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RESEARCH ARTICLE
Contents Vol 55(2)

Impact of sheep grazing on the soil seed bank of a managed ephemeral wetland: implications for management

Jason Nicol A D , Sally Muston B , Paula D’Santos C , Bernard McCarthy B and Sylvia Zukowski B
+ Author Affiliations
- Author Affiliations

A Environmental Biology, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia. Present address: South Australian Research and Development Institute, Aquatic Sciences, Inland Waters Program, PO Box 120, Henley Beach, SA 5022, Australia.

B Murray Darling Freshwater Research Centre, Lower Basin Laboratory, PO Box 3428 Mildura, Vic. 3502, Australia.

C New South Wales Murray Wetlands Working Group, PO Box 363, Buronga, NSW 2739, Australia.

D Corresponding author. Email: nicol.jason@saugov.sa.gov.au

Australian Journal of Botany 55(2) 103-109 https://doi.org/10.1071/BT04137
Submitted: 6 September 2004  Accepted: 23 October 2006   Published: 16 March 2007

Abstract

The seed bank is an important mechanism for the persistence of species in ephemeral wetlands, but grazing by domestic stock may change the seed bank and in turn the capacity of the system to recover from disturbance. The sediments of two areas in Thegoa Lagoon (Murray–Darling Basin), one area grazed by sheep when dry and the other ungrazed, were examined. The objective of the study was to determine whether and how the (1) germinable seed bank and (2) final plant communities differ between the grazed and ungrazed areas. The seed banks were subjected to one of the following three water depths: 5 cm above the surface of the water, 5 cm below the surface and 50 cm below the surface. The composition of the seed bank was determined by using the seedling-emergence technique for 12 weeks, with seedlings removed every 2 weeks. The final plant communities were determined at 12 weeks without removing seedlings. The seed bank from the grazed area had a significantly lower seed density (5600 ± 593 seeds m–2) and species richness (7 species) than the ungrazed area (37 683 ± 4492 seeds m–2, 16 species) (ANOVA: F1, 10 = 50.16, P < 0.0001). The floristic composition of the seed bank was also significantly different between the areas (NPMANOVA: F1, 10 = 15.44, P = 0.0032). Glinus lotoides was in higher abundance in the grazed area and Alternanthera denticulata, Persicaria lapathifolium, Polygonum plebium, Typha domingensis and Centipeda cunninghamii in the ungrazed area. Similarly, the final communities derived from the grazed and ungrazed areas were significantly different from each other (NPMANOVA: F1, 10 = 15.53, P = 0.0032). Greater numbers of Centipeda cunninghamii were present in the community from the grazed area and Alternanthera denticulata and Cuscuta campestris were present in larger numbers in the community from the ungrazed area. Water depth also had an impact on germination; no germination occurred in seed banks flooded to 50 cm and one Typha domingensis seedling was observed in a sample flooded to 5 cm. These results showed that grazing reduces the density and species richness of the seed bank and in turn changes the plant communities derived from the seed bank; however, if grazing is removed pest plants such as Cuscuta campestris may require control. In addition, managed drawdown or water-level fluctuations are important in exposing wetland sediments and allowing for species to recruit from the seed bank.


Acknowledgements

This study was initiated and funded by the New South Wales Murray Wetlands Working Group Inc. The authors also thank Dr Deborah Nias, Dr Chester Merrick, Lance Lloyd and the two anonymous referees for their comments on early drafts of the paper.


References


Anderson MJ (2001) A new method for non-parametric analysis of variance. Austral Ecology 26, 32–46.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Australian Bureau of Meteorology (2003) ‘Climate averages for Mildura airport.’

Bertiller MB (1992) Seasonal variation in the seed bank of a Patagonian grassland in relation to grazing and topography. Journal of Vegetation Science 3, 47–54.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Bray JR, Curtis JT (1957) An ordination of the upland forest communities of southern Wisconsin. Ecological Monographs 27, 325–349.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Brock MA, Theodore K, O’Donnell L (1994) Seed-bank methods for Australian wetlands. Australian Journal of Marine and Freshwater Research 45, 483–493.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Cunningham GM , Mulham WE , Milthorpe PL , Leigh JH (1981) ‘Plants of Western New South Wales.’ (New South Wales Government Printing Office: Sydney)

D’Santos P (2003) ‘Thegoa Lagoon: riparian vegetation and groundwater response to a drying phase.’ (New South Wales Murray Wetlands Working Group Inc.: Buronga, NSW)

Dufrene M, Legendre P (1997) Species assemblages and indicator species: the need for a flexible asymmetrical approach. Ecological Monographs 67, 345–366.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Grace JB (1993) The adaptive significance of clonal reproduction in angiosperms: an aquatic perspective. Aquatic Botany 44, 159–180.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Gross KL (1990) A comparison of methods for estimating seed numbers in the soil. Journal of Ecology 78, 1079–1093.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Jansen A, Robertson AI (2001) Relationships between livestock management and the ecological condition of riparian habitats along an Australian floodplain river. Journal of Applied Ecology 38, 63–75.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Jessop JP , Tolken HR (1986) ‘The flora of South Australia.’ (Government of South Australia Printer: Adelaide)

Jutila H (1998) Seed banks of grazed and ungrazed Baltic seashore meadows. Journal of Vegetation Science 9, 395–408.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Jutila H (2001) How does grazing by cattle modify the vegetation of coastal grasslands along the Baltic Sea? Annales Botanici Fennici 38, 181–200. open url image1

Lodge DM (1991) Herbivory on freshwater macrophytes. Aquatic Botany 41, 195–224.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Mathooko JM, Kariuki ST (2000) Disturbances and species distribution of the riparian vegetation of a Rift Valley stream. African Journal of Ecology 38, 123–129.
| Crossref | GoogleScholarGoogle Scholar | open url image1

McCune B , Mefford MJ (1999) ‘PC-ORD. Multivariate analysis of ecological data, version 4.28.’ (MjM Software Design: Glendon Beach, OR)

McCune B , Grace JB , Urban DL (2002) ‘Analysis of ecological communities.’ (MjM Software Design: Glendon Beach, OR)

Mesleard F, Lepart J, Grillas P, Mauchamp A (1999) Effects of seasonal flooding and grazing on the vegetation of former ricefields in the Rhone Delta (Southern France). Plant Ecology 145, 101–114.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Middleton BA, van der Valk AG, Mason DH, Williams RL, Davis CB (1991) Vegetation dynamics and seed banks of a monsoonal wetland overgrown with Paspalum distichum L. in northern India. Aquatic Botany 40, 239–259.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Newman S, McCormick PV, Miao SL, Laing JA, Kennedy WC, O’Dell MB (2004) The effect of phosphorus enrichment on the nutrient status of a northern Everglades slough. Wetlands Ecology and Management 12, 63–79.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Nicol JM (2004) Vegetation dynamics of the Menindee Lakes with reference to the seed bank. PhD thesis, The University of Adelaide, SA.

Nicol JM, Ganf GG (2000) Water regimes, seedling recruitment and establishment in three wetland plant species. Marine and Freshwater Research 51, 305–309.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Nicol JM, Ganf GG, Pelton GA (2003) Seed banks of a southern Australian wetland: the influence of water regime on final species composition. Plant Ecology 168, 191–205.
| Crossref | GoogleScholarGoogle Scholar | open url image1

O’Connor TG, Pickett GA (1992) The influence of grazing on seed production and seed banks of some African savanna grasslands. Journal of Applied Ecology 29, 247–260.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Riis T, Hawes I (2003) Effect of wave exposure on vegetation abundance, richness and depth distribution of shallow water plants in a New Zealand lake. Freshwater Biology 48, 75–87.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Roberts J , Marston F (2000) ‘Water regime of wetland and floodplain plants in the Murray–Darling Basin.’ (CSIRO Land and Water: Canberra, ACT)

Robertson AI, Rowling RW (2000) Effects of livestock on riparian zone vegetation in an Australian dryland river. Regulated Rivers: Research and Management 16, 527–541.
| Crossref | GoogleScholarGoogle Scholar | open url image1

SAS Institute Inc. (1996) ‘JMP In version 3.2.6.’ (SAS Institute Inc.: Cary, NC)

Thompson K (1992) The functional ecology of seed banks. In ‘Seeds: the ecology of regeneration in plant communities’. (Ed. M Fenner) pp. 231–258. (CAB International: Wallingford, UK)

van der Valk AG (1981) Succession in wetlands: a Gleasonian approach. Ecology 62, 688–696.
| Crossref | GoogleScholarGoogle Scholar | open url image1

van der Valk AG, Middleton BA, Williams RL, Mason DH, Davis CB (1993) The biomass of an Indian monsoonal wetland before and after being overgrown with Paspalum distichum L. Vegetatio 109, 81–90.
| Crossref | GoogleScholarGoogle Scholar | open url image1

van Oene H, van Deursen EJM, Berendse F (1999) Plant–herbivore interaction and its consequences for succession in wetland ecosystems: a modelling approach. Ecosystems 2, 122–138.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Wahren CH, Williams RJ, Papst WA (1999) Alpine and subalpine wetland vegetation on the Bogong High Plains, south-eastern Australia. Australian Journal of Botany 47, 165–188.
| Crossref | GoogleScholarGoogle Scholar | open url image1