1,721,005 research outputs found
The rise and fall of the black locust (Robinia pseudoacacia L.) in the Siro Negri Forest Reserve (Lombardy, Italy): lesson learned and future uncertainties
No full textThe alluvial forests of the Ticino valley have been greatly reduced in size and are now represented by only a small number of fragmented remnants. To study the natural development of the black locust, an invasive species, on relatively undisturbed lowland forests, two permanent plots were established in 2005 in the "Siro Negri" Forest Reserve.
The black locust became established almost exclusively between 1940 and 1960. The observed dynamic of the black locust in the Reserve was very similar to what has been observed in its native North American range: following the initial colonization, the black locust firmly established itself in the dominant and intermediate layers but did not regenerate. In addition to the absence of a significant younger population, the decline of the black locust is evident in an elevated mortality rate and higher proportion of black locust biomass in the total coarse woody debris (CWD)
Our results support the hypothesis that the best strategy to control the spread of black locust is to avoid disturbances that favour black locust colonization, and to wait for natural suppression of the species by other trees. Due to the lack of past reference conditions and the future uncertainties, ongoing monitoring will be needed to fully understand the dynamics of forest ecosystem change in the Reserve
Dinamica di Robinia pseudoacacia L. nell'evoluzione delle foreste ripariali del Parco del Ticino: l'esempio della Riserva "Bosco Siro Negri"
No full textStruttura e dinamica del bosco in popolamenti con presenza di robinia (Robinia pseudacacia L.) all'interno della Riserva integrale Siro Negri
No full textCoarse woody debris, forest structure and regeneration in the Valbona Forest Reserve, Paneveggio, Italian Alps
No full textStand structure, quality and quantity of coarse woody debris (CWD) and the importance of the stumps for the Norway spruce (Picea abies (L.) Karst.) regeneration were studied in the Valbona Forest Reserve in the eastern Italian Alps.
Past history, present structures, quantity and quality of coarse woody debris (CWD) are fundamental steps for increasing our knowledge of the natural forest stand dynamics. This is particularly relevant in the Italian Alps where all forests have been used by humans for millennia. Nevertheless, in the last decades there has been a noticeable reduction of the anthropogenic disturbance and, as a consequence, many forest stands have developed naturally even if their composition and structure still reflect past human activity.
The mean volume of CVM in the Valbona Forest Reserve was 23.4 m(3) ha(-1) ranging in the sampling plots between 0.0 and 89.3 m(3) ha(-1). Of the total volume of dead and living trees, CWD comprised 4.9%. Among the CWD, the volume of logs (37.6%) was greater than the volume of snags (32.0%) and stumps (30.4%). There are no significant differences in the quantity of CWD among the structural categories. The decomposition classes of the CWD are different in the three CWD types and are the result of the recent land-use history of the reserve: the stumps are present mainly in the most decomposed stages (III and IV) while the snags and the logs are present mainly in the first and in the second decay class, respectively. The stumps play an important role for the regeneration of the Norway spruce: more than 57% of the present dominant trees established on stumps and the present density of the regeneration on the stumps is five times the density of the regeneration on the ground. Stumps in advanced decay classes (III and IV) are more suitable for regeneration than those in early decay classes
Correction to: The largest European forest carbon stocks are in the Dinaric Alps old-growth forests: comparison of direct measurements and standardised approaches (Carbon Balance and Management, (2024), 19, 1, (15), 10.1186/s13021-024-00262-4)
No full textFollowing publication of the original article [1], the authors identified errors in the article title and in the author group. These errors have been updated with this correction. The article title “The largest European forest carbon stocks are in the Dinaric Alps old-growth forests: comparison of direct measurements and standardised approaches” was incorrectly written as “The largest European forest carbon sinks are in the Dinaric Alps old-growth forests: comparison of direct measurements and standardised approaches”. The given and family names of the authors “Alessia Bono, Giorgio Alberti, Roberta Berretti1, Milic Curovic, Vojislav Dukic and Renzo Motta” were incorrectly structured as “Bono Alessia, Alberti Giorgio, Berretti Roberta, Curovic Milic, Dukic Vojislav and Motta Renzo”. The original article has been corrected
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Decreased allopregnanolone induced by hormonal contraceptives is associated with a reduction in social behavior and sexual motivation in females rats
No full textFailure of acute ethanol administration to alter cerebral cortical and hippocampal allopregnanolone levels in C57BL/6J and DBA/2J mice
No full textAcute ethanol administration to rats stimulates the hypothalamic-pituitary-adrenal (HPA) axis and increases brain and plasma levels of the potent neurosteroid allopregnanolone. Increased allopregnanolone levels contribute to the anxiolytic, anticonvulsant, sedative and pro-aggressive actions of ethanol. It is not yet known if ethanol’s effects on allopregnanolone levels generalize across species. Indeed, studies in mice have reported that ethanol does not always alter brain and plasma allopregnanolone levels We thus explored the effects of ethanol administration on brain levels of allopregnanolone and its precursor progesterone in C57BL/6J and DBA/2J mice, two inbred strains with different sensitivity to behavioral effects of alcohol.
Male C57BL/6J and DBA/2J mice were injected with ethanol (1, 2, 3 or 4 g/kg, i.p.) or saline and were sacrificed 1 hour later or 15, 30, 60 and 120 minutes later for the time course studies. Allopregnanolone, progesterone and corticosterone levels were measured by radioimmunoassay in cerebral cortex and hippocampus.
Acute ethanol administration did not alter cerebral cortical and hippocampal levels of allopregnanolone and progesterone in both C57BL/6J and DBA/2J mice at any of the doses examined. Cerebral cortical levels of allopregnanolone and progesterone were also not altered at any of the time points examined in either strain. Acute ethanol administration dose-dependently increased corticosterone levels in the cerebral cortex and the hippocampus of both mouse strains. In C57BL/6J mice, corticosterone levels were increased by 319%, 352% and 448% in the cerebral cortex and by 284%, 218% and 368% in the hippocampus at the doses of 2, 3 and 4 g/kg, respectively, p<0.001. In DBA/2J mice, corticosterone levels were increased by 354%, 417%, 447% and 574% in the cerebral cortex and by 259%, 434%, 567% and 629% in the hippocampus at the doses of 1, 2, 3 and 4 g/kg, respectively, p<0.001. The effect of ethanol on cerebral cortical corticosterone levels was also time-dependent: in C57BL/6J mice it was apparent at 15 min (+155%), reached a peak at 60 min (+306%) and remained elevated at 120 min (+217%) from ethanol administration (p<0.001); in DBA/2J mice it was apparent at 30 min (+546%), reached a peak at 60 min (+1002%) and remained elevated at 120 min (+822%) from ethanol administration (p<0.001). These results suggest that ethanol administration is activating the HPA axis, as expected, and that ethanol might directly impair brain neurosteroid synthesis. Moreover, to evaluate if the effect of ethanol on allopregnanolone levels was specific to ethanol or not, we tested whether administration of morphine, which also increases cerebral cortical levels of allopregnanolone in rats, alters allopregnanolone and progesterone levels in male C57BL/6J and DBA/2J mice. Morphine administration increased cerebral cortical allopregnanolone levels in C57BL/6J mice (+77%, +93% and +88%, at the doses of 5, 10 and 30 mg/kg, respectively, p<0.01) and DBA/2J mice (+81% at the dose of 5 mg/kg, p<0.05). Morphine administration also increased progesterone levels in both strains. These results suggest that the impairment in brain neurosteroidogenesis in C57BL/6J and DBA/2J mice appears to be specific to ethanol.
Overall, these results show important species differences in the effects of ethanol on brain neurosteroidogenesis. Given that ethanol does not alter cerebral cortical and hippocampal concentrations of allopregnanolone and progesterone in the two mouse strains examined, the differential sensitivity to some of the behavioral effects of ethanol cannot be directly correlated to hormonal changes in C57BL/6J and DBA/2J mice
Decreased allopregnanolone induced by hormonal contraceptives is associated with a reduction in social behavior and sexual motivation in female rats
No full textRATIONALE:
Allopregnanolone is a neurosteroid involved in depression, memory, social, and sexual behavior. We have previously demonstrated that treatment with a combination of ethinylestradiol (EE) and levonorgestrel (LNG), two compounds frequently used in hormonal contraception, decreased brain allopregnanolone concentrations. These changes may contribute to some of the emotional and sexual disorders observed in hormonal contraceptive users.
OBJECTIVES:
We thus examined whether the reduction in allopregnanolone concentrations induced by long-term EE/LNG administration was associated with altered emotional, learning, social, and sexual behaviors.
METHODS:
Rats were orally treated with a combination of EE (0.030 mg) and LNG (0.125 mg) once a day for 4 weeks and were subjected to behavioral tests 24 h after the last administration.
RESULTS:
EE/LNG treatment reduced immobility behavior in the forced swim test, without affecting sucrose preference and spatial learning and memory. In the resident-intruder test, EE/LNG-treated rats displayed a decrease in dominant behaviors associated with a reduction in social investigation. In the paced mating test, EE/LNG treated rats showed a reduction in proceptive behaviors, while the lordosis quotient was not affected. Progesterone, but not estradiol, administration to EE/LNG-treated rats increased sexual activity and cerebrocortical allopregnanolone concentrations. Prior administration of finasteride decreased allopregnanolone concentrations and abolished the increase in proceptivity induced by progesterone administration.
CONCLUSIONS:
The decrease in brain allopregnanolone concentrations induced by EE/LNG treatment is associated with a reduction in social behavior and sexual motivation in female rats. These results might be relevant to the side effects sometimes exhibited by women taking hormonal contraceptives
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