Multi-decadal increases in shrub abundance in non-riverine red gum (Eucalyptus camaldulensis) woodlands occur during a period of complex land-use history
Jodi N. Price A B C and John W. Morgan AA Department of Botany, La Trobe University, Bundoora, Vic. 3086, Australia.
B Present address: Ecosystem Management, University of New England, Armidale, NSW 2351, Australia.
C Corresponding author. Email: jprice20@une.edu.au
Australian Journal of Botany 57(3) 163-170 https://doi.org/10.1071/BT07079
Submitted: 26 April 2007 Accepted: 31 March 2009 Published: 29 June 2009
Abstract
The history of land-use was examined in Eucalyptus camaldulensis Dehnh. woodland in the Victoria Valley of the Grampians National Park, south-eastern Australia, to help interpret changes in vegetation there during the last 50 years. We used aerial photography and dendrochronological data to quantify the amount of, and the rate of change in, the woody-vegetation cover between 1948 and 1997, and historical data to document land-use changes during this time. Aerial photographs indicated that in 1948, 56% of study area had <50% cover of woody plants. By 1997, 90% of the study area had >50% woody-plant cover. The native shrub Leptospermum scoparium J.R. Forst & G. Forst (Myrtaceae) was predominantly responsible for the increases in cover. Demographic analyses indicated that recruitment has been ongoing rather than episodic; large numbers of shrubs, however, have recruited since 1994. We hypothesise that the vegetation changes observed are likely a response to changes in land-use that have occurred since European occupation. Increased woody-plant cover followed the removal of sheep grazing in the long-term absence of fire. It is very likely that the long history of stock grazing, coupled with selective logging and associated soil disturbance, initiated a change in understorey vegetation by reducing competitive native tussock grasses and fuel loads to carry fires and this reduction was initially responsible for the encroachment of shrubs into the woodland. Recruitment has been ongoing in the absence of any recent land-use changes (most utilisation ceasing after the declaration of National Park status in 1984) and hence, this transformation from species-rich herbaceous woodland to shrubby woodland is expected to continue in the future.
Acknowledgements
Logistical and financial support for this research was provided by the Department of Botany, La Trobe University. Marty Gent assisted with aerial photograph analysis and Ian Lunt provided us with valuable insights into the wattle-bark industry. The manuscript was greatly improved by helpful comments from Wal Whalley, Bob Parsons and four anonymous reviewers.
Agnew ADQ,
Wilson JB, Sykes MT
(1993) A vegetation switch as the cause of a forest/mire ecotone in New Zealand. Journal of Vegetation Science 4, 273–278.
| Crossref | GoogleScholarGoogle Scholar |
Archer SR
(1989) Have southern Texas savannas been converted to woodlands in recent history? American Naturalist 134, 545–561.
| Crossref | GoogleScholarGoogle Scholar |
Archer SR,
Schimel DS, Holland EA
(1995) Mechanisms of shrubland expansion: land use, climate or CO2? Climatic Change 29, 91–99.
| Crossref | GoogleScholarGoogle Scholar |
Bahre CJ, Shelton ML
(1993) Historic vegetation change, mesquite increases, and climate in southeastern Arizona. Journal of Biogeography 20, 489–504.
| Crossref | GoogleScholarGoogle Scholar |
Bartolome J,
Plaixats J,
Fanlo R, Boada M
(2005) Conservation of isolated Atlantic heathlands in the Mediterranean region: the effects of land-use change in the Montseny biosphere reserve (Spain). Biological Conservation 122, 81–88.
| Crossref | GoogleScholarGoogle Scholar |
Bennett LT
(1994) The expansion of Leptospermum laevigatum on the Yanakie Isthmus, Wilson’s Promontory, under changes in the burning and grazing regimes. Australian Journal of Botany 42, 555–564.
| Crossref | GoogleScholarGoogle Scholar |
Bond WJ,
Midgley GF, Woodward FI
(2003) The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas. Global Change Biology 9, 973–982.
| Crossref | GoogleScholarGoogle Scholar |
Bond WJ,
Dickinson KJM, Mark AF
(2004) What limits the spread of fire-dependent vegetation? Evidence from geographic variation of serotiny in a New Zealand shrub. Global Ecology and Biogeography 13, 115–127.
| Crossref | GoogleScholarGoogle Scholar |
Bowman DMJS
(1998) The impact of aboriginal landscape burning on the Australian biota. New Phytologist 140, 385–410.
| Crossref | GoogleScholarGoogle Scholar |
Bren LJ
(1992) Tree invasion of an intermittent wetland in relation to changes in the flooding frequency of the River Murray, Australia. Australian Journal of Ecology 17, 395–408.
| Crossref | GoogleScholarGoogle Scholar |
Briggs JM,
Knapp AK,
Blair JM,
Heisler JL,
Hoch GA,
Lett MS, Carron JK
(2005) An ecosystem in transition: causes and consequences of the conversion of mesic grassland to shrubland. Bioscience 55, 243–254.
| Crossref | GoogleScholarGoogle Scholar |
Burrell JP
(1965) Ecology of Leptospermum in Otago. New Zealand Journal of Botany 3, 3–16.
Calder JA,
Wilson JB,
Mark AF, Ward G
(1992) Fire, succession and reserve management in a New Zealand snow tussock grassland. Biological Conservation 62, 35–45.
| Crossref | GoogleScholarGoogle Scholar |
Costello DA,
Lunt ID, Williams JE
(2000) Effects of invasion by the indigenous shrub Acacia sophorae on plant composition of coastal grasslands in south-eastern Australia. Biological Conservation 96, 113–121.
| Crossref | GoogleScholarGoogle Scholar |
Fensham RJ,
Fairfax RJ, Archer SR
(2005) Rainfall, land use and woody vegetation cover change in semi-arid Australian savanna. Journal of Ecology 93, 596–606.
| Crossref | GoogleScholarGoogle Scholar |
Franco JA, Morgan JW
(2007) Using historical records, aerial photography and dendroecological methods to determine vegetation changes in a grassy woodland since European settlement. Australian Journal of Botany 55, 1–9.
| Crossref | GoogleScholarGoogle Scholar |
Gardiner HG
(1986a) Dynamics of perennial plants in the Mulga (Acacia aneura F.Muell.) zone of Western Australia. I. rates of population change. Rangeland Journal 8, 18–27.
| Crossref | GoogleScholarGoogle Scholar |
Gardiner HG
(1986b) Dynamics of perennial plants in the mulga (Acacia aneura F.Muell.) zone of western Australia. 11. Survival of perennial shrubs and grasses. Australian Rangeland Journal 8, 28–35.
Gleadow R, Ashton DH
(1981) Invasion by Pittosporum undulatum of the forests of central Victoria. 1. Invasion patterns and plant morphology. Australian Journal of Botany 29, 705–720.
| Crossref | GoogleScholarGoogle Scholar |
Gott B
(2005) Aboriginal fire management in south-eastern Australia: aims and frequency. Journal of Biogeography 32, 1203–1208.
| Crossref | GoogleScholarGoogle Scholar |
Harrington GN, Johns GG
(1990) Herbaceous biomass in a Eucalyptus savanna woodland after removing trees and/or shrubs. Journal of Applied Ecology 27, 775–787.
| Crossref | GoogleScholarGoogle Scholar |
Harrington GN,
Oxley RE, Tongway DJ
(1976) The effects of European settlement and domestic livestock on the biological system in poplar box (Eucalyptus populnea) lands. Australian Rangeland Journal 1, 271–279.
| Crossref | GoogleScholarGoogle Scholar |
Heisler JL,
Briggs JM, Knapp AK
(2003) Long-term patterns of shrub expansion in a C4-dominated grassland: fire frequency and the dynamics of shrub cover and abundance. American Journal of Botany 90, 423–428.
| Crossref | GoogleScholarGoogle Scholar |
Kirkpatrick JB
(1986) The viability of bush in cities – ten years of change in an urban grassy woodland. Australian Journal of Botany 34, 691–708.
| Crossref | GoogleScholarGoogle Scholar |
Ledgard N, Davis M
(2004) Restoration of mountain beech (Nothofagus solandri var. cliffortioides) forest after fire. New Zealand Journal of Ecology 28, 125–135.
Lunt ID
(1990) Species-area curves and growth-form spectra for some herb-rich woodlands in western Victoria, Australia. Australian Journal of Ecology 15, 155–161.
| Crossref | GoogleScholarGoogle Scholar |
Lunt ID
(1998a) Allocasuarina (Casuarinaceae) invasion of an unburnt coastal woodland at Ocean Grove, Victoria: structural changes 1971–1996. Australian Journal of Botany 46, 649–656.
| Crossref | GoogleScholarGoogle Scholar |
Lunt ID
(1998b) Two hundred years of land use and vegetation change in a remnant coastal woodland in southern Australia. Australian Journal of Botany 46, 629–647.
| Crossref | GoogleScholarGoogle Scholar |
Mohan E,
Mitchell N, Lovell P
(1984) Environmental factors controlling germination of Leptospermum scoparium (manuka). New Zealand Journal of Botany 22, 95–101.
Molnar CD,
Fletcher D, Parsons RF
(1989) Relationships between heath and Leptospermum laevigatum scrub at Sandringham, Victoria. Proceedings of the Royal Society of Victoria 101, 77–87.
Morgan JA,
Milchunas DG,
LeCain DR,
West M, Mosier AR
(2007) Carbon dioxide enrichment alters plant community structure and accelerates shrub growth in the shortgrass steppe. Proceedings of the National Academy of Sciences, USA 104, 14724–14729.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Mullett T, Simmons D
(1995) Ecological impacts of the environmental weed sweet pittosporum (Pittosporum undulatum Vent.) in dry sclerophyll forest communities, Victoria. Plant Protection Quarterly 10, 131–138.
Polley HW,
Johnson HB, Mayeux HS
(1994) Increasing CO2: comparative responses of the C4 grass Schizachyrium and grassland invader Prosopis. Ecology 75, 976–988.
| Crossref | GoogleScholarGoogle Scholar |
Price JN, Morgan JW
(2006) Variability in plant fitness influences range expansion of Leptospermum scoparium. Ecography 29, 623–631.
| Crossref | GoogleScholarGoogle Scholar |
Price JN, Morgan JW
(2008) Woody plant encroachment reduces species richness of herb-rich woodlands in southern Australia. Austral Ecology 33, 278–289.
| Crossref | GoogleScholarGoogle Scholar |
Roques KG,
O’Connor TG, Watkinson AR
(2001) Dynamics of shrub encroachment in an African savanna: relative influences of fire, herbivory, rainfall and density dependence. Journal of Applied Ecology 38, 268–280.
| Crossref | GoogleScholarGoogle Scholar |
Rose S, Fairweather PG
(1997) Changes in floristic composition of urban bushland invaded by Pittosporum undulatum in northern Sydney, Australia. Australian Journal of Botany 45, 123–149.
| Crossref | GoogleScholarGoogle Scholar |
Sharp BR, Whittaker RJ
(2003) The irreversible cattle-driven transformation of a seasonally flooded Australian savanna. Journal of Biogeography 30, 783–802.
| Crossref | GoogleScholarGoogle Scholar |
Singer RJ, Burgman MA
(1999) The regeneration ecology of Kunzea ericoides (A.Rich.) J.Thompson at Coranderrk Reserve, Healesville. Austral Ecology 24, 18–24.
| Crossref | GoogleScholarGoogle Scholar |
Stephens JMC,
Molan PC, Clarkson BD
(2005) A review of Leptospermum scoparium (Myrtaceae) in New Zealand. New Zealand Journal of Botany 43, 431–449.
Thompson J
(1989) Leptospermum. Telopea 3, 302–447.
Van Auken OW
(2000) Shrub invasions of North American semiarid grasslands. Annual Review of Ecology and Systematics 31, 197–215.
| Crossref | GoogleScholarGoogle Scholar |
Walker J,
Robertson JA,
Penridge LK, Sharpe PJH
(1986) Herbage response to tree-thinning in a Eucalyptus crebra woodland. Australian Journal of Ecology 11, 135–140.
| Crossref | GoogleScholarGoogle Scholar |
Withers J, Ashton DH
(1977) Studies on the status of unburnt Eucalyptus woodland at Ocean Grove, Victoria. 1. The structure and regeneration. Australian Journal of Botany 25, 623–637.
| Crossref | GoogleScholarGoogle Scholar |
Yin R,
Mark AF, Wilson JB
(1984) Aspects of the ecology of the indigenous shrub Leptospermum scoparium (Myrtaceae) in New Zealand. New Zealand Journal of Botany 22, 483–507.
