Indicator description

Why is it indicative

What does the data show

Data

Acknowledgment

Indicator description

Rate of clearing, in hectares per annum, of terrestrial native vegetation types, by clearing activity. Clearing activities include for example forestry, agriculture, urban expansion, mining, road construction, impoundments (i.e. dam construction).

The proportion of each bioregion or planning and water management catchment modified by clearance of native vegetation (and its replacement by permanently cleared land such as urban areas, or vegetation of a different type such as pasture, crops or plantations).

Why is it indicative

The rate of vegetation clearing provides a measurable estimate of an important threat to terrestrial (land) biodiversity and geodiversity. Clearing vegetation reduces the total area of habitat available to extant species, and can increase the risk of local extinction. It also influences hydrological processes, which in turn affect fluvial and karst geomorphic processes.

The National Strategy for the Conservation of Australia's Biological Diversity and the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 list clearing of native vegetation as a threatening process. This indicator is a direct measure of the threatening process.

Changes in catchment vegetation cover types, especially from deep-rooted to shallow-rooted types (or vice-versa), have a major effect on important hydrological processes including the water runoff/infiltration balance which is central to water flow regimes and quality (groundwater and surface water) and thus to fluvial geomorphic processes. Vegetation clearance also affects soil erosion rates and thus the sediment and nutrient balance in river systems. Clearance of native vegetation is considered to be one of the most important human disturbances impacting on hydrological processes and natural fluvial and karst landforms and processes in Tasmania.

What does the data show

The analysis of the data within this indicator is broken down into the following sections, including links to the specific data:

• the clearing rates at the State and bioregion levels;
   
• clearance per individual vegetation type; and
   
• the proportion of native vegetation clearance in each bioregion and catchment within Tasmania.
   

Native vegetation clearance rates

• The conversion of native forest to plantations of either eucalypt or pine forest occurred in about 36% (6,490ha) of forest operations on State Forest and 24% (5,320ha) of harvesting operations on private land in 2000-01. Aside from small areas converted to non-forest use, the remaining forest harvested (10,860ha on State Forest) and 17,750ha on private land) was either logged partially and regenerated or clearfelled and regenerated with local seed. Conversion or clearance of native forest to plantation therefore still represents the smaller proportion of forest harvesting operations, although these rates have increased since 1994-95.
   
• The nature conservation impact of land clearance has decreased from earlier periods, as the highest rates of clearance have tended to shift from vegetation types of high conservation value to those that are well-reserved and relatively little depleted. Nevertheless, vegetation types of conservation significance continue to be cleared. Under the Regional Forest Agreement (1997) areas of native vegetation will continue to be converted to plantations (i.e. tree farms) (Kirkpatrick and Mendel 1999, unpublished report) in the future.
   
• The greatest losses of major forest types have been in swamp forests, grassy woodlands, and dry forests. Vegetation types of conservation significance continue to be cleared and there is no information as yet to indicate the effectiveness of the Forest Practices Amendment Act 2001 which was introduced to control clearance of forest communities.
   
• Of the 50 RFA forest communities, four accounted for 70% of all forest clearance approved by the Forest Practices Board between 1 July 1996 and 30 June 2001. The communities are: tall Eucalyptus delegatensis (7,059 ha); tall E. obliqua (20,109ha); dry E. obliqua (8,057ha); E. regnans (9,040ha).
   
• Wet eucalypt forest reduced in extent by 25,000 ha since the RFA was signed (Forest Practices Board 2002).
   
• The forest communities to have experienced the greatest percentage loss of area from their 1996 RFA extent include: Eucalyptus regnans (11.8%), wet E. viminalis forest on basalt (7.4%), E. viminalis / E. ovata / E. amygdalina / E. obliqua damp schelerophyll forest (7.2%), and inland E. amygdalina (5.7%).
   
• Since 1996, 7,100 ha of old-growth native forest has been converted to plantation, the majority of it wet eucalypt communities.
   
• Between 1 July 1997 to 30 June 2001, the permanent forest estate was reduced by 62,831 ha as a result of conversion (mainly for plantation or agriculture).
   

Proportion of native vegetation clearance per bioregion and catchment

• In 1999 three bioregions had below 10% of their areas cleared, including the West, Central Highlands and Southern Ranges bioregions. The Ben Lomond bioregion had only 18.3% cleared.
   
• The six remaining bioregions each had greater than 30% of their area cleared.
   
• The data indicates that as of 1999 the catchments least disturbed (<20% of their area) by land clearance are those in western and south-western Tasmania, and to a lesser extent parts of eastern Tasmania north of Swansea.
   
• The most disturbed catchments indicated in 1999 are those in areas of major agricultural development in the Midlands and north-west coast areas. Of these the most disturbed catchments are some of those along the far northwest coast. However, this indication is partly an artifact of the fact that the Planning and Management Catchment data set arbitrarily highlighted smaller catchments in that area whereas in some other coastal areas small catchments were simply amalgamated into one large 'catchment'.
   
• The indicator calculated excludes King Island (lack of data) and does not take into account lakes and artificial water impoundments. That is, for simplicity the data from the bioregion and catchment maps and the vegetation clearance layer were analysed as if the water bodies did not exist (neither data set recognises the presence of water bodies). Natural water bodies arguably should not be included in figures for 'uncleared' vegetation, whilst artificial impoundments arguably constitute areas of 'cleared' vegetation. The difference in figures obtained may be small in some catchments, but is arguably very significant in catchments such as the Gordon, Pieman, Mersey, Derwent and others that include large natural and/or artificial water bodies.
   

Data

Native vegetation clearance rates

Some technical and definitional issues pose difficulties for accurate reporting of land clearing in Tasmania. Satellite data in Tasmania is susceptible to cloud cover and there continues to be various technical challenges in change detection on Landsat data. The rate of change in land cover in Tasmania is also such that satellite data can be out of date once processing has been completed. Land clearing is also assessed from applications to harvest forest under the Tasmanian Forest Practices Act 1985.

Historic changes

The greatest losses of major vegetation types have been in swamp forests, grasslands and grassy woodlands, coastal heathland, dry forests and wetlands. The most threatened community types now are the grasslands and grassy woodlands. The least affected types since 1803 appear to be less agriculturally productive, such as alpine vegetation, and western moorland and scrub.

Clearance of selected vegetation types since 1803

Broad Vegetation Type	Amount pre-European arrival (ha)	Amount left in 1996 (ha) TASVEG	Amount lost (ha)	% total lost
Rainforest	759,830	560,990	198,840	26
Wet eucalypt forest	1,552,000	883,000	669,000	43
Dry eucalypt forest	2,898,319	1,582,000	1,316,319	45
Grassy woodlands	400,000	40,000	360,000	90
Swamp forest	39,000	19,500	19,500	50

Source: Draft Nature Conservation Strategy

The table below highlights the different assessments that have been conducted for determining clearance data across Tasmania since 1972. The different methodologies used in these assessments means that the rates of clearance are directly not comparable, making it difficult to provide any absolute Statewide clearing data. However, the total extent of native vegetation cleared in Tasmania since European settlement in 1803 has been calculated to be around 23%, or 1.560 million hectares (CARSAG APU data 2002).

Estimates of native vegetation clearing rates in Tasmania, 1972-00

Period	Clearing rates (ha/year)	Total cleared (ha)	Data source	Details of methodology
1972-80	18,725	149,800	Kirkpatrick and Dickenson (1982)	Satellite imagery*
1980-88	6,000	48,000	Kirkpatrick (1991)	Satellite imagery*
1988-94	10,429	62,574	Kirkpatrick and Jenkin (1995)	Satellite imagery*
1994-99	6,992	34,960	Kirkpatrick and Mendel (1999)	Satellite imagery*
1988-98	7,770	77,700	AGO 2002	Satellite imagery

* these studies include areas that have been converted from native forest to one of the following land uses: agriculture, plantations and hydroelectric impoundments (i.e. dam construction).

An intense period of land clearance occurred with European settlement as significant areas of native vegetation were cleared for agriculture. The later period of hydro-electric development in the west of the State resulted in substantial native vegetation reduction through inundation. More recently the pattern of native vegetation clearance has shifted from the drier parts of Tasmania towards the moister areas, and from the centre of the State towards the extremities. The nature conservation impact of land clearance has decreased from earlier periods, as the highest rates of clearance have tended to shift from vegetation types of high conservation value to those that are well-reserved and relatively little depleted. Nevertheless, vegetation types of conservation significance continue to be cleared, and under the Regional Forest Agreement (1997) vast areas of native vegetation will be converted to plantations (i.e. tree farms) (Kirkpatrick and Mendel 1999) in the future.

Further information, including the motivators for land clearance in Tasmania, is available in the National Carbon Accounting System Technical Report: Land Clearing: A Social History (AGO 2000).

Bioregional data

Vegetation clearing rates available bioregionally are those provided by the Forest Practices Board. Woody change data from Landsat remote sensing provides another perspective (RPDC 2002). There are significant differences between Forest Practices Board and Landsat change analysis. Landsat change analysis identifies all woody decreases irrespective of whether the land is to be regenerated to native vegetation cover after harvesting. Woody vegetation change analysis is also prone to errors in identifying harvesting of some agricultural crops as a woody vegetation decrease. These data therefore require further analysis before they could provide a truer perspective on bioregional vegetation change.

Tasmanian Forest Practices Act 1985, along with the Forest Practices Code governs commercial forestry operations on public and private land. A separate body, the Forest Practices Board, manages the Code. Under the Act, Forest Practices Plans must be drawn up for commercial harvesting operations before they are allowed to proceed. The table below gives a bioregional summary of the area of native forest approved for clearing by the Board between 1997 and 2001. Prior to 1997, the Forest Practices Board were not required to report the area approved for clearing each year.

Total area (ha) approved for clearing on public and private land, 1997-01

IBRA 4	1997-98	1998-99	1999-00	2000-01	Total
1	4,673	4,689	5,850	4,570	19,782
2	4,272	5,670	4,578	4,472	18,992
3	1,265	888	964	319	3,436
4	1,370	1,061	542	279	3,252
5	2,919	2,309	1,171	1,575	7,974
6	178	947	701	637	2,463
7	1,046	2,085	1,989	1,790	6,910
Total	15,723	17,649	15,795	13,642	62,809

IBRA 4: 1 Woolnorth, 2 Ben Lomond, 3 Midlands, 4 Freycinet, 5 Central Highlands, 6 West/ South-west, 7 D'entrecasteaux

Source: Adapted from Forest Practices Board (2000) data

Woody vegetation decrease (hectares) between 1994 and 2001, by IBRA 4 and 5

Caption: This information was obtained from change analysis of Landsat data from 1996 to 2001. Further information on methods is detailed in Land Cover.

IBRA 4	Decrease	IBRA 5	Decrease
1	45,629	1	12,999
2	23,117	2	34,215
3	9,843	3	10,085
4	6,967	4	3,699
5	22,800	5	14,963
6	5,807	6	5,849
7	8,234	7	17,782
8	3,369	8	15,164
-		9	11,265
Total	125,766		126,022

IBRA 4: 1 Woolnorth, 2 Ben Lomond, 3 Midlands, 4 Freycinet, 5 Central Highlands, 6 West/ South-west, 7 D'entrecasteaux, 8 Furneaux. IBRA 5: 1 King, 2 Northern Slopes, 3 Flinders 4 West, 5 Central Highlands, 6 Northern Midlands, 7 Ben Lomond, 8 Southern Ranges, 9 South-east.

Source: State of the Environment program and Ross Lincolne, Space Images.

Clearance per individual vegetation type data

The only vegetation clearing rates available by vegetation type are those provided by the Forest Practices Board.

Land clearance in Tasmania by forest vegetation type on public and private land, 1997-01

Caption: The data below only includes area of native forest approved for clearing by the Forest Practices Board. These figures do not include loss due to non-commercial forest clearing e.g. clearing for agriculture, housing, mining etc. Also, these figures do not include native forest areas that are clearfelled and then regenerated from native seeding.

RFA no.	RFA Forest Community	State total loss 1997-01	% loss since 1996 RFA area
1	Coastal E. amygdalina dry sclerophyll forest	1,760	0.92400
2	E. amygdalina forest on dolerite	1,475	0.82681
3	Inland E. amygdalina forest	1,477	5.71993
4	E. amygdalina forest on sandstone	439	1.45687
5	Allocasuarina verticillata forest	0	0.00000
6	E. brookeriana wet forest	117	2.55850
7	Acacia melanoxylon forest on flats	186	2.06140
8	Acacia melanoxylon forest on rises	386	2.90008
9	Banksia serrata woodland	0	0.00000
10	E. coccifera dry forest	0	0.00000
11	Callitris rhomboidea forest	0	0.00000
12	Dry E. delegatensis forest	2,786	0.96133
13	E. viminalis / E. ovata / E. amygdalina/ E. oblique damp sclerophyll forest	2,916	7.16462
14	Tall E. delegatensis forest	7,059	2.46805
15	King Billy pine with deciduous beech forest	0	0.00000
16	E. viminalis and/ or E. globulus coastal shrubby forest	0	0.00000
17	Grassy E.globulus forest	460	3.99167
18	Huon Pine forest	0	0.00000
19	King Island E. globulus / E. brookeriana / E . viminalis forest	0	0.00000
20	Leptospermum sp./Melaleuca squarrosa swamp forest	179	0.95871
21	Callidendrous and thamnic rainforest on fertile sites	3,413	1.77615
22	Thamnic rainforest on less fertile sites	226	0.05975
23	Melaleuca ericifolia forest	1	0.17007
24	Eucalytpus morrisbyi forest	0	0.00000
25	Dry E. nitida forest	12	0.00750
26	Found in Furneaux IBRA only.	*	*
27	Notelaea ligustrina / Pomaderris apetala forest	0	0.00000
28	Tall E. nitida forest	262	0.35192
29	Dry E. obliqua forest	8,057	4.90184
30	Tall E. obliqua forest	20,109	4.71466
31	Shrubby E. ovata forest	167	2.31462
32	Eucalyptus pulchella / E.globulus /E. viminalis grassy shrubby dry sclerophyll forest	342	0.22601
33	Pencil pine with deciduous beech forest	0	0.00000
34	Eucalyptus pauciflora forest on Jurassic dolerite	52	0.27608
35	Pencil pine forest	0	0.00000
36	E. pauciflora forest on sediments	0	0.00000
37	E. regnans forest	9,040	11.87224
38	E. risdoni forest	0	0.00000
39	E. rodwayi forest	89	1.02582
40	E. sieberi forest on granite	117	0.66120
41	Silver wattle (Acacia dealbata) forest	717	1.32530
42	E. sieberi forest on other sediments	103	0.22517
43	E. subcrenulata forest	1	0.00977
44	E. tenuiramis forest on granite	0	0.00000
45	E. tenuiramis forest on dolerite	6	0.07115
46	Inland E. tenuiramis forest	4	0.00727
47	E. viminalis grassy forest	567	0.50065
48	Found in Furneaux IBRA only.	*	*
49	Wet E. viminalis forest on basalt	308	7.35962
50	King billy pine forest	0	0.00000
	Total Cleared	62,833	1.97643

* no plans approved.

Source: Adapted from Forest Practices Board (2000) data

Percentage of harvesting operations by harvesting method, future land use and tenure - native forests only

Year	Tenure	Partial Logging	Clearfell followed by				Total / annum
			regeneration by seed	eucalypt plantation	pine plantation	non-forest use
1994-1995	State Forest (ha)	40%	52%	4%	4%	0	n.a.
	Private land (ha)	46%	7%	22%	6%	19%
1995-1996	State Forest (ha)	42%	47%	2%	9%	0	n.a.
	Private land (ha)	43%	8%	23%	5%	21%
1996-1997	State Forest (ha)	52%	34%	4%	10%	0	n.a.
	Private land (ha)	48%	7%	35%	5%	5%
1997-1998	State Forest (ha)	35.0%	23.0%	17.0%	23.0%	2%	n.a.
	Private land (ha)	40.0%	7.0%	37.0%	3.0%	13.0%
1998-1999	State Forest (ha)	33.0%	22.5%	26.0%	18.5%	0	n.a.
	Private land (ha)	42.4%	7.5%	38.2%	1.9%	10.0%
1999-2000	State Forest (ha)	26% (3,600)	17% (2,400)	41% (5,600)	16% (2,220)	4% (500)	35,120
	Private land (ha)	54% (11,200)	10% (2,100)	22% (4,500)	5% (1,100)	5% (1,900)
2000-2001	State Forest (ha)	43% (7,640)	18% (3,220)	24% (4,270)	12% (2,220)	2% (500)	42,060
	Private land (ha)	67% (16,320)	5% (1,430)	21% (5,240)	3% (80)	5% (1,140)
2001-2002	Public land (ha)	49% (7,860)	17% (2,750)	28% (4,530)	3% (460)	2% (330)	32,020
	Private land (ha)	69% (11,130)	6% (1,000)	16% (2,520)	1% (150)	8% (1,290)
Total 1999-02		57,750 52.8%	12,900 11.8%	26,660 24.4%	6,230 5.7%	5 660 5.1%	109,200

Source: Forest Practices Board Annual Reports

Proportion of native vegetation clearance per bioregion and catchment

A snapshot of land clearance for each bioregion and catchment for 1999 is presented based on Land Clearance Boundary data (Kirkpatrick and Mendel 1999) derived from Landsat images.

King Island was excluded from this analysis, since it was not covered by the Land Clearance data. King Island will be included in future analyses when/if vegetation clearance data for that region becomes available in future updates of the Land Clearance dataset.

The indicator does not take into account lakes and artificial water impoundments; that is, for simplicity the data from both the Land Clearance Boundary map and the bioregion and catchment layers were analysed as if the water bodies did not exist (neither data set recognises the presence of water bodies). However, natural water bodies arguably should not be included in figures for 'uncleared' vegetation, whilst artificial impoundments arguable constitute areas of 'cleared' vegetation. In addition, artificial impoundments obviously constitute a major impact on natural fluvial systems. The difference in figures obtained may be small in some catchments, but is arguably very significant in catchments such as the Gordon, Pieman, Mersey, Derwent and others that include large natural and/or artificial water bodies.

Proportion of native vegetation clearance per bioregions

Land clearance figures and boundaries (Kirkpatrick and Mendal 2000) for each bioregion (IBRA v.5) in Tasmania provide a snapshot indication of vegetation clearance pressures as at 1999. Statewide and bioregional assessments of land clearance for Tasmania are also provided in the Australian Natural Resources Atlas.

Proportion of native vegetation clearance per catchment

Vegetation land clearance figures and boundaries (Kirkpatrick and Mendal 2000) for each planning and management catchment in Tasmania provide a snapshot indication of vegetation clearance pressures as at 1999.

Clearance pressures in Greater Hobart and Launceston

Housing completions in Hobart and Launceston have potentially affected 805 ha of priority forest vegetation in Hobart and 291 ha of priority forest vegetation in Launceston in the period 1992-2002. This provides only a guide to the potential impacts on priority forest vegetation through urban growth as the proportion of a land parcel cleared of native vegetation for any housing completion is unknown and will vary depending on the lot size and the attitudes of builders and owners. Nevertheless, it provides an indication of development pressure on remnant vegetation. For native vegetation remaining following housing completions-particularly large-scale subdivisions-changes in hydrology, changes to fire regimes, and the introduction of weeds can ultimately result in the loss of native vegetation.

Area of land parcels in which housing completions occurred containing priority forest communities, 1992-2002 (Launceston Statistical Division)

Vegetation	Priority status	Area (ha)
Coastal E. amygdalina coastal forest	A	5.3
E. ovata - E. viminalis shrubby forest	A	14.3
E. viminalis grassy forest	A	6.6
E. vimin alis wet forest on basalt	A	0.0
Melaleuca ericifolia forest	A	0.3
	Class A Total	26.5
E. amygdalina inland forest	B	7.6
E. viminalis grassy forest	B	1.8
	Class B Total	9.4
Acacia dealbata forest	C	0.2
Coastal E. amygdalina coastal forest	C	87.3
E. amygdalina forest on dolerite	C	161.0
E. viminalis-E.ovata-E. amygdalina-E. obliqua damp sclerophyll forest	C	6.1
Melaleuca ericifolia forest	C	0.6
	Class C Total	255.1
	Grand Total	291.1

This table provides only a guide to the potential impacts on priority forest vegetation through urban growth as the proportion of a land parcel cleared of native vegetation for any housing completion is unknown and will vary depending on the lot size and the attitudes of land owners. Nevertheless, it does provide an indication of development pressure on remnant vegetation.

Area of land parcels in which housing completions occurred containing priority forest communities, 1992-2002 (Greater Hobart)

Vegetation	Priority status	Area (ha)
Allocasuarina verticillata forest	A	6.1
Eucalyptus ovata - E. viminalis shrubby forest	A	4.3
E. risdonii forest	A	15.4
E. tenuiramis inland forest	A	0.0
E. viminalis grassy forest	A	0.4
	Class A Total	26.3
E. amygdalina forest on sandstone	B	32.0
E. globulus grassy forest	B	73.4
E. tenuiramis inland forest	B	109.8
E. viminalis grassy forest	B	65.4
E. viminalis - E. globulus coastal shrubby forest	B	3.0
	Class B Total	283.7
Acacia dealbata forest	C	1.4
Coastal E. amygdalina coastal forest	C	59.9
E. amygdalina forest on dolerite	C	3.9
E. amygdalina inland forest	C	48.8
E. delegatensis dry forest	C	58.5
E. obliqua dry forest	C	81.1
E. obliqua tall forest	C	121.6
E. pulchella - E globulus - E viminalis grassy/shrubby forest	C	115.5
E. regnans forest	C	3.9
E. tenuiramis forest on dolerite	C	0.1
	Class C Total	494.7
	Grand Total	804.7

This table provides only a guide to the potential impacts on priority forest vegetation through urban growth as the proportion of a land parcel cleared of native vegetation for any housing completion is unknown and will vary depending on the lot size and the attitudes of land owners. Nevertheless, it does provide an indication of development pressure on remnant vegetation.

Acknowledgment

Adapted from core biodiversity indicators BD7 and IW3 (ANZECC 2000).