Marine zooplanktonic and benthic community respiration rates at Resolute, Canadian high Arctic

1997 ◽  
Vol 54 (5) ◽  
pp. 995-1005 ◽  
Author(s):  
H E Welch ◽  
T D Siferd ◽  
P Bruecker
Keyword(s):  
Benthic Community ◽  
Ecosystem Respiration ◽  
Seasonal Pattern ◽  
Late Summer ◽  
Dry Weight ◽  
High Arctic ◽  
Early Summer ◽  
Community Respiration ◽  
Respiration Rates ◽  
Total Ecosystem Respiration

Benthic community respiration rates and macrozooplankton (>202 µm) biomass and respiration rates were measured throughout a calender year at Resolute (74°42 prime N, 94°50 prime W). The plankton averaged 7.2 g dry weight · m-2 with no seasonal pattern and respired 82 g O2 · m-2 · yr-1. Gelatinous and chaetognath predators made up 10% of macrozooplankton biomass and respired 6.4% of planktonic respiration. The lipid content of the nongelatinous fraction fluctuated seasonaly from 64% of dry weight in midwinter to 46% in early summer. The benthic soft-bottom community inside Resolute Bay respired about 125 g O2 · m-2 · yr-1, with a twofold rate increase in late summer. Offshore on hard bottom the few measurements we obtained suggested a respiration rate of about 75 g O2 · m-2 · yr-1. The macrozooplankton and benthos were therefore approximately equal in energy flow. The total ecosystem respiration of 157 g O2 · m-2 · yr-1 corroborated a previous independent estimate of photosynthesis of 60 g C · m-2 · yr-1 for the region. Microplankton respiration appeared to be relatively low. Our results are consistent with the hypothesis that the proporion of primary production exported to the benthos increases with decreasing water temperature and depth, increasing latitude, and increasing cell size.

scholarly journals Soil CO<sub>2</sub> efflux of a larch forest in northern Japan

2010 ◽  
Vol 7 (11) ◽  
pp. 3447-3457 ◽  
Author(s):  
N. Liang ◽  
T. Hirano ◽  
Z.-M. Zheng ◽  
J. Tang ◽  
Y. Fujinuma
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Ecosystem Respiration ◽  
Late Summer ◽  
Early Summer ◽  
Larch Forest ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Soil C ◽  
Northern Japan

Abstract. We had continuously measured soil CO2 efflux (Rs) in a larch forest in northern Japan at hourly intervals for the snow-free period in 2003 with an automated chamber system and partitioned Rs into heterotrophic respiration (Rh) and autotrophic respiration (Rr) by using the trench method. In addition, we applied the soil CO2 concentration gradients method to continuously measure soil CO2 profiles under snowpack in the snowy period and to partition Rs into topsoil (Oa and A horizons) CO2 efflux (Ft) with a depth of 0.13 m and sub-soil (C horizon) CO2 efflux (Fc). We found that soil CO2 effluxes were strongly affected by the seasonal variation of soil temperature but weakly correlated with soil moisture, probably because the volumetric soil moisture (30–40% at 95% confidence interval) was within a plateau region for root and microbial activities. The soil CO2 effluxes changed seasonally in parallel with soil temperature in topsoil with the peak in late summer. On the other hand, the contribution of Rr to Rs was the largest at about 50% in early summer, when canopy photosynthesis and plant growth were more active. The temperature sensitivity (Q10) of Rr peaked in June. Under snowpack, Rs was stable until mid-March and then gradually increased with snow melting. Rs summed up to 79 gC m−2 during the snowy season for 4 months. The annual Rs was determined at 934 gC m−2 y−1 in 2003, which accounted for 63% of ecosystem respiration. The annual contributions of Rh and Rs to Rs were 57% and 43%, respectively. Based on the gradient approach, Rs was partitioned vertically into litter (Oi and Oe horizons) with a depth of 0.01–0.02 m, topsoil and sub-soil respirations with proportions of 6, 72 and 22%, respectively, on an annual basis. The vertical distribution of CO2 efflux was consistent with those of soil carbon and root biomass.

Seasonal changes in leaf and stem loline alkaloids in meadow fescue

2011 ◽  
Vol 62 (3) ◽  
pp. 261 ◽  
Author(s):  
Brian Patchett ◽  
Ravi Gooneratne ◽  
Lester Fletcher ◽  
Bruce Chapman
Keyword(s):  
Seasonal Changes ◽  
Seasonal Pattern ◽  
Late Summer ◽  
Early Spring ◽  
Early Summer ◽  
Sharp Decline ◽  
Meadow Fescue ◽  
Accumulation Pattern ◽  
Loline Alkaloids

Leaf and stem loline alkaloid concentration in 10 European meadow fescue (Festuca pratensis Huds.) lines grown in a field in Canterbury, New Zealand, were determined in samples collected six times between early spring 2004 and late autumn 2005. Significant differences in loline alkaloid concentrations were noted between lines and between harvest times. Higher total loline alkaloid concentrations (up to 4990 µg g–1) were found in stems compared to leaf (up to 1770 µg g–1). However, the seasonal accumulation pattern of different loline alkaloid concentrations in leaf and stem varied. In most lines, stem loline concentration peaked sharply in late spring and declined during early summer and autumn. The seasonal pattern of leaf loline alkaloid concentration followed the stem concentration except for a sharp decline in early summer followed by an increase in late summer. In most instances, the concentration of N-formyl loline was the highest > N-acetyl loline > N-acetyl norloline > N-methyl loline. The possible role of stem and leaf loline alkaloids to deter pasture-feeding insects is briefly discussed.

The rice rat Oryzomys palustris in a Delaware salt marsh: annual reproductive cycle

1993 ◽  
Vol 71 (7) ◽  
pp. 1457-1460 ◽  
Author(s):  
Kent E. Edmonds ◽  
Milton H. Stetson
Keyword(s):  
Salt Marsh ◽  
Breeding Season ◽  
Seasonal Pattern ◽  
Late Summer ◽  
Early Summer ◽  
Late Winter ◽  
Annual Reproductive Cycle ◽  
Monthly Basis ◽  
Lactating Females ◽  
Oryzomys Palustris

A population of the rice rat Oryzomys palustris inhabiting the Canary Creek salt marsh in Lewes, Delaware, was sampled on a monthly basis from September 1988 to December 1990. Males were assigned to the following age-classes on the basis of body mass: juveniles, 0 – 30 g; subadults, 31 – 50 g; adults, 51 g or greater. Testicular mass exhibited a seasonal pattern with lowest adult values in late autumn and early winter and peak values in late spring and early summer. Females showed similar patterns in uterine mass and vaginal patency. Pregnant and (or) lactating females were found from March to late September. The data suggest that the breeding season of the rice rat in southern Delaware begins in late winter and extends into late summer. Favorable environmental conditions may extend the breeding season for some individuals into autumn.

Seasonal dynamics of nutrients in a Carex meadow

1982 ◽  
Vol 60 (9) ◽  
pp. 1671-1678 ◽  
Author(s):  
Allan N. D. Auclair
Keyword(s):  
Aboveground Biomass ◽  
Seasonal Dynamics ◽  
Seasonal Changes ◽  
Late Summer ◽  
Dry Weight ◽  
Early Summer ◽  
Nutrient Accumulation ◽  
Maximum Accumulation ◽  
Mobility Of Elements ◽  
Uptake And Release

Nutrient accumulation in aboveground biomass and mobilization of nutrients in litter were studied on a Carex meadow in southern Quebec, Canada. Seasonal changes were characterized by short periods of rapid element uptake and release. By late May the total element levels were 80% of maximum. Accumulation of N, P, and K was rapid relative to early increments in biomass. Ca, Mg, and micronutrients were taken up from the soil solution across the season and levels paralleled changes in biomass. In early summer elements were released from litter more rapidly than litter dry weight declined. Mobility of elements decreased in the order K > Mg > P > N > Ca. Overwinter, 83% of K was released, whereas Ca concentration in litter increased overwinter and through the following summer. Immobilization of Fe in litter was pronounced. Overall, > 90% of the element mass in green late-summer shoots was retained in litter overwinter.

Growth of heath vegetation. II. The seasonal growth of a heath on ground-water Podzol at Wilson's Promontory, Victoria

1965 ◽  
Vol 13 (2) ◽  
pp. 281 ◽  
Author(s):  
RH Groves
Keyword(s):  
Soil Moisture ◽  
Ground Water ◽  
Shoot Growth ◽  
Late Summer ◽  
Dry Weight ◽  
Early Summer ◽  
Second Phase ◽  
Root Weight ◽  
Seasonal Growth ◽  
Third Phase

The seasonal growth of a heath on a ground-water podzol in southern Victoria is presented. Seasonal changes in the dry weight of standing vegetation, dry weight of surface roots, and soil moisture were followed. Three phases of growth are obvious. The first phase, shoot growth in late spring-early summer, may be the result of a redistribution of metabolites. During the second phase, a significant increase in the dry weight of tops may occur; this presumably leads to an increase in evapotranspiration and a decrease in soil moisture. Death of some roots then occurs, followed by abscission of older leaves and death of weaker plants. Any increase in the biomass of tops is thus cancelled in this heath ecosystem. With reduction in leaf area, evapotranspiration decreases and soil moisture increases. In this third phase in late summer, the root weight increases to approximately that of the previous winter. Thus the ecosystem maintains a fluctuating equilibrium in root-top biomass from year to year.

Influence of physiological phenology on the seasonal pattern of ecosystem respiration in deciduous forests

2014 ◽  
Vol 21 (1) ◽  
pp. 363-376 ◽  
Author(s):  
Mirco Migliavacca ◽  
Markus Reichstein ◽  
Andrew D. Richardson ◽  
Miguel D. Mahecha ◽  
Edoardo Cremonese ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Seasonal Pattern ◽  
Deciduous Forests

Effects of Dried Distillers’ Grains Cube Supplementation for Steers Grazing Introduced Pastures on Animal Performance and Forage Production

2021 ◽  
Vol 99 (Supplement_2) ◽  
pp. 12-13
Author(s):  
Jordan Adams ◽  
Rodney Farris ◽  
Scott Clawson ◽  
Earl Ward ◽  
Paul Beck
Keyword(s):  
Festuca Arundinacea ◽  
Statistical Power ◽  
Cynodon Dactylon ◽  
Animal Health ◽  
Late Summer ◽  
Early Summer ◽  
Distillers Grains ◽  
Forage Production ◽  
Trenbolone Acetate ◽  
Dried Distillers Grains

Abstract We evaluated the effects of supplementing dried distillers’ grains cubes (DDGS) and re-implantation of steers (n = 149; BW = 238 ± 13.8 kg) grazing tall fescue (Festuca arundinacea)/bermudagrass (Cynodon dactylon) pastures (n = 9 pastures, 7.2 ± 2.90 ha) from 14 April to 17 September 2020 (n = 155 d) in a split-plot design on steer performance and forage production. Main plot supplemental treatments (n = 3 pastures/treatment) included 1) Fertilized Control (FC), no supplementation on fertilized pastures (112 kg N/ha); 2) Fertilized Supplement (FS), supplemental DDGS fed at 2.9 kg 3-d/wk on fertilized pastures; and 3) Supplement (S), supplemented DDGS at 0.75% BW/d on unfertilized pastures prorated for 5-d/wk feeding. Steers were previously implanted during receiving with 40 mg trenbolone acetate and 8 mg estradiol (REV-G; Revalor G, Merck Animal Health). On July 7, steers in each pasture were randomly assigned to one of three re-implant treatments: 1) no re-implant; 2) REV-G; or 3) 200 mg progesterone and 20 mg estradiol (Synovex S, Zoetis Animal Health). Steers in FS and S gained more (P &lt; 0.01) than FC throughout the trial and final BW was greater (P &lt; 0.01) for FS and S compared with FC. Unexpectedly, re-implanting had no effect on ADG (P = 0.57) or BW (P = 0.34), but statistical power may be lacking. Supplemental efficiency was greater in the late summer for FS (P = 0.05) compared to S. Fertilizing pastures in FS and FC did not affect biomass (P = 0.39), however, CP was increased (P = 0.01) and acid and neutral detergent fibers tended to decrease (P = 0.06) relative to S in the early summer (April, May, June, and July), but did not differ in late summer (August and September). Based upon our analysis, DDGS is a suitable supplement and can replace N fertilizer for steers grazing introduced pastures.

scholarly journals 179 Using a 100% Dried Distillers Grains Cube as a Supplement for Steers Grazing Mixed Grass Prairie in Oklahoma

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 46-46
Author(s):  
Zane N Grigsby ◽  
Paul A Beck ◽  
Stacey A Gunter
Keyword(s):  
Animal Health ◽  
Late Summer ◽  
Estradiol Benzoate ◽  
Positive Control ◽  
Negative Control ◽  
Early Summer ◽  
Trenbolone Acetate ◽  
Mixed Grass Prairie ◽  
Mixed Grass ◽  
Main Plot

Abstract This research was conducted to determine effects of supplementation and implanting on BW gain by steers grazing mixed grass prairie (n = 12 pastures, 19.9 ± 0.7 ha) in northwest Oklahoma. Three main plot treatments were: 1) Negative Control (NC), no supplementation, 2) Positive Control (PC), supplemented with DDGS cubes, 1.8 kg/steer on alternate days in late summer, 3) High Supplement (HS), 1/3 increase in stocking rate with 0.75% BW supplemental DDGS cubes all season. Steers (n = 125, BW = 223.1 ± 23.2 kg) were stocked at 2.2 ha/steer for PC and NC, 1.3 ha/steer for HS. Grazing was from May 17 – September 27 (132 d). All steers were implanted with 200 mg progesterone and 20 mg estradiol benzoate (SYN, Synonvex S, Zoetis Animal Health) on May 17. On July 18 three reimplant treatments were applied: 1) no reimplant; 2) SYN; or 3) 40 mg trenbolone acetate and 8 mg estradiol (Revalor G, Merck Animal Health). Data were analyzed using the PROC MIXED in SAS as a split-plot experimental design. In early summer HS had 0.26 kg greater (P &lt; 0.01) ADG than NC and PC. Late summer gains of PC were 0.33 kg/d more (P ≤ 0.01) than NC; and HS gained 0.49 and 0.16 kg/day more (P ≤ 0.04) than NC and PC, respectively. Gain per hectare for PC (46 kg/ha) were greater (P &lt; 0.01) than NC (35 kg/ha) and more than doubled (P &lt; 0.01) with HS (89 kg/ha). Reimplanting had no effect on ADG (P ≥ 0.28). Late season supplementation with PC resulted in supplemental efficiency of 2.7 kg supplement/kg added gain compared with NC. Increased stocking rates with season long supplementation in HS resulted in supplemental efficiency of 3.8 kg supplement/kg added gain per hectare. Based on these data, a 100% DDGS cube is an effective supplement option to increase BW gain during the late summer or increase carrying capacity and gain during the summer grazing period in northwestern Oklahoma.

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