How widespread is woody plant encroachment in temperate Australia? Changes in woody vegetation cover in lowland woodland and coastal ecosystems in Victoria from 1989 to 2005

Ian Lunt, Lisa Winsemius, Simon McDonald, John W. Morgan, Remy Dehaan

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Abstract

Aim: Encroachment or densification by woody plants affects natural ecosystems around the world. Many studies have reported encroachment in temperate Australia, particularly in coastal ecosystems and grassy woodlands. However, the degree to which published studies reflect broad-scale changes is unknown because most studies intentionally sampled areas with conspicuous densification. We aimed to estimate changes in woody vegetation cover within lowland grassy woodland and coastal ecosystems in Victoria from 1989 to 2005 to determine whether published reports of recent encroachment are representative of broad-scale ecosystem changes.Location: All lowland grassy woodland and coastal ecosystems (c. 6.11 × 105 ha) in Victoria, Australia. Four major ecosystems were analysed: Plains woodlands, Herb-rich woodlands, Riverine woodlands and Coastal vegetation.Main conclusions: At the scale of observation, woody vegetation cover increased in all lowland woodland and coastal ecosystems over the 16-year period. Thus, published examples of encroachment in selected coastal and woodland patches do appear to reflect widespread increases in woody vegetation cover in these ecosystems. This densification appears to be associated with changes in land management rather than with post-fire vegetation recovery and is likely to be ongoing and long-lasting, with substantial implications for biodiversity conservation and ecosystem services.Methods: Changes in woody vegetation cover from 1989 to 2005 were assessed based on state-wide vegetation maps and Landsat analyses of woody vegetation cover conducted by the Australian Greenhouse Office's National Carbon Accounting System. The results show changes in woody cover within mapped patches of native vegetation, rather than changes in the extent of woody vegetation resulting from clearing and revegetation.Results: When pooled across all ecosystems, woody vegetation increased by 18,730 ha from 1989 to 2005. Woody cover within Riverine woodlands and within Plains woodlands each increased by >7000 ha. At the patch scale, the mean percentage cover of woody vegetation in each polygon increased by >5% in all four ecosystems: Riverine woodlands (+9.2% on average), Herb-rich woodlands (+7.6%), Plains woodlands (+6.7%) and Coastal vegetation (+5.9%). Regression models relating degree of encroachment to geographic and climatic variables were extremely weak (r2 ' 0.026), indicating that most variation occurred at local scales rather than across broad geographic gradients.
Original languageEnglish
Pages (from-to)722-732
Number of pages11
JournalJournal of Biogeography
Volume37
Issue number4
DOIs
Publication statusPublished - Apr 2010

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Victoria (Australia)
woody plant
woody plants
vegetation cover
woodlands
woodland
lowlands
ecosystems
vegetation
ecosystem
herb
woodland ecosystem
coastal ecosystem
herbs
revegetation
polygon
ecosystem service
land management
Landsat
land restoration

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@article{1a168c7a584144d394ebb252f326312b,
title = "How widespread is woody plant encroachment in temperate Australia? Changes in woody vegetation cover in lowland woodland and coastal ecosystems in Victoria from 1989 to 2005",
abstract = "Aim: Encroachment or densification by woody plants affects natural ecosystems around the world. Many studies have reported encroachment in temperate Australia, particularly in coastal ecosystems and grassy woodlands. However, the degree to which published studies reflect broad-scale changes is unknown because most studies intentionally sampled areas with conspicuous densification. We aimed to estimate changes in woody vegetation cover within lowland grassy woodland and coastal ecosystems in Victoria from 1989 to 2005 to determine whether published reports of recent encroachment are representative of broad-scale ecosystem changes.Location: All lowland grassy woodland and coastal ecosystems (c. 6.11 {\~A}— 105 ha) in Victoria, Australia. Four major ecosystems were analysed: Plains woodlands, Herb-rich woodlands, Riverine woodlands and Coastal vegetation.Main conclusions: At the scale of observation, woody vegetation cover increased in all lowland woodland and coastal ecosystems over the 16-year period. Thus, published examples of encroachment in selected coastal and woodland patches do appear to reflect widespread increases in woody vegetation cover in these ecosystems. This densification appears to be associated with changes in land management rather than with post-fire vegetation recovery and is likely to be ongoing and long-lasting, with substantial implications for biodiversity conservation and ecosystem services.Methods: Changes in woody vegetation cover from 1989 to 2005 were assessed based on state-wide vegetation maps and Landsat analyses of woody vegetation cover conducted by the Australian Greenhouse Office's National Carbon Accounting System. The results show changes in woody cover within mapped patches of native vegetation, rather than changes in the extent of woody vegetation resulting from clearing and revegetation.Results: When pooled across all ecosystems, woody vegetation increased by 18,730 ha from 1989 to 2005. Woody cover within Riverine woodlands and within Plains woodlands each increased by >7000 ha. At the patch scale, the mean percentage cover of woody vegetation in each polygon increased by >5{\%} in all four ecosystems: Riverine woodlands (+9.2{\%} on average), Herb-rich woodlands (+7.6{\%}), Plains woodlands (+6.7{\%}) and Coastal vegetation (+5.9{\%}). Regression models relating degree of encroachment to geographic and climatic variables were extremely weak (r2 ' 0.026), indicating that most variation occurred at local scales rather than across broad geographic gradients.",
keywords = "Open access version available, Australia, Densification, Ecosystem dynamics, Long-term vegetation change, Remote sensing analysis, Vegetation thickening, Woody plant encroachment, Woody weed invasion",
author = "Ian Lunt and Lisa Winsemius and Simon McDonald and Morgan, {John W.} and Remy Dehaan",
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language = "English",
volume = "37",
pages = "722--732",
journal = "Journal of Biogeography",
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publisher = "Wiley-Blackwell",
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How widespread is woody plant encroachment in temperate Australia? Changes in woody vegetation cover in lowland woodland and coastal ecosystems in Victoria from 1989 to 2005. / Lunt, Ian; Winsemius, Lisa; McDonald, Simon; Morgan, John W.; Dehaan, Remy.

In: Journal of Biogeography, Vol. 37, No. 4, 04.2010, p. 722-732.

Research output: Contribution to journalArticle

TY - JOUR

T1 - How widespread is woody plant encroachment in temperate Australia? Changes in woody vegetation cover in lowland woodland and coastal ecosystems in Victoria from 1989 to 2005

AU - Lunt, Ian

AU - Winsemius, Lisa

AU - McDonald, Simon

AU - Morgan, John W.

AU - Dehaan, Remy

N1 - Imported on 12 Apr 2017 - DigiTool details were: month (773h) = April 2010; Journal title (773t) = Journal of Biogeography. ISSNs: 0305-0270;

PY - 2010/4

Y1 - 2010/4

N2 - Aim: Encroachment or densification by woody plants affects natural ecosystems around the world. Many studies have reported encroachment in temperate Australia, particularly in coastal ecosystems and grassy woodlands. However, the degree to which published studies reflect broad-scale changes is unknown because most studies intentionally sampled areas with conspicuous densification. We aimed to estimate changes in woody vegetation cover within lowland grassy woodland and coastal ecosystems in Victoria from 1989 to 2005 to determine whether published reports of recent encroachment are representative of broad-scale ecosystem changes.Location: All lowland grassy woodland and coastal ecosystems (c. 6.11 × 105 ha) in Victoria, Australia. Four major ecosystems were analysed: Plains woodlands, Herb-rich woodlands, Riverine woodlands and Coastal vegetation.Main conclusions: At the scale of observation, woody vegetation cover increased in all lowland woodland and coastal ecosystems over the 16-year period. Thus, published examples of encroachment in selected coastal and woodland patches do appear to reflect widespread increases in woody vegetation cover in these ecosystems. This densification appears to be associated with changes in land management rather than with post-fire vegetation recovery and is likely to be ongoing and long-lasting, with substantial implications for biodiversity conservation and ecosystem services.Methods: Changes in woody vegetation cover from 1989 to 2005 were assessed based on state-wide vegetation maps and Landsat analyses of woody vegetation cover conducted by the Australian Greenhouse Office's National Carbon Accounting System. The results show changes in woody cover within mapped patches of native vegetation, rather than changes in the extent of woody vegetation resulting from clearing and revegetation.Results: When pooled across all ecosystems, woody vegetation increased by 18,730 ha from 1989 to 2005. Woody cover within Riverine woodlands and within Plains woodlands each increased by >7000 ha. At the patch scale, the mean percentage cover of woody vegetation in each polygon increased by >5% in all four ecosystems: Riverine woodlands (+9.2% on average), Herb-rich woodlands (+7.6%), Plains woodlands (+6.7%) and Coastal vegetation (+5.9%). Regression models relating degree of encroachment to geographic and climatic variables were extremely weak (r2 ' 0.026), indicating that most variation occurred at local scales rather than across broad geographic gradients.

AB - Aim: Encroachment or densification by woody plants affects natural ecosystems around the world. Many studies have reported encroachment in temperate Australia, particularly in coastal ecosystems and grassy woodlands. However, the degree to which published studies reflect broad-scale changes is unknown because most studies intentionally sampled areas with conspicuous densification. We aimed to estimate changes in woody vegetation cover within lowland grassy woodland and coastal ecosystems in Victoria from 1989 to 2005 to determine whether published reports of recent encroachment are representative of broad-scale ecosystem changes.Location: All lowland grassy woodland and coastal ecosystems (c. 6.11 × 105 ha) in Victoria, Australia. Four major ecosystems were analysed: Plains woodlands, Herb-rich woodlands, Riverine woodlands and Coastal vegetation.Main conclusions: At the scale of observation, woody vegetation cover increased in all lowland woodland and coastal ecosystems over the 16-year period. Thus, published examples of encroachment in selected coastal and woodland patches do appear to reflect widespread increases in woody vegetation cover in these ecosystems. This densification appears to be associated with changes in land management rather than with post-fire vegetation recovery and is likely to be ongoing and long-lasting, with substantial implications for biodiversity conservation and ecosystem services.Methods: Changes in woody vegetation cover from 1989 to 2005 were assessed based on state-wide vegetation maps and Landsat analyses of woody vegetation cover conducted by the Australian Greenhouse Office's National Carbon Accounting System. The results show changes in woody cover within mapped patches of native vegetation, rather than changes in the extent of woody vegetation resulting from clearing and revegetation.Results: When pooled across all ecosystems, woody vegetation increased by 18,730 ha from 1989 to 2005. Woody cover within Riverine woodlands and within Plains woodlands each increased by >7000 ha. At the patch scale, the mean percentage cover of woody vegetation in each polygon increased by >5% in all four ecosystems: Riverine woodlands (+9.2% on average), Herb-rich woodlands (+7.6%), Plains woodlands (+6.7%) and Coastal vegetation (+5.9%). Regression models relating degree of encroachment to geographic and climatic variables were extremely weak (r2 ' 0.026), indicating that most variation occurred at local scales rather than across broad geographic gradients.

KW - Open access version available

KW - Australia

KW - Densification

KW - Ecosystem dynamics

KW - Long-term vegetation change

KW - Remote sensing analysis

KW - Vegetation thickening

KW - Woody plant encroachment

KW - Woody weed invasion

U2 - 10.1111/j.1365-2699.2009.02255.x

DO - 10.1111/j.1365-2699.2009.02255.x

M3 - Article

VL - 37

SP - 722

EP - 732

JO - Journal of Biogeography

JF - Journal of Biogeography

SN - 0305-0270

IS - 4

ER -