variation of the germinable soil seed banks in a pasture infested by parthenium hysterophorus l.at kilcoy, south-eastern queensland

VARIATION OF THE GERMINABLE SOIL SEED BANKS IN A PASTURE INFESTED BY PARTHENIUM HYSTEROPHORUS L. AT KILCOY, SOUTH-EASTERN QUEENSLAND An Thi Kieu Do A report submitted as a requirement for the degree of Master of Agricultural Studies in The University of Queensland School of Land, Crop and Food Sciences Faculty of Natural Resources, Agriculture and Veterinary Science The University of Queensland, Gatton January, 2009 SCHOOL OF LAND, CROP AND FOOD SCIENCES i DECLARATION The work reported in this research project report has been carried out by the undersigned. Where reference has been made to the results of other workers, appropriate acknowledgment of the source of information has been made. Author AN DO This is to certify that the academic style and manner of presentation of the research project report are appropriate to the discipline, that all requirements of the University in relation to the deposition of records of research have been met and that the information contained in the report is a true representation of the data collected. Project Supervisors Prof. STEVE ADKINS Dr. CHRIS O’DONNELL Dr. DOUG GEORGE ii ACKOWLEDGEMENTS I would sincerely like to thank Professor Steve Adkins (principal supervisor), Dr. Chris O’Donnell (associate supervisor) and Dr. Doug George (associate supervisor) - who offered endless hours of patience, support and guidance - for their valuable roles in discussing ideas and problems associated with the project and for reading many drafts. Special thanks to Dr. Sheldon Navie who played a great role in identification botanical species and to Mr. Allan Lisle who assisted me with data analysis. Many thanks also to all of the staff of the School of Land, Crop and Food Sciences - The University of Queensland - who supported me with equipment and materials. The land owner, Mr. Syd Smith, was kind enough to provide me with the property-related information and to let me set up sites on his property. Thanks to Mr. Shane Noon, a Kilcoy officer, for helping locating the study sites. Special thanks to the UQ’s fellows, who accompanied with me on field trips and who made my life in Australia pleasurable. I greatly appreciate the financial support of the Australian Development Scholarship for my study at the University of Queensland. Finally, I gratefully acknowledge the support of my family members, who cared and encouraged me during the project. iii ABSTRACT Seed germination method was used to determine the germinable soil seed bank at two contrasting sites (one in a gully and another at the top of a ridge) within a sub-tropical pasture at Kilcoy, south-eastern Queensland, in January 2008 (mid-summer) and July 2008 (mid-winter). These two sites demonstrated differences in topography, soil type and moisture content and standing vegetation composition. During the period of study, the germinable soil seed bank at the two sites varied between 11,526 to 23,252 seeds/m 2 in the gully and between 10,136 to 12,799 seeds/m 2 at the top of the ridge. Parthenium weed (Parthenium hysterophorous L.) exhibited a moderately abundant and persistent seed bank in the gully (varying from 358 to 821 seeds/m 2 ) and at the top of the ridge (from 863 to 1,189 seeds/m 2 ). The weed was not the dominant species at either site, representing 1.5 to 7.1% of the total germinable seed bank in the gully and 8.5 to 9.3% of the total seed banks at the top of the ridge. The species richness and the species diversity of the germinable seed bank were high at both sites with no significant difference showing up between them or between summer and winter. This management plan, designed around chemical control, had not yet been in operation long enough to have the the desired effect of reducing the seed bank to below a desirable maximum level. The disproportional low percentage of highly desirable pasture species (including legume, palatable perennial grass and other native species) coupled with the presence of parthenium weed in the germinable soil seed bank indicates that the pasture is still in a degraded state. iv TABLE OF CONTENTS DECLARATION i ACKOWLEDGEMENTS ii ABSTRACT iii TABLE OF CONTENTS iii LIST OF TABLES vii LIST OF FIGURES viii LIST OF PLATES ix CHAPTER 1 1 INTRODUCTION 1 CHAPTER 2 3 LITERATURE REVIEW 3 2.1. Scope of the review 3 2.2. Parthenium weed (Parthenium hysterophorus L.) 3 2.2.1. Taxonomy and description of parthenium weed 3 2.2.2. The history of spread and present distribution 5 2.2.3. Habitat 7 2.2.4. Growth and development 8 2.2.5. Biology of parthenium weed seed 9 2.2.6. Parthenium weed and its significance 12 2.2.7. Parthenium weed management 16 2.3. Soil seed bank 23 2.3.1. Soil seed bank concept 23 2.3.2. Soil seed bank study approaches 27 2.3.3. Composition of the soil seed bank in grasslands 31 2.3.4. Factors affecting the soil seed banks in gr azed communities 32 v 2.3.5. Soil seed bank of parthenium weed 35 2.4. Kilcoy climate/land use of the study site 36 2.4.1. Kilcoy location 36 2.4.2. Kilcoy climate 36 2.4.3. Land use of the study site 38 2.5. Conclusion 38 CHAPTER 3 40 MATERIALS AND METHODS 40 3.1. Study sites 40 3.2. Sampling method 40 3.3. Analytical method 41 3.4. Statistical analysis 43 CHAPTER 4 44 RESULTS 44 4.1. Temporal variation in seed density and composition 44 4.2. Species richness and diversity 53 4.3. Life history 54 4.3.1. Annuals/biennials versus perennials 54 4.3.2. Life form 56 4.3.3. Introduced species versus native species 57 4.4. Germination rate 57 CHAPTER 5 61 DISCUSSION 61 5.1. Temporal variation in seed density and composition 61 5.2. Species richness and diversity 66 5.3. Life history 67 5.4. Germination rate 69 CHAPTER 6 71 CONCLUSION 71 vi REFERENCES 72 APPENDICES 82 Appendix 1. Temperatures ( 0 C) and humidity (%) at Kirkleagh (latitude 27.2’S, 82 Appendix 2. Mean (■), max(▲) and min (♦) temperature of the first 20 days of the germination trials in the glasshouse in January (A) and in July (B). 83 Appendix 3. Above ground vegetation species versus seed bank species at the gully 84 Appendix 4. Above ground vegetation species versus seed bank species at the top ridge 88 vii LIST OF TABLES Table 2.1. Recommendations on seed bank sample sizes from the literature 27 Table 2.2. The main advantages and disadvantages of the germination and the seed extraction methods for analysing soil seed banks. 30 Table 2.3. Temperatures ( 0 C) and humidity (%) at Kirkleagh (latitude 27 o 2’S, longtitude 152 o 34’E) for the period 1978 – 1993. 37 Table 4.1. Temporal variation in the germinable soil seed bank at the gully of the Kilcoy pasture. 45 Table 4.2. Temporal variation in the germinable soil seed bank at the top ridge of the Kilcoy pasture . 49 Table 4.3. Species richness and diversity (Shannon-Weiner Index) of the seed banks at the gully and the top ridge of the Kilcoy pasture. 54 Table 4.4. The spatial variation in the seed densities of annuals and perennials. 55 Table 4.5. Spatial variation in the seed densities of native and introduced species 57 Table 5.1. The contribution of difference plant groups to the viable seed banks in difference grassland types 63 viii LIST OF FIGURES Figure 2.1. A map of parthenium weed distribution in Australia based on herbarium records, where red dots represent the presence of parthenium weed 6 Figure 2.2. Diagrammatic representation of the four seed bank types 24 Figure 2.3. Long-term average rainfall at Lindfield (latitude: 26 o 84’S, longitude: 152 o 58’E, 14km away from the study sites). 37 Figure 3.1. Monthly rainfall (blue bars) in the year 2008, compared with long-term rainfall (black bars) averages of the period from 1988 to 2008 at Lindfield (14 km away from the study sites). 41 Figure 4.1. The germinable seed proportion of parthenium weed in comparison with that of other plant groups in the germinable soil seed banks at the gully in the Kilcoy pasture 48 Figure 4.2. The proportion of parthenium weed in comparison with other groups of species in the germinable soil seed banks at the top of a ridge in the Kilcoy pasture. 52 Figure 4.3. Life forms of species detected in the germinable soil seed banks from samples collected at the gully and the top ridge of the Kilcoy pasture during the entire study period 56 Figure 4.4. Seedling emergence of parthenium weed (○) and all other species (■) during the first 20 days after wetting the soil samples collected in January from a gully (A) and a top ridge (B) of the Kilcoy pasture. 58 Figure 4.5. Cumulative seedling emergence of parthenium weed (○) and all other species (■) during the first 20 days after wetting the soil samples collected in January from a gully (A) and a top ridge (B) of a Kilcoy pasture 58 Figure 4.6. Seedling emergence of parthenium weed (○) and all other species (■) during the first 20 days after wetting the soil samples collected in July from a gully (A) and a top ridge (B) of a Kilcoy pasture. 59 ix Figure 4.7. Cumulative seedling emergence of parthenium weed (○) and all other species (■) during the first 20 days after wetting the soil samples collected in July from a gully (A) and a top ridge (B) of a Kilcoy pasture. 60 LIST OF PLATES Plate 2.1. Parthenium weed (Parthenium hysterophorus L.). (a) Early seedling growth with hairy true leaves and alternate leaf arrangement; (b) Late seedling growth with rosette growth habit and deeply lobed leaves 4 Plate 2.2. Mature plant. Note the small white flower heads and much-branched terminal panicles 5 [...]... density of the soil seed bank is influenced by the seed- production capability of above-ground vegetation (Coffin & Lauenroth 1989) The main objective of this study is to measure the size and temporal and spatial variation in the germinable seed bank of parthenium weed in a grazed pasture at Kilcoy, south-eastern Queensland The composition of the entire germinable seed bank was also determined in order... railway tracks, bus stops on road sides and other waste lands (Mahadevappa 1999) Parthenium weed has also spread into Trinidad, Guyana, Jamaica, Nepal, Israel, South Korea, Taiwan, North Vietnam, Bangladesh, Sri Lanka, southern China, certain Pacific islands (Vanuatu, New Caledonia, Tahiti and Hawaii) and Indian islands (the Mascarenes, the Seychelles, Rodriguez, Bourbon and Mauritius) (Mahadevappa... and South Africa, parts of South East Asia, to certain Pacific Islands, to India, Pakistan, and Australia It has spread at an alarming rate achieving the status of a major weed within a relatively short period of time (Adkins & Navie 2006; Kohli et al 2006; Mahadevappa 1999; Navie et al 1998b; Picman & Picman 1984; Reddy et al 2007; Singh et al 2004) In Australia, parthenium weed was declared one of. .. 2070 (Adamson 1996) Farmers owning parthenium weed -infested pastures face a further negative impact on supplying pasture seeds and forage because of quarantine legislation on the movement of these products out of parthenium weed-contaminated properties (Evans 1997) An average of 600 parthenium weed seeds were detected per kg of contaminated pasture seeds when sampling in parthenium weed -infested pastures,... on heavy black soils 7 (Dale 1981) Parthenium weed can adapt to the areas with a wide range of annual rainfall, varying from 200 mm to 1,150 mm (Dale 1981) It has been reported that the major parthenium weed infestation areas in Australia are in the sub-coastal regions of central Queensland, where annual rainfall ranges between 500 and 700 mm with a dominant summer incidence (Haseler 1976) Parthenium. .. non-nutritious and unable to sustain grazing animals (Chippendale & Panetta 1994) This results in significant reductions in pasture carrying capacity by up to 40% in Australia (McFadyen 1992) and even as much as 90% in India (Evans 1997) Cattle grazing in parthenium weedinfested grasslands gain less weight in comparison to those feeding in parthenium weedfree areas This coupled with the additional cost for parthenium. .. 1989; Viragh & Gerencser 1988) Some of the most important characteristics of populations reproducing primarily by seeds are the capacity of individual plants in determining the seed production and the adaptive capability of the species which can define the period when the seeds retain their viability in the soil The latter trait can mean a survival mechanism for a given population at the same time Therefore,... various approaches that are used to manage the weed are also mentioned The second part of the review stresses the importance of studying the soil seed bank in relation to pasture management and briefly reviews factors affecting the composition and size of soil seed banks An overview of parthenium weed soil seed banks is included as well 2.2 Parthenium weed (Parthenium hysterophorus L.) 2.2.1 Taxonomy and... weed particularly favours areas where brigalow (Acacia harpophylla F.Muell ex Benth.) and gidyea (Acacia cambagei R.T.Baker) low open forests have been cleared (Dale et al 1978) Recently cleared lands used for livestock are the common areas with heavy parthenium weed infestations (Holman 1981) This is the case in Australia where the main parthenium weed -infested areas are beef feeding pastures (Anon... structural composition and dynamics of the diversity of the native flora The presence of parthenium weed tends to replace the dominant flora in a wide range of habitats including native grasslands, open woodlands, river banks, floodplains, national wildlife parks and wastelands (Asad & Rukhsana 2006; Chippendale & Panetta 1994; Evans 1997; Kohli et al 2006; Navie et al 1998b) Whenever invading natural communities, . Table 4.1. Temporal variation in the germinable soil seed bank at the gully of the Kilcoy pasture. 45 Table 4.2. Temporal variation in the germinable soil seed bank at the top ridge of the. spatial variation in the germinable seed bank of parthenium weed in a grazed pasture at Kilcoy, south-eastern Queensland. The composition of the entire germinable seed bank was also determined. Pakistan, and Australia. It has spread at an alarming rate achieving the status of a major weed within a relatively short period of time (Adkins & Navie 2006; Kohli et al. 2006; Mahadevappa