The dynamics of Trifolium repens in a permanent pasture I. The population dynamics of leaves and nodes per shoot axis

1989 ◽  
Vol 237 (1287) ◽  
pp. 133-173 ◽  
Keyword(s):  
Spatial Variation ◽  
Trifolium Repens ◽  
Death Rate ◽  
Birth Rate ◽  
Soil Surface ◽  
Early Spring ◽  
Late Winter ◽  
Seasonal Fluctuations ◽  
Permanent Pasture ◽  
One Year

The framework is developed for a formal quantitative analysis of the vegetative dynamics of Trifolium repens , based on partitioning the components of its growth. The method is used to describe the vegetative dynamics of T. repens in one pasture during the course of one year. Seasonal and spatial variation were analysed by regression on several environmental variables. The present paper includes only a partial analysis, covering the dynamics of leaves and nodes per shoot axis. The remainder of the analysis will be presented in subsequent papers. The production of modules per shoot axis, and the subsequent mortality of leaves, and burial and mortality of nodes, showed different patterns of spatial and seasonal variability, and different types of response to the environment. There was much seasonal and little spatial variation in rates of birth, burial and death of leaves and nodes. In contrast, there was relatively little seasonal and much spatial variation in the numbers of leaves and nodes, even though these numbers are determined by present and past births and deaths. The rate of production of leaves by individual apices varied from 0.01 per day to 0.19 per day. It appeared to be determined largely by temperature, probably of the apex, but also to some extent by genotype. Leaves survived for 1-21 weeks. The risk of leaf mortality varied with the age of the leaf, the number of sheep in the field, and the season. Leaves born in November tended to live longest, and those born in summer with many sheep shortest. At least 56% of leaves were utilized by sheep, the remainder dying from other causes. Seasonal fluctuations in death rate of leaves tended to lag three weeks behind fluctuations in birth rate, but with additional fluctuations caused by changes in grazing. The lag caused there to be a minimum of 1-5 leaves per axis in January, and a maximum of 3-12 in August, although at all times the number of leaves was increasing on some axes and decreasing on others. Axes were progressively buried by worm casts and leaf litter within 0-39 weeks of birth. The rate of burial appeared to be determined largely by earthworm activity and by treading by sheep. In autumn and early spring, nodes and internodes were buried faster than new ones were born. As a result, as few as three internodes were exposed on average in March, compared with a maximum mean of 20 in August. By late winter, some axes were entirely buried and started to grow vertically upwards towards the soil surface. Nodes survived for 14-85 weeks, the mean longevity being 51 weeks. On average, each axis bore 25 nodes, with a range of 10-49 nodes. Seasonal fluctuations in death rate lagged some 4-8 weeks behind those in birth rate. Survivial of nodes and internodes was dependent on the establishment and survival of roots. When the oldest rooted node on an axis died, all of the axis between it and the next rooted node also died. The development of pseudo-taproots increased the longevity of nodes by 100 days. Leaves had much shorter lives than their nodes. The ‘average’ shoot axis bore 3.5 nodes with leaves, 4.2 nodes still visible but without leaves, and 17.6 nodes buried beneath worm casts and litter.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

scholarly journals Abundance and diversity of soil arthropods and fungi in shelterbelts integrated with pastures in the central tablelands of New South Wales, Australia

2012 ◽  
Vol 58 (No. 12) ◽  
pp. 560-568 ◽  
Author(s):  
E.W. Mbuthia ◽  
J.H. Shariff ◽  
A. Raman ◽  
D.S. Hodgkins ◽  
H.I. Nicol ◽  
...  
Keyword(s):  
Organic Matter ◽  
Biological Diversity ◽  
Soil Depth ◽  
Soil Surface ◽  
Early Spring ◽  
Late Winter ◽  
Soil Arthropods ◽  
South Wales ◽  
Abundance And Diversity ◽  
The Relationship

Shelterbelts are important for the sustainability of agriculture because they provide a variety of benefits to farmers and the society. Several published papers demonstrate that integration of shelterbelts with agroecosystems offers positive outcomes, such as better yield, more congenial microclimate, and greater organic matter levels. Nonetheless, soil biological diversity, the driver of greater organic matter levels, has not been convincingly tested and verified yet. In addressing this gap, we measured abundance and diversity of populations of arthropods and fungi in three<br />11-year old shelterbelts integrated with pasture to determine whether a correlation exists between the abundance of and diversity in populations of arthropods and fungi in two seasons: late autumn-early winter (May&ndash;June 2011) and late winter-early spring (August&ndash;September 2011). Litter from the soil surface and soil from two depths were sampled at increasing distance from the midpoint of shelterbelts for the extraction of arthropods and isolation culturing of fungi. The relationship among distance, depth and biodiversity of different groups of arthropods and fungi was analysed using linear regression. We found that over both seasons arthropod abundance in the litter and soil declined with increasing distance from the midpoint of the shelterbelts, and with soil depth. However, fungi abundance in either season was not affected by proximity to the shelterbelt but increased with greater soil depth. Distance from the shelterbelt midpoints did not bear an impact on the diversity richness of both arthropods and fungi.

scholarly journals Human Sapovirus among Outpatients with Acute Gastroenteritis in Spain: A One-Year Study

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 144 ◽  
Author(s):  
Miguel F Varela ◽  
Enrique Rivadulla ◽  
Alberto Lema ◽  
Jesús L Romalde
Keyword(s):  
Acute Gastroenteritis ◽  
Age Groups ◽  
The Elderly ◽  
Mean Value ◽  
Early Spring ◽  
Clinical Samples ◽  
Late Winter ◽  
Viral Pathogen ◽  
One Year ◽  
Different Strains

Viral agents of human gastroenteritis affect people of all ages across the globe. As a mainly self-limiting disease, it is difficult to evaluate the real prevalence of etiological agents circulating in each region. Many of the analyzed outbreaks are caused by viruses of the family Caliciviridae, especially the genus Norovirus (NoV). Most studies have focused on other enteric viruses, leaving sapovirus (SaV) underestimated as an important emerging human threat. This one-year study analyzed clinical samples from hospital outpatients with acute gastroenteritis in Spain, with the aim of revealing the importance of human SaV as an emerging viral pathogen. A total of 2667 stools were tested using reverse transcription (RT)-qPCR to detect and quantify SaV. Sapovirus was detected in all age groups, especially in infants, children, and the elderly. The prevalence was 15.64% (417/2667), and was slightly higher in 0–2- and 3–5-year-olds (19.53% and 17.95%, respectively) and much lower in 13–18-year-olds (9.86%). Positive samples were detected throughout the year, with peaks of detection during autumn and the late winter to early spring months. The mean value for the quantified samples was 6.5 × 105 genome copies per gram of stool (GC/g) (range 2.4 × 103–6.6 × 1011 GC/g). RT-nested PCR and sequencing were used for further genotyping. Genetic characterization showed a predominance of genogroup I (GI), followed by GII and GIV. The detection of multiple genotypes suggests the circulation of different strains without any clear tendency. The results obtained suggest SaV as the second major gastroenteritis agent after NoV in the region.

scholarly journals Characterising terrestrial influences on Antarctic air masses using Radon-222 measurements at King George Island

2014 ◽  
Vol 14 (18) ◽  
pp. 9903-9916 ◽  
Author(s):  
S. D. Chambers ◽  
S.-B. Hong ◽  
A. G. Williams ◽  
J. Crawford ◽  
A. D. Griffiths ◽  
...  
Keyword(s):  
Late Summer ◽  
Early Spring ◽  
Late Winter ◽  
South American ◽  
King George Island ◽  
Air Masses ◽  
Diurnal Cycles ◽  
Baseline Values ◽  
One Year ◽  
Radon Measurements

Abstract. We report on one year of high-precision direct hourly radon observations at King Sejong Station (King George Island) beginning in February 2013. Findings are compared with historic and ongoing radon measurements from other Antarctic sites. Monthly median concentrations reduced from 72 mBq m−3 in late-summer to 44 mBq m−3 in late winter and early spring. Monthly 10th percentiles, ranging from 29 to 49 mBq m−3, were typical of oceanic baseline values. Diurnal cycles were rarely evident and local influences were minor, consistent with regional radon flux estimates one tenth of the global average for ice-free land. The predominant fetch region for terrestrially influenced air masses was South America (47–53° S), with minor influences also attributed to aged Australian air masses and local sources. Plume dilution factors of 2.8–4.0 were estimated for the most terrestrially influenced (South American) air masses, and a seasonal cycle in terrestrial influence on tropospheric air descending at the pole was identified and characterised.

Dispersal of Juvenile Brushtail Possums, Trichosurus vulpecula, after a Control Operation

1997 ◽  
Vol 24 (3) ◽  
pp. 279 ◽  
Author(s):  
P. E. Cowan ◽  
R. E. Brockie ◽  
R. N. Smith ◽  
M. E. Hearfield
Keyword(s):  
Initial Density ◽  
Early Spring ◽  
Late Winter ◽  
Trichosurus Vulpecula ◽  
Radio Tracking ◽  
Dispersal Behaviour ◽  
Long Distance ◽  
Control Operation ◽  
Preferred Direction ◽  
One Year

Long-distance movements of juvenile brushtail possums (Trichosurus vulpecula) from three habitats on farmland in Hawke’s Bay, New Zealand, were studied by radio-tracking after a poisoning operation. In the five years after the possum population on the study site had been reduced by 90%, the population recovered to about half its initial density. During that time, about 25% of radio-tagged juveniles dispersed 2 km or more, a maximum of 12·8 km from their natal area, with no significantly preferred direction. A greater proportion of males dispersed than females. All but one of the juveniles dispersing did so before they were one year old, and most made several moves before settling. The bimodal timing of dispersal in summer and late winter–early spring reflected an underlying similar pattern of breeding. A higher proportion of possums dispersed from the low-density pastoral and cropping habitat than from the higher-density habitats of swamp and willows. The dispersal behaviour of juveniles after the control operation differed little from that before, suggesting that dispersal of possums is not strongly influenced by density-dependent factors at the natal site.

Cycles of reproduction and condition in Tasmanian blue mussels, Mytilus edulis planulatus

1984 ◽  
Vol 35 (3) ◽  
pp. 307 ◽  
Author(s):  
TG Dix ◽  
A Ferguson
Keyword(s):  
Mytilus Edulis ◽  
Early Spring ◽  
Late Winter ◽  
Reproductive Condition ◽  
Late Autumn ◽  
Blue Mussels ◽  
Early Autumn ◽  
Condition Indices ◽  
One Year ◽  
Autumn And Winter

Major spawning by M. e. planulatus occurred in the late winter or early spring at Hinders Reef, Margate and Birchs Bay in 1980 and 1981. Spawning occurred also over the summer and early autumn although a major spawning was indicated during this period at only one site in one year. At the two sites where temperatures were recorded, the major spring spawning occurred at about or just above 10�C. Gonads built up reproductive condition during late autumn and winter at all sites in 1980 and 1981. Condition indices were highest at these times and fell when spring spawning occurred.

The winter treatment of grapevines with zinc and its interaction with time of pruning

1964 ◽  
Vol 4 (14) ◽  
pp. 241 ◽  
Author(s):  
BG Coombe
Keyword(s):  
Zinc Sulphate ◽  
Field Experiments ◽  
Early Spring ◽  
Late Winter ◽  
Early Winter ◽  
Zinc Treatment ◽  
One Year ◽  
June July

Field experiments on dormant Sultana vines showed that yields were increased by applying zinc sulphate solutions immediately after pruning. Treatment by the swabbing of pruning cuts gave similar results to a cover spray. Increasing the concentration of zinc sulphate (up to the maximum tested-35 per cent) increased yield and no bud injury was seen. A delay of a day or more between pruning and treatment drastically reduced its effectiveness. Shorter intervals were tested but the results fluctuated ; a possible reason for this is discussed. The movement of zinc along Sultana canes was gauged by analysis of sections of cane cut up at varying times after swabbing the pruned end. In one year zinc moved at least 20 inches within two days, whereas, in another, it moved only 10 inches after one month. The yield of Grenache vines was increased when pruning was delayed from early winter until late winter and early spring. Zinc treatment increased yields in vines pruned in June, July, and August, but depressed yields when applied to vines pruned in September.

Long-distance movments of juvenile brushtail possums (Trichosurus vulpecula) on farmland, Hawkes Bay, New Zealand

1996 ◽  
Vol 23 (2) ◽  
pp. 237 ◽  
Author(s):  
PE Cowan ◽  
RE Brockie ◽  
GD Ward ◽  
MG Efford
Keyword(s):  
New Zealand ◽  
Early Spring ◽  
Late Winter ◽  
Trichosurus Vulpecula ◽  
Radio Tracking ◽  
Juvenile Male ◽  
Long Distance ◽  
Male And Female ◽  
The Difference ◽  
One Year

Long-distance movements of juvenile male and female brushtail possums (Trichosurus vulpecula) at a farmland site, Hawke's Bay, New Zealand, were studied by radio-tracking. About 20% of radio-tagged possums dispersed more than 2 km, moving up to 11.5 km from their natal area, most in a north-easterly direction. The proportion of males that dispersed was higher than that of females, but the difference was not statistically significant. All juveniles dispersing did so before they were one year old. The bimodal timing of dispersal in summer and late winter to early spring reflected an underlying similar pattern of breeding. Most possums made several moves before settling. A higher proportion of possums dispersed from the lowdensity area of pastoral and cropping land than from the higher-density areas of swamp and willows. A few dispersal records of ear-tagged animals were also obtained; most records were of males from the area of pastoral and cropping land, and movements ranged from 3 to 25 km.

scholarly journals Monilinia vaccinii-corymbosi Apothecial Development Associated With Mulch Depth and Timing of Application

Plant Disease ◽  
2017 ◽  
Vol 101 (5) ◽  
pp. 807-814
Author(s):  
Jade Florence ◽  
Jay Pscheidt
Keyword(s):  
Soil Surface ◽  
Vaccinium Corymbosum ◽  
Early Spring ◽  
Douglas Fir ◽  
Late Winter ◽  
Bare Ground ◽  
Application Timing ◽  
Ground Treatment ◽  
Treatment Application ◽  
Blueberry Leaves

Pseudosclerotia of Monilinia vaccinii-corymbosi overwinter on the soil surface and develop apothecia in early spring, supplying primary inoculum for mummy berry disease of blueberry. Burial of pseudosclerotia in soil and incubation in the dark have previously been identified as critical factors inhibiting M. vaccinii-corymbosi apothecial development. Mulches of Douglas-fir (Pseudotsuga menziesii) sawdust at 2.5 or 5 cm depths, blueberry leaves (Vaccinium corymbosum cv. Bluetta) at a 2.5 cm depth, and a bare ground (no mulch) control were assessed for an effect on apothecial development in the spring for 2 years. Mulches were applied corresponding to pseudosclerotial overwintering stages. Loss of mulch depth was also assessed throughout the overwintering season. A 5 cm depth of Douglas-fir sawdust was associated with greater apothecial suppression in comparison with bare ground. Douglas-fir sawdust at a 2.5 cm depth varied in effectiveness, while 2.5 cm of blueberry leaves was not more effective at suppressing apothecial development than the bare ground treatment. Application timing did not affect apothecial development, but mulches lost significantly more depth when applied at the beginning of the overwintering season as compared with late winter mulches. Therefore, loss of mulch thickness due to weathering and/or decomposition may also affect apothecial development.

Effects of Drought and Elevated Soil Temperature on Apple Root Lifespan

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 549e-549
Author(s):  
D.M. Eissenstat ◽  
Liqin Wang ◽  
D.E. Flores-Alva
Keyword(s):  
Soil Temperature ◽  
Death Rate ◽  
Birth Rate ◽  
Plant Competition ◽  
Soil Surface ◽  
Hot Water ◽  
Root Dynamics ◽  
Drought Treatment ◽  
Root Mortality ◽  
Root Lifespan

Root lifespan has important consequences for plant growth and productivity, plant competition, and nutrient cycling. However, compared to aboveground parts, much less is know about root systems. Root dynamics of `Red Chief' Delicious on M26 rootstock trained on a trellis were examined near State College, Pa., using minirhizotrons. Soil was heated 5 °C above ambient at a depth of 5 cm by circulating hot water over a stainless steel grid on the soil surface. Soil temperature (by thermocouples) and soil moisture (by TDR) were monitored to a depth of 1 m. Root birth rate peaked between late May and mid-June, during a period of rapid shoot elongation and fruit expansion. Death rate was highest in July. There was no evidence of alternate growth between roots and shoots. Drought and elevated soil temperature increased root mortality. Median lifespan of fine roots near the soil surface (<20 cm) was least in the heated-drought treatment (30 d) and longest in the unheated-irrigated treatment (56 d). Heating caused substantial increases in root birth rate, thus, causing higher populations in the heated than unheated treatments despite the increased root death rate in the heated soil.

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