Fluxes of CH4, N2O, and kinetics of denitrification in disturbed and undisturbed forest soil in India

2014 ◽  
Vol 94 (2) ◽  
pp. 237-249 ◽  
Author(s):  
Nani Raut ◽  
Bishal K. Sitaula ◽  
Lars R. Bakken ◽  
Peter Dörsch
Keyword(s):  
Forest Soil ◽  
Soil Disturbance ◽  
Ecosystem Functions ◽  
Closed Chamber ◽  
Four Seasons ◽  
Undisturbed Forest ◽  
Net Flux ◽  
Disturbed Forest ◽  
One Year ◽  
Kinetics Of

Raut, N., Sitaula, B. K., Bakken, L. R. and Dörsch, P. 2014. Fluxes of CH4, N2O, and kinetics of denitrification in disturbed and undisturbed forest soil in India. Can. J. Soil Sci. 94: 237–249. Soil disturbance due to grazing has been severe in Indian forests. This may alter ecosystem functions such as the cycling of nitrogen, and may hence affect the emission of greenhouse gases. We measured fluxes of CH4 and N2O with a closed chamber technique throughout one year in a forest of Western Ghats, Karnataka state, southwest India and determined the product stoichiometry of denitrification under standard anoxic incubations in soil samples from disturbed and undisturbed forest. In both areas, there was a net flux of CH4 from the atmosphere to the soil, and the undisturbed forest soil was a stronger sink for CH4 than the disturbed (P<0.05). The accumulated CH4 uptake averaged for all four seasons was 1.5 times higher in undisturbed than disturbed forest. Contrary to our expectation, the N2O emission was significantly higher for undisturbed than for disturbed forest (P<0.05). The accumulated N2O emission averaged for all four seasons was 1.6 times higher in undisturbed than disturbed forest. Together our data suggest that increase of N2O release and decrease in CH4 sink in soil induced by grazing disturbance can affect the global warming potential (GWP) of forest in this region. The incubation study showed a strong correlation between oxic respiration rate (R) and subsequent denitrification rate (D) and the ratio D/R was 1:3 and 1:6 for soil from undisturbed and disturbed soils, respectively. The N2O/(N2+N2O) product ratio of denitrification tended to be higher in undisturbed than disturbed site, despite lower soil pH.

scholarly journals The use of disturbed and undisturbed forest by masked titi monkeys Callicebus personatus melanochir is proportional to food availability

Oryx ◽  
2002 ◽  
Vol 36 (2) ◽  
pp. 133-139 ◽  
Author(s):  
Stefanie Heiduck
Keyword(s):  
Home Range ◽  
Atlantic Rainforest ◽  
Forest Types ◽  
Clear Cut ◽  
Titi Monkey ◽  
Eastern Brazil ◽  
Titi Monkeys ◽  
Undisturbed Forest ◽  
Disturbed Forest ◽  
One Year

The masked titi Callicebus personatus melanochir is a threatened primate, endemic to the Atlantic rainforest of eastern Brazil. The Atlantic rainforest has been reduced to only 5% of its former extent, and only 2% consists of undisturbed forest. The survival of the masked titi monkey is therefore dependent on its ability to utilise disturbed forest habitat. A group of four masked titi monkeys was observed for one year in a plot that contained both disturbed and undisturbed forest. The group used a home range of 22 ha, which comprised 58% undisturbed forest, 31% selectively logged forest and 11% forest that was regrowing after a clear-cut. The titi monkeys did not use the different forest types in proportion to the availability of each within their home range: undisturbed forest was used more than expected from its proportional availability, and disturbed forest was used less than expected. Use of forest types appeared to be determined by the availability of food resources. Undisturbed forest had the most food per unit area and regrowing forest had the least. This study shows that masked titi monkeys may be able to survive in disturbed forest habitats if these areas are of high enough quality to contain sufficient food and other resources.

scholarly journals Declining Levels of Neutralizing Antibodies Against SARS-CoV-2 in Convalescent COVID-19 Patients One Year Post Symptom Onset

2021 ◽  
Vol 12 ◽  
Author(s):  
Tiandan Xiang ◽  
Boyun Liang ◽  
Yaohui Fang ◽  
Sihong Lu ◽  
Sumeng Li ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Protein S ◽  
Igg Antibodies ◽  
Neutralizing Activity ◽  
Specific Igg ◽  
One Year ◽  
Kinetics Of

Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies recognizing the nucleocapsid (N) protein or the receptor binding domain (RBD) of the spike protein (S). After one year, approximately 90% of recovered patients still had detectable SARS-CoV-2-specific IgG antibodies recognizing N and RBD-S. Intriguingly, neutralizing activity was only detectable in ~43% of patients. When neutralization tests against the E484K-mutated variant of concern (VOC) B.1.351 (initially identified in South Africa) were performed among patients who neutralize the original virus, the capacity to neutralize was even further diminished to 22.6% of donors. Despite declining N- and S-specific IgG titers, a considerable fraction of recovered patients had detectable neutralizing activity one year after infection. However, neutralizing capacities, in particular against an E484K-mutated VOC were only detectable in a minority of patients one year after symptomatic COVID-19. Our findings shed light on the kinetics of long-term immune responses after natural SARS-CoV-2 infection and argue for vaccinations of individuals who experienced a natural infection to protect against emerging VOC.

scholarly journals Vegetation responses to season of fire in an aseasonal, fire-prone fynbos shrubland

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3591 ◽  
Author(s):  
Tineke Kraaij ◽  
Richard M. Cowling ◽  
Brian W. van Wilgen ◽  
Diba R. Rikhotso ◽  
Mark Difford
Keyword(s):  
Floristic Composition ◽  
Fire Season ◽  
Summer Drought ◽  
Winter Rainfall ◽  
Recruitment Success ◽  
Floral Diversity ◽  
Four Seasons ◽  
Different Seasons ◽  
Varied Response ◽  
One Year

Season of fire has marked effects on floristic composition in fire-prone Mediterranean-climate shrublands. In these winter-rainfall systems, summer-autumn fires lead to optimal recruitment of overstorey proteoid shrubs (non-sprouting, slow-maturing, serotinous Proteaceae) which are important to the conservation of floral diversity. We explored whether fire season has similar effects on early establishment of five proteoid species in the eastern coastal part of the Cape Floral Kingdom (South Africa) where rainfall occurs year-round and where weather conducive to fire and the actual incidence of fire are largely aseasonal. We surveyed recruitment success (ratio of post-fire recruits to pre-fire parents) of proteoids after fires in different seasons. We also planted proteoid seeds into exclosures, designed to prevent predation by small mammals and birds, in cleared (intended to simulate fire) fynbos shrublands at different sites in each of four seasons and monitored their germination and survival to one year post-planting (hereafter termed ‘recruitment’). Factors (in decreasing order of importance) affecting recruitment success in the post-fire surveys were species, pre-fire parent density, post-fire age of the vegetation at the time of assessment, and fire season, whereas rainfall (for six months post-fire) and fire return interval (>7 years) had little effect. In the seed-planting experiment, germination occurred during the cooler months and mostly within two months of planting, except for summer-plantings, which took 2–3 months longer to germinate. Although recruitment success differed significantly among planting seasons, sites and species, significant interactions occurred among the experimental factors. In both the post-fire surveys and seed planting experiment, recruitment success in relation to fire- or planting season varied greatly within and among species and sites. Results of these two datasets were furthermore inconsistent, suggesting that proteoid recruitment responses are not related to the season of fire. Germination appeared less rainfall-dependent than in winter-rainfall shrublands, suggesting that summer drought-avoiding dormancy is limited and has less influence on variation in recruitment success among fire seasons. The varied response of proteoid recruitment to fire season (or its simulation) implies that burning does not have to be restricted to particular seasons in eastern coastal fynbos, affording more flexibility for fire management than in shrublands associated with winter rainfall.

Kinetics of NO2 air space absorption in isolated rat lungs

1992 ◽  
Vol 73 (5) ◽  
pp. 1939-1945 ◽  
Author(s):  
E. M. Postlethwait ◽  
S. D. Langford ◽  
A. Bidani
Keyword(s):  
Steady State ◽  
Tidal Volume ◽  
Gas Phase ◽  
Initial Rate ◽  
Quasi Steady State ◽  
Closed Chamber ◽  
First Order ◽  
First Order Kinetics ◽  
Rat Lungs ◽  
Kinetics Of

We previously showed, during quasi-steady-state exposures, that the rate of inhaled NO2 uptake displays reaction-mediated characteristics (J. Appl. Physiol. 68: 594–603, 1990). In vitro kinetic studies of pulmonary epithelial lining fluid (ELF) demonstrated that NO2 interfacial transfer into ELF exhibits first-order kinetics with respect to NO2, attains [NO2]-dependent rate saturation, and is aqueous substrate dependent (J. Appl. Physiol. 71: 1502–1510, 1991). We have extended these observations by evaluating the kinetics of NO2 gas phase disappearance in isolated ventilating rat lungs. Transient exposures (2–3/lung at 25 degrees C) employed rebreathing (NO2-air) from a non-compliant continuously stirred closed chamber. We observed that 1) NO2 uptake rate is independent of exposure period, 2) NO2 gas phase disappearance exhibited first-order kinetics [initial rate (r*) saturation occurred when [NO2] > 11 ppm], 3) the mean effective rate constant (k*) for NO2 gas phase disappearance ([NO2] < or = 11 ppm, tidal volume = 2.3 ml, functional residual capacity = 4 ml, ventilation frequency = 50/min) was 83 +/- 5 ml/min, 4) with [NO2] < or = 11 ppm, k* and r* were proportional to tidal volume, and 5) NO2 fractional uptakes were constant across [NO2] (< or = 11 ppm) and tidal volumes but exceeded quasi-steady-state observations. Preliminary data indicate that this divergence may be related to the inspired PCO2. These results suggest that NO2 reactive uptake within rebreathing isolated lungs follows first-order kinetics and displays initial rate saturation, similar to isolated ELF.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural Recovery of Compacted Soils in an Upland Hardwood Forest in Indiana

1992 ◽  
Vol 9 (4) ◽  
pp. 138-141 ◽  
Author(s):  
Thomas W. Reisinger ◽  
Phillip E. Pope ◽  
Sheldon C. Hammond
Keyword(s):  
Bulk Density ◽  
Soil Disturbance ◽  
Hardwood Forest ◽  
Silt Loam ◽  
Total Sale ◽  
Compacted Soils ◽  
South Central ◽  
Timber Sales ◽  
Density Values ◽  
Undisturbed Forest

Abstract Recovery of soils compacted from conventional ground-based logging operations was assessed on six upland oak-hickory timber sales in south central Indiana. Two areas were selectively harvested in each of the years 1984, 1986, and 1988. Mean bulk density of undisturbed forest soils ranged from 0.93 to 1.02 mg/m3 for the silt loam soils found on all six study areas. Even though soil disturbance averaged 18% of the total sale area immediately after harvesting, the visible amount of soil disturbance decreased to 2.0 and 2.5% for the areas sampled 2 and 4 years after logging, respectively. Compacted soils on secondary skid trails (i.e., 1.08 mg/m3) recovered to preharvest bulk density in 2 to 4 years, but primary skid trails and landings with higher bulk density values (i.e., 1.19 to 1.28 and 1.35 mg/m3) will require somewhat longer than 4 years to recover. North. J. Appl. For. 9(4):138-141.

Environmental and chemical factors regulating methane oxidation in a New Zealand forest soil

Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 767 ◽  
Author(s):  
Sally J. Price ◽  
Francis M. Kelliher ◽  
Robert R. Sherlock ◽  
Kevin R. Tate ◽  
Leo M. Condron
Keyword(s):  
New Zealand ◽  
Water Content ◽  
Forest Soil ◽  
Oxidation Rate ◽  
Field Capacity ◽  
Soil Disturbance ◽  
Great Sensitivity ◽  
Ch4 Oxidation ◽  
Chemical Factors ◽  
Very High

Tropospheric methane (CH4) is oxidised by soil microbes called methanotrophs. We examined them in soil samples from a pristine Nothofagus forest located in New Zealand. Laboratory incubations indicated the presence of high-affinity methanotrophs that displayed Michaelis–Menton kinetics (Km = 8.4 µL/L where Km is the substrate concentration at half the maximal rate). When the soil was dried from its field capacity water content of 0.34 to 0.16 m3/m3, CH4 oxidation rate increased nearly 7-fold. The methanotrophs were thus metabolically poised for very high activity, but substrate availability was commonly limiting. When water content was held constant, CH4 oxidation rate nearly doubled as temperature increased from 5 to 12°C, a range found in the forest. By contrast, CH4 oxidation rate did not change much from 12 to 30°C, and it was zero at 35°C. When water content and temperature were held constant, the optimal soil pH for CH4 oxidation was 4.4, as found in the forest. Soil disturbance by nitrogen (N) and non-N salt amendment decreased CH4 oxidation rate, but this depended on the amendment species and concentration. The methanotrophs were adapted to native conditions and exhibited a great sensitivity to disturbance.

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