent spread of the invasive woody alien plant Melia azedarach L. (Meliaceae) in Sicily
2013
This paper aims at reporting the ongoing process of naturalization of Melia azedarach L. in Sicily. In fact, over half a century after the first detection of spontaneous self-sown seedlings, an abrupt increase of naturalization cases has been recorded by the authors during the last twenty years. More in detail, M. azedarach successfully colonized many suburban lowland areas along the coasts of the island which are characterised by thermo-Mediterranean bioclimate. According to both field and literature data, a gradual spread of M. azedarach in the island can be expected, although it is not possible to predict the speed with which this will occur. Historical information on its introduction at…
Acacia cyclops A. Cunn. ex G. Don (Leguminosae) in Italy: first cases of naturalization
2012
The first two cases of naturalization of Acacia cyclops are reported for Italy. Young trees were observed growing in the wild some 15 years ago on Linosa (Pelagie Islands, Strait of Sicily). A decade later, this alien plant should no longer be considered as a casual, since a very intensive process of self-sown regeneration has been observed in some plantations on Lampedusa, the major island of the same Archipelago. The available literature suggests the need for careful monitoring of the ongoing invasion process, as A. cyclops has already shown a very invasive behaviour elsewhere within Mediterranean-type biomes due to its ability to withstand high environmental stresses. As migrating birds …
Démarche statistique pour la sélection des indicateurs par Random Forests pour la surveillance de la qualité des sols
2013
The volume of data, and the large number of biological variables to be tested (one hundred), require analytical techniques, such asRandom Forests, which can overcome the problem of multi-colinearity for the selection of indicators, sensitive to various factors.Random Forests methodology is appropriate for the selection of the most discriminant variables. So, we searched for the best wayto select them, by bringing together all biological variables, representing the Microflora and Fauna. This approach focuses on impactindicators from the Bio2 program, indicators of flora and indicators of accumulation (snails) were not included.This work has been implemented on the three factors of discrimina…
Effect of number of seed parents on the genetic diversity of artificially regenerated stands of holm oak
2007
Artificial populations of holm oak (Quercus ilex L. s.l.) and their natural seed origin populations selected from Andalusia (Southern Spain) and Sicily (Southern Italy) were analysed with six nuclear microsatellite loci to explore the effect of seed collection methods. Low effective allele numbers (3.07-6.67) and extremely low effective populations sizes (35.4-102.9) were detected in both reforestation stands, probably due to an inappropriate forester seed collection strategy limited to a few mother trees. Analysis of simulated progenies showed that optimal sampling size to obtain seed collections genetically similar to the origin populations should range from 20 to 50 individuals, but coul…
Holocene treeline in the northern Andes (Ecuador): new evidence from soil charcoals
2006
Soil charcoals represent a record for palaeoecological studies. For the first time pedoanthracology is applied to northern Andes of Ecuador to study the Holocene treeline. The first results show that the upper treeline was lower than today in the late Pleistocene and in the Middle Holocene. A wide amount of charcoals dated ca. 13000 cal. yr. BP could be caused by fires linked to the first presence of man at these altitudes.
Hybriden vonParus melanolophus undParus ater im Nepal-Himalaya
1972
Im Dhaulagiri-Gebiet des nepalischen Himalaya wurde eine Zone der Uberlappung (?) und Hybridisierung vonParus melanolophus undParus ater aemodius entdeckt. Das kritische Material (Anhang, Tafel 1) und die okologisch-biologische Situation (Abschnitt 1, 2) werden in ihrer Bedeutung ausfuhrlich diskutiert (Abschnitt 3–5). Nach den bisherigen Kenntnissen ist die Kontaktzone schmal. In ihr tretenaemodius- undmelanolophus-ahnliche, sowie morphologisch von beiden auffallig abweichende, zimtbauchige (Tafel 1: 3, 8) Hybriden auf. Unter Berucksichtigung aller vorhandenen okologisch-biologischen Information wird aus dem morphologischen Befund der Populationen auf das Bestehen partieller Isolationsmech…
Effect of laboratory procedures on the integrity of a sandy-loam soil sample for bi-directional measurement of saturated hydraulic conductivity
2011
Practical and validated methods to measure anisotropy of saturated, Ks, or field-saturated, Kfs, soil hydraulic conductivity on a single soil sample are still lacking. The objective of this investigation was to test factors affecting anisotropy measured in a sandy-loam soil by the constant-head laboratory permeameter and the modified cube method. The ratio, RK, between the conductivity results obtained with a long (6 h) and a short (0.5 h) duration run varied from a minimum of 0.29 to a maximum of 0.88 with the considered experimental procedure, differing by both the employed constant-head device (Mariotte bottle, siphon) and the initial soil water content (unsaturated, saturated). Maximum …
Predicting maximum annual values of event soil loss by USLE-type models
2017
Abstract Previous experimental investigations showed that a large proportion of total plot soil erosion over a long time period is generally due to relatively few, large storms. Consequently, erosion models able to accurately predict the highest plot soil loss values have practical importance since they could allow to improve the design of soil conservation practices in an area of interest. At present USLE-based models are attractive from a practical point of view, since the input data are generally easy to obtain. The USLE was developed with specific reference to the mean annual temporal scale but it was also applied at the event scale. Other models, such as the USLE-M and the USLE-MM, app…