Chemical transformations in downed logs and snags of mixed boreal species during decomposition

2013 ◽  
Vol 43 (9) ◽  
pp. 785-798 ◽  
Author(s):  
Manuella Strukelj ◽  
Suzanne Brais ◽  
Sylvie A. Quideau ◽  
Virginie A. Angers ◽  
Hedi Kebli ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Forest Floor ◽  
Near Infrared ◽  
Resonance Spectroscopy ◽  
Chemical Transformations ◽  
Wide Range ◽  
Coniferous Wood ◽  
Detrital Carbon ◽  
Carbon Retention

Snags and downed logs are substantial components of the detrital carbon pool in boreal forests. Effects of their decomposition on chemical and physical characteristics of the forest floor remain relatively unknown. The main objective of this study was to characterize chemical transformations of decaying logs and snags of common tree species in the boreal mixedwood forest. Logs and snags from a wide range of decay classes were sampled and analyzed by solid-state 13C nuclear magnetic resonance spectroscopy and by near-infrared spectroscopy. Little or moderate chemical changes appeared in fresh and moderately decayed snags and logs, but in well-decayed logs, substantial degradation of carbohydrates and increases in lignin concentrations occurred. Deciduous species had initially more carbohydrates than coniferous species, but decomposition narrowed their differences, and in well-decayed logs, species differed mainly in terms of their lignin concentrations. Well-decayed deciduous logs reached very low wood densities, and their integration into the forest floor and long-term preservation remains questionable. In contrast, chemical composition of well-decayed coniferous logs resembles that of lignic forest floor (i.e., forest floor originating from deadwood decomposition), with preserved lignins, carbohydrates, and alkyl carbon compounds. Decomposed coniferous wood thus contributes to chemical heterogeneity of the forest floor, possibly promoting diversity of decomposers as well as carbon retention in soils.

Effects of organic matter removal, soil compaction, and vegetation control on 5-year seedling performance: a regional comparison of Long-Term Soil Productivity sites

2006 ◽  
Vol 36 (3) ◽  
pp. 529-550 ◽  
Author(s):  
Robert L Fleming ◽  
Robert F Powers ◽  
Neil W Foster ◽  
J Marty Kranabetter ◽  
D Andrew Scott ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Compaction ◽  
Forest Floor ◽  
Soil Productivity ◽  
Individual Tree ◽  
Seedling Performance ◽  
Organic Matter Removal ◽  
Vegetation Control ◽  
Wide Range

We examined fifth-year seedling response to soil disturbance and vegetation control at 42 experimental locations representing 25 replicated studies within the North American Long-Term Soil Productivity (LTSP) program. These studies share a common experimental design while encompassing a wide range of climate, site conditions, and forest types. Whole-tree harvest had limited effects on planted seedling performance compared with the effects of stem-only harvest (the control); slight increases in survival were usually offset by decreases in growth. Forest-floor removal improved seedling survival and increased growth in Mediterranean climates, but reduced growth on productive, nutrient-limited, warm–humid sites. Soil compaction with intact forest floors usually benefited conifer survival and growth, regardless of climate or species. Compaction combined with forest-floor removal generally increased survival, had limited effects on individual tree growth, and increased stand growth in Mediterranean climates. Vegetation control benefited seedling growth in all treatments, particularly on more productive sites, but did not affect survival or alter the relative impact of organic matter removal and compaction on growth. Organic matter removal increased aspen coppice densities and, as with compaction, reduced aspen growth.

Phytomass and detrital carbon storage during forest regrowth in the southeastern United States Piedmont

1989 ◽  
Vol 19 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Paula M. Schiffman ◽  
W. Carter Johnson
Keyword(s):  
United States ◽  
Carbon Storage ◽  
Forest Floor ◽  
Carbon Sink ◽  
Southeastern United States ◽  
Forest Products ◽  
Site Preparation ◽  
Natural Forests ◽  
Detrital Carbon

Carbon in soil, forest floor, and phytomass was estimated for two chronosequences of loblolly pine (Pinustaeda L.) plantations, as well as agricultural fields and natural Virginia pine (P. virginiana Mill.) forests. One plantation chronosequence was initiated on postagricultural fields and the other following clearing of natural second-growth pine forests and site preparation. Natural reforestation of old fields over 50–70 years increased carbon storage by about 235%, from about 55 000 to 185 000 kg/ha. Carbon in phytomass accounted for the greatest proportion of the increase (76%), followed by forest floor (13%) and surface soil (10%). Old field plantations stored more carbon than natural forests by approximately 42 000 kg/ha (22%). Virtually all of the gain was in phytomass. The contemporary practice of converting natural forests to plantations yielded only a modest gain in carbon (24%), and this in phytomass scheduled for harvest, not in detritus. The results showed negligible oxidative losses of carbon from soils after harvest and site preparation. Site preparation which includes burning may actually cause slow but long-term increases in detrital carbon as charcoal. Forest floor losses during conversion are largely regained by rotation end. Global carbon models need to be amended to incorporate these findings. Stabilization of the forest land base in the Piedmont foretells a rapidly declining capacity to store carbon at past rates. In terms of carbon gained, the current practice of converting natural forests to plantations is no substitute for the farm to forest conversions of past decades. Whether the southeastern United States Piedmont will continue to act as a net carbon sink depends largely on the balance between gains in detrital carbon, principally from charcoal produced by repeated site preparation, and the extent to which forest products from highly productive plantations are placed in long-term versus short-term storage.

scholarly journals Long-Term In Vivo Biocompatibility of Single-Walled Carbon Nanotubes

2019 ◽  
Author(s):  
Thomas V. Galassi ◽  
Merav Antman-Passig ◽  
Zvi Yaari ◽  
Jose Jessurun ◽  
Robert E. Schwartz ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Near Infrared ◽  
Complete Blood Count ◽  
Aggregation State ◽  
Single Walled Carbon ◽  
Wide Range ◽  
Short And Long Term

AbstractOver the past two decades, measurements of carbon nanotube toxicity and biodistribution have yielded a wide range of results. Properties such as nanotube type (single-walled vs. multi-walled), purity, length, aggregation state, and functionalization, as well as route of administration, greatly affect both the biocompatibility and biodistribution of carbon nanotubes. These differences suggest that generalizable conclusions may be elusive and that studies must be material- and application-specific. Here, we assess the short- and long-term biodistribution and biocompatibility of a single-chirality DNA-encapsulated single-walled carbon nanotube complex upon intravenous administration that was previously shown to function as an in-vivo reporter of endolysosomal lipid accumulation. Regarding biodistribution and fate, we found bulk specificity to the liver and >90% signal attenuation by 14 days in mice. Using near-infrared hyperspectral microscopy to measure single nanotubes, we found low-level, long-term persistence in organs such as the heart, liver, lung, kidney, and spleen. Measurements of histology, animal weight, complete blood count, and biomarkers of organ function all suggest short- and long-term biocompatibility. This work suggests that carbon nanotubes can be used as preclinical research tools in-vivo without affecting acute or long-term health.

scholarly journals New Spectroradiometers Complying with the NDSC Standards

2006 ◽  
Vol 23 (2) ◽  
pp. 241-251 ◽  
Author(s):  
Sigrid Wuttke ◽  
Gunther Seckmeyer ◽  
Germar Bernhard ◽  
James Ehramjian ◽  
Richard McKenzie ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Near Infrared ◽  
Monitoring Network ◽  
Photochemical Reactions ◽  
Atmospheric Conditions ◽  
Spectral Measurements ◽  
Visible Radiation ◽  
Wide Range ◽  
New Instrument

Abstract The investigation of the effect of solar ultraviolet (UV) and visible radiation on biological organisms and photochemical reactions requires spectral measurements of the desired radiation parameters of high accuracy. The Network for the Detection of Stratospheric Change (NDSC) and the World Meteorological Organization have set up stringent requirements for high-quality spectral measurements of ultraviolet radiation. It is shown that two new instruments comply with these standards. One is the newly developed spectroradiometer of the Institute of Meteorology and Climatology, University of Hannover, Hannover, Germany. It is capable of covering the spectral range from the UV to the near-infrared (290–1050 nm) in a comparably fine resolution. One major aim is to deploy this instrument as a traveling NDSC spectroradiometer. The other new instrument is built for the U.S. National Science Foundation's UV Monitoring Network. It is designed to monitor UV and visible irradiance at high latitudes and covers a wavelength range from 280 to 600 nm. Data of both instruments show deviations of less than 5% for a wide range of atmospheric conditions compared to a NDSC spectroradiometer owned by the Climate Monitoring and Diagnostics Laboratory during the fifth North American Interagency Intercomparison for UV Spectroradiometers. Such deviations represent state-of-the-art instrumentation for conducting long-term measurements of solar UV radiation capable of detecting trends and supporting long-term measurements by traveling standards. Furthermore, there is now an instrument capable of measuring solar irradiance in a wavelength range from 250 to 1050 nm.

The impacts of long-term, high intensity N addition on the chemical composition of soil organic matter in a boreal forest

2020 ◽  
Author(s):  
Shun Hasegawa ◽  
John Marshall ◽  
Torgny Näsholm ◽  
Mark Bonner
Keyword(s):  
Chemical Composition ◽  
Boreal Forests ◽  
Terrestrial Ecosystems ◽  
Molecular Characteristics ◽  
Organic Layer ◽  
Resonance Spectroscopy ◽  
N Addition ◽  
Vegetation Types ◽  
Pyrolysis Gas

<p>The intense use of fertilisers for agricultural and forest management purposes as well as atmospheric nitrogen (N) deposition has changed ecosystem stoichiometry in some parts of the planet, drawing great attention to the long-term impacts of N additions on carbon (C) sequestration. Soil organic matters (SOMs) are the major sink of C in terrestrial ecosystems and hence it is essential to understand the impacts of N addition on SOM not only quantitatively but also qualitatively. In temperate and boreal forests, chronic N addition generally suppresses SOM decomposition and increases C accumulation. The potential mechanisms for this have long been discussed and yet to be unearthed.</p><p>Here, we examined the impacts of long-term N addition on the chemical composition of SOMs in boreal forests situated in northern Sweden under two vegetation types (Norway spruce or Scots pine) and a range of N addition regimes where N addition rates varied between 3 and 70 kg N ha<sup>-1</sup> year<sup>-1</sup>, duration between 12 and 32 years and total added amount between 50 and 2000 kg N ha<sup>-1</sup>. Soil samples were collected from the organic layer (litter and humus layers) and analysed for the chemical composition of SOMs using two metrics: pyrolysis gas chromatography–mass spectrometry (GC/MS) and solid-state <sup>13</sup>C nuclear magnetic resonance spectroscopy (<sup>13</sup>C-NMR).</p><p>We found that the chemical composition of SOMs shifted with soil C:N ratios regardless of vegetation types, or duration and rates of N addition. Preliminary results suggest that the observed shift in chemical composition in SOMs may have been attributed to altered decomposition of lignin and carbohydrate-derived compounds. This was in line with previous research conducted in the same study sites that demonstrated added-N enhanced non-enzymatic brown-rot lignin oxidation relative to enzymatic white-lot lignin mineralisation.<span> </span>Here, the comprehensive examination of SOM chemical composition demonstrates altered molecular characteristics of SOMs with soil C:N conditions. This may help us to elucidate the mechanisms by which N addition alters the balance of decomposition and accumulation of SOMs.</p>

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

Modern prevention and active longevity programs on the basis of disruptive domestic technologies: positive experience and prospects for application

2020 ◽  
pp. 66-73
Author(s):  
A. Simonova ◽  
S. Chudakov ◽  
R. Gorenkov ◽  
V. Egorov ◽  
A. Gostry ◽  
...  
Keyword(s):  
Personalized Medicine ◽  
Early Detection ◽  
Laboratory Diagnostics ◽  
Positive Experience ◽  
Practical Application ◽  
Wide Range ◽  
Integrated Program ◽  
Long Term Experience ◽  
Early Detection And Prevention

The article summarizes the long-term experience of practical application of domestic breakthrough technologies of preventive personalized medicine for laboratory diagnostics of a wide range of socially significant non-infectious diseases. Conceptual approaches to the formation of an integrated program for early detection and prevention of civilization diseases based on these technologies are given. A vision of the prospects for the development of this area in domestic and foreign medicine has been formed.

To the 70th anniversary of World Meteorological Organization. Scientific and technical cooperation of Hydrometeorological Center of the USSR/Russia in the Programs of World Meteorological Organization

2020 ◽  
pp. 117-138
Author(s):  
S.V. Borshch ◽  
◽  
R.M. Vil’fand ◽  
D.B. Kiktev ◽  
V.M. Khan ◽  
...  
Keyword(s):  
Environmental Monitoring ◽  
High Efficiency ◽  
World Meteorological Organization ◽  
70Th Anniversary ◽  
Technical Level ◽  
Technical Cooperation ◽  
Wide Range

The paper presents the summary and results of long-term and multi-faceted experience of international scientific and technical cooperation of Hydrometeorological Center of Russia in the field of hydrometeorology and environmental monitoring within the framework of WMO programs, which indicates its high efficiency in performing a wide range of works at a high scientific and technical level. Keywords: World Meteorological Organization, major WMO programs, representatives of Hydrometeorological Center of Russia in WMO

Research on the Economic Organization Environmental Impact

2017 ◽  
Vol 68 (3) ◽  
pp. 599-601
Author(s):  
Dan Paul Stefanescu ◽  
Oana Roxana Chivu ◽  
Claudiu Babis ◽  
Augustin Semenescu ◽  
Alina Gligor
Keyword(s):  
Economic Activity ◽  
Economic Organization ◽  
Economic Activities ◽  
Environmental Implications ◽  
Minimal Impact ◽  
Wide Range ◽  
Material Environment ◽  
Negative Effect ◽  
Harmful Effects

Any economic activity carried out by an organization, can generate a wide range of environmental implications. Particularly important, must be considered the activities that have a significant negative effect on the environment, meaning those which pollute. Being known the harmful effects of pollution on the human health, the paper presents two models of utmost importance, one of the material environment-economy interactions balance and the other of the material flows between environmental factors and socio-economic activities. The study of these models enable specific conditions that must be satisfied for the economic processes friendly coexist to the environment for long term, meaning to have a minimal impact in that the residues resulting from the economic activity of the organization to be as less harmful to the environment.

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