Defoliation and its effects on Enneapogon avenaceus and Cenchrus ciliaris populations during two summer growth periods in central Australian rangelands.

1984 ◽  
Vol 6 (1) ◽  
pp. 17 ◽  
Author(s):  
OJH Bosch ◽  
ML Dudzinski
Keyword(s):  
Growth Period ◽  
Cenchrus Ciliaris ◽  
Seed Head ◽  
Matter Production ◽  
Popu Lations ◽  
Woodland Communities ◽  
Open Woodland ◽  
Summer Growth ◽  
Grazing Pressures

The frequency and intensity of defoliation on Enneapogon avenaceus (oat grass) and Cenchrus ciliaris (buffel grass) populations under various grazing pressures were studied during two summer gowth periods. The effects of defoliation on seed head production and long term productivity were also investigated. The degree to which cattle concentrated on E. avenaceus is directly related to the available E. a~,enacetrs biomass. In contrast, the degree of concentration on C. ciliaris populations is not only a function of the availability of C. ciliaris biomass, but also of the available palatable ephemeral biomass. Highest seed head production for both species came from ungrazed and lightly-defoliated plants. Sufficient seed replenishment for continued persistence of E. avenaceus populations was obtained when more than 60% of the plants in the population were ungrazed or only Lightly-defoliated. In this study continued dry matter production of C. ciliaris populations was not affected by defoliation. Longer term investi- gations are needed to define defoliation thresholds for the management of this species. Perennial C. ciliaris plants in open woodland communities nre important for the persistence of the shortlived E. aal'crracects popu- lations. Cattle concentrated more on C. ciliaris than on E. avenaceus plants during the fu~t two weeks of a growth period, which allowed the latter to grow and even to start producing seed before cattle concentrate on them.

Long-term outcomes after corrective cartilaginous joint resection based on arthrographic findings of duplicated thumbs

2021 ◽  
Vol 46 (4) ◽  
pp. 367-372
Author(s):  
Kousuke Iba ◽  
Akira Saito ◽  
Megumi Hanaka ◽  
Toshihiko Yamashita
Keyword(s):  
Growth Period ◽  
Joint Space ◽  
Type Ii ◽  
Scoring Method ◽  
Joint Congruency ◽  
Thumb Duplication ◽  
Age At Surgery ◽  
Joint Connection

We report greater than 10-year outcomes in duplicated thumbs following corrective cartilaginous resection during the growth period. We have undertaken corrective resection of cartilaginous joint connections based on intraoperative arthrographic findings to reconstruct favourable alignment in six Wassel Type II and IV thumb duplication in six patients. The age at surgery was 13 months (range 10–15), and the average post-surgical follow-up was 134 months (range 120–160). We observed five excellent and one good outcome using the Japanese Society for Surgery of the Hand scoring method. Favourable joint congruency and alignment were preserved, and no growth plate arrest or joint space narrowing was present more than 10 years after surgery. We conclude that corrective resection of the cartilaginous joint based on intraoperative arthrographic findings has long-term reliability for duplicated thumbs, especially those of Wassel Type II and IV, which have a cartilaginous joint connection. Levels of evidence: IV

scholarly journals Residual effects of superficial liming on tropical soil under no-tillage system

2016 ◽  
Vol 51 (9) ◽  
pp. 1633-1642 ◽  
Author(s):  
Claudio Hideo Martins da Costa ◽  
Carlos Alexandre Costa Crusciol ◽  
Jayme Ferrari Neto ◽  
Gustavo Spadotti Amaral Castro
Keyword(s):  
Grain Yield ◽  
Dry Matter ◽  
Block Design ◽  
Residual Effects ◽  
Available Phosphorus ◽  
Long Term Effects ◽  
Matter Production ◽  
Randomized Complete Block Design ◽  
Tillage System

Abstract The objective of this work was to evaluate the long-term effects of the surface application of lime on soil fertility and on the mineral nutrition and grain yield of soybean, and of black oat and sorghum in crop succession. The experiment was carried out on a clayey Oxisol, in a randomized complete block design, with four replicates. Treatments consisted of lime the rates of 0, 1,000, 2,000, and 4,000 kg ha-1, applied in October 2002 and November 2004. Soil samples were collected at five soil layers, down to 0.60-m depth. Surface liming was effective in reducing soil acidity and increasing Ca2+ and Mg2+ contents in the subsurface. Moreover, it increased available phosphorus contents and soil organic matter in the long term (48 to 60 months after the last lime application). Surface liming improved plant nutrition, mainly for N, Ca, and Mg, and increased dry matter production and grain yield of the crops, even in years with regular distribution of rainfall. The greatest productivities of soybean, black oat, and sorghum were obtained with the respective estimated lime doses of 4,000, 2,333, and 3,281 kg ha-1, for shoot dry matter, and of 2,550, 3,555, and over 4,000 kg ha-1, for grain yield.

Summer–winter transitions in Antarctic ponds I: The physical environment

2011 ◽  
Vol 23 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Ian Hawes ◽  
Karl Safi ◽  
Brian Sorrell ◽  
Jenny Webster-Brown ◽  
David Arscott
Keyword(s):  
Physical Environment ◽  
Average Rate ◽  
Growth Period ◽  
Ice Formation ◽  
Freezing Process ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Continental Antarctica ◽  
The Antarctic ◽  
Summer Growth

AbstractMeltwater ponds are one of the most widespread aquatic habitats in ice-free areas of continental Antarctica. While most studies of such systems occur during the Antarctic summer, here we report on ice formation and water column attributes in four meltwater ponds on the McMurdo Ice Shelf during autumn, when they went from ice-free to > 80 cm thickness of ice. Ice thickness grew at an average rate of 1.5 cm d-1 in all ponds and as ice formed, salts and gases were excluded. This resulted in conductivity rising from 3–5 to > 60 mS cm-1 and contributed to the ebullition of gases. Incorporation of gas bubbles in the ice resulted in a high albedo and under-ice irradiance declined faster than incident, the former falling below 1 W m-2 (daily average) by early April. After two months of ice formation, only 0–15% of the volume of each pond was still liquid, although this represented 5–35% of the pond sediment area, where much of the biological activity was concentrated. We suggest that the stresses that the freezing process imposes may be as important to structuring the biotic communities as those during the more benign summer growth period.

SWINE PERFORMANCE ENHANCEMENT WITH COOLING AS INFLUENCED BY SUMMER GROWTH PERIOD AND WEATHER

2013 ◽  
Author(s):  
T. C. Bridges ◽  
L. W. Turner ◽  
R. S. Gates and D. G. Overhults
Keyword(s):  
Performance Enhancement ◽  
Growth Period ◽  
Summer Growth

scholarly journals Nitrate leaching and N2-fixation in grasslands of different composition, age and management

2004 ◽  
Vol 142 (2) ◽  
pp. 141-151 ◽  
Author(s):  
J. ERIKSEN ◽  
F. P. VINTHER ◽  
K. SØEGAARD
Keyword(s):  
Perennial Ryegrass ◽  
Nitrate Leaching ◽  
Dry Matter ◽  
Grazing Intensity ◽  
Dry Matter Production ◽  
Leaching Losses ◽  
N Removal ◽  
Matter Production ◽  
Over Time

Grass-legume associations may offer a way of improving the N efficiency of dairy farming, but may also have an adverse impact on the environment by increasing leaching losses. Nitrate leaching from four cropping sequences with different grassland frequency and management (long-term grazed, long-term cut, cereals followed by 1 and 2-year grazed leys) were investigated on a loamy sand in central Jutland for both unfertilized grass-clover (perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.)) and fertilized perennial ryegrass (300 kg N/ha) swards during 1997–2002. Furthermore, 1 year (2001) of N2 fixation in 1-, 2- and 8-year-old grass-clover pastures was determined. Nitrate leaching from grazed unfertilized grass-clover was always considerably lower than from grazed fertilized ryegrass. The effect of grassland age on nitrate leaching was insignificant in grass-clover but clear in grazed ryegrass, where levels increased dramatically with sward age. In production years 6–8, leaching from grass-clover was only 9–13% of the comparable losses from ryegrass. Under the cutting regime grass-clover showed a significant reduction in both yield and N-removal with increasing sward age, whereas for ryegrass these figures did not show any decreasing trend. N2 fixation was lower in 8-year-old swards compared with fully established 2-year-old swards as a consequence of lower dry matter production, lower clover content and a lower proportion of clover-N derived from the atmosphere. The results from the present study indicate that the higher leaching losses observed in fertilized grass compared with unfertilized grass-clover systems were caused by (1) a reduction in N2-fixation in grass-clover over time and (2) a reduction in dry matter production in grass-clover over time, lowering the grazing intensity and the recycling of grassland N via animal excreta.

scholarly journals Long-term standardized forest phenology in Sweden: a climate change indicator

2019 ◽  
Author(s):  
Ola Langvall ◽  
Mikaell Ottosson Löfvenius
Keyword(s):  
Climate Change ◽  
Quantitative Methods ◽  
Food Resource ◽  
Growth Period ◽  
Phase Changes ◽  
Gradual Change ◽  
Active Growth ◽  
Statistical Precision ◽  
Active Growth Period

Abstract Because climate change alters patterns of vegetative growth, long-term phenological measurements and observations can provide important data for analyzing its impact. Phenological assessments are usually made as records of calendar dates when specific phase changes occur. Such assessments have benefits and are used in Citizen Science monitoring. However, these kinds of data often have low statistical precision when describing gradual changes. Frequent monitoring of the phenological traits of forest trees and berries as they undergo gradual change is needed to acquire good temporal resolution of transitions relative to other factors, such as susceptibility to frosts, insects, and fungi, and the use of berries as a food resource. Intensive weekly monitoring of the growth of apical and branch buds and the elongation of shoots and leaves on four tree species, and the abundance of flowers and berries of bilberry and lingonberry, has been performed in Sweden since 2006. Here, we present quantitative methods for interpolating such data, which detail the gradual changes between assessments in order to describe average rates of development and amount of interannual variation. Our analysis has shown the active growth period of trees to differ with latitude. We also observed a change in the timing of the maximum numbers of ripening berries and their successive decline. Data from tree phenology assessments can be used to recommend best forestry practice and to model tree growth, while berry data can be used to estimate when food resources for animals are most available.

Biomass and nutrient element dynamics in Douglas-fir: effects of thinning and nitrogen fertilization over 18 years

1996 ◽  
Vol 26 (3) ◽  
pp. 376-388 ◽  
Author(s):  
A.K. Mitchell ◽  
H.J. Barclay ◽  
H. Brix ◽  
D.F.W. Pollard ◽  
R. Benton ◽  
...  
Keyword(s):  
Net Primary Production ◽  
N Uptake ◽  
Basal Area ◽  
Stem Bark ◽  
N Fertilization ◽  
Douglas Fir ◽  
Total Biomass ◽  
Matter Production ◽  
Second Period

The effects of thinning (two-thirds of basal area removed) and N fertilization (448 kg N/ha as urea) on biomass and nutrition of a 24-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand at Shawnigan Lake were studied over 18 years. At years 0, 9, and 18 after treatments, the aboveground biomass and N, P, K, Ca, and Mg contents of stemwood, stem bark, foliage, and dead and live branches were determined (kg/ha), and increments in these properties (kg•ha−1•year−1) were calculated for the 0–9 and 9–18 year periods. Foliar biomass was increased by both treatments during the first period and also by thinning in the second period. Aboveground net primary production (ANPP) per unit of foliage biomass (foliage efficiency) was increased by treatments in the 0–9 year period. The combined effects of increased foliage mass and foliage efficiency resulted in increased total biomass production. Thinning and fertilization increased the uptake of all elements except for P with fertilization. This increase may have contributed to the long-term increase in stem growth. Retranslocation of elements before foliage shedding was important for tree nutrition, but was not improved by fertilization during the 9–18 year measurement period. The efficiency of N use in dry matter production (ANPP/unit of N uptake) was decreased by fertilization. This implied that poor sites would respond better to fertilization than rich sites.

Long-term monitoring of climatic and nutritional affects on tree growth in interior Alaska

2010 ◽  
Vol 40 (7) ◽  
pp. 1325-1335 ◽  
Author(s):  
J. Yarie ◽  
K. Van Cleve
Keyword(s):  
Tree Growth ◽  
Black Spruce ◽  
Growth Period ◽  
Early Spring ◽  
Large Set ◽  
Primary Control ◽  
Forest Types ◽  
Interior Alaska ◽  
State Factor

The comparative analysis of a large set of long-term fertilization and thinning studies in the major forest types of interior Alaska is summarized. Results indicate that nutrient limitations may only occur during the early spring growth period, after which moisture availability is the primary control of tree growth on warm sites. The temperature dynamics of both air and soil set seasonal bounds on the nutrient and moisture dynamics for all forest types. Air and soil temperature limitations are the primary control of intraseasonal growth in the colder topographic locations in interior Alaska. These locations are usually dominated by black spruce (Picea mariana (Mill.) Britton, Sterns, Poggenb.) vegetation types. The seasonal progression of factors controlling growth is strongly tied to the state factor structure of the landscape.

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