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Temperature sensitivity and decomposition rate of 101 leaf litter types from Mediterranean ecosystems
Get PDFLitter decomposition is a fundamental process, and the number of published studies has steadily increased in recent
decades. However, few experiments have systematically compared a large number of litter types and evaluated their
temperature sensitivity. We conducted a two-year experiment on the decomposition of litter bags containing 101
leaf litter sampled in Mediterranean ecosystems and incubated under laboratory conditions at 4 °C, 14 °C, and
24 °C. Litter was chemically characterized and analysed for carbon (C), nitrogen (N), cellulose and lignin concentra
tion, C/N, and lignin/N ratios, which serve as predictors of decomposition rate. The sensitivity of litter decay rate to
temperature was evaluated usingQ10. Leaflitter chemistry varied widelyin nitrogencontent (range 0.52–6.80 %), lig
nin content (range1.53–49.31 %), C/Nratio (range 5.21–77.78),andlignin/Nratio(range0.34–34.90).Litterdecom
position rate was negatively related to initial lignin concentration, lignin/N ratio, and C/N ratio, but only in the early
stage. In the late stages of decomposition, litter decay rate was negatively correlated with initial N concentration but
positively correlated with C/N and lignin/N ratios. Temperature sensitivity was negatively correlated with N concen
tration and positively correlated with lignin andlignin/N ratio.Itisnoteworthy that, contraryto expectations, temper
ature sensitivity exhibited a hump-shaped relationship with decay rate. N, C/N, and lignin/N ratios should be used
with caution because their predictive power is reversed with respect to decomposition rate during the decomposition
process. In addition, the new findingthat temperature sensitivity has a hump-shaped relationship with decomposition
rate deserves further confirmation and could be considered in ecosystem-level organic C modeling
Dieback of the cushion plant Silene acaulis at its southern limit of distribution in the Apennines
No full textHere, we quantified the dieback of Silene acaulis subsp. bryoides along a 500 m elevational transect from 1900 to 2400 m a.s.l. in the Sibillini Group (Apennines). We also investigated the role of the 2022 summer heat wave that affected the Apennines as a putative cause. The intensity of the dieback was not uniformly distributed across the elevational gradient, but was widespread at 1900 and 2000 m a.s.l. and decreased with increasing elevation. Specifically, 40.7% and 38.4% of plants were affected by dieback at 1900 and 2000 m a.s.l., respectively, but less than 1% at elevations above 2300 m a.s.l. Regarding climate, the maximum air temperature in 2022 was 3.7, 4.5, and 3.4 degrees C above the respective long-term average in May, June, and July. A similar trend was observed for the minimum temperature. The monthly maximum (21.5 degrees C) and minimum (14.6 degrees C) temperatures in July were the highest ever recorded since the monitoring station was commissioned in 2005. In terms of daily maximum temperatures, three consecutive days with temperatures above 25 degrees C were recorded in July 2022, an upper limit that has only been reached on four days in the last 17 years. Regarding precipitation, 180 mm of precipitation fell during the May-August growing season compared to the long-term average of 255 mm, a decrease of 30%. More importantly, only 15.2 mm of rain fell in July 2022, compared to a long-term average of 54.3 mm. The sudden dieback of Silene highlights the vulnerability of high elevation vegetation to climate change. Moreover, the loss of Silene cushions is alarming for the survival of the species, which is long lived but very slow growing
Microbiota Management for Effective Disease Suppression: A Systematic Comparison between Soil and Mammals Gut
No full textBoth soil and the human gut support vast microbial biodiversity, in which the microbiota plays critical roles in regulating harmful organisms. However, the functional link between microbiota taxonomic compositions and disease suppression has not been explained yet. Here, we provide an overview of pathogen regulation in soil and mammals gut, highlighting the differences and the similarities between the two systems. First, we provide a review of the ecological mechanisms underlying the regulation of soil and pathogens, as well as the link between disease suppression and soil health. Particular emphasis is thus given to clarifying how soil and the gut microbiota are associated with organic amendment and the human diet, respectively. Moreover, we provide several insights into the importance of organic amendment and diet composition in shaping beneficial microbiota as an efficient way to support crop productivity and human health. This review also discusses novel ways to functionally characterize organic amendments and the proper operational combining of such materials with beneficial microbes for stirring suppressive microbiota against pathogens. Furthermore, specific examples are given to describe how agricultural management practices, including the use of antibiotics and fumigants, hinder disease suppression by disrupting microbiota structure, and the potentiality of entire microbiome transplant. We conclude by discussing general strategies to promote soil microbiota biodiversity, the connection with plant yield and health, and their possible integration through a “One Health” framework
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Fungal endophytes affect plant response to leaf litter with contrasting chemical traits
No full textPlant litter decomposition is a crucial process of nutrient cycling within ecosystems. However, many studies have shown that, apart from its several beneficial effects, organic matter decomposition can be disadvantageous to seed germination, seedling growth, and physiological activity of plants. Litter decomposition was reported to affect both plants and their associated soil microbial communities. The aim of this work was to test the relationships between seed-associated endophytic fungi on the either positive or negative plant's response to different litter types. Leaf material of four species was collected and used in a decomposition experiment inside a growth chamber for 120 days. The plant growth experiment was set in a greenhouse using Trifolium repens and Triticum durum with and without their associated endophytic fungi in the presence of the different litter species at two decay levels (fresh litter and after 120 days of decomposition). Results demonstrated that fresh litter exerted a strong inhibition effect on the plant total biomass when compared to decomposed litter. Moreover, seed-associated endophytic fungi enhanced the inhibitory effect of litter in the observed experimental conditions. The removal of seed-associated endophytic fungi improved the capacity of tested plants to resist to litter inhibitory effect
Distribution and vegetation of Pinus mugo subsp. mugo dieback patches in Maiella massif (Central Italy)
No full textBiochar and Compost Application either Alone or in Combination Affects Vegetable Yield in a Volcanic Mediterranean Soil
No full textTrichoderma enriched compost, BCAs and potassium phosphite control Fusarium wilt of lettuce without affecting soil microbiome at genus level
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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