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Litter Samples (litter + sample)
Selected AbstractsNutrient Dynamics of Soil Derived from Different Parent Material on Barro Colorado Island, Panama,BIOTROPICA, Issue 2 2000Joseph B. Yavitt ABSTRACT I compared the concentrations of N, P, and S in both litter and mineral soil (0,15 cm depth) from three old-growth, tropical moist forests on Barro Colorado Island (BCI), Panama. Each site was on a different substrate (i.e., parent material), but otherwise had similar climate, vegetation, and topography. There were no site differences in concentrations of N and S for either litter or soil. Concentrations of litter P and soil-extractable P were greater for the andesite (igneous rock) site than for two sites on different sedimentary rocks; however, concentrations of several other litter and soil P fractions did not differ among sites. Patterns in soil P fractions suggested advanced soil development to the point that parent material has little control of P dynamics. Litter samples from each site, leached in the laboratory, released similar amounts of N, P, and S to the soil, indicating no differences in rates of turnover in the litter and in fluxes from litter into the mineral soil among sites. I expected more site differences in soil nutrient dynamics given vastly different parent materials and soil types (i.e., Oxisol vs. Alfisol) and very shallow soil on BCI that brings the parent material close to the plant root zone. Erosion and soil mixing may explain the uniformity in soil nutrient dynamics across the sites. [source] Foraging animals create fertile patches in an Australian desert shrublandECOGRAPHY, Issue 5 2009Alex I. James Fertile patches are created and maintained by a combination of physical and biologically-mediated processes including soil disturbance by animals. We examined the creation of fertile patches by 4 vertebrates, the greater bilby Macrotis lagotis, burrowing bettong Bettongia lesueur, European rabbit Oryctolagus cuniculus, and Gould's sand goanna Varanus gouldii within dunes, ecotones, and swales in a dunefield in arid South Australia. These animals all create pits when foraging for subterranean food resources. We hypothesized that 1) the effect of pits on litter capture would vary among landscapes and animal species, 2) larger pits would trap more litter and seed, 3) pits would contain more viable seed than the surrounding matrix, and 4) the effect of pits on soil chemistry would vary among animal species, and be greater in landscapes with more finely textured soils. We found that litter was restricted almost exclusively to the pits, and was greater in pits with larger openings. Litter capture was greater in ecotones and dunes than in swales. A total of 1307 seedlings from 46 genera germinated from litter samples taken from the pits, but no seedlings emerged from samples taken from soil surrounding the pits. Foraging pits contained significantly higher levels of total C and N than surrounding soil, and total C and N concentrations were greatest in swales and lowest in dunes. Pits contained ca 55% more mineralisable N that surface soils, and pits constructed by bilbies and bettongs contained half the concentration of mineralisable N as those of rabbits and goannas. Concentrations of mineral N and mineralisable N were also greatest in the swales. Our results demonstrate the importance of animal-created pits as nutrient sinks and sites for seedling establishment, and suggest that changes in the composition of arid zone vertebrates may have resulted in profound changes to nutrient and soil dynamics in arid Australia. [source] Non-enzymatic hydrolysis of fluorescein diacetate (FDA) in a Mediterranean oak (Quercus ilex L.) litterEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008E. Alarcón-Gutiérrez Summary We show the presence of interfering substances when the total microbial activity in litter samples is measured with fluorescein diacetate (FDA), and we propose some methodological modifications to avoid such interference. Three distinct litter layers (the OhLn, the OhLv and the OhLf) of evergreen oak (Quercus ilex L.) were characterized by 13C CPMAS NMR and the spectra show that the recalcitrant aromatic and phenolic compounds increase with the degree of degradation of litter. A wide range of sources of interference in the hydrolysis of FDA was found. To understand the origin of this interference, sterilized litter materials (i.e. ,-irradiated or autoclaved) and a wide range of organic substances (i.e. amino acids, glucose, sorbitol and organic humic acids) were investigated. Insignificant differences on the FDA hydrolysis activity (FDA activity) were found in the ,-irradiated and non-irradiated OhLn litter, indicating that ,-irradiation does not destroy enzymes. Conversely, after heat-sterilization of litter, samples showed FDA activity corresponding to 60, 34.8 and 30.8% (in the OhLn, the OhLv and the OhLf layers, respectively) of that of control litters. This indicates the presence of non-enzymatic interfering substances in the FDA assays. As the humification and litter depth increased, hydrolysis of FDA due to interferences decreased, indicating degradation and/or chelation of interfering substances. We hypothesize that lysine, arginine, histidine and cysteine are mainly responsible for the hydrolysis of FDA. We suggest that the use of phosphate buffer (50 mm, pH 7.0) with incubation <,30 minutes, in combination with a temperature between 30 and 40°C, produces insignificant interference in the determination of the final FDA activity in litter samples. [source] Identification of a Brevibacterium marker gene specific to poultry litter and development of a quantitative PCR assayJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2010J.L. Weidhaas Abstract Aim:, To identify a DNA sequence specific to a bacterium found in poultry litter that was indicative of faecal contamination by poultry sources. Methods and Results:, Faecally contaminated poultry litter and soils were used as source material for the development of a quantitative polymerase chain reaction (qPCR) method targeting the 16S rRNA gene of a Brevibacterium sp. The identified sequence had 98% nucleotide identity to the 16S rRNA gene of Brevibacterium avium. The qPCR method was tested on 17 soiled litter samples; 40 chicken faecal samples; and 116 nontarget faecal samples from cattle, swine, ducks, geese, and human sewage collected across the United States. The 571-bp product was detected in 76% of poultry-associated samples, but not in 93% of faecal samples from other sources. Marker concentrations were 107,109 gene copies per gram in soiled litter, up to 105 gene copies per gram in spread-site soils, and 107 gene copies per litre in field run-off water. Results were corroborated by a blinded study conducted by a second laboratory. Conclusion:, The poultry-specific PCR product is a useful marker gene for assessing the impact of faecal contamination as a result of land-applied poultry litter. Significance and Impact of the Study:, This study describes the first quantitative, sensitive and specific microbial source tracking method for the detection of poultry litter contamination. [source] Use of mid-infrared spectroscopy in the diffuse-reflectance mode for the prediction of the composition of organic matter in soil and litterJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2008Bernard Ludwig Abstract Mid-infrared spectroscopy (MIRS) is assumed to be superior to near-infrared spectroscopy (NIRS) for the prediction of soil constituents, but its usefulness is still not sufficiently explored. The objective of this study was to evaluate the ability of MIRS to predict the chemical and biological properties of organic matter in soils and litter. Reflectance spectra of the mid-infrared region including part of the near-infrared region (7000,400,cm,1) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C CPMAS-NMR spectroscopy. A partial least-square method and cross-validation were used to develop equations for the different constituents over selected spectra ranges after several mathematical treatments of the spectra. Mid-infrared spectroscopy predicted well the C : N ratio: the modeling efficiency EF was 0.95, the regression coefficient (a) of a linear regression (measured against predicted values) was 1.0, and the correlation coefficient (r) was 0.98. Satisfactorily (EF , 0.70, 0.8 , a , 1.2, r , 0.80) assessed were the contents of C, N, and lignin, the production of dissolved organic carbon, and the contents of carbonyl C, aromatic C, O-alkyl C, and alkyl C. However, the N mineralization rate, the microbial biomass and the alkyl,to,aromatic C ratio were predicted less satisfactorily (EF < 0.70). Limiting the sample set to mineral soils did generally not result in improved predictions. The good and satisfactory predictions reported above indicate a marked usefulness of MIRS in the assessment of chemical characteristics of soils and litter, but the accuracies of the MIRS predictions in the diffuse-reflectance mode were generally not superior to those of NIRS. [source] Near-infrared spectroscopy can predict the composition of organic matter in soil and litterJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2006Thomas Terhoeven-Urselmans Abstract The usefulness and limitations of near-infrared reflectance spectroscopy (NIRS) for the assessment of several soil characteristics are still not sufficiently explored. The objective of this study was to evaluate the ability of visible and near-infrared reflectance (VIS-NIR) spectroscopy to predict the composition of organic matter in soils and litter. Reflectance spectra of the VIS-NIR region (400,2500 nm) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C-CPMAS-NMR spectroscopy. A modified partial least-square method and cross-validation were used to develop equations for the different constituents over the whole spectrum (1st to 3rd derivation). Near-infrared spectroscopy predicted well the C : N ratios, the percentages of O-alkyl C and alkyl C, the ratio of alkyl C to O-alkyl C, and the sum of phenolic oxidation products: the ratios of standard deviation of the laboratory results to standard error of cross-validation (RSC) were greater than 2, the regression coefficients (a) of a linear regression (measured against predicted values) ranged from 0.9 to 1.1, and the correlation coefficients (r) were greater than 0.9. Satisfactorily (0.8 , a , 1.2, r , 0.8, and 1.4 , RSC , 2.0) assessed were the contents of C, N, and production of DOC, the percentages of carbonyl C and aromatic C and the ratio of alkyl C to aromatic C. However, the N-mineralization rate and the microbial biomass were predicted unsatisfactorily (RSC < 1.4). The good and satisfactory predictions reported above indicate a marked usefulness of NIRS in the assessment of biological and chemical characteristics of soils and litter. [source] Pheromonally mediated colonization patterns in the velvet worm Euperipatoides rowelli (Onychophora)JOURNAL OF ZOOLOGY, Issue 4 2000S. D. Barclay Abstract We demonstrate that the males of the peripatopsid Euperipatoides rowelli secrete a pheromone from crural papillae, which acts as an attractant to both males and females of the species. Patterns of colonization of decomposing logs and differences in sex ratio between incipient vs established populations indicate that males are the initial dispersers and colonizers, finding suitable log habitats in an exploratory fashion, while females subsequently colonize logs. This results in a disproportionately high frequency of males in newly colonized logs, followed by a gradual increase in female proportion. We argue that females use the aggregating pheromone secreted by males to target appropriate rotting log microhabitats, resulting in a clumped distribution of females compared to a more random distribution for males among recently colonized logs. This mode of colonization reduces the time that animals, especially females, spend outside the safety of suitable logs, and the risk-taking strategy of male exploration may explain the marked sex ratio bias in favour of females in the population. Rapid and non-random dispersal may also account for the contradictory evidence of unexpectedly high rates of colonization of new logs, yet a paucity of animals in leaf litter samples. The possibility that pheromone trails play a part in the dispersal process is discussed. [source] Species-specific detection of Lobaria pulmonaria (lichenized ascomycete) diaspores in litter samples trapped in snow coverMOLECULAR ECOLOGY, Issue 9 2001J.-C. Walser Abstract The foliose lichen Lobaria pulmonaria has suffered a substantial decline in central and northern Europe during the twentieth century and is now considered to be critically endangered in many European lowland regions. Based on demographic studies, it has been proposed that under the present environmental conditions and forest management regimes, dispersal of diaspores and subsequent establishment of new thalli are insufficient to maintain the remnant small lowland populations. Chances of long-term survival may therefore be reduced. The data and analytical power of these demographic studies are limited. Since lichen diaspores show very few species-specific morphological characteristics, and are therefore almost indistinguishable, the accurate assessment of diaspore flux would be a fundamental first step in better understanding the life cycle of L. pulmonaria. Here we present a new molecular approach to investigate the dispersal of L. pulmonaria diaspores in its natural environment by specifically identifying small amounts of DNA in snow litter samples at varying distances from known sources. We used a species-specific polymerase chain reaction (PCR) primer pair to amplify the ribosomal internal transcribed spacer region (ITS rDNA) and a sensitive automated PCR product detection system using fluorescent labelled primers. We detected considerable amounts of naturally dispersed diaspores, deposited as far as 50 m away from the closest potential source. Diaspores were only found in the direction of the prevailing wind. Diaspore deposition varied from 1.2 diaspores per m2 per day at 50 m distance from the source to 15 diaspores per m2 per day at 1 m distance. The method described in this paper opens up perspectives for studies of population dynamics and dispersal ecology mainly in lichenized ascomycetes but also in other organisms with small, wind-dispersed diaspores. [source] Insect herbivores and their frass affect Quercus rubra leaf quality and initial stages of subsequent litter decompositionOIKOS, Issue 1 2008Christopher J. Frost Defoliation-induced changes in plant foliage are ubiquitous, though factors mediating induction and the extent of their influence on ecosystem processes such as leaf litter decomposition are poorly understood. Soil nitrogen (N) availability, which can be affected by insect herbivore frass (feces), influences phytochemical induction. We conducted experiments to test the hypotheses that insect frass deposition would (1) reduce phytochemical induction following herbivory and (2) increase the decomposition and nutrient release of the subsequent leaf litter. During the 2002 growing season, 80 Quercus rubra saplings were subjected to a factorial experiment with herbivore and frass manipulations. Leaf samples were collected throughout the growing season to measure the effects of frass deposition on phytochemical induction. In live foliage, herbivore damage increased tannin concentrations early, reduced foliar N concentrations throughout the growing season, and lowered lignin concentrations in the late season. Frass deposition apparently reduced leaf lignin concentrations, but otherwise did not influence leaf chemistry. Following natural senescence, litter samples from the treatment groups were decomposed in replicated litterbags for 18 months at the Coweeta Hydrologic Laboratory, NC. In the dead litter samples, initial tannin concentrations were lower in the herbivore damage group and higher in the frass addition group relative to their respective controls. Tannin and N release rates in the first nine months of decomposition were also affected by both damage and frass. However, decomposition rates did not differ among treatment groups. Thus, nutrient dynamics important for some ecosystem processes may be independent from the physical loss of litter mass. Overall, while lingering effects of damage and even frass deposition can therefore carry over and affect ecosystem processes during decomposition, their effects appear short lived relative to abiotic forces that tend to homogenize the decomposition process. [source] | |||||||||||||