The role of seedbanks in invasions by Hyparrhenia hirta (L.) Stapf in Australia

2019 ◽  
Vol 41 (5) ◽  
pp. 383 ◽  
Author(s):  
Vinod K. Chejara ◽  
Paul Kristiansen ◽  
R. D. B. (Wal) Whalley ◽  
Brian M. Sindel ◽  
Christopher Nadolny
Keyword(s):  
South African ◽  
Seed Production ◽  
Seed Dormancy ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Perennial Grass ◽  
Seed Banks ◽  
Invasive Weed ◽  
South Wales ◽  
Poor Seed

Hyparrhenia hirta (L.) Stapf (also known as Coolatai grass, South African bluestem or thatching grass) has become a serious invasive weed in Australia. Within its native range, it is generally regarded as a useful grass particularly for thatching, and seed production is low with a low soil seed bank of from 2 to 200seedsm–2. Several hundred accessions of H. hirta were deliberately introduced into Australia up until the 1980s and nearly all were discarded because of poor seed production. However, at least one introduction in the 1890s in northern New South Wales (NSW), Australia, has possibly contributed to the present serious weed problem. Annual seed production from roadside stands in northern NSW ranged from 7000 to 92000seedsm–2 in 2015. The soil seed bank under dense H. hirta infestations in the same region in 2006 and 2007, was found to be ~30000seedsm–2 mostly confined to the top 2cm, with few dormant seeds and a large reduction of these numbers over the next 12 months when further seed input was prevented. Similar studies of other perennial grass weeds have found seed banks of similar sizes, but dormancy mechanisms ensure that their seed banks last for at least 10 years without further seed input. These results suggest that the present weedy populations of H. hirta have dramatically increased fecundity enabling a large seed bank to develop beneath dense stands. The development of seed dormancy and consequently a long-lived seed bank would make this weed even more difficult to control. Until seed dormancy develops, control of H. hirta in northern NSW can be effective provided further input into the seed bank can be prevented.

Seed production and seedling emergence of Giant Parramatta grass on the north coast of New South Wales

1996 ◽  
Vol 36 (3) ◽  
pp. 299 ◽  
Author(s):  
TS Andrews ◽  
RDB Whalley ◽  
CE Jones
Keyword(s):  
Seed Production ◽  
Seed Bank ◽  
New South ◽  
New South Wales ◽  
Seed Banks ◽  
North Coast ◽  
The North ◽  
South Wales ◽  
Seed Fall ◽  
The Impact

Inputs and losses from Giant Parramatta grass [GPG, Sporobolus indicus (L.) R. Br. var. major (Buse) Baaijens] soil seed banks were quantified on the North Coast of New South Wales. Monthly potential seed production and actual seed fall was estimated at Valla during 1991-92. Total potential production was >668 000 seeds/m2 for the season, while seed fall was >146000 seeds/m2. Seed fall >10000 seeds/m2.month was recorded from January until May, with further seed falls recorded in June and July. The impact of seed production on seed banks was assessed by estimating seed banks in the seed production quadrats before and after seed fall. Seed banks in 4 of the 6 sites decreased in year 2, although seed numbers at 1 damp site increased markedly. Defoliation from mid-December until February, April or June prevented seed production, reducing seed banks by 34% over 7 months. Seed banks in undefoliated plots increased by 3300 seeds/m2, although seed fall was estimated at >114 000 seeds/m2. Emergence of GPG seedlings from artificially established and naturally occurring, persistent seed banks was recorded for 3 years from bare and vegetated treatment plots. Sown seeds showed high levels of innate dormancy and only 4% of seeds emerged when sown immediately after collection. Longer storage of seeds after collection resulted in more seedlings emerging. Estimates of persistent seed banks ranged from 1650 to about 21260 seeds/m2. Most seedlings emerged in spring or autumn and this was correlated with rainfall but not with ambient temperatures. Rates of seed bank decline in both bare and vegetated treatment plots was estimated by fitting exponential decay curves to seed bank estimates. Assuming no further seed inputs, it was estimated that it would take about 3 and 5 years, respectively, for seed banks to decline to 150 seeds/m2 in bare and vegetated treatments.

The role of soil temperature and seed dormancy in the creation and maintenance of persistent seed banks of Nassella trichotoma (serrated tussock) on the Northern Tablelands of New South Wales

2020 ◽  
Vol 42 (2) ◽  
pp. 85
Author(s):  
Annemieke Ruttledge ◽  
Ralph D. B. Whalley ◽  
Gregory Falzon ◽  
David Backhouse ◽  
Brian M. Sindel
Keyword(s):  
Seed Bank ◽  
New South ◽  
Soil Seed Bank ◽  
Seed Banks ◽  
Early Summer ◽  
Secondary Dormancy ◽  
South Wales ◽  
The Creation ◽  
Persistent Soil Seed Bank

A large and persistent soil seed bank characterises many important grass weeds, including Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock), a major weed in Australia and other countries. In the present study we examined the effects of constant and alternating temperatures in regulating primary and secondary dormancy and the creation and maintenance of its soil seed bank in northern NSW, Australia. One-month-old seeds were stored at 4, 25°C, 40/10°C and 40°C, in a laboratory, and germination tests were conducted every two weeks. Few seeds germinated following storage at 4°C, compared with seeds stored at 25°C, 40/10°C and 40°C. Nylon bags containing freshly harvested seeds were buried among N. trichotoma stands in early summer, and germination tests conducted following exhumation after each season over the next 12 months. Seeds buried over summer and summer plus autumn had higher germination than seeds buried over summer plus autumn plus winter, but germination increased again in the subsequent spring. Seeds stored for zero, three, six and 12 months at laboratory temperatures were placed on a thermogradient plate with 81 temperature combinations, followed by incubation at constant 25°C of un-germinated seeds. Constant high or low temperatures prolonged primary dormancy or induced secondary dormancy whereas alternating temperatures tended to break dormancy. Few temperature combinations resulted in more than 80% germination.

Teaching Seed Bank Ecology in an Undergraduate Laboratory Exercise

1995 ◽  
Vol 9 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Emilie E. Regnier
Keyword(s):  
Seed Production ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Species Abundance ◽  
Conventional Tillage ◽  
Seed Banks ◽  
Soil Disturbance ◽  
Life Cycles ◽  
Weed Seed ◽  
Laboratory Exercise

The study of weed life cycles, reproductive strategies, and the soil seed bank is emphasized in the undergraduate weed science course at Ohio State University as central to an understanding of the survival of weeds in the environment. A laboratory exercise was conducted every spring and fall academic quarter from 1991 to 1993 to demonstrate the effects of long-term cropping and soil disturbance histories on weed seed banks and aboveground weed communities. Five sites with diverse histories of culture were sampled; these included a field cultivated in vegetables under continuous conventional tillage for 59 yr, a field cultivated in field corn under continuous no-tillage for 11 yr, a 24 yr-old turfgrass research farm, a 70 yr-old forest, and a section of the forest border. Students conducted a survey of the weeds growing at the sites and separated and identified seeds from soil samples over a 3-wk period in weekly 2-h laboratory periods. Students wrote reports interpreting the data based on their knowledge of the site histories, weed life cycles, and weed seed production and longevity characteristics. The data were consistent over academic quarters as well as with published research, indicating that the survey and soil sampling techniques provided a reasonably accurate representation of the weed flora and soil seed populations. Weeds found growing at the sites were primarily summer annuals at the vegetable site, and a mix of summer and winter annuals, biennials, and perennials at the remaining sites. Annual weeds dominated the seed banks of all sites with common lambsquarters, pigweed spp., and common purslane being the most commonly found seeds. The presence of most seeds in the soil could be explained by a combination of species seed production and seed longevity characteristics and species abundance in the standing community. Interpretation of the data required students to integrate and apply lecture material and provided an excellent thinking exercise.

scholarly journals Similarity between seed bank and herb layer in a natural deciduous temperate lowland forest

2011 ◽  
Vol 79 (2) ◽  
pp. 157-166 ◽  
Author(s):  
Maciej Wódkiewicz ◽  
Anna Justyna Kwiatkowska-Falińska
Keyword(s):  
Seed Bank ◽  
Soil Seed Bank ◽  
Similarity Index ◽  
Seed Banks ◽  
Herb Layer ◽  
Managed Forests ◽  
Lowland Forest ◽  
Soil Seed Banks ◽  
Dominance Structure ◽  
Species Similarity

Forest seed banks mostly studied in managed forests proved to be small, species poor and not reflecting aboveground species composition. Yet studies conducted in undisturbed communities indicate a different seed bank characteristic. Therefore we aimed at describing soil seed bank in an undisturbed forest in a remnant of European lowland temperate forests, the Białowieża Forest. We compared similarity between the herb layer and seed bank, similarity of seed bank between different patches, and dominance structure of species in the herb layer and in the seed bank of two related oak-hornbeam communities. We report relatively high values of Sorensen species similarity index between herb layer and seed bank of both patches. This suggests higher species similarity of the herb layer and soil seed bank in natural, unmanaged forests represented by both plots than in fragmented communities influenced by man. Although there was a set of core seed bank species present at both plots, yielding high Sorensen species similarity index values, considerable differences between plots in seed bank size and dominance structure of species were found, indicating spatial variability of studied seed bank generated by edaphic conditions. Dominance structure of species in the herb layer was not reflected in the underlying seed bank. This stresses, that natural forest regeneration cannot rely only on the seed bank, although some forest species are capable of forming soil seed banks. While forest seed banks may not reflect vegetation composition of past successional stages, they may inform on history and land use of a specific plot.

scholarly journals Rainfall in growing season determines the size of an annual-dominated soil seed bank in a desert ecosystem

2020 ◽  
Author(s):  
Ya-Fei Shi ◽  
Zengru Wang ◽  
Bing-Xin Xu ◽  
Jian-Qiang Huo ◽  
Rui Hu ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Species Composition ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Growing Season ◽  
Seed Banks ◽  
Desert Ecosystem ◽  
Perennial Herb ◽  
Desert Ecosystems ◽  
Soil Seed Banks

Soil seed banks may offer great potential for restoring and maintaining desert ecosystems that have been degraded by climate change and anthropogenic disturbance. However, few studies have explored the annual dynamics in the composition and relative abundance of these soil seed banks. We conducted a long-term observational study to assess the effects of environmental factors (meteorology and microtopography) and aboveground vegetation on the soil seed bank of the Tengger Desert, China. The desert seed bank was dominated by annual herbs. We found that more rainfall in the growing season increased the number of seeds in the soil seed bank, and that quadrats at relatively higher elevations had fewer seeds. The species composition had more similarity in the seed bank than in the aboveground vegetation, though the seed bank and aboveground vegetation did change synchronously due to the rapid propagation of annuals. Together, our findings suggest that the combined effects of environmental factors and plant life forms determine the species composition and size of soil seed banks in deserts. Thus, if degraded desert ecosystems are left to regenerate naturally, the lack of shrub and perennial herb seeds could crucially limit their restoration. Human intervention and management may have to be applied to enhance the seed abundance of longer-lived lifeforms in degraded deserts.

Seasonal variation in soil seed bank size and species composition of selected habitat types in Maputaland, South Africa

Bothalia ◽  
2007 ◽  
Vol 37 (2) ◽  
pp. 249-258 ◽  
Author(s):  
M. J. S. Kellerman ◽  
M. W. Van Rooyen
Keyword(s):  
South Africa ◽  
Seasonal Variation ◽  
Species Composition ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Woody Species ◽  
Forest Edge ◽  
Seed Banks ◽  
Habitat Types ◽  
Open Woodland

Seasonal variation in seed bank size and species composition of five selected habitat types within the Tembe Elephant Park. South Africa, was investigated. At three-month intervals, soil samples were randomly collected from five different habitat types: a, Licuati forest; b, Licuati thicket; c, a bare or sparsely vegetated zone surrounding the forest edge, referred to as the forest/grassland ecotone; d, grassland; and e, open woodland. Most species in the seed bank flora were either grasses, sedges, or forbs, with hardly any evidence of woody species. The Licuati forest and thicket soils produced the lowest seed densities in all seasons.  Licuati forest and grassland seed banks showed a two-fold seasonal variation in size, those of the Licuati thicket and woodland a three-fold variation in size, whereas the forest/grassland ecotone maintained a relatively large seed bank all year round. The woodland seed bank had the highest species richness, whereas the Licuati forest and thicket soils were poor in species. Generally, it was found that the greatest correspondence in species composition was between the Licuati forest and thicket, as well as the forest/grassland ecotone and grassland seed bank floras.

Dynamics in the emergence of dormant and non-dormant herbaceous species from the soil seed bank from a Brazilian dry forest

2020 ◽  
Vol 13 (3) ◽  
pp. 256-265 ◽  
Author(s):  
José Djalma de Souza ◽  
Bruno Ayron de Souza Aguiar ◽  
Danielle Melo dos Santos ◽  
Vanessa Kelly Rodrigues de Araujo ◽  
Júlia Arruda Simões ◽  
...  
Keyword(s):  
Seed Bank ◽  
Linear Models ◽  
Temporal Dynamics ◽  
Soil Seed Bank ◽  
Seed Banks ◽  
Dry Forest ◽  
Herbaceous Species ◽  
Physical Dormancy ◽  
Soil Seed Banks ◽  
Interspecific Differences

Abstract Aims In dry tropical forests, herbaceous species may have dormancy mechanisms and form persistent and transient seed banks in the soil. Evolutionarily acquired, these mechanisms are efficient for the establishment and survival of these herbs, especially in forests with unpredictable climates, such as the Caatinga. Thus, our objective was to verify whether the studied herbaceous species adopt the physical dormancy mechanism and how these natural barriers are overcome, to understand the temporal dynamics existing in the soil seed bank from a Brazilian dry tropical forest. Methods Seeds of five native herbaceous species from the Caatinga forests were selected and submitted to pre-germinative treatments for verifying the presence of physical dormancy. We collected soil samples in the rainy and dry seasons for four consecutive years and monitored the emergence of the selected herbaceous in the greenhouse. We verified the differences in germination and seed bank emergence in the soil by generalized linear models. Important Findings The presence and absence of physical dormancy were observed in seeds from Caatinga herbaceous species. We found intraspecific and interspecific differences in the herbaceous emergence from soil seed banks between years and climatic seasons. In perennial herbs, consecutive lack of emergence between seasons and years was frequent, which suggests a direct relationship with the mechanism of physical dormancy and the environmental conditions necessary to overcome integument barriers. In these species, seed dimorphism and dormancy may confer additional advantages to their survival. Moreover, presenting intermediate levels of physical dormancy in an annual species may be an evolutionary adjustment to rainfall unpredictability. In contrast, we found that the annual herb without dormancy is more sensitive to seasonal and interannual climate changes, as evidenced by the increase and significant reduction of its emergence in the soil seed bank. These differences acquired evolutionarily are advantageous for the establishment of herbaceous populations, mainly in semiarid regions with an unpredictable climate.

scholarly journals Dormancy-Breaking and Germination Requirements for Seeds of Sorbus alnifolia (Siebold & Zucc.) K.Koch (Rosaceae), a Mesic Forest Tree with High Ornamental Potential

Forests ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 319
Author(s):  
Yuhan Tang ◽  
Keliang Zhang ◽  
Yin Zhang ◽  
Jun Tao
Keyword(s):  
Seed Dormancy ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Natural Habitat ◽  
Eastern China ◽  
Forest Tree ◽  
Germination Percentage ◽  
Cold Stratification ◽  
Dormancy Breaking ◽  
Breaking Dormancy

Sorbus alnifolia (Siebold & Zucc.) K.Koch (Rosaceae) is an economically important tree in the temperate forests of Eastern China. In recent decades, ever-increasing use and modification of forestlands have resulted in major degeneration of the natural habitat of S. alnifolia. Moreover, S. alnifolia seeds germinate in a complicated way, leading to a high cost of propagation. The current study aimed to determine the requirements for breaking seed dormancy and for germination as well as to characterize the type of seed dormancy present in this species. Moreover, the roles of temperature, cold/warm stratification, and gibberellic acid (GA3) in breaking dormancy were tested combined with a study of the soil seed bank. The results showed that intact seeds of S. alnifolia were dormant, requiring 150 days of cold stratification to achieve the maximum germination percentage at 5/15 °C. Exposure of the seeds to ranges of temperatures at 15/25 °C and 20/30 °C resulted in secondary dormancy. Scarifying seed coat and partial removal of the cotyledon promoted germination. Compared with long-term cold stratification, one month of warm stratification plus cold stratification was superior in breaking dormancy. Application of GA3 did not break the dormancy during two months of incubation. Seeds of S. alnifolia formed a transient seed bank. The viability of freshly matured S. alnifolia seeds was 87.65% ± 11.67%, but this declined to 38.25% after 6-months of storage at room temperature. Seeds of S. alnifolia have a deep physiological dormancy; cold stratification will be useful in propagating this species. The long chilling requirements of S. alnifolia seeds would avoid seedling death in winter.

Soil Seed Banks of Adjacent Unlogged Rain-Forest Types in North-Queensland

1990 ◽  
Vol 38 (3) ◽  
pp. 261 ◽  
Author(s):  
AW Graham ◽  
MS Hopkins
Keyword(s):  
Seed Bank ◽  
Forest Type ◽  
Soil Seed Bank ◽  
Floristic Composition ◽  
Seed Banks ◽  
Scaling Analysis ◽  
Forest Types ◽  
Total Size ◽  
Soil Seed Banks ◽  
Secondary Species

The size and floristic composition of soil seed banks under four adjacent, unlogged and structurally different rainforest types were assessed by exposing 17 surface soil samples (to 40mm depth) to germination-house conditions. The mean size of the seed bank in the undisturbed forest types was 240 seeds m-2 (s.d. 139). Seeds of secondary species dominated the soil seed banks in all forest types, although weed seeds constituted only 0.6-4.0%. Some forest types had characteristic component secondary species in the buried seed bank. Agglomerative classification and multidimensional scaling analysis of quantitative sample data indicated that the parent structural-environmental forest type was the dominant influence in determining composition of the soil seed banks. Comparisons of the seed banks of the intact rainforest with those of nearby disturbed forests showed the former to be 35 to 50% smaller in total size, and lacking in some distinctive secondary species. It was concluded that disturbance, both within and adjacent to rainforest, may influence soil seed bank compositions, and hence future patterns of regeneration.

Sign in / Sign up

Export Citation Format

Share Document