Litter Samples Research Articles

An exploratory analysis of seabed litter dynamics in the SE German Bight

The accumulation of marine litter on coastal seabeds is influenced by various anthropogenic and environmental factors. To identify litter accumulation areas on the seafloor, it is necessary to understand the interaction of these parameters. This study analyses the seafloor litter occurrence in the southeastern North Sea, based on samples collected between October 2017 and March 2019. Litter data were combined with hydrographic, high-resolution in situ measurements and further geographic as well as anthropogenic factors for statistical analyses. Benthic litter showed a mean density of 2473 ± 3116 items km−2, and plastics consisting mainly of fisheries-related items represented the majority of identified objects. The statistical analyses suggest that salinity and temperature gradients, the meridional bottom currents, as well as the distance of the station to the coastline have a significant effect on benthic litter abundance. Direct combination of litter sampling and hydrographic measurements can improve the understanding of seabed litter dynamics.

Leaf Litter Decomposition and Nutrient Release Dynamics of Flemingia semialata Roxb. - A Potential Woody Perennial Species for Mountain Agroforestry

ABSTRACT Leaf litter decomposition and nutrient release dynamics of Flemingia semialata Roxb. were studied from May 2016 to April 2017 using the litter bag technique. The study on litter dynamics is needed to assess the nutrient release pattern before introduction in degraded or marginal lands or agroforestry systems for soil nutrient management practices in hilly northeast states of India. The initial N concentration, lignin content, and lignin/N ratio of leaf litter had significant positive correlations with decay coefficients. The annual decay rate constant (k) for dry matter was 0.01 day−1 (3.65 year−1) with t50 and t99 values of 96.43 and 695.73 days, respectively, indicating faster leaf litter decomposition. Initial C (51%), N (2.38%), and low lignin concentrations with low C/N (21.53) and lignin/N (4.05) ratios could be important factors in faster mass loss from the litter samples. The P mineralization k P (2.19) rate was higher than k N (0.73), indicating the slower release rate of N. The weight loss during decomposition was positively correlated with rainfall (r = 0.42) and temperature (r = 0.39). The study suggests that F. semialata leaf litter could be useful for regulating soil nutrient pool through faster litter turnover and can therefore be exploited as plantation and/or agroforestry species for soil and water conservation in degraded slopy terrain of the region.

Soil Fauna of Ranibari Community Forest, Kathmandu, Nepal

Abstract Ranibari Community Forest (RCF) is the important forest patch present within the highly urbanized Kathmandu Valley with information gaps on soil fauna. This study aimed to explore the soil meso and macrofauna of the forest. Fourteen random quadrats (1 × 1 m2) were laid within seven blocks. Leaf litter samples and soil cores were collected, screened, sieved, and searched under a white sheet, once a fortnight from May to November 2019. The results showed that the diversity, abundance, and richness of soil fauna were the highest in the summer season (H´ = 2.897, abundance = 1,973, S = 84) dominated by Collembola. The Soil Biological Quality Index (QBS-ar) value was also found to be the highest in summer (QBS-ar = 417) and successively decreased in succeeding seasons. Soil fauna was diverse and evenly distributed in soil layers throughout the seasons, but the abundance was greater in leaf litters, particularly in summer. Fauna like Chilopoda, Diplopoda, Haplotaxida, and Isopoda were seen to be affected negatively by soil temperature in summer and autumn seasons. Soil moisture content was found to be positively correlated with immature insects, earthworms, and millipedes in the rainy and autumn seasons. Besides, the pH of the soil was seen to affect Diplura only in the autumn season. The relation of fauna with the physicochemical parameters (temperature, moisture, and pH) and also with other taxa showed their ecological roles and adaptation to a specific microclimate.

Biomass distribution pattern and stoichiometric characteristics in main shrub ecosystems in Central Yunnan, China.

BackgroundWith the exacerbating effects of the global climate change and the more and more attention to the study of plant carbon sink, an increasing number of researches on plant carbon sinks has grown. Although many studies exist on shrub vegetation, soil and litters, most studies focus on the community structure, biomass, surface soil of single plant and shrub layer vegetation, and lack the studies which included the potential relationships between climate change and ecological stoichiometric elements, comprehensive research on main species, even herb and litter layer. In order to provide relevant theoretical basis and data support, it is necessary to take the main terrestrial shrub ecosystem in Central Yunnan as the starting point to analyze and explore its carbon sink distribution characteristics, formation causes, the correlation between climatic factors (temperature and precipitation) and stoichiometric elements, which from community and species levels.MethodsPlants which originated from 12 main shrub species, litter and soil samples which collected in 69 plots were from 23 plots (Q1–Q23) of 11 cities (countries) in the central Yunnan, China. The biomass and carbon density distribution pattern of each shrub ecosystem and the potential correlations with main climate factors was explored and identified. Some indexes were analyzed such as biomass and carbon density of each part of the shrub ecosystem distribution pattern, correlation, significant changes, formation reasons with the mean value (±standard deviation: SD). Through the redundancy analysis(RDA) of carbon (c), nitrogen (n), phosphorus (P) and main climate factors (precipitation and temperature), the distribution pattern of stoichiometric elements in shrub ecosystem can be judged.Results(1) The above-ground biomass (AGB), under-ground biomass (UGB) and root-shoot ratio (R/S) were between 1.13–2.03 t/hm2, 0.62–1.49 t/hm2, and 0.38–0.84, the carbon element was distributed in herb layer under-ground part and rhizomes of the shrub layer mostly. (2) The fitting slope of AGB and UGB of shrub communities and species was in accordance with the allometric distribution growth relationship, the R/S of shrubs was smaller than other vegetation types. Mean annual temperature (MAT) and mean annual precipitation (MAP) are not the main factors which affect the biomass and R/S. (3) The contents of C, N and P elements in leaves were significantly higher than other parts in shrub layer. P in shrub layer above-ground part is much higher than under-ground part. The surface soil layer has the highest C content, and decreased with the depth, so as the impact of vegetation and litter on the content of soil elements. Both of the correlation of MAT with N content of leaf, C/N of stem, the correlation of MAP with C content, C/N of soil is the greatest.

Prairie strips' effect on transport of antimicrobial resistance indicators in poultry litter.

Poultry litter is a valuable nutrient resource for agricultural production but is also a potential source for introducing antibiotic resistance genes (ARGs) and litter-associated bacteria (LAB) to the environment. Prairie strips have been demonstrated as an effective conservation practice to improve environmental quality in agroecosystems. This research aims to assess prairie strips' potential for reducing the transport of LAB and ARGs in runoff after litter application. Plot-scale rainfall simulations were performed using a replicated block design, with soil and surface runoff samples taken during the rainfall event. Microbial taxa and ARGs were characterized in the litter, soil, and water samples. In plots with litter application, LAB and ARGs were mainly detected in runoff, with very low detection in soils. Detection of ARGs in runoff, irrespective of strip installations, is consistent with previous observations of litter as a source of antimicrobial resistance (AMR) risks. The effectiveness of prairie strips to remove LAB and ARGs varied. In two of the three prairie strip plots, fewer AMR indicators were detected relative to control plots, suggesting that the prairie strips can potentially reduce these risks. In one plot, which was also associated with increased flow rate, we observed increased AMR indicators despite the installation of a prairie strip. Our observations highlight the need to prioritize understanding of soil properties even within the same site. Although we show that prairie strips can potentially reduce AMR risks, further research is needed to better understand the influence of rainfall timing, soil, and litter characteristics.

Distribution of mercury in foliage, litter and soil profiles in forests of the Qinling Mountains, China

Forest ecosystems have been confirmed to be a sink of the global mercury (Hg) in the biogeochemical cycle. However, few studies have investigated the distribution of Hg in forest ecosystems on a regional scale in China. This work aimed to investigate the concentrations, distribution and influential factors of Hg in the Qinling Mountains forests in central China. Foliage, litter and soil profile samples were collected at 24 sampling sites across the Qinling Mountains forests. The results of the present study showed that the concentrations of Hg in foliage, litter, organic soils and mineral soils were maintained at relatively low levels compared with those in subtropical forests of Southwest China. The average Hg concentrations followed the order litter (74 ± 34 ng g−1) > organic soil (71 ± 37 ng g−1) > mineral soil (34 ± 21 ng g−1) > foliage (31 ± 15 ng g−1). Mercury in foliage showed no obvious spatial pattern, likely due to differences in tree species and ages across the sampling sites. Higher concentrations of Hg in litter were observed on the southern slope (low altitude), while the distribution of Hg in organic soils was the opposite. Both the tree species and environmental parameters (altitude, temperature and precipitation) controlled the Hg concentrations in litter by regulating the decomposition rate of the litter. There were significantly positive correlations between the Hg concentrations and soil organic carbon, nitrogen and sulfur in all soil layers, indicating that organic matter has a high geochemical affinity for Hg in soils. Because of the lower turnover rate and the higher accumulation of organic matter in high altitude and low temperature areas, Hg loss from biogeochemical cycling processes was effectively reduced. The spatial distribution of Hg in forests soil can be shaped by the distribution of organic matter at the regional scale.

Certesella larai (Amoebozoa: Arcellinida: Hyalospheniformes) a new soil testate amoeba species from the Dominican Republic and Chile challenges the definition of genera Certesella and Porosia

Microbial diversity is known to be huge but remains only partly documented. Testate amoebae are a relatively well studied group or free-living protists that build morphologically characteristic shells on which the taxonomy of this group is mainly based. Among testate amoebae, the Hyalospheniformes are especially well documented and are a model group for microbial biogeography. Here we describe a new species of genus Certesella from Sphagnum mosses and forest litter samples collected in the Dominican Republic and Chile. We name this species Certesella larai to honour our esteemed colleague Enrique Lara. This species bears two large pores connected by tube, which are characteristic of the genera Porosia and Certesella. The new species fits best in the latter genus given the presence of a distinct, sometimes denticulated, neck with a bulge that is absent in genus Porosia but occurs in Certesella. Its elongated shape (length/breadth ratio 2.03–2.58) only overlaps with C. certesi, which is distinguishable by the presence of a distinct longitudinal groove in the neck region that is absent from the new species. Interestingly most specimens lacked the internal teeth which are usually present in members of genus Certesella. As such, while the morphology of C. larai strongly suggests a belonging to genus Certesella, molecular analyses are still required to confirm its phylogenetic position, clarify the relationships among all species in genera Porosia and Certesella and the definition and validity of these two genera. The presence of this new species in two rather distant regions – Caribbean and central Chile – suggests it is likely widespread, but possibly rare. However, this perception may be due to a sampling bias in favour of Sphagnum mosses and wet and organic-rich habitats. This illustrates the need for a more systematic sampling effort to document the full and mostly unknown taxonomic diversity of soil protists.

Properties of Animal-Origin Ash—A Valuable Material for Circular Economy

In the presented paper, two types of animal-origin biomass, cow dung and chicken litter, are characterized in terms of combustion-related problems and ash properties. It was found that these parameters strongly depend on the farming style. Whether it is cow dung or chicken litter, free-range raw materials are characterized by higher ash contents than industrial farming ones. Free-range samples contain chlorine at lower levels, while industrial farming samples are chlorine rich. Free-range samples are characterized by the predominant content of silica in the ash: 75.60% in cow dung and 57.11% in chicken litter, while industrial farming samples contain more calcium. Samples were classified by 11 “slagging indices” based on the ash and fuel composition to evaluate their tendencies for slagging, fouling, ash deposition and bed agglomeration. Furthermore, an assessment was made against the current EU law regulations, whether the ashes can be component materials for fertilizers. The phosphorus concentration in the investigated ashes corresponds to 4.09–23.73 wt% P2O5 and is significantly higher in industrial chicken litter samples. The concentrations of Hg, Cu, As, Ni, Cd and Pb in all samples are below the limits of the UE regulations. However, concentrations of Cr in all samples and Zn in industrial chicken litter exceed these standards.

Seasonal litterfall and nutrients in an Atlantic Forest fragment

Litter dynamics is one of the fundamental processes for the growth and maintenance of native forest fragments, being considered the main pathway for nutrient cycling in forests. Studies on litter production and nutrient content therefore provide insights that provide a better understanding of nutrient dynamics. This study identifies the seasonality and meteorological conditions that influence the quantity and return of nutrients through litter in an Atlantic Forest fragment. Litter sampling was carried out monthly in 12 permanent plots. Each plot contained 5 littertraps distributed systematically. The litter was classified, and the dry mass and nutrients in the leaves and branches and miscellaneous fractions was quantified. Seasonal behavior was observed, with the highest depositions in the winter season. The average annual production was 6.78 Mg ha-1, with 64.9% being composed of leaves. The mean annual nutrient intake was 135.1, 115.7, 39.7, 23.5, 17.6 and 4.6 kg ha-1 for Ca, N, K, Mg, S and P, respectively. The meteorological variable precipitation influenced the deposition pattern. The increase in nutrient-use efficiency in the second year compared to the first indicates that plants strategically may be re-translocating relative amounts of their nutrients under water stress conditions.
 Keywords: ecosystem functions, nutrient cycling, secondary succession.

Warming and grazing enhance litter decomposition and nutrient release independent of litter quality in an alpine meadow

Abstract Warming and grazing, and litter quality jointly determine litter decomposition and nutrient releases in grazing ecosystems. However, their effects have previously been studied in isolation. We conducted a two factorial experiment with asymmetric warming using infrared heaters and moderate grazing in an alpine meadow. Litter samples were collected from all plots in each treatment, among which some subsamples were placed in their original plots and other samples were translocated to other treatment plots to test the relative effects of each treatment on litter decomposition and nutrient releases. We found that warming rather than grazing alone significantly increased total losses of litter mass, total organic carbon, total nitrogen (TN) and total phosphorus (TP) per unit area due to increases in both mass loss rates and litter biomass. However, grazing with warming did not affect their total mass losses because increased mass loss was offset by decreased litter biomass compared with the control. Seasonal mean soil temperature better predicted litter decomposition than litter lignin content or carbon to nitrogen ratio. There were interactions between warming and grazing, but there were no interactions between them and litter quality on litter decomposition. The temperature sensitivity of TN loss was higher than that of TP loss per unit area. Our results suggest that increased temperature has a greater effect on litter decomposition and nutrient release than change in litter quality, and that more N release from litter could result in greater P deficiency in the alpine meadow.

IMPACT OF LITTER TURNOVER ON CARBON CYCLING IN FORESTS WITH DRAINED AND NATURALLY WET NUTRIENT-RICH ORGANIC SOILS IN LATVIA

Litter production is a key parameter for estimation of forest soil carbon (C) stock. The aim of the study was to evaluate carbon stock in above and below-ground litter in forests with drained and naturally wet nutrient-rich organic soils in Latvia to improve National GHG inventory and to integrate data into AGM and EPIM models. To estimate C input with tree above-ground litter, sampling of litter was done in 46 research sites in Latvia. A modelling approach based on a literature review was used to estimate C input with tree below-ground litter and litter of ground vegetation. Our study highlights a connection between C input to soil with litter and stand characteristics – stand basal area, stand age and dominant tree species. There is a trend for C input from above- and below- ground litter to increase along with increasing stand basal area. In conifer stands the C input with ground vegetation increased with stand basal area, whereas for broadleaves the trend is reverse. There is still uncertainty regarding C input with below-ground litter and ground vegetation. In order to improve the modeling approach additional data and country-specific models are required.

Survival of Escherichia coli in Airborne and Settled Poultry Litter Particles

Simple SummaryAirborne transmission is recognized as an important mechanism of disease spreading in livestock and poultry production, yet is far from being fully understood. Evaluating the impact of airborne transmission requires information of the microbial survivability. We determined the survivability of the E. coli—a common microbial species found in poultry environment—in airborne particles, settled dust, and poultry litter under laboratory environmental conditions. The poultry litter which contained mainly manure mixed with fresh wood shavings was collected from a commercial farm. Results of the study showed that the half-life time of airborne E. coli was 5.7 ± 1.2 min. The half-life time of E. coli in poultry litter and settled particles was 15.9 ± 1.3 h and 9.6 ± 1.6 h, respectively. The findings of this study will help better estimate the impact of airborne transmission of E. coli in poultry production.Airborne Escherichia coli (E. coli) in the poultry environment can migrate inside and outside houses through air movement. The airborne E. coli, after settling on surfaces, could be re-aerosolized or picked up by vectors (e.g., caretakers, rodents, transport trucks) for further transmission. To assess the impacts of airborne E. coli transmission among poultry farms, understanding the survivability of the bacteria is necessary. The objective of this study is to determine the survivability of airborne E. coli, settled E. coli, and E. coli in poultry litter under laboratory environmental conditions (22–28 °C with relative humidity of 54–63%). To determine the survivability of airborne E. coli, an AGI-30 bioaerosol sampler (AGI-30) was used to collect the E. coli at 0 and 20 min after the aerosolization. The half-life time of airborne E. coli was then determined by comparing the number of colony-forming units (CFUs) of the two samplings. To determine the survivability of settled E. coli, four sterile Petri dishes were placed on the chamber floor right after the aerosolization to collect settled E. coli. The Petri dishes were then divided into two groups, with each group being quantified for culturable E. coli concentrations and dust particle weight at 24-h intervals. The survivability of settled E. coli was then determined by comparing the number of viable E. coli per milligram settled dust collected in the Petri dishes in the two groups. The survivability of E. coli in the poultry litter sample (for aerosolization) was also determined. Results show that the half-life time of airborne E. coli was 5.7 ± 1.2 min. The survivability of E. coli in poultry litter and settled E. coli were much longer with the half-life time of 15.9 ± 1.3 h and 9.6 ± 1.6 h, respectively. In addition, the size distribution of airborne E. coli attached to dust particles and the size distribution of airborne dust particles were measured by using an Andersen impactor and a dust concentration monitor (DustTrak). Results show that most airborne E. coli (98.89% of total E. coli) were carried by the dust particles with aerodynamic diameter larger than 2.1 µm. The findings of this study may help better understand the fate of E. coli transmitted through the air and settled on surfaces and evaluate the impact of airborne transmission in poultry production.

Short-term and long-term effects of antimicrobial use on antimicrobial resistance in broiler and turkey farms

ABSTRACT Antimicrobials have been widely used in poultry, promoting antimicrobial resistance (AMR) emergence and spread. Resistant bacteria selected by antimicrobial use (AMU) can contaminate the farm environment and transfer resistance genes to other bacteria, providing opportunities for persistence and (re-)colonization of subsequent flocks and potentially jeopardizing antimicrobial treatments. We investigated the effects of AMU on AMR in poultry in the long-term (due to historical AMU in the farm) and in the short-term (due to current AMU in a flock). Litter samples from 35 broiler and 35 turkey farms in North-East Italy were sampled longitudinally for AMR testing of E. coli indicator bacteria in 2019/2020. Differences in AMR as a function of historical AMU (Defined Daily Doses in 2016–2018), current AMU in the sampled flock, farm size and season were tested using Generalized Estimating Equation regression analysis. In both broilers and turkeys, the highest resistance levels were observed for sulfamethoxazole (>70%), followed by ampicillin (54–60%). Only a few positive associations between historical levels of penicillin use and the specific resistance levels to penicillin in broiler farms, and the overall historical AMU and resistance to trimethoprim in turkey flocks, were significant. Current AMU showed significant effects on resistance to sulfamethoxazole, trimethoprim, ciprofloxacin and tetracycline in turkey flocks. Significant effects of farm size on some AMR levels were also identified. We found a stronger association between current AMU and AMR compared to historical AMU and AMR. AMR persistence in the farm environment in the absence of direct AMU pressure needs to be further investigated. RESEARCH HIGHLIGHTS Sulfamethoxazole and ampicillin resistance are the highest in E. coli isolates of both broilers and turkeys. Short-term effects of antibiotic use on resistance are seen more often than long-term effects. Historical penicillin use is associated with penicillin resistance in broilers. There is an association between historical use and resistance to trimethoprim in turkeys.

Transmission of Antibiotic-Resistant Escherichia coli from Chicken Litter to Agricultural Soil

A growing concern regarding the use of animal manure as fertilizer is the contamination of soil, plants, and the environment with a variety of antibiotic-resistant and pathogenic bacteria. This study quantified and characterized the antibiotic resistance profiles of Escherichia coli in soil before and after chicken litter application to determine the impact of manure on the soil resistome. Litter and soil samples were collected from a sugarcane field before and after litter application. E. coli was isolated and quantified using the Colilert®-18/Quanti-tray® 2000 and 10 randomly selected isolates from the positive wells of each Quanti-tray were putatively identified on eosin methylene blue agar. Real-time PCR was used to confirm the isolates by targeting the uidA gene. Antibiotic susceptibility test against 18 antibiotics was conducted using the disk diffusion method, and the multiple antibiotic resistance index was calculated. Soil amendment with chicken litter significantly increased the number of antibiotic-resistant E. coli in the soil. Among the 126 E. coli isolates purified from all the samples, 76% showed resistance to at least one antibiotic, of which 54.2% were multidrug-resistant (MDR). The highest percentage resistance was to tetracycline (78.1%), with the least percentage resistance (3.1%) to imipenem, tigecycline, and gentamicin. The isolates also showed resistance to chloramphenicol (63.5%), ampicillin (58.3%), trimethoprim-sulfamethoxazole (39.6%), cefotaxime (30.2%), ceftriaxone (26.0%), cephalexin (20.8%), cefepime (11.5%), amoxicillin-clavulanic acid (11.5%), cefoxitin (10.4%), Nalidixic acid (9.4%), amikacin (6.3%), and ciprofloxacin (4.2%). Of the 54.2% (52/96) MDR, the highest number was isolated from the litter-amended soil (61.5%) and the least isolates from soil samples collected before litter application (1.9%). The relatively higher mean MAR index of the litter-amended soil (0.14), compared to the soil before the amendment (0.04), suggests soil pollution with antibiotic-resistant E. coli from sources of high antibiotic use. E. coli could only be detected in the soil up to 42 days following manure application, making it a suitable short-term indicator of antibiotic resistance contamination. Notwithstanding its relatively short detectability/survival, the application of chicken litter appeared to transfer antibiotic-resistant E. coli to the soil, enhancing the soil resistome and highlighting the consequences of such agricultural practices on public health.

Allometric scaling, biomass accumulation and carbon stocks in natural highland bamboo (Oldeania alpina (K. Schum.) Stapleton) stands in Southwestern Ethiopia

Bamboos provide a number of ecosystem services, including the provision of a permanent carbon (C) sink. The present study was undertaken in the Sheka forest, currently recognized as a UNESCO Biosphere Reserve. The objectives of this study were to: (1) develop species- and site-specific allometric models for biomass estimation and (2) quantify the carbon storage capacity of highland bamboo stands. A total of 12 plots each measuring 10 m x 10 m were established at a distance of 200 m in the forest. 96 culms were harvested for the development of biomass estimation equations. Litter samples were collected in 1 m x 1 m subplots, while soil samples were collected at 0–10, 10–20, 20–40, and 40–60 cm soil depths for determination of soil organic carbon (SOC) contents. The estimated mean DBH, basal area and plant height were 7.0 cm, 53.2 m2 ha−1 and 12.9 m, respectively. The study has established allometric scaling of plant height with stem diameter in highland bamboo. It has also established that the allometric model is superior to commonly used non-linear H-DBH models. Aboveground biomass was estimated at 93 Mg ha−1 with mean C stocks of 43.7 Mg ha−1. The estimated below-ground biomass was 18.6 Mg ha−1 with C stocks of 8.7 Mg ha−1. The C stocks in the litter layer were estimated at 1.57 Mg ha−1. Average soil C storage was estimated at 388.12 Mg ha−1 within the 0–60 cm soil depth. In total, the natural highland bamboo stands store approximately 442.1 Mg C ha−1. The estimated C stocks were comparable with values reported for bamboos in Ethiopia and elsewhere. It is concluded that natural highland bamboo stands play a significant role as carbon sinks. The insights gained in this study are expected to be applicable to Afromontane ecosystems where highland bamboo occurs in Africa.

Artificial Intelligence System for Automatic Imaging, Quantification, and Identification of Arthropods in Leaf Litter and Pitfall Samples

Artificial Intelligence System for Automatic Imaging, Quantification, and Identification of Arthropods in Leaf Litter and Pitfall Samples

Mites and helminths infestation in Lebanese broiler farming systems.

This study aims at the identification of endo- and ectoparasites in broiler farms while assessing their prevalence in semi-open and closed rearing systems in Lebanon. Seventeen semi-open and six closed broiler farms were investigated in various Lebanese provinces between March and September 2020 and 2021. Intestinal and composite litter samples were collected and observed for morphological identification of prevalent parasites. Results notably revealed the prevalence of mites in all of the surveyed farms. Moreover, mixed mite-helminth infestation was recorded in 100% of the semi-open farms and 50% of the closed ones. The northern fowl mite Ornithonyssus sylviarum was the predominant chicken parasitic mite in both systems. The poultry red mite Dermanyssus gallinae, was present in 6% of the semi-open farms and was not detected in closed farms. The mammalian itching mite Sarcoptes scabiei and the grain mite Acarus siro were also identified and had similar prevalence pattern as the red poultry mite. Eggs and/or larvae stages of one parasitic helminth species, Ascaridia galli, were detected in half of the semi-open and closed farms while adult worms were not present. This study documents for the first time the prevalence of specific endo- and ectoparasites in Lebanese broiler farms, reflecting managerial problems and poor biosecurity practices. Nevertheless, the identification of specific parasites in this work paves the way towards implementing proper control methods against these overlooked, yet devastating, organisms.

INFLUENCE OF CANOPY TYPES ON NUTRIENT AVAILABILITY IN SOIL AND LITTER POOLS OF A FOREST ECOSYSTEM

Influence of forest canopy types on nutrient availability in litter and soil pools of a forest ecosystem was studied. Four plots each were chosen randomly for open and close forest canopies. In each plot, 4 belt transects were laid, and in each transect, vegetation was sampled. Four litter traps were set in each plot, to collect litter samples in open and close canopies. In each plot, three soil samples (at 0-15 and 15-30 cm) were obtained in the open and close canopies with a soil auger and conveyed to the laboratory for analyses. The open and close canopy plots had 10 and 15 tree species. The close canopy had higher values for sand (91.19±0.01%), and silt (6.56± 0.01%) while the open canopy had high values for clay (3.13±0.01%). The pH of soil was very strongly acidic in the open (4.93±0.02) and close (4.56±0.58) canopies. Higher values for electrical conductivity (0.08±0.005 ds/m), total nitrogen (0.08±0.003 %), organic carbon (3.13±0.001 %), available phosphorus (13.06±0.01mg/kg), Ca (12.04±0.02 cmol/kg), Mg (6.62±0.58 cmol/kg), EA (2.25±0.01 cmol/kg) and ECEC (21.27±1.15 cmol/kg) were recorded in soil of the close canopy while higher values for Na (0.11±0.01 cmol/kg), K (0.13±0.02 cmol/kg) and base saturation (90.83±0.01%) were recorded in soil of the open canopy. For the litter, organic carbon (45.25±7.31%), total nitrogen (1.14±0.06%), Ca (18.33±1.45mg/kg), Mg (8.91±1.16mg/kg), K (284.89±12.25mg/kg), Na (75.71±8.32mg/kg) and P (2.60±0.41mg/kg) were higher in the close forest canopy. This study has implications in deforestation, nutrient availability and cycling as well as forest management and protection.

Buried pipeline installation impacts on soil structure and crop root decomposition

AbstractThe severe manipulation of soil that occurs in the right‐of‐way (ROW) easement areas for pipeline installation leads to soil degradation and yield loss. The objectives of this study were to investigate the use of the Visual Evaluation of Soil Structure method (VESS) and root litter sampling as alternative ways to characterize pipeline installation impacts on soil degradation. Digital images of aggregate specimens and root samples were obtained from disturbed (trenched and highly trafficked ROW areas) and undisturbed (adjacent to the ROW) soil profiles one month after maize (Zea mays L.) harvest in Iowa. Images of soil aggregates indicated that pipeline installation deteriorated soil structure. Root attributes were significantly (p < 0.05) affected by the ROW activities. The non‐decomposed root mass in the highly trafficked area (3,568 kg ha–1) was two times greater than the root mass in undisturbed soil (1,779 kg ha–1). These data provide evidence that soil structure quality and root decomposition rates are affected by soil disturbance. The VESS and root measurements can be used in future studies to evaluate the impacts of soil disturbance.

Root litter decomposition in a sub-Sahelian agroforestry parkland dominated by Faidherbia albida

In agroforestry systems, fine roots grow at several depths due to the mixture of trees and annual crops. The decomposition of fine roots contributes to soil organic carbon stocks and may impact soil fertility, particularly in poor soils, such as those encountered in sub-Sahelian regions. The aim of our study was to measure the decomposition rate of root litter from annual and perennial species according to soil depth and location under and far from trees in a sub-Sahelian agroforestry parkland.Soil characteristics under and far from the trees were analysed from topsoil to 200 cm depth. Faidherbia tree, pearl millet and cowpea root litter samples were buried in litterbags for 15 months at 20, 40, 90 and 180 cm depths.Root litter decomposition was mainly impacted by soil moisture and soil depth. Faidherbia decomposed more slowly (36 ± 12% remaining mass after 15 months) than cowpea and pearl millet roots (23 ± 7% and 29 ± 11% respectively). Pearl millet aboveground biomass, at harvesting time, was twice as high under (992 g m−2) than far (433 g m−2) from the tree, and belowground biomass (0–200 cm of depth) was 30.9 g m−2 and 19.6 g m−2 under and far from the tree, respectively. Faidherbia fine roots contributed slightly (p-value < 0.1) to higher stocks of C under the tree (7761 ± 346 g m−2) than far from it (5425 ± 558 g m−2) and from 0 cm down to 200 cm depth.