Litter Content Research Articles

Longitudinal Changes in Campylobacter and the Litter Microbiome throughout the Broiler Production Cycle.

Broiler chickens are an important source of Campylobacter to humans and become colonized on the farm, but the role of the litter in the ecology of Campylobacter is still not clear. The aim of this study was to examine the relationship between Campylobacter and the changes in the litter microbiome throughout the broiler production cycle. Twenty-six commercial broiler flocks representing two production types (small and big broilers) were followed from 1 to 2 weeks after placement to the end of the production cycle. Composite litter samples from the broiler chicken house were collected weekly. Litter DNA was extracted and used for Campylobacter jejuni and Campylobacter coli qPCR as well as for 16S rRNA gene V4 region sequencing. Campylobacter jejuni concentration in litter significantly differed by production type and flock age. Campylobacter jejuni concentration in litter from big broilers was 2.4 log10 units higher, on average, than that of small broilers at 3 weeks of age. Sixteen amplicon sequence variants (ASVs) differentially abundant over time were detected in both production types. A negative correlation of Campylobacter with Bogoriella and Pseudogracilibacillus was observed in the litter microbiome network at 6 weeks of flock age. Dynamic Bayesian networks provided evidence of negative associations between Campylobacter and two bacterial genera, Ornithinibacillus and Oceanobacillus, at 2 and 4 weeks of flock age, respectively. In conclusion, dynamic associations between Campylobacter and the litter microbiome were observed during grow-out, suggesting a potential role of the litter microbiome in the ecology of Campylobacter colonization and persistence on farm. IMPORTANCE This study interrogated the longitudinal association between Campylobacter and broiler litter microbiome in commercial broiler flocks. The results of this investigation highlighted differences in Campylobacter dynamics in the litter throughout the broiler production cycle and between small and big broilers. Besides documenting the changing nature of the microbial networks in broiler litter during grow-out, we detected bacterial genera (Oceanobacillus and Ornithinibacillus) negatively associated with Campylobacter abundance and concentration in litter via the Bayesian network framework. These bacteria should be investigated as possible antagonists to Campylobacter colonization of the broiler environment.

Preface: Functional biogeography in Japanese cedar

Preface: Functional biogeography in Japanese cedar

Effects of long-term enclosing on distributions of carbon and nitrogen in semia-arid grassland of Inner Mongolia

The effects of long-term grazing exclusion on Carbon (C) and Nitrogen (N) partitioning in the green-plant–litter–root–soil system of grassland are unknown. As such, in this study, we evaluated the C and N contents, stocks, and ecological stoichiometry in Inner Mongolian grasslands by enclosing them for 18 and 39 years inside a fence (F18 and F39, respectively), in comparison with those outside the fence (F0), an area that was under long-term grazing. In F18 and F39, C and N stocks were higher in green plants and litter (undecomposed, incompletely decomposed, and completely decomposed litter), but C and N stocks were lower in the roots and soil (P < 0.05). The N stocks in F39 in incompletely and completely decomposed litter were lower (P < 0.05) compared with those in F18. The C contents in green plants and soil were 5% higher in F39 than in F18, whereas the N contents of litter and soil were 17.13%–37.92% lower. The C/N ratio in green plants and litter substantially increased after long-term enclosure, but decreased in roots and soil. The C/N ratio in litter and soil in F39 was 6.5%–36% higher than at F18, but 1.2%–8.2% lower in green plants and roots. Finally, following long-term enclosure, C and N were primarily transported from the soil and roots to green plants and litter. After 39 years of enclosing, C primarily moved from the litter to soil, while N primarily transferred from the soil to roots, compared with 18 years of enclosing. Our results indicated that the duration of enclosure has different effects on C and N distribution in the green-plant–litter–root–soil system. In conclusion, long-term grazing exclusion is not beneficial for soil C and N sequestration in the grasslands of Inner Mongolia.

Assessment of metal exposure (uranium and copper) in fatty acids and carbohydrate profiles of Calamoceras marsupus larvae (Trichoptera) and Alnus glutinosa leaf litter.

Physiological changes were explored in fatty acids (FA) and carbohydrate (CHO) composition in the shredder Calamoceras marsupus larvae (Trichoptera) and leaf litter (C. marsupus food) exposed to copper and uranium under natural and experimental conditions. We measured FA and CHO content in leaf litter and larvae specimens from reference and impacted streams, and exposed for 5 weeks to four realistic environmental concentrations of copper (35 μg L-1 and 70 μg L-1) and uranium (25 μg L-1 and 50 μg L-1). Regarding FA, (1) leaf litter had a reduced polyunsaturated FA (PUFA) content in metal treatments, s (14 to 33% of total FA), compared to natural conditions (≥39% of total FA). Leaf litter exposed to uranium also differed in saturated FA (SFA) composition, with lower values in natural conditions and higher values under low uranium concentrations. (2) C. marsupus had/showed low PUFA content under Cu and U exposure, particularly in high uranium concentrations. Detritivores also decreased in PUFA under exposure to both metals, particularly in high uranium concentrations. On the other hand, (1) microorganisms of the biofilm colonizing leaf litter differed in CHO composition between natural (impacted and reference) and experimental conditions, with glucose and galactose being consistently the most abundant sugars, found in different amounts under copper or uranium exposure; (2) CHO of detritivores showed similar high galactose and fucose concentrations in contaminated streams and high copper treatments, whereas low copper treatment showed distinct CHO profiles, with higher mannose, glucose, arabinose, and fucose concentrations. Our study provides evidence of metal exposure effects on FA and CHO contents at different trophic levels, which might alter the quality of food flow in trophic webs.

Fungal Community Composition as Affected by Litter Chemistry and Weather during Four Years of Litter Decomposition in Rainshadow Coastal Douglas-Fir Forests.

Climate and litter chemistry are major factors influencing litter decay, a process mediated by microbes, such as fungi, nitrogen-fixing bacteria and ammonia-oxidizing bacteria. Increasing atmospheric CO2 concentrations can decrease nitrogen (N) and increase condensed tannin (CT) content in foliar litter, reducing litter quality and slowing decomposition. We hypothesized that reduced litter quality inhibits microbes and is the mechanism causing decomposition to slow. Litterbags of Douglas-fir needles and poplar leaves with a range of N (0.61–1.57%) and CT (2.1–29.1%) treatment and natural acid unhydrolyzable residue (35.3–41.5%) concentrations were placed along climatic gradients in mature Douglas-fir stands of coastal British Columbia rainshadow forests. The structure (diversity, richness and evenness) and composition of microbial communities were analyzed using DGGE profiles of 18S, NifH-universal and AmoA PCR amplicons in foliar litter after 7, 12, 24 and 43 months of decay. High CT and low N concentrations in leaf litter were associated with changes in microbial community composition, especially fungi. Contrary to our hypothesis, high CT and low N treatments did not inhibit microbial colonization or diversity. The joint effects of air temperature and soil moisture on microbial community composition at our sites were more important than the effects of initial litter chemistry.

THE INFLUENCE OF SEASONS ON METAL BIOACCUMULATIONAND OXIDATIVE STRESS IN SENTINEL ORGANISMS IN SOUTHAFRICAN URBAN FORESTS

Variations in Al, Fe and Mn concentrations in soil, leaf litter, moss, lichen and pill millipedes, as well as the induced oxidative stress effect of metals on the organisms, between the dry and the wet season within two Afromontane forests in the Western Cape were investigated. The two forests in the closest proximity of the Cape Town city centre and urban pollution sources were chosen to determine the difference of metal contamination between the dry, hot and cold, wet season. Three sampling sites were chosen within each forest at different altitudes on Table Mountain, as well asa control site, where the soil, leaf litter and each organism were randomly collected in both the dry and the wet seasons for metal and biochemical analysis. The metals in the wet season in both of the forests showed higher concentrations, as did the forest closest to the Cape Town city centre.This is indicative of higher levels of pollution due to increased anthropogenic activities in the wetseason. Oxidative stress in organisms was apparent in the varying tGSH levels, of which the dryseason mostly revealed the higher concentrations. Oxidative lipid damage (measured as MDA) levels were generally increased during the wet season when the metal concentrations were higher as a result of prominent brown haze episodes in winter. Urban forest ecosystems in urban cities may suffer irreparable damage resulting from metal contamination, more so in the colder wet season.

UV radiation doubles microbial degradation of standing litter in a subtropical forest

Abstract UV radiation has been recognized as a direct driver of litter decomposition by photodegrading organic matter in dryland ecosystems. However, the importance and mechanism of UV radiation on litter decomposition, especially on standing litter, in humid forest ecosystems remain unclear. We conducted a factorial experiment in a humid subtropical forest gap, manipulating the effects of UV radiation on the decomposition of standing litter under different microbial conditions. After 366 days of standing incubation, under normal conditions (UV pass with microorganisms), up to 40.63% of the litter mass was lost. However, under a UV pass without microorganisms, litter mass loss was only 16.30%. Under a UV block, the mass loss of litter with microorganisms was 27.68% and that of litter without microorganisms was 15.54%. Without microorganisms, UV radiation had no significant effect on the mass loss of litter carbon. However, UV radiation increased the DOC concentration of litter. And in the presence of microorganisms, UV radiation contributed to an increased mass loss of lignin by 16.72% and of cellulose by 14.75%. No negative effects of UV radiation on microorganisms were observed. These results suggest that UV radiation increased the net mass loss of litter by 106.67%, and this doubling promotion was achieved through microbial degradation. Synthesis. The increase in microbial degradation under UV radiation may be linked to the increased degradability of lignin and cellulose caused by photodegradation. Our study indicates that direct photodegradation by UV radiation could be weak in subtropical forests, but UV photofacilitation generates rapid turnover of carbon in this system.

What will polyethylene film mulching bring to the root-associated microbial community of Paeonia ostii?

Plastic film mulching can increase crop yield and is widely used in agricultural production, but long-term mulching could adversely affect plant growth. To investigate the related mechanism, we studied the bacterial communities in different root-associated compartments of Paeonia ostii, a perennial oil crop, under polyethylene film mulching for threeyears by full-length 16S rDNA sequencing technology, and measured the soil physicochemical properties and enzyme activities. We found that enzyme activities and available nutrients in the soil tended to decrease after long-term mulching. Analysis of bacterial community composition revealed that the endosphere may be another potential source of the root-associated microbiome of P. ostii, and the rhizoplane plays a selective gating role in the enrichment processes for P. ostii microbiome assembly. Long-term mulching affected the abundance of dominant bacterial communities in different root-associated compartments and reduced the bacterial richness in the endosphere, but increased bacterial interactions in each compartment, as well as between different compartments. We speculate that this is mainly related to the decrease of litter content and the serious degradation of polyethylene film after long-term mulching, which resulted in microplastics and other harmful substances entering the soil. Our study further explained the reasons for the harm of long-term film mulching on plants to guide the rational use of plastic film. KEY POINTS: •Soil enzyme activities and available nutrients decreased after long-term mulching. •Mulching affected the dominant bacterial abundance in different root-associated compartments. •Mulching increased bacterial interactions among compartments.

The prevalence and concentration of Salmonella enterica in poultry litter in the southern United States.

Poultry litter is applied to crop production land in the southern United States as a waste management strategy as it is a nitrogen-rich fertilizer and plentiful throughout the region. While litter is a known reservoir for human enteric pathogens including Salmonella enterica, little is known regarding pathogen prevalence, concentration, and common serotypes within the material. Litter from thirteen farms across four southern states was examined for Salmonella. Samples (n = 490) from six of the thirteen (46.2%) farms tested positive. Thirty-three samples out of 490 (6.7%) were Salmonella positive. Salmonella was ca. 95% less likely to be collected from stacked litter piles than from the poultry house floor or pasture, and every day increase in litter age reduced the likelihood of recovering Salmonella by 5.1%. When present, concentrations of Salmonella in contaminated poultry litter were variable, ranging from <0.45 to >280,000 MPN/g. The most prevalent serotypes found were Kentucky (45.5%), Kiambu (18.2%), and Michigan (12.1%). Salmonella Kentucky also had the greatest distribution and was found on 4 of the 6 (66.7%) positive farms. Results from this survey demonstrated that Salmonella prevalence and concentration in poultry litter is highly variable, and good agricultural practices are critical to safely use poultry litter as a soil amendment on fresh produce fields.

The State of Beach Litter Pollution during the COVID-19 Pandemic: A Case Study of the Israeli Coasts

This research examines the impact of the COVID-19 pandemic on marine litter pollution along the Israeli coast, which constitutes a terminal area in the Mediterranean Sea large-scale circulation. Surveys for litter were conducted on four beaches along the Israeli Mediterranean coast. Sampling was done pre-pandemic in June, September, and December of 2019; during the first year of the pandemic in March, June, September, and December of 2020; and during the second year of the pandemic in March 2021. The study revealed that during the first year of the pandemic, beach litter concentration was reduced by 47 ± 27% on all beaches. The decrease in beach litter continued during the second year on most beaches (34 ± 22% reduction) and was most observable for plastic products, which have a high potential to float and travel long distances. The decline in beach litter concentration in the Israeli beaches during the pandemic was statistically significant. The barcode analysis indicates the appearance of non-Israeli debris on the shores (22-81% pre-COVID-19 and 5-47% during-COVID-19), which supports the assumption that the reduction in marine litter pollution was affected by the decline in beach activity both locally and in other coastal neighboring countries. An additional effect of the pandemic was the appearance of single-use plastic masks and gloves in April 2020, influenced by the epidemic’s regulations and restrictions. Despite the decline in beach marine litter concentration during COVID-19, plastic pollution is a high concern in this heavily populated coastal region. Our data set provides an indication for the potential of local and regional regulations to reduce further beach litter pollution and a baseline for continuous monitoring of these processes. Highlights The impact of COVID-19 on beach litter pollution along Israel’s coast was studied Significant decline in beach litter concentration during the Covid-19 pandemic. Barcode analysis reveals debris is 22-57% from non-local sources. Litter associated with COVID-19 was identified for the first time just as pandemic start

Age-Related Changes in Water and Nitrogen Utilization in Crop Trees and Understory Vegetation in a Hinoki Cypress Plantation Forest in Kochi City, Southern Japan

Age-related changes in water and nitrogen utilization of crop and understory vegetation in a hinoki cypress plantation forest were investigated from the age of 21 to 46 years in Kochi City, southern Japan. Nitrogen concentration in the leaf litter of hinoki cypress showed a decreasing trend with forest age. The leaf δ15N of hinoki cypress was related to a quadratic function and increased from the age of 21 to 26 years and then decreased to the age of 46 years. These results suggest that older hinoki cypress trees utilize soil nitrogen sources with lower δ15N values, and the competition for soil nitrogen with understory vegetation should be stronger. Carbon isotope discrimination (Δ13C) of hinoki cypress decreased from the age of 21 to 30 years and then increased to the age of 46 years. In contrast, the intrinsic water-use efficiency (iWUE) of hinoki cypress increased from the age of 21 to 36 years and then decreased to the age of 46 years. These findings suggest that hinoki cypress trees in the earlier time increased their iWUE by reducing stomatal opening. In the earlier time, the stomatal opening of understory vegetation increased due to higher soil water availability with decreasing stand density of crop trees. In the later time, the iWUE of hinoki cypress decreased due to lower photosynthetic capacity with nitrogen limitation. These results suggest that the increase in the iWUE of hinoki cypress in response to elevated atmospheric carbon dioxide levels should be smaller in the later time because of stronger competition with understory vegetation for soil nitrogen resources.

KADAR AIR, pH, SUHU, DAN KADAR AMONIA PADA LITTER DI DUA ZONASI YANG BERBEDA PADA KANDANG CLOSED HOUSE

This research was a case study which aimed to determine the water content, ammonia content, pH, and temperature of litter in the zonation in the closed house. This research was carried out in March 2021-April 2021, for 28 days in the Closed-house unit of the Department of Animal Husbandry, Faculty of Agriculture, University of Lampung. The closed house unit used was 40 meters long and 8 meters wide with a capacity of 5,495 broiler DOCs. The closed house zone was divided into two, namely zone 1 (20x8m) located near the cooling pad occupied by 2,747 DOCs and in zone 2 (20x8m) which is near the exhaust fan occupied by 2,748 DOCs. The results showed that Zone 1 near the cooling pad had lower water content, ammonia, pH, and litter temperature compared to Zone 2 which was close to the exhaust fan.&#x0D; &#x0D; Keywords: Ammonia, Closed-house zoning, Litter temperature, pH, Water content

Extracellular Enzyme Stoichiometry Reveals Soil Microbial Carbon and Phosphorus Limitations in the Yimeng Mountain Area, China

Soil extracellular enzymes are considered key components in ecosystem carbon and nutrient cycling, and analysing their stoichiometry is an effective way to reveal the resource limitations on soil microbial metabolism. In this study, the soil and litter of Quercus acutissima plots, Pinus thunbergii plots, Quercus acutissima–Pinus thunbergii mixed-plantation plots, herb plots, and shrub plots in the state-owned Dawa Forest Farm in the Yimeng Mountain area were studied. The total carbon (C), nitrogen (N), and phosphorus (P) contents of litter and the physical and chemical properties of soil were analyzed, along with the activities of four extracellular enzymes related to the soil C, N, and P cycle: β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), L-leucine aminopeptidase (LAP), and acid phosphatase (AP). The extracellular enzyme stoichiometric model was used to study and compare the metabolic limitations of soil microorganisms in different plots, and the driving factors of microbial metabolic limitations were explored by redundancy and linear regression analyses. The results showed that the values of BG/(NAG + LAP) were all higher than 1, the values of (NAG + LAP)/AP all lower than 1, and the vector angles of the five plots all greater than 45°, which indicated that the soil microorganisms were relatively limited by C and P. Redundancy and linear regression analysis revealed that soil physical properties (e.g., soil moisture) and litter total C make greater contributions to soil extracellular enzymes and stoichiometry than the other investigated soil parameters, whereas soil chemical properties (e.g., soil organic C and available P) predominantly controlled vector properties. Therefore, microbial metabolism limitations are greatly regulated by soil physical and chemical properties and litter total C and N. Compared with the forest plots, the soil microbial C (1.67) and P (61.07°) limitations of herb plots were relatively higher, which means that the soil microbial communities of forest plots are more stable than those of herb plots in the Yimeng Mountain area. Forest plots were more conducive than other plots to the improvement of soil microbial ecology in this area. This study could be important for illuminating soil microbial metabolism and revealing soil nutrient cycling in the Yimeng Mountain area ecosystem of China.

Tylosin in anaerobic reactors: degradation kinetics, effects on methane production and on the microbial community.

Tylosin eliminated in animal waste, during therapeutic treatment, can be efficiently removed in anaerobic systems. The present study investigated the influence of tylosin concentration and assessed its degradation kinetics and the microorganisms involved in each stage of its anaerobic digestion (hydrolysis/acidogenesis; acetogenesis; methanogenesis). The results showed a stimulating effect on methane production with increasing tylosin concentration in the poultry litter up to 80mg kg-1 tylosin (232.9 NL CH4kg SV-1). As for tylosin degradation, greater removal of antibiotics was observed in the methanogenic phase (88%), followed by acetogenic (84%) and hydrolytic/acidogenic (76%) phases. The higher rate of tylosin degradation obtained in the methanogenic step, is mainly related to the co-metabolic effect exerted by the presence of acetate and its degradation by acetoclastic methanogens. Indeed, metagenomic analyses suggested a syntrophic action between archaea of ​​the genus Methanobacterium, and bacteria such as Clostridium and Flexilinea, which seemed decisive for tylosin degradation.

Impact of multiple beach activities on litter and microplastic composition, distribution, and characterization along the southeast coast of India

A regional understanding of beach litter abundance, distribution, and composition is fundamental to formulate strategies to manage litter pollution in a particular area. The present study aimed to quantify and characterize the macro (2.5 cm to 1m), meso (5 mm–2.5 cm), and micro litter (≤5 mm) in the intertidal and backshore area of six sandy beaches utilized for various activities along the southeast coast of India. Macro litter was collected within 100m transects, while meso and micro litter was collected within 1 m2 quadrats (n = 5) from each beach's intertidal and backshore regions. In this study, the average beach litter concentrations were 0.24 ± 0.14 items/m2 (macro), 8.2 ± 5.6 items/m2 (meso), and micro litter was 505 ± 121 particles/kg of dry sediment. The backshore had a higher litter concentration than the intertidal area. Beaches closer to urban centers and multiple activities had higher litter abundance than more remote beaches. Using the Clean Coast Index (CCI), four beaches i.e., Neelankarai, Kovalam, Auroville, and Paradise are characterized as moderately clean beaches, whereas, the other two beaches i.e., Nemmeli and Palar are clean and very clean, respectively. Even though the beaches were found to be moderately clean, there is an urgent need to improve local waste management of beach litter. We suggest regular cleaning of river banks, a strict ban of single-use plastic in the beach area, and raising awareness e.g., by involving school and college students adopting a local beach.

Effects of low crude protein content and glycine supplementation on broiler chicken performance, carcass traits, and litter quality.

• Low-protein diets decreased broiler chicken performance from 10 to 42 d of age. • The use of Gly in low protein diets did not improve broiler chicken performance. • The use of Gly in low protein diets increased broiler chicken meat quality. The objective of this experiment was to investigate the effects of crude protein (CP) content with or without Gly supplementation on performance, carcass traits, and litter quality of broiler chickens. One-day-old male broiler chickens were fed isoenergetic diets and were assigned to 5 treatments (12 replicates; 8 broiler chickens/replication). The CP content was different among treatments (starter diet from 22% to 19%, grower diet from 20% to 17%, finisher diet from 18% to 15%). The lowest CP concentration in diets has occurred in treatments 4 and 5, while the CP concentrations in diets in treatments 1, 2, and 3 were greater. Diet from treatment 5 was supplemented with Gly. During the starter period, there were no differences in performance among treatments. In the grower, finisher, and in whole periods, the reduction in CP concentration lowered the broiler chicken performance, regardless of supplementation of Gly in comparison to control treatment in which the protein content has not been decreased ( P < 0.05). The reduction in CP in diets also decreased breast muscles, however, the supplementation of Gly decreased fat deposition and increased carcass weight ( P < 0.05). The reduction in CP in diets affected improvement litter quality (litter dry matter and N content) ( P < 0.05) and also decreasing blood urea N content in litter ( P = 0.066). Results indicate that a decrease of CP in diets influenced negatively performance (body weight gain, feed intake, and feed conversion ratio) of broiler chickens (except starter period), percentage of breast muscles, and percentage of abdominal fat. The use of synthetic Gly did not improve broiler chicken performance, however increased carcass quality by reducing fatness.

Timing of leaf fall and changes in litter nutrient concentration compromise estimates of nutrient fluxes and nutrient resorption efficiency

Nutrient resorption in the canopy and return to soil with litterfall are two major nutrient processes in forested ecosystems. However, leaf-fall phenology and seasonal dynamics of canopy nutrient concentration have not been comprehensively quantified, compromising the confidence in estimates of litterfall nutrient fluxes and nutrient resorption efficiency. Here, we used high-frequency litter collections for 28 species in nine plots for a temperate deciduous broadleaved forest in northeastern China. Based on leaf-fall phenology and temporal shifts in nitrogen (N) and phosphorus (P) concentrations in leaf litter for major tree species, we quantified the errors in canopy nutrient flux and resorption efficiency for 15 species and nine plots. The day of year (DOY) of start of leaf-fall, DOY of peak leaf-fall, and the length of leaf-fall period differed dramatically among tree species. Concentrations of N and P in leaf litter usually declined during the summer and autumn seasons. Annual nutrient fluxes in total canopy litterfall at the ecosystem level were 65.70 ± 6.14 kg N ha−1 and 4.70 ± 0.80 kg P ha−1 of which leaf litterfall accounted for 78 and 76%, respectively. The N (NRE) and P (PRE) resorption efficiencies at the ecosystem level calculated based on the percentage of nutrient pool resorbed from canopy leaves were 49.8 ± 3.9 and 48.0 ± 7.1%, respectively. Calculating nutrient fluxes with species-specific nutrient concentration at the DOY of peak leaf-fall (Nupeak) underestimated N and P fluxes by an average of 11 and 14%; the corresponding errors in N and P fluxes estimated using plot-specific Nupeak were –5 and –7%. In addition, NRE and PRE for major species based on Nupeak were overestimated by an average of 9 and 12%, and those for nine plots by 11 and 17%; using plot-specific Nupeak lowered mean errors in NRE and PRE to 10 and 11%. These results indicate that estimating canopy nutrient fluxes and resorption efficiency using litterfall collected at the DOY of peak leaf-fall can lead to non-negligible errors, and species-specific combined litterfall collected at and slightly before the DOY of peak leaf-fall may be a better metric for estimating nutrient flux and resorption efficiency at both species and ecosystem scales.

Accumulated litter, nutrient stock and decomposition 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. Therefore, studies on accumulated litter and nutrient content provide information for a better understanding of nutrient dynamics. The aim of the study was to evaluate leaf litter and nutrient stock in different seasons and the instantaneous rate of decomposition in an Atlantic Forest Fragment over two years. Litter sampling was carried out in 12 permanent plots with dimensions of 20 m x 50 m. Litter dry mass and nutrient concentration were determined. The average annual accumulation of litter was 5269 kg ha-1. There was no statistically significant difference in the amount of litter between seasons. There was a statistically significant difference in the contents of N, P, K Ca and Mg between the different seasons. Nutrient stocks were 123.3, 92.8, 13.2, 11.8, 9.6, 3.0 kg ha-1 year-1 for Ca, N, Mg, S, K and P respectively. The total of nutrients in the accumulated litter was 253.7 kg ha-1 year-1. The litter renewal time was 281 days. The times required for 50% and 95% litter decomposition were 196 and 850 days. The average litter stocks, nutrients and decomposition are in line with other studies, indicating that the Atlantic Forest fragment seasonal semi-deciduous presents indicators of nutrient cycling. These results show that the ecosystem is sustainable from the point of view of cycling and nutrient release.&#x0D; Keywords: ecosystem functions, nutrient cycling, secondary succession.

Copper content in soils and litter from fruit orchards in Central Chile and its relationship with soil microbial activity

This study assessed both the soil and litter copper (Cu) levels and their relationships with soil microbial activity, in fruit-tree production areas of central Chile where Cu-based pesticides are intensively sprayed. Samples of soil (0–20 cm depth) and litter from a number of selected orchards (kiwi, table grape, plum, and cherry) were collected and analysed for their Cu content and C-induced soil microbial activity. Results showed that the mean total soil Cu level was 225 mg/kg and soluble soil Cu was less than 0.01% of total soil Cu, as expected from pH values of study soils (range of 6.33 to 7.93). However, leaf litter Cu content was 3–7 times higher than in soil (mean of681 mg/kg). Despite the soil and leaf litter Cu concentrations, no effect was observed on the C-induced soil microbial activity. We conclude that leaf litter exerts a protective role, preventing the entry of Cu into the soil and thus soil microbial toxicity.

Perennial monocropping of khat decreased soil carbon and nitrogen relative to multistrata agroforestry and natural forest in southeastern Ethiopia

Monocropping of perennial cash crops providing livelihood for smallholders is replacing native forest throughout the tropics, but there is no direct empirical evidence on the impact on soil organic carbon (SOC) and nitrogen (N) relative to multistrata-agroforestry-based cash cropping. In particular, the impact of the conversion of forests and multistrata-agroforestry-based cash cropping to a rapidly expanding perennial monocropping of khat (Catha edulis Forskal) is not known. We investigated the potential of cash cropping integrated in multistrata agroforestry to alleviate SOC and N loss from converted native forest, relative to cash monocropping. We assessed empirically SOC and N stocks in the 40-cm-deep soil surface layer of three matched adjacent plots of native forest, multistrata agroforestry, and perennial cash monocropping, within nine replicate groups of the three land uses. The fixed mass method was applied. The estimated rates of the annual SOC and N losses were 3.0 and 3.4 times greater, respectively, in areas converted to khat monocropping than in agroforestry systems producing both coffee (Coffea arabica) and khat. Additionally, the carbon and N contents in leaf litter and fine roots were greater in agroforestry than in khat. The results indicated that multistrata-agroforestry-based cash cropping maintains most of the SOC and N stocks of converted native forests lost in conversion to cash monocropping khat than in agroforestry-based cash cropping. This warrants economic incentives to prevent the loss of the current stocks, while enabling cash crop income by smallholders. Reducing forest SOC and N stock decline in agroforestry through system management deserves attention as well.