Reproductive size thresholds and seedling survival in Acacia harpophylla (Mimosaceae)

2017 ◽  
Vol 65 (5) ◽  
pp. 438
Author(s):  
John M. Dwyer
Keyword(s):  
Genetic Diversity ◽  
Sexual Reproduction ◽  
Population Genetic ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
New South ◽  
Minimum Size ◽  
First Year ◽  
South Wales ◽  
Size Threshold

Acacia harpophylla F.Muell. ex Benth. (brigalow) forests and woodlands formerly occupied at least 8.7 M ha of Queensland and New South Wales, but less than 10% persists in isolated fragments and linear strips within a matrix of exotic beef pasture and dryland cropping. Given the relatively rapid and widespread clearing of brigalow forests, recent research has focussed on restoration via naturally resprouting vegetation. However, our understanding of A. harpophylla sexual reproduction and seedling recruitment remains poor. This study, undertaken following a widespread masting event in late 2007, aimed to (1) quantify initial densities of A. harpophylla germinants; (2) estimate subsequent seedling survival during the first year; and (3) determine minimum size thresholds for sexual reproduction in A. harpophylla. Initial densities averaged >46 000 seedlings ha–1, but only 438 seedlings ha–1 (<1%) were estimated to remain after a year. Although mortality was high, seedling recruitment is probably still sufficient to replace senescing stems and augment population genetic diversity to some extent. A reproductive size threshold of 10 cm diameter was identified, providing useful information to predict when naturally resprouting stands will begin to participate in masting events.

Ecology of Nassella neesiana, Chilean needle grass, in pastures on the Northern Tablelands of New South Wales. II. Seedbank dynamics, seed germination, and seedling recruitment

2003 ◽  
Vol 54 (6) ◽  
pp. 621 ◽  
Author(s):  
M. R. Gardener ◽  
R. D. B. Whalley ◽  
B. M. Sindel
Keyword(s):  
Seed Production ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
New South ◽  
Seedling Emergence ◽  
New South Wales ◽  
Separate Experiment ◽  
Bare Ground ◽  
Total Percentage ◽  
South Wales

This is the second in a series of papers investigating the ecology of Nassella neesiana (Trin. & Rupr.) Barkworth (Chilean needle grass) in pastures on the Northern Tablelands of New South Wales. The reasons for its success as a pasture weed are discussed. Nassella neesiana has a large and persistent soil seedbank. After 3 years without seed input, the seedbank declined from 4676 to 1323 seeds/m2. When an exponential decay curve was fitted to the data it was predicted that the seedbank would reach 10 seeds/m2 after 12.4 years. When seed production was large in 1996, 41.6% of seeds produced were incorporated into the seedbank, whereas in 1995 and 1997 the smaller seed production was only sufficient to maintain seedbank numbers. Furthermore, it is likely that the seedbank numbers were underestimated because they did not include basal cleistogenes. In a separate experiment, basal cleistogenes were found to contribute a further 20% to the seedbank.A small proportion of the viable seeds in a natural seedbank emerged from bare ground over 2 years. Seedling survival was high, with 78% of those germinating from bare ground surviving for at least 20 months. Several experiments were designed to investigate the mechanisms of this germination and survival. It appears that the seeds of N. neesiana have an after-ripening requirement of between 3 months and 1 year for maximum germination. Lemma removal from seeds stored for 8 months increased germination from 49 to 82%. The rate of germination and the total percentage of seeds germinating also increased with time of burial in the ground. Of seeds that had been buried for 2 years, 90% germinated after laboratory incubation compared with 48% of seeds stored in the laboratory as controls. Depth of seed burial appears to affect seedling emergence and survival. A smaller number of seedlings emerged from 0–10 mm and they had lower survival than those from seed buried at 10–20 mm.

Variation in vegetation cover and seedling performance of tree species in a forest-savanna ecotone

2019 ◽  
Vol 35 (2) ◽  
pp. 74-82 ◽  
Author(s):  
Hamza Issifu ◽  
George K. D. Ametsitsi ◽  
Lana J. de Vries ◽  
Gloria Djaney Djagbletey ◽  
Stephen Adu-Bredu ◽  
...  
Keyword(s):  
Vegetation Cover ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Tree Cover ◽  
First Year ◽  
Transplant Experiment ◽  
Tree Seedling ◽  
Savanna Woodland ◽  
Specific Effects ◽  
Species Specific

AbstractDifferential tree seedling recruitment across forest-savanna ecotones is poorly understood, but hypothesized to be influenced by vegetation cover and associated factors. In a 3-y-long field transplant experiment in the forest-savanna ecotone of Ghana, we assessed performance and root allocation of 864 seedlings for two forest (Khaya ivorensis and Terminalia superba) and two savanna (Khaya senegalensis and Terminalia macroptera) species in savanna woodland, closed-woodland and forest. Herbaceous vegetation biomass was significantly higher in savanna woodland (1.0 ± 0.4 kg m−2 vs 0.2 ± 0.1 kg m−2 in forest) and hence expected fire intensities, while some soil properties were improved in forest. Regardless, seedling survival declined significantly in the first-year dry-season for all species with huge declines for the forest species (50% vs 6% for Khaya and 16% vs 2% for Terminalia) by year 2. After 3 y, only savanna species survived in savanna woodland. However, best performance for savanna Khaya was in forest, but in savanna woodland for savanna Terminalia which also had the highest biomass fraction (0.8 ± 0.1 g g−1 vs 0.6 ± 0.1 g g−1 and 0.4 ± 0.1 g g−1) and starch concentration (27% ± 10% vs 15% ± 7% and 10% ± 4%) in roots relative to savanna and forest Khaya respectively. Our results demonstrate that tree cover variation has species-specific effects on tree seedling recruitment which is related to root storage functions.

What Trainee Teachers and Teachers Should Know About Aboriginal Children.

1979 ◽  
Vol 7 (5) ◽  
pp. 29-32
Author(s):  
Keyword(s):  
New South ◽  
New South Wales ◽  
Aboriginal Education ◽  
First Year ◽  
First Year Teachers ◽  
Trainee Teachers ◽  
Aboriginal Students ◽  
South Wales ◽  
Aboriginal Children ◽  
Consultative Group

The New South Wales Aboriginal Education Consultative Group feels that more emphasis needs to be placed on the training of teachers in regards to Aboriginal education.Many first year teachers are sent to country areas with a relatively high percentage of Aboriginal students. In the main, these teachers have had little or no contact with Aboriginal children or parents.

Effects of logging and fire on small mammals in Mumbulla State Forest, near Bega, New South Wales

1987 ◽  
Vol 14 (2) ◽  
pp. 163 ◽  
Author(s):  
D. Lunney ◽  
B. Cullis ◽  
P. Eby
Keyword(s):  
Small Mammals ◽  
New South ◽  
New South Wales ◽  
Canopy Cover ◽  
Ground Cover ◽  
First Year ◽  
Severe Effect ◽  
South Wales ◽  
Antechinus Stuartii ◽  
Rattus Fuscipes

This study of the effects of logging on small mammals in Mumbulla State Forest on the south coast of New South Wales included the effects of a fire in November 1980 and a drought throughout the study period from June 1980 to June 1983. Rattus fuscipes was sensitive to change: logging had a significant impact on its numbers, response to ground cover, and recapture rate; fire had a more severe effect, and drought retarded the post-fire recovery of the population. The three species of dasyurid marsupials differed markedly in their response to ground cover, canopy cover, logging and fire. Antechinus stuartii was distributed evenly through all habitats and was not affected by logging, but fire had an immediate and adverse effect which was sustained by the intense drought. A. swainsonii markedly preferred the regenerating forest, and was not seen again after the fire, the failure of the population being attributed to its dependence on dense ground cover. Sminthopsis leucopus was found in low numbers, appeared to prefer forest with sparse ground cover, and showed no immediate response to logging or fire; its disappearance by the third year post-fire suggests that regenerating forest is inimical to the survival of this species. Mus musculus showed no response to logging. In the first year following the fire its numbers were still very low, but in the next year there was a short-lived plague which coincided with the only respite in the 3-year drought and, importantly, occurred in the intensely burnt parts of the forest. The options for managing this forest for the conservation of small mammals include minimising fire, retaining unlogged forest, extending the time over which alternate coupes are logged and minimising disturbance from heavy machinery.

Sydney rock oyster farming in Australia.

2020 ◽  
Author(s):  
John Nell
Keyword(s):  
New South ◽  
Quality Assurance Program ◽  
First Year ◽  
Water Sampling ◽  
Time To Market ◽  
Profit Margins ◽  
Rock Oyster ◽  
South Wales ◽  
Sampling Programme

Abstract The 120-year-old Sydney rock oyster industry in New South Wales (NSW) and southern Queensland is one of the oldest aquaculture industries in Australia. The industry has been forced to adapt to competition from other species, tighter harvesting and oyster storage and handling requirements as well as eroding profit margins. Recent changes in farming practices include the move away from stick culture to single seed culture, as the half-shell market demands a more uniformly shaped oyster. When selective breeding demonstrated that it could reduce time to market (50 g whole weight) by nearly a year out of an industry average of 3.5 years, the industry wanted to try hatchery technology. Although the industry had never used hatchery technology before, it purchased 10 million spat or 8% of its annual spat requirement from hatcheries in 2003-2004, the first year that they were made available to farmers. The industry also embraced the Australian Shellfish Quality Assurance Program, which requires that shellfish harvest areas be classified on the basis of a sanitary survey and the results of an ongoing strategic water-sampling programme. This programme ensures product safety for the consumers and helps to provide the industry with a long-term future.

The individual and health sector costs of asthma: the first year of a longitudinal study in New South Wales

2005 ◽  
Vol 29 (5) ◽  
pp. 429-435 ◽  
Author(s):  
Patricia Kenny ◽  
Emily Lancsar ◽  
Jane Hall ◽  
Madeleine King ◽  
Meredyth Chaplin
Keyword(s):  
Longitudinal Study ◽  
New South ◽  
New South Wales ◽  
Health Sector ◽  
First Year ◽  
South Wales ◽  
The Individual

A Decade of Mark-Recapture of Platypuses on The Duckmaloi River: Any New Insights into Population Dynamics?

1998 ◽  
Vol 20 (2) ◽  
pp. 302
Author(s):  
D. Goldney
Keyword(s):  
Sex Ratio ◽  
New South ◽  
First Year ◽  
Mark Recapture ◽  
South Wales ◽  
Adult Status ◽  
Second Year ◽  
Gill Netting ◽  
Population Numbers

A long-term mark-recapture program has been carried out on the Duckmaloi Weir (near Oberon, New south Wales) and associated river over the period 1986 to the present. The pipehead weir creates a long shallow ·pool&apos; about 2.5 ha in area, ideal for gill-netting platypuses. One hundred and eighty-two (182) individual animals have been captured in excess of 500 times. The majority of animals have been captured in the weir pool. A very dynamic situation exists with new adults and juveniles being captured on a regular basis and conversely captured animals "disappearing" on a regular basis from the system. Some individuals exhibit both transience and site attachment characteristics. However, relatively few animals remain site attached for long periods of time. Sixty nine percent of individuals are captured two or fewer times. Band loss cannot account for this phenomenon. Of the captured animals, 11.3% have been caught more than 5 times. The sex ratio of the population favours females in first capture adults (1:1.72) but males in first capture juveniles (1:0.73). Females are more likely to be recaptured than males. The sex ratio of juveniles varies significantly from year to year. The period between recaptures varies greatly and can be up to 6 years. Four animals have been captured over nine years (3 females/1 male) but no animal has been captured every year of the study. Recruitment has occurred at levels able to maintain the current population numbers. Thirty percent of available adults have been found lactating, including second year females. Seventy one percent of first year capture juveniles and 89.9% of first capture adults "disappear" within two years of first capture. Forty two percent of juvenile animals reach adult status before "disappearing".

Effect of prolonged undernutrition on the recovery and reproductive performance of maiden Merino ewes

1967 ◽  
Vol 7 (24) ◽  
pp. 7 ◽  
Author(s):  
P McInnes ◽  
TJ Grainger ◽  
MD Smith
Keyword(s):  
Body Weight ◽  
Reproductive Performance ◽  
New South ◽  
New South Wales ◽  
The Other ◽  
First Year ◽  
Treatment Groups ◽  
South Wales ◽  
Feeding Trials ◽  
The Mean

Data are presented on the recovery and reproductive performance of 2 1/2-year-old maiden Merino ewes after a prolonged period of undernutrition. The 217 sheep had been hand-fed on a submaintenance ration in pen feeding trials at Glenfield, New South Wales. During the seven months of the trials they had lost 6 kg (28 to 22 kg) body weight. They were transported to Condobolin in south-western New South Wales, divided into two treatment groups and run on good quality pastures. One group was joined immediately (May 1959) and again ten months later, and the other group was mated after six months at Condobolin (in October 1959) and again 12 months later. The ewes recovered rapidly. The mean weight of both groups had reached 30 kg within six weeks and 40 kg within six months. In the first year 73 of the 100 May-mated ewes bore lambs, but only 38 of these lambs were weaned. Ewes bearing lambs had a higher body weight at the start of joining and gained more during joining than the barren ewes. At the other three joinings (October 1959, May 1960, October 1960) lambing percentage was from 86-89 and weaning percentage from 62-69-both normal for the district. The proportion of twin lambs (3-6 per cent) was low. Wool weight in 1959 was not affected by time of mating or by pregnancy.

Sign in / Sign up

Export Citation Format

Share Document