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Partitioning of carbon and nitrogen during decomposition of 13C15N‐labeled beech and ash leaf litter 
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下载免费PDF全文 Christina Langenbruch Mirjam Helfrich Rainer Georg Joergensen Jennifer Gordon Heinz Flessa 《植物养料与土壤学杂志》2014,177(2):178-188
The aim of this study was to determine the influence of leaf‐litter type (i.e., European beech—Fagus sylvatica L. and European ash—Fraxinus excelsior L.) and leaf‐litter mixture on the partitioning of leaf‐litter C and N between the O horizon, the topsoil, the soil microbial biomass, and the CO2 emission during decomposition. In a mature beech stand of Hainich National Park, Thuringia, Germany, undisturbed soil cores (?? 24 cm) were transferred to plastic cylinders and the original leaf litter was either replaced by 13C15N‐labeled beech or ash leaf litter, or leaf‐litter‐mixture treatments in which only one of the two leaf‐litter types was labeled. Leaf‐litter‐derived CO2‐C flux was measured every second week over a period of one year. Partitioning of leaf‐litter C and N to the soil and microbial biomass was measured 5 and 10 months after the start of the experiment. Ash leaf litter decomposed faster than beech leaf litter. The decomposition rate was negatively related to initial leaf‐litter lignin and positively to initial Ca concentrations. The mixture of both leaf‐litter types led to enhanced decomposition of ash leaf litter. However, it did not affect beech leaf‐litter decomposition. After 5 and 10 months of in situ incubation, recoveries of leaf‐litter‐derived C and N in the O horizon (7%–20% and 9%–35%, respectively) were higher than in the mineral soil (1%–5% and 3%–8%, respectively) showing no leaf‐litter‐type or leaf‐litter‐mixture effect. Partitioning of leaf‐litter‐derived C and N to microbial biomass in the upper mineral soil (< 1% of total leaf‐litter C and 2%–3% of total leaf‐litter N) did not differ between beech and ash. The results show that short‐term partitioning of leaf‐litter C and N to the soil after 10 months was similar for ash and beech leaf litter under standardized field conditions, even though mineralization was faster for ash leaf litter than for beech leaf litter. 相似文献
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Inorganic toxicants in soils of North Rhine-Westphalia. I. Evaluation of multi-modal frequency distributions In 335 soil samples from North Rhine-Westphalia the contents of 18 elements were quantified (total contents, mobilizable fraction (extraction with EDTA cocktail), mobile fraction (extraction with NH4NO3). An inspection of the resulting histograms revealed that the distribution of element contents in soils is not normal and even not log-normal. The appearance of several peaks indicates the existence of multi-modal distributions with various independent sub-distributions. Two methods for analysing such data sets are presented. The parametric approach assumes several single lognormal components, which are fitted by the Expectation Maximization Algorithm. In a nonparametric approach the Kernel Density Estimation is used. With this procedure five to ten concentration levels can be determined per element for our data set with corresponding groups of soil samples being characterized by common features (e.g., parent material, region of origin, specific source of pollution). This way, e.g., background concentrations for potentially toxic elements can be derived. The parametric approach is lacking sharpness of separation in the case of more than four subdistributions. 相似文献
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Findings of previous studies suggest that there are relations between thermal stability of soil organic matter (SOM), organo‐mineral associations, and stability of SOM against microbial decay. We aimed to test whether thermal oxidation at various temperatures (200°C, 225°C, 275°C, 300°C, 400°C, or 500°C) is capable of isolating SOM fractions with increasing stability against microbial degradation. The investigation was carried out on soils (Phaeozem and Luvisol) under different land‐use regimes (field, grassland, forest). The stability of the obtained soil organic carbon (SOC) fractions was determined using the natural‐13C approach for continuously maize‐cropped soils and radiocarbon dating. In the Luvisol, thermal oxidation with increasing temperatures did not yield residual SOC fractions of increasing microbial stability. Even the SOC fraction resistant to thermal oxidation at 300°C contained considerable amounts of young, maize‐derived C. In the Phaeozem, the mean 14C age increased considerably (from 3473 y BP in the mineral‐associated SOC fraction to 9116 y BP in the residual SOC fraction after thermal oxidation at 300°C). An increasing proportion of fossil C (calculated based on 14C data) in residual SOC fractions after thermal oxidation with increasing temperatures indicated that this was mainly due to the relative accumulation of thermally stable fossil C. We conclude that thermal oxidation with increasing temperature was not generally suitable to isolate mineral‐associated SOC fractions of increasing microbial stability. 相似文献
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Soil C dynamics below the plow layer have been little studied, despite a suspected large C‐stabilization potential of subsurface horizons. The objective of this study was to test two simple models (model A: single compartment for C3‐ and for C4‐derived C; model B: division of C3‐ and C4‐derived C into active and passive compartments) in their ability to simulate the C dynamics in subsoil horizons of a Haplic Phaeozem after conversion from C3 (rye) to C4 cropping (maize). The models were calibrated on an unfertilized maize soil and then validated on a maize soil with NPK fertilization. Both models simulated well C3‐C and C4‐C dynamics in the investigated soil depths (20–40 cm and 40–60 cm). In all cases, the model efficiency EF was > 0, which indicated that the simulated values described the trend in the measured data better than the mean of the observations. However, we observed some inconsistency in the obtained parameter set (e.g., a higher proportion of passive C for C4‐derived than for C3‐derived C or a very low decomposition rate constant for passive C4‐C in 40–60 cm), which we assume to result from data restrictions on the investigated soils. More detailed data on SOC pools and turnover rates in subsoils which are generally not yet available for most experimental plots is vitally needed—especially for applying more sophisticated C‐dynamics models. 相似文献
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AC Morini NCG Pieri KCS Roballo DS Martins CE Ambrósio JC Morini Junior PO Favaron AHH Minervino FVT Pereira MA Miglino 《Reproduction in domestic animals》2016,51(4):509-514
Many researches describe the embryonic developmental features in domestic animals; however, in farm animals, they are scarce. Most farm animal studies are related to assisted reproduction and embryos transfer techniques. But, morphological features and size measure to estimate the age gestation are rarely reported in literature. Thus, in this study, we described the developmental changes in the bubaline (Bubalus bubali) concepts from 21 to 60 days of gestation. Our results revealed that buffalo embryos similar morphological characteristics similar to other mammalian species. Also, similarities between bovine and bubaline persist; except on foetal stages when buffalos have a faster development than bovine. Therefore, buffalo's gestation period exhibits some varieties and accurate embryo age is more difficult. Yet, when we use a combination of the crown–rump, macroscopic analysis and alizarin red, it is possible to describe better the whole embryogenesis stages of the buffalo and which can contribute for future reproduction researches and applications in veterinary practice. 相似文献
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森林分类区划是为了解决天然林的修养生息和恢复发展而提出的,但禁伐区、限伐区、商品林经营区划分在实施过程中存在一些问题。文章主要针对其存在的问题,提出一些可行性的建议和对策。 相似文献
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CE Reid BD Gartrell M Van Andel KJ Stafford EO Minot K McInnes 《New Zealand veterinary journal》2020,68(2):84-91
ABSTRACTAims: To characterise and classify wounds in sheep suspected to have been caused by attacks by kea (Nestor notabilis) (kea strike), and to report the prevalence of these wounds on five high country farms in the South Island of New Zealand.Methods: Data were collected from farms between 28 August 2012 and 20 September 2013. Sheep were examined opportunistically immediately after shearing for signs of wounds caused by kea. The age and sex of sheep were also recorded. Wounds were measured and characterised as recent, healing, or healed, and the estimated true prevalence was calculated for each farm.Results: Injuries consistent with kea strike wounds were identified in 70/13,978 (0.5%) sheep examined. The estimated true prevalence varied between farms, from 0 (95% CI?=?0–0.16) to 1.25 (95% CI?=?0.97–1.61)%. Of the 76 wounds identified, 61 (80%) were located in the lumbar region, and 74 (97%) consisted of full-thickness ulceration of the skin, one showed evidence of injury to muscle and one to bone. The median length of the 63 wounds measured was 6 (min 1, max?23.5) cm, and 10/63 (13%) were categorised as recently healed, 47/63 (62%) as healing, and 17/63 (22%) as recent wounds.Conclusions: The results of this study show that kea strike on sheep was occurring at a low prevalence on the high country farms surveyed. The wounds identified were survivable, but the welfare impact of kea strike on sheep should be considered in balance with the conservation status of kea. There was clear variation in the prevalence of wounds attributed to kea strike between the farms but we were not able to identify the risk factors contributing to these differences. Future studies of kea strike should examine variables such as altitude, local kea density and distribution, and differences in kea strike management and husbandry practices, and should include high country farms without a history of kea strike. 相似文献
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AIM: To determine the suitability of a reversible, injectable anaesthetic combination including medetomidine, butorphanol and atropine to produce the degree of immobilisation required to allow blood sampling in young pigs. METHODS: Twenty 6-week-old crossbred, intact male pigs were sedated with an intramuscular (I/M) injection of 80 µ'g/kg medetomidine, 200 µ'g/kg butorphanol and 25 µ'g/kg atropine. Heart and respiratory rates and rectal temperatures were monitored. Excessive salivation, gagging, laryngeal reflex, presence of pedal reflex and deep and surface analgesia were noted. Time of injection and the time when pigs reached mild and full sedation were also recorded. RESULTS: Mild sedation was produced in 90% of pigs after 5.6 (SEM 0.96) min (n=18; median 5, range 2–16 min), and full sedation (lateral recumbency and loss of jaw tone) in 60% of pigs after 12.5 (SEM 2.14) min (n=12; median 10, range 5-28 min). The depth and duration of sedation were very variable and most animals were easily aroused. Ninety percent of the animals required the administration of halothane by mask to allow blood sampling, but the amount of halothane required was small. Heart and respiratory rates decreased (p<0.001) but remained within the normal range. Rectal temperature was above normal at the time of sedation and at the time of blood sampling when the ambient temperature was 29° C but not when the ambient temperature was reduced to 25°C. CONCLUSIONS: The combination of medetomidine, butorphanol and atropine at these doses produced sedation of variable depth and duration that was insufficient on its own to allow blood sampling in the majority of pigs. Hyperthermia can occur in temperature-controlled environments when using medetomidine, butorphanol and atropine in pigs. Reduction of stress and a quieter environment may improve the effects of the anaesthetic combination. 相似文献